TEST PAPER 2 Flashcards

Question

25. A 77-year-old man is brought into A&E with progressive increase in back pain. There is a history of known moderately large aortic aneurysm in the notes. A contrast CT is organised because the patient is haemodynamically stable. CT does not show any evidence of a ruptured aneurysm. All of the following are findings of pending rupture, except A. Drape sign B. Tangential calcium sign C. Focal discontinuous intimal calcification D. Retroperitoneal haematoma E. High attenuation crescent

Answer 1

25. D. Retroperitoneal haematoma A retroperitoneal haematoma adjacent to an abdominal aortic aneurysm is the most common imaging finding of abdominal aortic aneurysm rupture. The most common finding predictive of rupture is increase in aneurysm size, and thus it is the most common indicator for elective surgical management. Decreasing thrombus-lumen ratio is also predictive of increasing aneurysm size. The rest include drape sign, tangential calcium sign, focal discontinuous intimal calcification and high attenuation crescent. High attenuation crescent represents an internal dissection of blood into either the peripheral thrombus or the aneurysm wall. It is one of the earliest and most specific imaging manifestations of the rupture process.

Answer 2

26. C. Hepatic artery thrombosis In the early post-operative period (<72 hours after transplantation), increased hepatic artery resistance (resistive index of >0.8) is a frequent finding, but resistance ordinarily returns to a normal level within a few days. Increased hepatic artery resistance is associated with older donor age and a prolonged period of ischaemia. Hie estimated incidence of hepatic artery thrombosis among liver transplant recipients is 4%-12% in adults and 42% in children. This is one of the most feared complications, as it may lead to fulminant hepatic necrosis. In addition, in liver grafts, biliary ducts are supplied exclusively by small branches of the hepatic artery; therefore, arterial thrombosis may lead to biliary ischaemia and necrosis. Prompt diagnosis of hepatic artery thrombosis is extremely important because early intervention (with thrombectomy, hepatic artery reconstruction or both) may allow graft salvage. However, most patients ultimately require retransplantation. Even after retransplantation, the mortality rate approaches 30%. Risk factors for hepatic artery thrombosis include a significant difference in hepatic artery calibre between the donor and the recipient, an interpositional conduit for the anastomosis, a previous stenotic lesion of the celiac axis, excessive duration of cold ischaemia time, ABO blood type incompatibility, cytomegalovirus infection and acute rejection.

Answer 3

27. D. Fibroadenoma Non-enhancing internal septations were initially described to have a high specificity in fibroadenoma diagnosis; however, this feature has recently been described in PTs and cancers and thus has little value when considered alone .Although morphological findings are important in lesion characterisation, breast cancers may have a benign appearance. In particular, 30% of familial breast cancers revealed a mass showing benign morphological features with a round or oval shape, smooth margins and homogeneous internal enhancement. It should be considered that all enhancing masses in women with genetic risks are suitable for biopsy when there is a lack of typical cyst or fat necrosis findings.

Answer 4

28. C. Anterior cruciate ligament This is a classic plain film appearance of a Segond fracture. Segond fracture is an avulsion fracture at the proximal, non-articular aspect of the lateral tibia. The presence of this fracture is strongly associated with injury to other knee structures like the medial meniscus. However, it is the anterior cruciate ligament that is most commonly injured (75%-100%).

Answer 5

29. E. Sequestrated disc Protrusion is present if the greatest distance between the edges of the disc material presenting outside the disc space is less than the distance between the edges of the base of that disc (wider than tall). Extrusion is present when, in at least one plane, any one distance between the edges of the disc material beyond the disc space is greater than the distance between the edges of the base of the disc material or when no continuity exists between the disc material beyond the disc space and that within the disc space (taller than wide). The latter form of extrusion is best specified as sequestration if the displaced disc material has lost continuity completely with the parent disc. The term migration may be used to signify displacement of disc material away from the site of extrusion. Herniated discs in the craniocaudal (vertical) direction through a gap in the vertebral end plate are referred to as intravertebral herniations (Schmorl nodes).

Answer 6

30. B. 2 Grading of reflux: Grade I: Reflux into distal ureters Grade II: Reflux into collecting system (without calyceal dilatation/blunting) Grade III: All of the above, plus mild dilatation of the pelvis and calices Grade IV: All of the above, plus moderate dilatation (clubbing of calices) Grade V: All of the above, plus severe tortuosity of the ureter Prognosis: Grades I—III VUR resolve with maturation of the ureterovesical junction; Grades IV and V require surgery to avoid renal scarring, renal impairment and/or hypertension.

Answer 7

31. A. DeBakey 1 - Stanford A

Answer 8

32. B. Peutz-Jeghers syndrome Peutz-Jeghers syndrome is a disorder characterised by mucocutaneous pigmentation and gastrointestinal hamartomas. The syndrome is an autosomal, dominant, inherited trait and occurs with equal frequency in male and female subjects. Mucocutaneous pigmentation, a characteristic feature of this syndrome, is manifested by melanotic deposits around the nose, lips and buccal mucosa hands and feet. Peutz-Jeghers polyps can be found from the stomach to the rectum and are most common in the small intestine, particularly the jejunum and ileum.``

Answer 9

33. D. Differentiate residual disease from post-surgical scar MRI of the breast has evolved into an important adjunctive tool with multiple indications in breast imaging, as recommended by US and European guidelines. Breast MRI is currently the most sensitive detection technique for breast cancer diagnosis. The indications are staging before treatment planning, screening of high-risk women, evaluation of response to neoadjuvant chemotherapy, patients with breast augmentation or reconstruction, occult primary breast cancer, breast cancer recurrence, identifying residual tumour in positive surgical margins and characterisation of equivocal findings. Differentiating early post-operative scarring from residual breast tumour is not possible because of similar enhancement characteristics of post-surgical scarring.

Answer 10

34. C. L2/3 generalised disc bulge with left lateral recess stenosis Medial aspect of the knee corresponds to the L3 dermatome. lateral recess stenosis at L2/3 will affect the transiting L3 nerve root, whereas foramina! stenosis will affect the exiting L2 nerve root.

Answer 11

35. E. Congenital dislocation of hips Split cord malformations (SCMs) are relatively rare forms of occult spinal dysraphism and tethered spinal cord syndrome. SCMs are of two types. Type I consists of two hemicords, each contained within its own dural sheath and separated by a median bony spur, and Type II consists of two hemicords housed in a single dural tube separated by a fibrous median septum. There are recognised associations with myelomeningocele, Chiari malformation, tethering of cord, hypertrichosis, nevus, lipoma, dimple or haemangioma overlying the spine, clubfoot (50%), muscle wasting and progressive scoliosis.

Answer 12

36. B. Normal trachea and anterior oesophageal indentation Aberrant right subclavian artery Aberrant right subclavian artery with a left-sided aortic arch or aberrant left-sided subclavian artery with a right-sided aortic arch both result in posterior impression on the oesophagus on a barium swallow, with normal appearance of the trachea. An aberrant left pulmonary artery or pulmonary vascular sling runs in between the trachea and oesophagus, resulting in an anterior indentation on the oesophagus and a posterior indentation on the trachea. Other entities that can result in anterior indentation on the oesophagus arc a bronchogenic cyst, trachea-oesophageal node or a tracheal neoplasm extending posteriorly. Anterior tracheal, posterior tracheal and lateral oesophageal impression occurs with double aortic arch. The right arch is higher than the left, resulting in an S-shaped oesophagogram on AP view. Reverse ‘3’ indentation of the oesophagus and normal trachea occurs with coarctation of the aorta.

Answer 13

37. D. Hypoplastic left heart syndrome Hypoplastic left heart syndrome presents with early onset (days) of cyanosis and heart failure, leading to collapse and death in a few weeks of life. Associated cardiac malformations include pre- and post-ductal coarctation of the aorta, PDA, VSD, patent foramen ovale and so on. Truncus arteriosus presents with minimal cyanosis in newborn infants; signs of heart failure are usually absent. Heart failure is evident in older infants. Tetralogy of Fallot presents in early infancy with cyanosis, usually not present in early infancy, leading to clubbing; dyspnoea, heart failure, failure to thrive and paroxysmal hypercyanotic spells. X-ray shows a boot-shaped heart with oligaemic lungs. Transposition of the great arteries is a medical emergency. Infants usually present in the first few hours or days with worsening duct-dependent cyanosis. Hypoxia is severe, but heart failure is not a feature. X-ray shows an 'egg on end’ or ‘egg on string’ appearance. Tricuspid atresia presents in the first few days of life with increasing cyanosis; other clinical features are dependent on associated PDA or VSD.

Answer 14

38. D. A cobweb sign demarcates the true lumen. The beak sign and a larger cross-sectional area were the most useful indicators of the false lumen for both acute and chronic dissections. Features generally indicative of the true lumen included outer wall calcification and eccentric flap calcification. In cases showing one lumen wrapping around the other lumen in the aortic arch, the inner lumen was invariably the true lumen. Outer wall calcification always indicated the true lumen on scans of acute dissections. False lumen thrombus was significantly more frequent in chronic dissections than acute dissections. Cobwebs are specific for the false lumen but are only rarely observed.

Answer 15

39. D. Obesity Periportal halos are defined as circumferential zones of decreased attenuation identified around the peripheral or subsegmental portal venous branches on contrast-enhanced CT. These halos probably represent fluid or dilated lymphatics in the loose areolar zone around the portal triad structures. While this CT finding is non-specific, it is abnormal and should prompt close scrutiny of the liver in search of an underlying aetiology. Periportal halos, which may be due to blood, are commonly seen in patients with liver trauma. Periportal oedema may cause this sign in patients with congestive heart failure and secondary liver congestion, hepatitis, or enlarged lymph nodes and tumours in the porta hepatis, which obstruct lymphatic drainage. This CT sign has also been observed in liver transplants (probably secondary to disruption and engorgement of lymphatic channels) and in recipients of bone marrow transplants, who might develop liver oedema from microvenous occlusive disease. Although the precise pathophysiologic basis of periportal tracking has not been proven, it represents a potentially important CT sign of occult liver disease.

Answer 16

40. A. Supine position There are several prerequisites for maximising the sensitivity and specificity of breast MRI, including the following: * High magnetic field strength with a highly homogeneous magnetic field. * Bilateral image acquisition with a prone-positioning bilateral breast coil. * Unenhanced imaging with a T2-weighted and 3D T1-weighted pre- and post-IV gadolinium. * Selection of a phase-encoding direction minimises artefacts. * Homogeneous fat suppression. * Thin-section acquisitions (section thickness of 3 mm or less). * Pixel size of less than 1 mm in each in-plane direction. * Temporal resolution of less than 2 minutes for imaging of both breasts.

Answer 17

41. D. Right foraminal disc osteophyte at C5/6 Lateral aspect of the forearm and the thumb corresponds to the C6 dermatome. Foraminal osteophyte at C5/6 will impinge upon the exiting C6 nerve root. (cf. foraminal osteophyte at a thoracic or lumbar level, e.g., T4/5 or L4/5, which will impinge upon the exiting T4 or L4 nerve roots, subject to the discrepancy between number of cervical vertebra and cervical roots. Note that the exiting root at C7/T1 is C8.)

Answer 18

42. D. X-ray can often be normal. Atlanto-occipital dislocation shows the following on lateral radiograph of the cervical spine: >10 mm soft-tissue swelling anterior to C2, with pathological convexity (80%), basion-dens interval of >12 mm, odd’s ratio (distance between the basion and the posterior arch of the atlas divided by opisthion and anterior arch of atlas) >1, and basion-posterior axial line interval >12 mm anterior/>4 mm posterior to axial line. Direct signs include loss of congruity of articular surfaces of atlas and occipital condyle. Normal X-ray in the presence of atlanto-occipital dislocation is rare.

Answer 19

43. B. Coronal The appearance here describes brachycephaly. Craniosynostosis is the premature fusion of cranial sutures and may be isolated or may present as part of a craniofacial syndrome. It typically alters the shape of the cranial vault. Broad categories include simple craniosynostosis, involving only one suture, or compound craniosynostosis, where two or more sutures are involved.

Answer 20

44. C. String-of-beads appearance of the retinal artery Fibromuscular dysplasia (FMD) is an idiopathic, segmentary, non-inflammatory and non atherosclerotic disease that can affect all layers of both small- and medium-calibre arteries. Vascular loops, fusiform vascular ectasia and a string-of-beads aspect are typical presentations. Arterial dissection, aneurysm and subarachnoid haemorrhage are less typical radiologic presentations. The affected arteries are mainly the renal arteries, extracranial carotid and vertebral arteries, mesenteric arteries and intracranial carotid arteries. Central retinal artery occlusion is a rarely recognised feature of fibromuscular dysplasia.

Answer 21

45. B. Hypointense liver relative to spleen on T1 and T2 MR imaging is the best non invasive method for measuring the level of iron in the liver for the purposes of confirming the diagnosis, determining the severity, and monitoring therapy with high sensitivity, specificity, and positive and negative predictive values. The accumulation of iron ions in the tissues, because of the super-paramagnetic properties of the ions, causes local distortion in the magnetic fields and relaxation of the spins, which results in shortening of the longitudinal relaxation time (T1), the transverse relaxation time (T2) and particularly the transverse relaxation time as affected by magnetic field inhomogeneity (T2*). This effect causes a loss of signal intensity in the affected organs that is proportional to the iron deposition. In the general protocol applied to an abdominal study, it is not possible to estimate the hepatic iron concentration, although most of the time it is possible to diagnose iron overload. This can be done by using ‘dual sequence’ (gradient in and out of phase) MR imaging, which demonstrates decreased signal intensity in the affected tissues on the in-phase images compared with the out of-phase images. That effect is the opposite of the effect observed in patients with steatosis. This occurs because the echo time of the in-phase sequence is usually higher than that of the out-of-phase sequence; therefore, the in-phase pulse sequence is more sensitive to iron deposits because of the increased T2* effect.

Answer 22

46. E. Thin hypointense pseudocapsule and fat content on T1W images Fat necrosis appears as well circumscribed with translucent areas in the centre (homogenous fat density of the oil cyst). Occasionally, it shows curvilinear or eggshell calcification in the wall. On US, it appears as a hypoechoic or anechoic mass with ill- or well-defined margins, with or without acoustic shadowing or as a complex cyst. On MRI, even if the lesion appears irregular in both shape and margin, with a rim enhancement, the key to diagnosis is a fat internal signal on unenhanced sequences without fat suppression (high on T1-weighted images).

Answer 23

47. C. To assess for extra-articular fluid The purpose of the T2-weighted fluid-sensitive sequence in MR shoulder arthrography is the identification of extra-articular fluid, for example, bursal fluid or paralabral cysts, which may not be visualised on the isolated Tl weighted post-contrast sequences, particularly if there is no intra- articular communication. T2-weighted imaging also helps to identify abnormal fluid in the rotator cuff tendons by eliminating magic angle because of high TE.

Answer 24

48. B. Lefort I involves the maxilla and medial wall of the orbit. Lefort fractures always involve the pterygoid process/plates. Lefort I fractures are transverse maxillary fractures, involving the alveolar ridge and inferior wall of maxillary sinus. There is detachment of the teeth bearing alveolar process of maxilla. The orbits are not involved. Lefort II fractures are also called pyramidal fractures and they involve the maxilla and the medial wall of the orbit. They can be unilateral. Lefort III fractures are also called craniofacial disassociation or disjunction and involves the maxilla and medial and lateral wall of the orbit (zygomatic arch).

Answer 25

49. C. Mitral valve insufficiency Dissection involving the ascending aorta can result in fatal complications, which include aortic rupture, cardiac tamponade, acute aortic regurgitation and acute myocardial infarction from dissection involving the coronary arteries. Involvement of the arch vessels results in morbidity from neurological complications.

Answer 26

50. B. Primary sclerosing cholangitis Primary sclerosing cholangitis (PSC) is an idiopathic, chronic, fibrosing inflammatory disease of the bile ducts that eventually leads to bile duct obliteration, cholestasis and biliary cirrhosis. A strong association with inflammatory bowel disease, especially ulcerative colitis, is noted (70% of cases). Although the cause of PSC is unknown, most experts believe it to be an autoimmune process because PSC may be associated with other autoimmune diseases such as retroperitoneal fibrosis, mediastinal fibrosis and Sjögren syndrome. The rate of progression is unpredictable, with up to 49% of symptomatic patients eventually developing biliary cirrhosis and liver failure. Treatment is usually palliative and includes medical therapy with orally administered agents such as ursodiol (ursodeoxycholic acid) or endoscopic or percutaneous mechanical dilation of dominant strictures. Cholangiographic findings usually include multifocal, intrahepatic bile duct strictures alternating with normal-calibre ducts, which sometimes produce a beaded appearance.

Answer 27

51. D. Lactating adenoma Lactating adenomas are newly discovered painless lumps that appear during the third trimester or lactation. They are a freely mobile, homogenous hypoechoic or isoechoic mass with posterior acoustic enhancement (most common) and septa. The lesion regresses after breastfeeding.

Answer 28

52. E. Tumoural calcinosis Tumoural calcinosis is a rare familial disease, typically presenting in young men of African origin, with progressive large nodular juxta-articular calcified soft-tissue masses. Patients have normal serum calcium and phosphorus and do not have any evidence of renal, metabolic or collagen-vascular disease. The hips are the most frequently affected, followed by the elbows, shoulders and feet, and the disease is usually along the extensor surface of the joints. The knees are almost never affected. Occasionally, fluid fluid levels are seen with the calcium lying inferiorly, termed the sedimentation sign. The joints themselves are normal.

Answer 29

53. D. Ependymoma Radiographs of patients with ependymomas may reveal scoliosis, canal widening with vertebral body scalloping, pedicle erosion or laminar thinning. Ependymomas enhance intensely after intravenous administration of iodinated contrast material. Most spinal cord ependymomas are iso- or hypointense on T1-weighted images. Any hyperintensity suggests haemorrhage. They are hyperintense to the cord on T2-weighted images. About 20% 33% of ependymomas demonstrate the cap sign, a rim of extreme hypointensity (hemosiderin) seen at the poles of the tumour on T2-weighted images. This finding is secondary to haemorrhage, which is common in ependymomas and other highly vascular tumours (e.g., paraganglioma, haemangioblastoma) Most cases (60%) also show evidence of cord oedema around the masses. The average number of vertebral segments involved with abnormal signal intensity is 3.6. Cysts are a common feature, with 78%-84% of ependymomas having at least one cyst. Subependymomas represent a variant of central nervous system (CNS) ependymomas. MR imaging findings are not sufficiently unique to enable the differentiation of ependymomas from subependymomas; however subependymomas are eccentric, may not enhance and may not have surrounding oedema.

Answer 30

54. B. Scimitar syndrome Hypogenetic lung syndrome, also known as congenital venolobar syndrome or scimitar syndrome, is primarily a complex developmental lung abnormality with anomalous venous return. The most common features are lung hypoplasia, anomalous pulmonary venous return to IVC, pulmonary artery hypoplasia, bronchial anomalies and systemic arterial supply to hypoplastic lung. It almost always occurs on the right side and is slightly more common in women. One constant component of this syndrome is an anomalous pulmonary vein or veins draining at least a part or the entire affected lung most commonly to the inferior vena cava just above or below the diaphragm. Uncommonly, the anomalous vein may drain into hepatic, portal, azygos veins; the coronary sinus; or the right atrium. A scimitar vein is a vertical curvilinear opacity in the right mid-lower lung, running along the right heart border inferomedially towards the diaphragm to join the IVC. A scimitar vein present on a frontal chest radiograph is called the scimitar sign.

Answer 31

55. D. Flow characteristic at the aneurysm neck An aneurysm occurs when a vessel diameter exceeds 1.5 times its normal size. In the abdomen this corresponds to 3 cm. These aneurysms should be repaired when the diameter exceeds 5-5.5 cm or the aneurysm expands more than 1 cm per year. The greatest benefit of 3D volume-rendered imaging is the depiction and precise measurement of angulation in aneurysms with marked tortuosity. The proximal landing zone consists of the region from the inferior-most renal artery to the beginning of the aneurysm. The maximal acceptable neck diameter is 32 mm. The length of the neck should be at least 15 mm (although one device allows a 7 mm neck). The angle between the superior portion of the aneurysm neck and the suprarenal aorta is preferably less than 60°. Study results suggest higher complications for aneurysms larger than 5.5-6.5 cm. The shape can be described as saccular or fusiform. The residual lumen through the aneurysm should measure approximately 18 mm to allow passage and proper deployment of the device. The preferred distal landing zone is the common iliac artery. Evaluation is similar to that of the proximal neck with assessment of diameter, length, tortuosity and degree of calcification and thrombus. The common iliac artery diameter should not be larger than 25 mm, and at least 10 mm of length is required for an adequate .seal.

Answer 32

56. D. Crohn’s disease In Crohn’s disease involving either the small bowel or colon, broad linear ulcers that crisscross in longitudinal and transverse directions can produce a pseudopolypoid appearance usually termed cobblestoning.

Answer 33

57. E. Needs IV contrast Does not need IV contrast The advantages of mammograms include their reliable detection of calcification, lower cost than MRI, wide availability and their imaging speed, which is faster than MRI. The disadvantages include difficulty in presence of implants, discomfort caused by compression, difficulty in imaging dense breasts and the need to reposition the breast for different views. The advantages of MRI are its higher sensitivity, ability to be used with implants, good performance with dense breasts, not requiring compression, ability to image both breasts simultaneously and improved tissue resolution. The disadvantages of MRI are that it may not show calcification, is not good for DCIS, leads to many false-positive findings and is expensive.

Answer 34

58. B. Diffuse idiopathic skeletal hyperostosis (DISH) DISH is not a cause of acro-osteolysis. Other causes of acro-osteolysis include leprosy, frost bite, electrical and thermal burns, PVC workers, sarcoidosis, rheumatoid arthritis, Reiter syndrome, pyknodysostosis, syringomyelia and hyperparathyroidism.

Answer 35

59. C. Haemangioblastoma Haemangioblastomas manifest with diffuse cord expansion and variable signal intensity on T1-weighted images, most commonly isointense (50%) or hyperintense (25%) relative to the cord. On T2-weighted images, they have high signal intensity with intermixed focal flow voids. Surrounding oedema and a cap sign may be seen. Although up to 25% of haemangioblastomas may appear to be solid, cyst formation or syringohydromyelia is very common (up to 100% in some series). In fact, some cases may have the classic appearance of a cystic mass with an enhancing mural nodule characteristic of cerebellar haemangioblastomas. Contrast-enhanced imaging typically shows an intensely homogeneous enhancing tumour nodule.

Answer 36

60. E. Langerhans cell histiocytosis The vast majority of vertebra plana lesions in relatively healthy children are caused by an eosinophilic granuloma of Langerhans cell histiocytosis. The other available options are all possible, but less common, differential diagnoses. There is usually preservation of the disc space and no kyphosis. The posterior elements are rarely involved. Platyspondyly (multiple flat vertebral bodies, as opposed to vertebra plana) specially affecting lumbar vertebra by 2-3 years of age is a typical feature of Morquio syndrome.

Answer 37

61. A. Size of aorta at the level of the renal artery Several important characteristics of the aneurysm must be accurately described for standard stent-graft sizing. The aneurysm is described in terms of the proximal landing zone, the aneurysm sac, the distal landing zone and the vascular access. Reported diameters should include the aorta at the level of the most inferior renal artery, the aortic neck 15 mm distal to the lowest renal artery, aorta at the bifurcation, the largest aneurysm sac diameter and the size of the common iliac arteries. Additional measurements include the length of the aneurysm neck, the length from the lowest renal artery to the aortic bifurcation and the length of the aneurysm sac. The length of the distal landing zone is described as the distance from the aortic bifurcation to the common iliac artery bifurcation. Minimal diameters should be recorded in the distal landing zone and external iliac artery access vessels.

Answer 38

62. D. Pyogenic liver abscess Pyogenic abscesses, particularly when multiple, may be caused by haematogenous dissemination of either gastrointestinal infection via the portal vein or disseminated sepsis via the hepatic artery, ascending cholangitis or superinfection of necrotic tissue. Over one-half of liver abscesses are polymicrobic. Escherichia coli is the most common bacterium, but other anaerobic and aerobic organisms can be involved. Pyogenic abscesses demonstrate no sex predilection but most commonly involve middle aged patients. On US, pyogenic micro-abscesses may manifest as either discrete hypoechoic nodules or ill-defined areas of distorted hepatic echogenicity. There may be little or no enhanced through transmission. At contrast-enhanced CT, they appear as multiple small, well-defined hypoattenuating lesions. Faint rim enhancement and perilesional oedema can be observed, findings that help differentiate them from hepatic cysts.

Answer 39

63. B. Pleomorphic Calcifications are likely to be malignant if they are clustered rather than scattered throughout the breast and vary in size and shape (pleomorphic) and if they are found in a linear or ductal distribution. Benign calcifications could be coarse, ‘popcorn’ (fibroadenoma); ‘eggshell’ and curvilinear as in fat necrosis; ‘tramline’ (vascular), ‘broken needle’ or ‘lead pipe’ as in duct ectasia; punctate, stellate, and ‘teacup’ as in fibrocystic change.

Answer 40

64. B. The blood supply of the proximal pole enters at the waist. The blood supply to the proximal pole of the scaphoid enters at the waist and courses proximally. A waist fracture can therefore interrupt this tenuous blood supply, leading to avascular necrosis of the proximal pole or delayed/non-union. Non-displaced fractures are often treated conservatively, whereas displaced fractures usually require reduction and internal fixation. The scaphoid bone is the most commonly fractured carpal bone and tends to result from a fall on outstretched hand in a younger population rather than the common dorsally angulated distal radial fractures (Colles fracture). A high index of suspicion should be used when reporting trauma plain films of the wrist, and follow-up imaging following a period of conservative management should be employed when there is clinical concern but unremarkable presentation radiographs.

Answer 41

65. B. Paraspinal mass is useful in differentiating metastatic from benign fracture. Distinction between metastatic and acute osteoporotic compression fractures could be made on the basis of MR imaging findings. A convex posterior border of the vertebral body is more frequent in metastatic compression fractures than acute osteoporotic compression fractures. A higher frequency of abnormal signal intensity of the pedicle or posterior element has been observed in metastatic compression fractures. Epidural soft-tissue mass is suggestive of malignant vertebral collapse. A paraspinal mass is not helpful in differentiation of the cause of vertebral collapse but is more commonly encountered in the setting of metastatic compression, where it is typically focal rather than diffuse. Signal intensity abnormalities in the marrow of vertebrae other than the collapsed vertebrae are more frequently seen in metastatic compression fractures than acute osteoporotic compression fractures. Enhancement on post-contrast T1-weighted FS images is not useful in differentiation of acute osteoporotic fractures from malignant compression fracture, but it may be useful for old or chronic fractures, which will not show intense enhancement. Moreover, on diffusion-weighted imaging (DWI) vertebral metastases with compression fractures can be safely distinguished from vertebra with benign compression fractures based on significantly different ADC- values.

Answer 42

66. A. Pyknodysostosis Pyknodysostosis is a congenital abnormality that should be considered in the differential diagnosis of osteosclerosis. The patients arc typically short, have hypoplastic mandibles, widened cranial sutures, Wormian bones, brachycephaly, clavicular dysplasia, thick skull base and hypoplasia or non-pneumatisation of the paranasal sinuses. The distinguishing feature is aero-osteolysis with sclerosis. The distal phalanges appear as if they have been put in a pencil sharpener - they are pointed and dense.

Answer 43

67. C. The tip of the electrode is placed in the centre of the lesion. In RFA, a high-frequency, alternating current with a wavelength of 460-500 kHz is emitted through an electrode placed within the targeted tissue. Grounding pads applied to the patient’s thighs complete the electrical circuit. Cell death starts at 49 degrees. Temperature above 60 degrees causes immediate cell death, and tissue charring occurs at 105 degrees. Cell death is induced by the denaturation of proteins. For percutaneous imaging-guided RFA, the energy is delivered into the target tissue by means of needle like electrodes. Unlike in a typical biopsy, the electrode tip should be advanced to the deep margin of the tumour. On follow-up CT, ablated tumours often have internal areas of increased attenuation or increased signal intensity at CT and MRI. Areas of contrast enhancement (>10 HU or >15% with CT and MRI, respectively) are indicative of residual viable RCC. Residual viable tumour can be treated with additional ablation sessions. Heat-sink phenomena refers to the reduction in tissue temperature due to the conductive effects of adjacent vessels or airways. It is an explanation for distortion of the ablation zone and poor outcome in larger lesions. The heat-sink effect can be overcome by pharmacologically reducing blood flow, intra-arterial embolisation, intravascular balloon occlusion, Pringle manoeuvre or reducing treatment zone.

Answer 44

68. B. Cholangiocarcinoma Intrahepatic cholangiocarcinoma is the second most common primary hepatic tumour. Various risk factors have been reported for intrahepatic cholangiocarcinoma, and the radiologic and pathologic findings of this disease entity may differ depending on the underlying risk factors. Intrahepatic cholangiocarcinoma can be classified into three types on the basis of gross morphologic features: mass-forming (the most common), periductal infiltrating and intraductal growth. There are a number of recognised risk factors for cholangiocarcinoma that all share the common feature of chronic biliary" inflammation: liver flukes (Opisthorchis viverrini, Clonorchis sinensis), hepatolithiasis (recurrent pyogenic cholangitis), PSC, viral infection (human immunodeficiency virus, hepatitis B virus, hepatitis C virus, Epstein-Barr virus), anomalies and malformations (anomalous pancreaticobiliary junction and choledochal cyst, fibrocystic liver diseases, such as Caroli disease), environmental or occupational toxins (Thorotrast, dioxin, polyvinyl chloride), biliary tract enteric drainage procedures and heavy alcohol consumption

Answer 45

69. D. Suspicious masses need biopsy. Although the use of contrast-enhanced MRI of the breast has increased both the sensitivity and the specificity of breast cancer detection, common causes of false-positive and rarer causes of false-negative diagnoses still occur. Irregular heterogeneous enhancement is not typical of a benign lesion, hence biopsy is required. In addition, note that cancers can present with smooth well-defined margins, hence an apparent benign appearance in a patient with BRCA1 mutation should with be regarded with caution and may need biopsy.

Answer 46

70. B. Calcaneonavicular coalition Tarsal coalition is best confirmed with CT. CT and MRI can show direct bony continuity (osseous coalition) or fluid/cartilage intensity on MR/irregular serrated articular surface in case of cartilaginous coalition. A calcaneonavicular coalition shows the classic anteater’s nose appearance on lateral radiograph. The C sign is seen on a lateral radiograph in a patient with talocalcaneal coalition. Prominent talar beak is also associated with talocalcaneal coalition. Both calcaneonavicular and talocalcaneal coalition are equally common.

Answer 47

71. D. Melanoma Drop metastasis refers to CSF seeding of intracranial neoplasm. Post-contrast images show ‘sugar coating’ of the brain and spinal cord in patients with leptomeningeal drop metastases or leptomeningeal carcinomatosis. It can occur secondary to CNS involvement by distant primary tumours as well as primary CNS neoplasms. CNS tumours with drop metastasis include PNET, medulloblastoma, anaplastic glioma, ependymoma, germinoma, pineoblastoma, pineocytoma and rarely choroid plexus carcinoma and angioblastic meningioma. Non-CNS primaries include breast, lung, melanoma and lymphoma.

Answer 48

72. B. Osteogenesis imperfecta Osteogenesis imperfecta is an inherited disorder that results from mutations in either the COL1A1 or COL1A2 gene of Type 1 collagen. The disease is usually apparent at birth or in childhood, but more mild forms of the disease may not be apparent until adulthood. The disease is classified into Types I-IV, with Type I, the mildest form, being described above. The presenile hearing loss is caused by otosclerosis. The differential diagnosis can be resolved by the extra-skeletal manifestations (blue sclerae and dentinogenesis imperfecta). The other types are Type II (lethal perinatal). Type III (severe progressive) and Type IV (moderately severe).

Answer 49

73. A. TACE is useful in patients with Child-Pugh Class C cirrhosis. TACE combines the effect of targeted chemotherapy with the effect of ischaemic necrosis induced by arterial embolisation. TACE provides a survival benefit in primary hepatocellular carcinoma (HCC) based on randomised controlled studies. The normal parenchyma of the liver receives two-thirds of its necessary blood supply from the portal vein and the remaining one-third from the hepatic artery. However, it is well known that vascularisation of HCC is mostly dependent on the hepatic artery. TACE is not done for patients with a severely compromised liver function such as Child Pugh classification C or late B. Though superselective TACE may be attempted in a patient with compromised liver function, if the patient has a diffuse or massive HCC or an HCC involving the major portal veins, this precludes the practice of safe TACE. The underlying factors associated with increased procedural complication include compromised liver function, main portal vein obstruction, biliary tract obstruction and a previous history of bile duct surgery.

Answer 50

74. E. Pneumatosis coli Pneumatosis is the presence of gas bubbles within the wall of the involved segment of bowel. It is seen in a wide variety of conditions. It is widely divided into two groups: primary (idiopathic) and secondary. Conditions associated with secondary pneumatosis include obstruction, pulmonary disease such as COPD and asthma, vascular conditions such as ischaemia and infarction, inflammatory conditions such as Crohn’s and UC, necrotising enterocolitis, drugs such as steroids and chemotherapy, collagen vascular diseases such as scleroderma, SLE and dermatomyositis.

Answer 51

75. E. Renal papillary necrosis Urographic findings during this period of early ischaemic change are usually normal. On CT, the early ischaemic changes are best depicted on nephrographic phase scans as small, poorly marginated areas of diminished enhancement at the tip of the medullary pyramid. Calyceal deformities in renal papillary necrosis occur in three forms: medullary (round or oval cavity, calyceal blunting), papillary (triangular cavity, ‘lobster daw’ appearance) and in situ. If the papilla detaches completely, a typical ring-like shadow is produced by the necrotic papilla in a contrast material-filled cavity; if the sloughed papillae remain in situ there is a ‘signet ring* appearance.

Answer 52

76. C. Secondary synovial osteochondromatosis Primary synovial osteochondromatosis is a benign self-limiting monoarticular disorder characterised by proliferation and metaplastic transformation of the synovium with formation of multiple intra articular cartilaginous or osteocartilaginous loose bodies. The form is not associated with OA, whereas the secondary form is associated with articular surface disintegration. Classic radiographic features include multiple loose intra-articular bodies in varying grades of mineralisation. MRI shows varying grades of intermediate to high T1 signal to the loose bodies depending on the amount of mature osseous element (cf. pigmented villonodular synovitis, which shows low signal debris/areas on T2-weighted images; lipoma arborescens, which shows metaplastic frond-like synovial fat with high signal on T1-weighted images; and synovial haemangioma with mixed features).

Answer 53

77. D. Congenital short pedicles Spinal stenosis is defined as encroachment of the spinal canal or lateral recess by bone or soft- tissue components. Congenital short pedicles are idiopathic or developmental, secondary to achondroplasia, hypochondroplasia, Down’s syndrome and Morquio disease. Acquired causes include hypertrophy of ligamentum flavum, facet joint OA, disc protrusion, spondylolysis or spondylolisthesis, surgical fusion, fracture (benign or metastatic), Paget’s disease, epidural lipomatosis and ossification of the posterior longitudinal ligament.

Answer 54

78. D. Gaucher disease Although the Ashkenazi Jews are particularly predisposed to this hereditary condition, Gaucher disease is not confined to any particular ethnic group or sex. Splenic enlargement is detected in up to 95% of cases. There is abnormal modelling of the distal femur and proximal tibia secondary to marrow infiltration, leading to an ‘Erlenmeyer flask’ deformity. However, this feature is not diagnostic for Gaucher disease and may be seen in all the other answer options. Diffuse medullary osteoporosis, bone infarcts and sharply circumscribed endosteal lytic lesions (owing to marrow replacement) can also be seen. The combination of Jewish ancestry, the radiographic features described and splenomegaly makes Gaucher disease the most likely diagnosis.

Answer 55

79. A. It depends on the histology of the tumour being treated. The most common complication of TACE is post-embolisation syndrome, which consists of transient abdominal pain and fever occurring in 60% 80% of patients after TACE. Elevation of the level of hepatic transaminases typically accompanies post-embolisation syndrome. Whether post-embolisation syndrome reflects damage to the normal liver parenchyma or tumour necrosis is uncertain. Though prolonged hospitalisation may be required to monitor a patient and to control abdominal pain, vomiting and/or malaise, post-embolisation syndrome is self limiting within 3-4 days, and the use of antibiotics is not necessary to treat the fever. Hepatic failure after TACE is related to TACE-induccd ischaemic damage to the non-tumorous liver tissue. Several risk factors have been identified, including portal vein obstruction, use of a high dose of anticancer drugs and Lipiodol, a high level of bilirubin, prolonged prothrombin time and advanced Child-Pugh class. Other TACE-related complications occur in less than 10% of treatment sessions and include ischaemic cholecystitis, hepatic abscesses and biliary strictures. Development of a liver abscess has been linked to previous intervention in the biliary system being prone to an ascending biliary infection. Upper gastrointestinal complications such as gastritis, ulceration and bleeding can occur by the regurgitation of embolic agents into the gastric arteries (anatomical variants), which should be recognised on pretreatment imaging.

Answer 56

80. A. Desmoid tumour-Gardner’s syndrome Aggressive fibromatosis, or intra-abdominal Desmoid tumour, represents a benign proliferative process that has a tendency to locally recur. Mesenteric involvement is more often seen in cases related to typical familial adenomatous polyposis syndrome (PAPS) (Gardner syndrome). At CT, the margins of these lesions may appear irregular or smooth. The specific diagnosis of a mesenteric Desmoid tumour would be strongly suggested by a known diagnosis of FAPS or its associated CT findings, such as colonic polyps or masses, previous total colectomy, and polyps or masses involving the duodenum, stomach or periampullary region.

Answer 57

81. C. Diuretic administration reduces the time during which images can be obtained. T2-weighted techniques were the first clinically relevant means of visualising the urinary tract with MRI. Static-fluid MR urography does not require the excretion of contrast material and is therefore useful for demonstrating the collecting system of an obstructed, poorly excreting kidney. Static-fluid MR urograms can be obtained in 1-2 seconds, which allows multiple images to be obtained sequentially in a short period of time and played as a cine loop. Cine MR urography is particularly helpful in confirming the existence of urinary tract stenosis. For patients with non- dilated systems, the use of hydration, diuretics or compression may enhance the quality of MR urography. In case of excretory MR urogram, a gadolinium-based contrast agent is administered intravenously, and the collecting systems are imaged during the excretory phase. Gadolinium shortens the T1 relaxation time of the urine, allowing the urine to initially appear bright on T1-weighted images. Diuretic administration can improve the quality of excretory MR urography by enhancing urine flow, resulting in dilution and uniform distribution of gadolinium based contrast material throughout the urinary tract; it also expands the temporal window during which images can be obtained. The primary imaging sequence for excretory MR urography is the 3D gradient-echo sequence. Fat suppression enhances the conspicuity of the ureters and is recommended. Motion suppression is critical for MR urographic sequences, and breath hold acquisitions have been shown to better demonstrate the pelvicaliceal systems compared with respiratory triggering. IV hydration is preferred to oral hydration because fluid-filled structures can interfere with imaging on T2 sequences. MR urography is more sensitive and specific for non-calculous urinary tract obstruction than unenhanced CT. CT is more sensitive for stone disease. MRU is also used for evaluation of congenital urinary tract anomalies and haematuria, whereas the role of MRU for screening patients at risk for urothelial malignancy has yet to be defined.

Answer 58

82. C. 2.0 mmol/L It is important when performing MR arthrography that the correct concentration of gadolinium is used in order to achieve the best arthrographic result. Too concentrated or too dilute a solution will result in a suboptimal study. A dose of 2 mmol/L is the recognised concentration of Gd-DTPA; this can be achieved by adding 0.8 mL of neat Gd-DTPA to 100 mL of normal saline. An alternative method would be to inject 4 mL of Gd-DTPA into a 500 mL bag of normal saline to achieve the same 2 mmol/L concentration. It is also important to avoid inadvertent intra-articular injection of air, as this will result in susceptibility artefact at the subsequent MRI that may limit its diagnostic accuracy.

Answer 59

83. B. Sacrococcygeal teratoma Sacrococcygeal teratoma is the most common presacral germ cell tumour in children and the most common solid tumour in neonates. The benign form accounts for 60% of all sacrococcygeal teratomas. Benign teratomas are predominantly cystic; have attenuation similar to fluid on CT; and may include bone, fat and calcification. Cystic areas appear low on T1-weighted and high on T2-weighted MRI. Fatty tissue demonstrates high signal intensity on T1-weighted images, whereas calcification is depicted as a signal void. The coccyx is always involved, even in benign sacrococcygeal teratoma, and must be resected with the tumour. Malignant teratomas are more solid, and haemorrhage and necrosis are common. Approximately 50% of benign teratomas contain calcification, whereas it is seldom seen in malignant tumours. Malignant teratomas may metastasise. Anterior sacral meningocoele is a congenital abnormality that arises from herniation of the CSF-filled dura mater through a sacral foramen or a defect in the sacral bone. Eccentric defect in sacrum results in a scimitar appearance on plain film.

Answer 60

84. C. Morquio syndrome The mucopolysaccharidoses are a group of inherited diseases characterised by abnormal storage and excretion in the urine of various mucopolysaccharides. Patients with these diseases have short stature and characteristic plain film findings. A characteristic finding in the hands is a pointed proximal fifth metacarpal base that has a notched appearance to the ulnar aspect. There is generalised flattening of the vertebral bodies (platyspondyly). Hunter and Hurler syndromes demonstrate an anterior vertebral beak that is inferiorly positioned, whereas Morquio syndrome demonstrates an anterior vertebral beak that is centrally positioned. Although achondroplasia can cause rounded anterior beaking in vertebra of the upper lumbar spine, the findings described within the hands are more typical of the mucopolysaccharidoses.

Answer 61

85. E. Fibroids with high Tl signal pretreatment respond better to UFE. UFE is a minimally invasive treatment for uterine fibroids. MRI should be used to evaluate patients before and after UFE to accurately assess fibroid location within the uterus. fibroid number and size, and the presence or absence of fibroid enhancement on contrast material-enhanced images. Absolute contraindications include pregnancy, known or suspected gynaecologic malignancy, and current uterine or adnexal infection; relative contraindications include contrast material allergy, coagulopathy and renal failure. Pedunculated subserosal fibroids with a narrow stalk (<2-3 cm) are a relative contraindication to UFE because of the potential risk of detachment. Cervical fibroids tend to respond less favourably. The maximum size threshold for embolisation is 13-15 cm. Above this, the post-embolisation volume may still result in bulk symptoms, and the necrosis from a large fibroid may result in a protracted post embolisation syndrome. Fibroids with increased cellular content and degenerate fibroids may demonstrate a high signal on T2-weighted MRI; however, a heterogeneous or markedly hyperintense T2 signal suggests degeneration. Completely hyalinised fibroids have low T2. T1 hyperintensity pre-MRI suggests fatty or haemorrhagic/red degeneration and is a negative predictor of success with a lower reduction in vascularity compared to fibroids with a low T1 signal. After successful embolisation, fibroids may undergo progressive liquefaction with increasing T2 signal. Volume reduction is greater in T2 hyperintense fibroids and hypervascular fibroids compared to hypovascular ones. Persistent enhancement post embolisation is sign of incomplete fibroid infarction. An increase in signal on T1-weighted images is typically observed immediately after embolisation.

Answer 62

86. E. Ulcerative colitis Gallbladder carcinoma is highly lethal, as anatomic factors promote early local spread. The ease with which this tumour invades the liver and surrounding structures, including the biliary tree, contributes to its high mortality. The median survival is 6 months, indicating that the majority of patients present with advanced disease. Epidemiologic studies have shown that female sex, age, postmenopausal status and cigarette smoking are risk factors. Ethnic origin, increased body mass and physician-diagnosed typhoid arc risk factors in the high-incidence populations of La Paz, Bolivia, and Mexico City, Mexico. Exposure to chemicals used in the rubber, automobile, wood finishing and metal fabricating industries has been associated with an increased risk of gallbladder carcinoma. Cholelithiasis is a well-established risk factor for the development of gallbladder carcinoma, and gallstones arc present in 74%-92% of affected patients. Gallstones cause chronic irritation and inflammation of the gallbladder, which leads to mucosal dysplasia and subsequent carcinoma. Porcelain gallbladder is an uncommon condition in which there is diffuse calcification of the gallbladder wall, and 10%-25% of patients with this condition have gallbladder carcinoma. Several pathologic and congenital anatomic anomalies are associated with a higher prevalence of gallbladder carcinoma, compared with that in the general population. These conditions include congenital cystic dilatation of the biliary tree, choledochal cyst, anomalous junction of the pancreaticobiliary ducts (with or without a coexistent choledochal cyst) and low insertion of the cystic duct The cross-sectional imaging patterns of gallbladder carcinoma have been described as a mass replacing the gallbladder in 40%-65% of cases, focal or diffuse gallbladder wall thickening in 20%-30% and an intraluminal polypoid mass in 15%-25%.

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87. B. Von Hippel-Lindau syndrome Von Hippel-Lindau (VHL) disease is a rare, inherited, multisystem disorder that is characterised by development of a variety of benign and malignant tumours. The spectrum of clinical manifestations of the disease is broad. These include retinal and CNS haemangioblastomas (mostly affecting cerebellum/posterior fossa), endolymphatic sac tumours, renal cysts and tumours (renal cell carcinoma), pancreatic cysts and tumours (serous cystadenoma, adenocarcinoma and neuroendocrine tumours), pheochromocytomas, and epididymal cystadenomas. Retinal haemangioblastomas are among the most frequently and earliest detected VHL disease lesions.

Answer 64

88. C. Plantar fibromatosis Plantar fibromas are benign fibrous nodules commonly affecting the medial plantar fascia, with typical anatomical location, ultrasound and MRI findings. Plantar fibromas are well defined and hypoechoic, appearing along the plantar fascia on ultrasound; some are vascular on Doppler. On MRI they are mainly low on T1-weighted and T2-weighted sequences, although sometimes T2-weighted signal is high secondary’ to an increased cellular component. Variable enhancement post-gadolinium is noted. They are bilateral in 10%-25%, and association with Dupuytren’s contracture, palmar fibromatosis and Peyronie’s disease has been described.

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89. E. PICA The location of blood in cases of subarachnoid haemorrhage from a ruptured aneurysm can pinpoint the site of aneurysm in 70% of cases.

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90. A. Klippel-Trenaunay syndrome Klippel-Trenaunay syndrome is a sporadic, rare, mesodermal abnormality that usually affects a single lower limb. It is characterised by a triad of a port wine naevus (unilateral cutaneous capillary haemangioma often in a dermatomal distribution on the affected limb), overgrowth of distal digits/entire extremity (involving soft tissue and bone) and varicose veins on the lateral aspect of the affected limb. Although the other options can produce limb hypertrophy, they would not be expected to show all the features of the triad described.

Answer 67

91. E. Ovarian dysfunction after UAE is more common in women under 45 years. MRI with contrast is required to delineate uterine and ovarian artery anatomy prior to treatment. In most cases, bilateral UAE is needed, because most uterine fibroids, whether single or multiple, receive blood supply from both uterine arteries. Women over 45 years of age have been shown to have a higher prevalence of uterine-ovarian arterial anastomoses and are at increased risk for ovarian dysfunction after UAE. Although infrequent, major adverse events can occur and include ovarian failure or amenorrhea, fibroid expulsion and rarely venous thromboembolism. Intracavitary fibroids are more likely to be expelled. Ischaemia leading to uterine necrosis, arterial dissection, endometritis and fibroid infarction are other complications. On MRI, endometritis may manifest as uterine enlargement with T1 hyperintense intracavitary haematoma; gas appears as a signal void on all sequences. Contrast enhancement may increase the conspicuity of intracavitary fluid collections. Embolic agents used for fibroids include PVA (300-350 microns) or embospheres, whereas agents used for postpartum haemorrhage are gel foam particles, coils (occasionally) or n-butyl-cyanoacrylate (glue).

Answer 68

92. E. Child-Pugh Class C cirrhosis Absolute and relative contraindications for conventional TACE in patients with HCC are as follows. Absolute contraindications: * Decompensated cirrhosis (Child-Pugh C or higher) * Jaundice * Clinical encephalopathy * Refractory ascites * Extensive tumour with massive replacement of both lobes * Severely reduced portal vein flow * Technical contraindications to hepatic intra-arterial treatment * Renal insufficiency (creatinine clearance <30 mL/min) Relative contraindications; * Tumour size >10 cm. * Co-morbidities involving compromised organ function such as cardiovascular and lung disease. * Untreated varices present a high risk of bleeding. * Bile duct occlusion or incompetent papilla due to stent or surgery.

Answer 69

93. D. Bilateral involvement in 75% The GU tract is the second most common site after lungs. A single kidney is involved in 75% of cases. Radiological features include TB pyonephrosis (putty kidney), small shrunken kidney with dystrophic or amorphous calcification (autonephrectomy), irregular eroded calyx (moth-eaten appearance), cavities connected to the collecting system, hydrocalycosis and infundibular strictures, phantom and amputated calyces, kink of renal pelvis, and renal stones. Strictures in the ureter result in sawtooth, corkscrew, beaded and pipestem ureter. Calcification is seen in the distal ureter, whereas bladder wall calcification is rare. Bladder TB results in thick-walled small volume thimble’ or shrunken bladder. Prostate TB causes radiating, streaky, low-signal areas on T2-weighted images (watermelon sign).

Answer 70

94. A. Diffuse bone metastasis The findings of the bone scan are those of a so-called super scan. This is when a bone scan reveals a strikingly high radiotracer uptake within bone, compared with soft tissues, and diminished to absent renal uptake. A variety of diseases that cause diffusely increased bone turnover can demonstrate this picture. Widespread bone lesions, such as diffuse skeletal metastases, are the most frequent cause, but other causes include myelofibrosis, aplastic anaemia, leukaemia and widespread Paget disease. Metabolic causes include renal osteodystrophy, osteomalacia, hyperparathyroidism and hypothyroidism. Unlike in metastatic disease, the uptake in metabolic bone disease is more uniform in appearance and extends to the distal appendicular skeleton.

Answer 71

95. B. Arachnoid cyst Arachnoid cysts are CSF-containing intra arachnoid cysts with ventricular communication or brain maldevelopment. They can be congenital or acquired (leptomeningeal cyst). Most are asymptomatic, but they can present with weakness, mass effect, seizure, headache, developmental delay or craniomegaly. The most common site is the middle cranial fossa anteriorly. On MRI, they are CSF density, well defined, low on T1-weighted and high on T2-weighted images, without enhancement or calcification. They can erode the inner table of the calvarium.

Answer 72

96. D. Brain,stem glioma Ring enhancement is seen in the most aggressive necrotic/cystic tumours. Displacement of the fourth ventricle is typical of brainstem glioma. Most diffuse brainstem gliomas do not enhance and do not show restricted diffusion. Classic medulloblastoma typically arises from the roof of the fourth ventricle and is midline in location in 75% 90% of cases. They are hyperdense on CT; show contrast enhancement in >90% and show restricted diffusion. Atypical teratoid-rhabdoid tumour mimics medulloblastomas radiologically and histologically and have been often misdiagnosed in the past.

Answer 73

97. A. Right heart failure The TIPS procedure is effective in achieving portal decompression and in managing some of the major complications of portal hypertension. Indications for TIPS include variceal bleeding, secondary prevention, acute bleeding refractory to medical and endoscopic treatments, refractory ascites, hepatorenal syndrome, Budd-Chiari syndrome, hepatic veno-occlusive disease, hepatic hydrothorax and portal hypertensive gastropathy

Answer 74

98. E. T4N2M0

Answer 75

99. A. Xanthogranulomatous pyelonephritis Xanthogranulomatous pyelonephritis (XGP) is a chronic suppurative infection in chronic renal obstruction, that is, associated with staghorn calculus. MDCT often shows an enlarged kidney, associated staghorn calculus (75%), perirenal inflammatory stranding or fluid and, low attenuation fatty masses replacing renal parenchyma. US shows hypoechoic dilated calyces with echogenic rim or with low-level internal echoes replacing the normal renal parenchyma

Answer 76

100. A. Still disease Still disease is a clinical manifestation of polyarticular juvenile rheumatoid arthritis characterised by fever, rash, hepatosplenomegaly and pericarditis. There is periosteal reaction of the hand phalanges and broadening of bones with cortical thickening. The presence of advance arthropathy in the hands at such a young age along with the other clinical findings would be compatible with this condition. Lyme disease tends to follow a monoarticular pattern with involvement of the large joints, usually the knee, with the radiological findings not as profound as that of juvenile rheumatoid arthritis.

Answer 77

101. A. Haemangioblastoma Haemangioblastoma (HB) is a vascular tumour of the CNS. It occurs most often in the cerebellum, where it is the most common primary neoplasm in adults. Single tumours may be sporadic, but multiple tumours are almost always associated with VHL disease. The most common MR pattern of LIB is an enhancing solid mural nodule with an adjacent non-enhancing cyst. The cyst is typically low on T1-weighted and high on T2-weighted images, but it can have areas of high T1 signal from fat or haemorrhage. HB can also look purely cystic, solid or a mural nodule with enhancing cystic wall. HB almost never calcifies. Pilocytic astrocytoma are cystic, with larger mural nodule, calcification, thick walls and no contrast blush to the mural nodule on angiography.

Answer 78

102. D. Craniopharyngioma The differential diagnosis would include Rathke cleft cyst, but that is usually intrasellar and thin-walled in appearance. Craniopharyngioma contains calcification and is heterogeneous on MR. Medulloblastoma is usually infratentorial and within the posterior fossa arising in the roof of the fourth ventricle, appears hyperdense on CT, and shows contrast enhancement. Macroadenoma is typically seen in an older age group, whereas microadenoma is hypointense on Tl and non- enhancing post-gadolinium.

Answer 79

103. D. Severe portal hypertension The main risk factors for developing HE include age >65 years, child score >12, prior HE, placement of a large diameter stent (>10 mm) and low PPG (<5 mm Hg).

Answer 80

104. B. Inability to identify T4 tumour. In the setting of primary rectal cancer, MRI is used to assist in staging, in identifying patients who may benefit from preoperative chemotherapy-radiation therapy, and in surgical planning. Currently, surgical resection with stage-appropriate neoadjuvant combined-modality therapy is the mainstay in the treatment of rectal cancer. In the past decade, the increasingly widespread adoption of total mesorectal excision (TME) has resulted in a dramatic decline in the prevalence of local recurrence from 38% to less than 10%. TME is a surgical technique that entails cn bloc resection of the primary tumour and the mesorectum by means of dissection along the mesorectal fascial plane or the circumferential resection margin (CRM). The evolution of surgical techniques and the shift to neoadjuvant chemotherapy-radiation therapy, along with the prognostic heterogeneity of stage T3 tumours, necessitate accurate preoperative staging primarily in terms of tumour (T) and nodal (N) staging, depth of tumour invasion outside the muscularis propria (early versus advanced stage T3 tumours) and the relationship of the tumour to the potential CRM. Accurate assessment of these factors allows the triage of patients to up front surgical resection or short- or long course preoperative radiation therapy or chemotherapy-radiation therapy with appropriate modification of the CRM. Recent studies have shown that high-resolution MRI is a reliable and reproducible technique with high specificity' (92%) for predicting a negative CRM, the relationship of the tumour to the CRM and the depth of tumour invasion outside the muscularis propria.

Answer 81

105. E. Retrocaval ureter Retrocaval ureter classically shows medial deviation at L3/4, returning to a more normal position anterior to the iliac vessels. Malakoplaki are rare plaque-like intramural lesions related to chronic UTI, affecting the bladder, ureter, collecting system and even renal parenchyma. They are not premalignant. Schistosomiasis and endometriosis typically cause multiple strictures, which can resemble multiple filling defects. Ureteritis cystica and pyeloureteritis cystica arc fairly common post-inflammatory conditions resulting in ureteric filling defects. Other causes include multiple calculi (Steinstrasse), blood clots or multiple vascular collaterals.

Answer 82

106. C. Reflex sympathetic dystrophy Reflex sympathetic dystrophy, a syndrome that causes significant discomfort, is thought to be due to 'sympathetic overflow’, which may explain the pain, warmth and swelling of the involved extremity. At bone scintigraphy, reflex sympathetic dystrophy usually manifests as diffuse, uniformly increased uptake throughout the affected region. Occasionally, reflex sympathetic dystrophy may manifest as a focal abnormality limited to, for example, the hand or knee. Decreased radiotracer accumulation has also been described, especially in children. Three-phase bone scanning has an accuracy of over 90% and is the radionuclide procedure of choice for diagnosing osteomyelitis in bone not affected by underlying conditions. The first (dynamic) phase reflects the relative amount of blood flow to the area of interest, whereas the second (blood pool) phase reflects the amount of activity that has extravasated into the tissues around the area of interest. The third (delayed [bone]) phase reflects the rate of bone turnover. The classic appearance of osteomyelitis on three-phase bone scans consists of focal hyperperfusion, focal hyperaemia and focally increased bone uptake. Abnormalities at radionuclide bone imaging reflect increased bone mineral turnover in general, not infection specifically. Therefore, conditions associated with increased bone mineral turnover (e.g., tumours, fractures, joint neuropathy) may mimic osteomyelitis at three-phase bone scintigraphy. Under these circumstances, three-phase bone imaging is less useful, primarily because of diminished specificity

Answer 83

107. B. Cavernous angioma A cavernous angioma is a ‘mulberry-like’ vascular malformation. MR! is the most sensitive modality for the diagnosis. With T2-weighted sequences, the lesion is typically characterised by an area of mixed signal intensity, with a central reticulated core and a peripheral rim of decreased signal intensity related to deposition of hemosiderin. Diffuse axonal injury shows multifocal microbleeds as low signal on GRE or SWI sequences. AVM are identified by serpiginous filling defects with large draining veins and feeding arteries. Haem atom as will have mixed signal and will have surrounding oedema and mass effect, unless they are very small.

Answer 84

108. B. Astrocytoma About 50%-70% of all primary intracranial tumours are astrocytoma; it is also the most common paediatric brain neoplasm, accounting for 40%-50%.

Answer 85

109. B. Reversal of diastolic flow is specific for renal vein thrombosis. Acute tubular necrosis is the most common cause of ‘delayed graft function’, whereas chronic rejection is the most common cause of late graft loss. US findings of diminished renal function include renal enlargement, increased cortical thickness, increased or decreased echogenicity of the renal cortex, loss of corticomedullary differentiation, prominent pyramids, collecting system thickening and effacement of the central sinus echo complex. Elevated resistive index (>0.8) is a non-specific parameter of renal transplant dysfunction; reversal of diastolic flow may also be seen. Renal artery stenosis is the most common vascular complication of transplantation. Doppler criteria include (1) velocities of greater than 2 m/sec, (2) a velocity gradient between stenotic and prestenotic segments of more than 2:1 and (3) marked distal turbulence. Although reversal of diastolic flow is non-specific, the combination with absent venous flow is virtually diagnostic of renal vein thrombosis. Renal artery thrombosis is diagnosed by lack of intrarenal venous and arterial flow. Renal vein stenosis results in three- to fourfold increase in flow velocity. Intrarenal arteriovenous fistulas and pseudoaneurysms are the result of vascular trauma during percutaneous biopsy. Extrarenal arteriovenous fistulas and pseudoaneurysms are extremely uncommon. They typically occur as a result of surgical technique rather than percutaneous biopsy. Small crescentic peritransplant fluid collections seen immediately after transplantation are most likely haematomas or seromas and are not significant More complex collections identified later in the post operative period with clinical evidence of infection may represent abscesses. Although the appearance of urinomas is non-specific, internal septations are seen less often than in haematomas. Lymphocele results in a rounded collection along the mid-ureter, associated with hydronephrosis.

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110. E. All of the above High-spatial resolution MRI has already been established as an accurate tool for the preoperative staging of rectal cancer and has resulted in marked improvements in staging accuracy compared with historic studies. MRI also defines the relationship between a tumour and the mesorectal fascia, which denotes the CRM at TME. The potential CRM is considered involved if the tumour extends to within 1 mm of this fascia. Patients with locally advanced T3 or T4 disease or disease involving the potential CRM on baseline MRI are offered chemoradiation therapy (CRT). This approach has been shown to decrease the post-operative tumour recurrence rate. The Magnetic Resonance Imaging and Rectal Cancer European Equivalence (MERCURY) study evaluated consecutive patients undergoing both primary surgery and preoperative therapy with histopathologic correlation and analysed survival outcomes. The results of the study showed that post-CRT MRI assessment of tumour regression grade correlated with disease free survival and overall survival and, thus, with patient prognosis. Furthermore, post treatment MRI prediction of potential CRM involvement also gave prognostic information regarding the risk of local recurrence.

Answer 87

111. D. Enlarged prostate Causes of reduced bladder volume include interstitial cystitis, TB cystitis (thimble bladder), cystitis cystica, schistosomiasis, surgical resection and radiation therapy. Prostate enlargement, urethral strictures and Marion’s disease (primary bladder neck obstruction) result in increased bladder volume.

Answer 88

112. B. Scapholunate ligament tear Single-compartment and three-compartment injection techniques have been described for wrist magnetic resonance arthrography. In the three compartment technique, the mid-carpal and distal radio ulnar joints are initially injected with approximately 1-1.5 ml. of iodinated contrast under fluoroscopic guidance. About 3 ml. of dilute gadolinium is then injected into the radiocarpal compartment after confirmation of the needle-tip position with the injection of a small volume of iodinated contrast. Contrast should normally be confined to the radiocarpal joint with no leak of contrast into the DRUJ proximally or the mid carpal joint distally. If contrast extends lateral to the lunate, between it and the scaphoid this is diagnostic of a full thickness scapholunate ligament tear.

Answer 89

113. B. Osmotic myelinolysis Patients with osmotic demyelination syndrome typically present with severe electrolyte disturbances, which lead to seizures or encephalopathy. A symmetric trident-shaped area in the central pons is a characteristic finding on T2-weighted and FLAIR MRI. The ventrolateral pons and the pontine portion of the corticospinal tracts arc typically spared. Decreased signal intensity, with no mass effect, is a classic finding on 'Ll -weighted images. Less commonly, lesions appear isointense relative to surrounding brain tissue on Tl and do not enhance after the administration of contrast material. Case reports have suggested that restricted diffusion may be seen earlier than the classic T2 changes. It has been noted that myelinolysis can occur outside the pons, a condition that is referred to as extrapontine myelinolysis. Sites of extrapontine myelinolysis include the basal ganglia and cerebral white matter and, less commonly, the peripheral cortex, hippocampi and lateral geniculate bodies. Extrapontine myelinolysis occurs in conjunction with central pontine myelinolysis; however, it may also be seen in isolation.

Answer 90

114. D. Ependymoma Medulloblastoma is the most common neoplasm of the posterior fossa in childhood and is the most malignant infratentorial tumour; however, it arises from the roof of the fourth ventricle. Calcification is an atypical feature of medulloblastoma. Brainstem gliomas displace the fourth ventricle. Pilocytic astrocytoma commonly occurs in the cerebellar hemispheres, not in the fourth ventricle. Ependymoma is the third most common posterior fossa tumour in children. The point of origin is the floor of the fourth ventricle in ependymoma, versus the roof in medulloblastoma. Calcification is a common feature seen in 50% of ependymoma cases, and contrast enhancement is heterogeneous. Although not pathognomonic, the plastic nature of ependymoma results in the classic presentation of a fourth ventricle mass extending through the foramen of Luschka (15%) or foramen of Magendie (60%).

Answer 91

115. A. Infection There is a general agreement that 0.70 should be considered the upper limit of normality in adults but not in children, in whom resistive index values are typically higher, especially within the first year of life. Renal resistive index (RRI) is used for assessment of chronic renal allograft rejection, detection and management of renal artery stenosis, evaluation of progression of risk in chronic kidney disease, differential diagnosis in acute and chronic obstructive renal disease, and more recently as a predictor of renal and overall outcome in the critically ill patient.

Answer 92

116. D. Findings that might be seen in active long-standing Crohn’s disease include submucosal fat deposition, pseudosacculation, surrounding fibro-fatty proliferation and fibrotic strictures. The main diagnostic purpose of CT enterography in the setting of Crohn’s disease is to differentiate active inflammatory strictures from fibrotic strictures in order to guide therapy. CT features of active Crohn’s disease include mucosal hyperenhancement, wall thickening (thickness >3 mm), mural stratification with a prominent vasa recta (comb sign) and mesenteric fat stranding, all of which are exquisitely demonstrated at CT enterography. The capability of CT enterography for depicting extra-enteric disease allows the simultaneous diagnosis of complications associated with Crohn’s disease, such as obstruction, sinus tract, fistula and abscess formation. Mural enhancement is the most sensitive indicator of active Crohn’s disease. Care should be taken to compare bowel loops with similar distention, since both the jejunum and normal collapsed loops may demonstrate regions of higher attenuation simulating enhancement. Inadequately distended bowel loops may be difficult to assess, and secondary signs of active disease, such as mesenteric fat stranding, vasa recta prominence or complications such as fistulas and abscesses should be sought to maximise the accuracy of a diagnosis of active disease. Prominence of the vasa recta adjacent to the inflamed loop of bowel (comb sign), along with increased mesenteric fat attenuation, is the most specific CT feature of active Crohn’s disease. Findings that might be seen in inactive long-standing Crohn’s disease include submucosal fat deposition, pseudosacculation, surrounding fibro-fatty proliferation and fibrotic strictures.

Answer 93

117. C. Risk of death is high in renal artery aneurysm rupture in non-pregnant patients. The decision to repair a renal artery aneurysm (RAA) should be based on several factors, including patient age, gender, anticipated pregnancy in female patients and anatomic features including its size. An isolated aneurysm smaller than 2 cm is unlikely to rupture. Rupture of RAAs is unlikely in most patients. Although some consider calcification to be protective of rupture, no correlation between calcification and risk of rupture is evident. Rupture has historically been associated with a high death rate, especially during pregnancy, and pregnancy is associated with an increased risk of aneurysm rupture. In non-pregnant patients, RAA rupture is likely to be associated with death in less than 10% of cases. Reports suggest that nephrectomy is not always a certain outcome of a RAA rupture, and attempts at kidney salvage in properly selected patients can be justified.

Answer 94

118. B. Baker’s cyst A Baker’s cyst, or popliteal cyst, is essentially a communicating synovial cyst from the posterior joint capsule. The location of the cyst, which tracks between the medial head of the gastrocnemius and semimembranosus tendon, is characteristic. Pes anserinus bursitis refers to inflammation of the bursa around the conjoined tendon insertions of the gracilis, sartorius and semitendinosus muscles at the anteromedial aspect of the proximal tibia. A large parameniscal cyst is a differential, but this requires a meniscal horizontal tear and no mention of this is made.

Answer 95

119. D. Myelomeningocele Chiari I malformation, also called cerebellar tonsillar ectopia, is often an abnormality affecting the hind brain in isolation. Associations of Chiari I malformation include syringohydromyelia, hydrocephalus, basilar impression or basilar invagination, occipitalization of the atlas, unfused posterior arch of Cl, platybasia and Klippel-Feil anomaly. Myelomeningocele are not associated with Chiari 1 but Chiari II malformation.

Answer 96

120. B. Cerebellar pilocytic astrocytoma The classic imaging appearance of a JPA, which is observed in 30%-60% of cases, is of a large cyst with a solid mural nodule within one of the cerebellar hemispheres; less commonly, JPA may present on imaging as a predominantly solid mass with little to no cyst-1 ike component. Enhancement patterns may vary, but JPA most commonly (46%) appears as a cyst with an enhancing wall and an intensely enhancing mural nodule. DWT of )PAs shows no restricted diffusion, which is consistent with the characteristics of a low grade tumour. Although both haemangioblastoma and pilocytic astrocytoma appear similar, the latter is more common within the first two decades, with peak between birth and 9 years of age. Medulloblastoma and ependymoma occur in the fourth ventricle. Arachnoid cyst does not enhance post-contrast.

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