GENITOURINARY IMAGING 3 Flashcards

Question

Radiolucent calculi are best detected by?

Answer 1

CT * Uric acid * Xanthine (rare) * Mucoprotein matrix calculi (lucent even on CT though) * indinavir (lucent even on CT).

Answer 2

Classification * The American Association for the Surgery of Trauma (AAST) renal injury scale, most recently updated in 2018, is the most widely used grading system for renal trauma. * The 2018 update incorporates "vascular injury" (i.e. pseudoaneurysm, arteriovenous fistula) into the imaging criteria for visceral injury. Classification * Severity is assessed according to the **depth of renal parenchymal damage** and **involvement** of the **urinary collecting system** and **renal vessels**. * grade I * **subcapsular haematoma or contusion, without laceration** * grade II * **superficial laceration ≤1 cm depth not involving the collecting system** (no evidence of urine extravasation) * **perirenal haematoma** confined within the perirenal fascia * grade III * **laceration \>1 cm not involving the collecting system (no evidence of urine extravasation)** * **vascular injury or active bleeding confined within the perirenal fascia** * grade IV * laceration involving the collecting system with **urinary extravasation** * laceration of the renal pelvis and/or complete ureteropelvic disruption * **vascular injury to segmental renal artery or vein** * **segmental infarctions** without associated active bleeding (i.e. due to vessel thrombosis) * **active bleeding extending beyond the perirenal fascia (i.e. into the retroperitoneum or peritoneum)** * grade V * **shattered** kidney * **avulsion** of renal hilum or **laceration of the main renal artery** or **vein**: devascularisation of a kidney due to hilar injury * **devascularised** kidney with **active bleeding** Additional points * **advance one grade for multiple injuries up to grade III** * _"vascular injury"_ (i.e. pseudoaneurysm or AV fistula) - appears as a focal collection of vascular contrast **which decreases in attenuation on delayed images** * _"active bleeding" -_ focal or diffuse collection of vascular contrast which **increases in size or attenuation on a delayed phase** * **Case courtesy of Dr Sachintha Hapugoda, Radiopaedia.org, rID: 70451**

Answer 3

The radiographic density of a calculus depends mainly on its calcium content.

Answer 4

Common Underlying Conditions 1. Diabetes mellitus (DM) 2. Immunosuppression 3. Obstruction

Answer 5

Medullary Nephrocalcinosis A common mnemonic used to remember the aetiology of medullary nephrocalcinosis is: HAM HOP Mnemonic * H: hyperparathyroidism * A: (renal tubular) acidosis * M: medullary sponge kidney * H: hypercalcaemia/hypercalciuria * O: oxalosis * P: papillary necrosis Causes (primer of Dx imaging) * HPT (hypercalciuria, hypercalcemia), 40% * Renal tubular acidosis (RTA), 20% * Medullary sponge kidney, 20% * Papillary necrosis * Lasix in infancy * Nephrotoxic drugs (amphotericin B) * Chronic pyelonephritis * Oxalosis may produce both medullary and cortical nephrocalcinosis. Case courtesy of Dr Wael Nemattalla, Radiopaedia.org, rID: 7499

Answer 6

Associations (Rare) of Medullary sponge kidney 1. Hemihypertrophy 2. Beckwith-Wiedemann syndrome 3. Congenital pyloric stenosis 4. Ehlers-Danlos syndrome 5. cortical renal cysts 6. horseshoe kidney 7. renal ectopia 8. autosomal-dominant polycystic kidney disease (ADPKD), 9. RTA [http://learningradiology.com/archives2008/COW%20322-Medullary%20Sponge%20Kidney/medspongecorrect.htm](http://learningradiology.com/archives2008/COW%20322-Medullary%20Sponge%20Kidney/medspongecorrect.htm)

Answer 7

Cortical Nephrocalcinosis Usually dystrophic calcification [https://www.slideshare.net/pathologydept/intracellular-accumulations-and-calcifications-22-92016](https://www.slideshare.net/pathologydept/intracellular-accumulations-and-calcifications-22-92016)

Answer 8

1. **Pyelosinus backflow** (forniceal rupture): extravasation along infundibula, renal pelvis, ureter 2. **Pyelotubular backflo**w (no rupture): backflow into terminal collecting ducts; thin streaks with fanlike radiation from the papillae 3. **Pyelointerstitial backflow**: extravasation into parenchyma and subcapsular structures; more amorphous than pyelotubular backflow 4. **Pyelolymphatic backflow**: dilated lymphatic vessels (may occasionally rupture): thin irregular bands extending from hilum or calyces 5. **Pyelovenous backflow:** contrast in interlobar or arcuate veins; rarely seen because venous flow clears contrast material rapidly: renal vein extends superiorly from renal hilum. Pyelosinus rupture https://www.tandfonline.com/doi/pdf/10.3109/00016925309175821 Fig. 18 a. -- Large extravasation in: the entire kidney extending toward\> the hilus~ and both medially and laterally around theuretrr. Pig. 18b. - Some minutes later. The bulk of the sinous extravasate has been resorbcd; subcapsular accumulation of contrabt rriedi- um around the lower pole of the kidney medially.

Answer 9

Lobster claw sign of Renal Papillary Necrosis (RPN) Case courtesy of Dr Matt A. Morgan, Radiopaedia.org, rID: 40421

Answer 10

Infants: 1. dehydration, 2. shock, 3. trauma, 4. sepsis, 5. sickle cell disease

Answer 11

Complications * Forniceal rupture (pyelosinus backflow); inconsequential in isolation if urine is uninfected; chronic leak may result in periureteral/retroperitoneal fibrosis. Case * Chronic calculous pyelonephritis * XGP in the presence of staghorn calculus * Squamous metaplasia (leukoplakia); more common in pyelocalyceal system and upper ureter than lower ureter or bladder. Cholesteatoma may result from desquamation of keratinized epithelium. Case courtesy of Dr Chris O'Donnell, Radiopaedia.org, rID: 49889

Answer 12

Extracorporeal Shock Wave Lithotripsy (ESWL) * Best results with calcium oxalate and uric acid stones and calculi \<2.5 cm. Larger calculi are better treated by percutaneous removal. * Contraindications for ESWL include: * Patient not eligible for anesthesia * Severe bleeding * Pregnancy * UTI * Nonfunctioning kidneys * Gross obesity * Small children * Tall patients (\>200 cm) * Distal obstruction * Calyceal neck stenosis * UPJ obstruction * Prostatic enlargement * Renal artery aneurysm * Complications of ESWL * Intrarenal; subscapular and perinephric hematoma * Decrease in effective renal plasma flow

Answer 13

Nonopaque calculi (on KUB) * **Uric acid** * gout, * treatment of myeloproliferative disorders * 10% * **Xanthine** * (rare) * **Mucoprotein matrix calculi** * **** in poorly functioning, infected urinary tracts * lucent even on CT) * rare * **Indinavir** * Protease inhibitor used in HIV treatment * Can result in radiolucent stones (even on CT).

Answer 14

Renal Manifestation of Acquired Immunodeficiency Syndrome (AIDS) AIDS-related renal abnormalities are seen in most AIDS patients during the course of their illness. AIDS nephropathy refers to irreversible renal failure in 10% of patients and is seen in end-stage disease. Imaging Features * Increased cortical US echogenicity, 70%; (tubulointerstitial abnormalities) * Renal enlargement without hydronephrosis, 40% * Focal hypoechoic (US)/low-attenuation (CT) lesions (infection, tumor), 30% Increased bilateral renal parenchymal echogenicity, using the liver as acoustic window, with decreased renal sinus fat. Bilateral kidneys enlarged: right kidney longitudinally measures 144 mm, and the left kidney 123 mm. Case Discussion 46 year old male diagnosed with HIV two years ago, initiated on treatment and subsequently defaulted treatment few weeks later. Now presented with generalised weakness. On physical examination patient appeared chronically ill: wasted and pale, with generalised oedema. Laboratory results (on presentation): Urea: 33.8 mmol/L Creatinine: 637 umol/L eGFR: 8 mL/min/1.73 m2 Hb: 4.0 g/dL Case courtesy of Dr Julius Rozmiarek, Radiopaedia.org, rID: 62615 CD4: 102 cell/uL HIV viral load: 3,833,345 copies/mL Laboratory results from a year prior to presentation demonstrated normal kidney functions. Sent for abdominal ultrasound to rule out acute or chronic kidney injury.

Answer 15

What are the imaging features of Medullary Sponge kidney? * Striated nephrogram (contrast in dilated collecting ducts), “brush like” appearance * Cystic tubular dilatation usually 1–3 mm; occasionally larger, usually too small for CT resolution * Punctate calcifications in medullary distribution (located in dilated tubules), 50% * Differentiate on IVP from “papillary blush,” a normal variant, representing amorphous enhancement without tubular dilation, streaks, or globules; nephrocalcinosis; or pyramidal enlargement. Papillary blush is also an inconstant finding on successive IVPs. Medullary sponge kidney. The collecting system and renal pelvis appear normal. However, there are striated and saccular collections of contrast material within the renal papilla of the medulla.∫ https://radiologykey.com/kidneys-2/

Answer 16

* **Common causes of false-positive examinations:** * Extrarenal pelvis * Peripelvic cyst * Vessels: differentiate with color Doppler * Vesicoureteral reflux, full bladder * High urine flow (overhydration, furosemide) * Corrected long-standing obstruction with residual dilatation * Prune-belly syndrome

Answer 17

Nephrocalcinosis and Lithiasis * Renal calcifications can be located in * renal parenchyma * nephrocalcinosis * abnormal tissue * dystrophic calcification in cysts/tumors * collecting system * nephrolithiasis * calculi

Answer 18

“Steinstrasse:” several calculi are bunched up along the ureter (common after lithotripsy). Case courtesy of Dr Ali Abougazia, Radiopaedia.org, rID: 22713

Answer 19

Complications of Renal Abscess * Retroperitoneal spread of abscess * Renocolic fistula * Renal vein Thrombosis Case Discussion * Thick-walled enhancing cystic mass in the mid pole of the right kidney. * Right perinephric inflammatory change and thickening of Gerota's fascia. * Renal abscesses usually form following pyelonephritis. Immuno-suppressed patients are most susceptible, particularly those with diabetes mellitus. * Small abscesses may be treated with antibiotics only. Larger abscesses are typically treated with an image-guided percutaneous drain insertion, as in this case. * Successful resolution was achieved in 36 hours following ultrasound-guided percutaneous drainage. * Case courtesy of Dr Ian Bickle, Radiopaedia.org, rID: 29853

Answer 20

Pressure-flow study for determining ureteral obstruction or resistance in dilated, nonrefluxing upper urinary tracts. Useful test particularly in patients with surgically corrected obstruction having residual dilatation and/or symptoms. Because the test is invasive and time-consuming, it is usually reserved for cases with equivocal diuretic renograms. 1. Catheterize bladder and inject contrast to exclude refluxing megaureter. 2. Obtain percutaneous access to collecting system with 20-gauge needle. 3. Connect extension tubing, three-way stopcock, and manometer to both antegrade needle and bladder catheter. The bases of both manometers have to be set at the same level as the tip of the antegrade needle. 4. Connect perfusion pump to antegrade needle and bladder catheter. 5. Obtain spot and overhead radiographs during perfusion (intermittent fluoroscopic monitoring). 6. Pressures in collecting system and bladder are recorded during delivery of known flow rates (5, 10, 15 mL/min), and pressure differences are calculated. 7. Pressure difference of \>15 mm is abnormal, and test should be terminated.

Answer 21

Amputated Calyx Urogenital TB

Answer 22

Role of imaging studies: Define underlying pathology * Obstruction * Reflux * Calculus Rule out complications * Abscess * Emphysematous pyelonephritis * Determine presence of chronic changes such as scarring

Answer 23

XGP Imaging Features * Large or staghorn calculus (thought to cause obstruction and inflammatory response), 75%; in the remaining 25% of patients, XGP is due to UPJ obstruction or ureteral tumors. * Enlarged, nonexcreting kidney * Multiple nonenhancing low-attenuation masses (–10 to 30 HU): xanthomatous masses. The masses may extend beyond the kidney into the perinephric space. There may be a thin peripheral ring of enhancement. * Fine calcifications may be present in xanthomatous masses. * Thickened Gerota fascia * May be associated with psoas abscess Case courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org, rID: 9931 Case Discussion Features are consistent with xanthogranulomatous pyelonephritis and pre-existing staghorn calculus. Case courtesy of Dr Laura Jimenez Juan (CT) and Dr Natalie Yang (MRI)

Answer 24

Infundibulopelvic Dysgenesis Spectrum of diseases characterized by hypoplasia or aplasia of the upper collecting system: * Calyceal diverticulum * Pyelogenous cyst * Multiinfundibular stenosis * PUJ stenosis * Infundibulopelvic stenosis * Multicystic kidney

Answer 25

Squamous Cell Carcinoma (SCC) * Represent 5% of renal pelvis tumors and \<1% of all renal tumors * Frequently associated with: * leukoplakia * chronic irritation * nephrolithiasis * schistosomiasis Figure 12b. Squamous cell carcinoma in a 50-year-old man with chronic calculus disease and left flank pain. (a) Axial unenhanced CT scan shows a high-attenuation stone (arrow) in the left renal pelvis. A tiny amount of air (arrowhead) due to previously performed percutaneous nephrostomy is seen in the renal sinus. (b) Axial contrast-enhanced CT scan obtained during the excretory phase shows an infiltrative mass (arrows) in the renal pelvis that extends to the renal parenchyma. Note the metastatic lymph nodes (arrowhead) in the paraaortic space. https://pubs.rsna.org/doi/10.1148/rg.24si045503

Answer 26

Calcium stone in a 45-year-old man. (A) Plain radiograph shows two radiopaque stones (arrows) in the right kidney. Note that the stones are homogeneously dense and have a smooth surface. (B) IVU demonstrates that the stones are located in the ureteropelvic junction (arrows) and obstructive hydronephrosis is seen in the right kidney Halo appearance (edema) around distal ureter may resemble appearance of ureterocele (pseudoureterocele) or bladder carcinoma. Thickness of radiolucent halo of pseudoureterocele is typically \>2 mm as opposed to ureterocele. https://link.springer.com/chapter/10.1007/978-3-642-05322-1\_26

Answer 27

* **Imaging Features** * Gas in collecting system and/or renal parenchyma * Gas may extend to Gerota fascia (high mortality) * **Treatment** * Nephrectomy * In poor surgical candidates or in patients with focal disease, percutaneous drainage has been used as a temporizing or, occasionally, definitive therapy. * Case courtesy of Dr G Balachandran, Radiopaedia.org, rID: 10179 * **Scout CT scan film shows air pockets in the right renal fossa**. * CT scan upper abdomen shows air pockets in right perinephric space and enlarged right kidney. * A thirty-five years old female patient was referred for evaluation of abdominal pain. She was a known case of **diabetes mellitus with renal failure.** The scout CT film shows pockets of air collection in the right renal fossa. The NECT confirms the air collection to be in the perinephric space. Contrast study was not done due to poor renal parameters.

Answer 28

Congenital Megacalyces There is no obstruction. Congenital condition in which there are too many enlarged calyces (20–25; normal is 10–14). **Associated with hypoplastic pyramids**, resulting in polyclonal, faceted calyces rather than the blunting that is seen with obstruction. **Associated with megaureter.** **There is no obstruction,** and the remainder of the collecting system is normal. Renal parenchyma and renal function are normal. The cause is not known; there may be congenital underdevelopment of pyramids, “burnt-out” fetal obstruction, reflux or abnormal branching of collecting system. https://www.eurorad.org/case/4844

Answer 29

Risk Factors 1. Urinary obstruction (e.g., benign prostatic hyperplasia, calculi) 2. Vesicoureteral reflux 3. Pregnancy (dilatation of ureters) 4. Diabetes mellitus 5. Immune deficiency 6. Instrumentation

Answer 30

Renal Masses: What the Urologists Would Like to Know 1. Solid or cystic? 2. Does it arise from parenchyma or collecting system? 3. Size and exact location 4. Staging if malignant 5. Variant vascular or collecting system anatomy

Answer 31

Squamous metaplasia (leukoplakia) * What is this a complication of? * **renal stones** * What could occur? * **Cholesteatoma may result from desquamation of keratinized epithelium.** * more common in pyelocalyceal system and upper ureter than lower ureter or bladder. * https://casereports.bmj.com/content/2017/bcr-2017-220682 * Interestingly, he never had imaging evidence of renal stone, although had mild hydronephrosis one time. CT urogram demonstrated an ill-defined filling defect in the anterior right renal pelvis measuring approximately 13×3 mm in axial dimensions (figure 1). During the episodes of flank pain, he can feel ‘something’ sloughing off and traversing through the ureter. Excreted material is shown in figure 2. The presence of keratin in the ureteroscopic specimen indicated squamous metaplasia of the urothelial tract. We thus diagnosed him with renal keratinising desquamative squamous metaplasia (KDSM) and treated conservatively with adequate hydration and pain management.

Answer 32

“Pipestem ureter” refers to a narrow, rigid, aperistaltic segment Urogenital TB

Answer 33

Renal Abscess Imaging Features ( Fig. 4.6 ) * Well-delineated focal renal lesion * Central necrosis (no enhancement with IV contrast) * Thickened, hyperemic abscess wall with contrast enhancement * Perinephric inflammatory involvement: * Thickening of gerota fascia * Stranding of perirenal fat mass Case Discussion * Renal abscess and renal vein thrombosis. * Renal abscess and renal vein thrombosis. * Patient is HIV positive, and an IVDU. He presented with sepsis. * Case courtesy of Associate Professor Natalie Yang, Radiopaedia.org, rID: 9960

Answer 34

IVP * Kidney * Delayed nephrogram * (peak enhancement at \>30 min after IV injection, slow fading) * Delayed renal (peak) density may be higher than in normal kidney. * Faint radial striations of nephrogram * Negative pyelogram: * nephrogram with delayed pyelogram resulting in dilated unopacified calyces outlined by opacified parenchyma * Dunbar crescents (caliceal crescents): * thin rings or crescents at interface with calyx and parenchyma resulting from contrast in dilated collecting ducts; disappear when collecting system is completely opacified * Atrophy of renal parenchyma in chronic obstruction: “rim nephrogram” or “shell nephrogram”

Answer 35

Imaging Features * Peripheral calcifications (medullary pyramids are spared) * **Tramline calcifications are classic:** interface of necrotic cortex and viable subcapsular cortex * Columns of Bertin may be calcified. * US: hyperechoic cortex Alport syndrome and Tramline calcifications.

Answer 36

Medullary sponge kidney * Dysplastic dilatation of renal collecting tubules (ducts of Bellini). * Cause: developmental. * Usually detected in young adults (20–40 years) as an incidental finding. * Usually there are no signs, but there can be urine stasis, UTI, calculi, and hematuria. * In 10%, progressive renal failure may develop. * Relatively common (0.5% of IVP). * May involve one or both kidneys or be confined to a single papilla. Case Discussion * Case courtesy of Dr Fazel Rahman Faizi, Radiopaedia.org, rID: 69363 * The kidneys reveal echogenic renal medullary pyramids. No convincing acoustic shadowing is noted to suggest calculi. * There are three rounded cysts in the medullary region of the right kidney- one in the upper pole and two in the lower pole- with internal debris. * Another medullary cyst in the upper pole of the left kidney. * The right renal pelvis is prominent, however, no lithiasis was noted in the pelvicalyceal system as well as the right ureter.The features are in keeping with medullary sponge kidneys with medullary nephrocalcinosis. * In this case, the patient was referred to the hospital with gastrointestinal symptoms. These findings were incidental and irrelevant to the patient's complaint.

Answer 37

Acute Pyelonephritis * Acute bacterial infection of the kidney and urinary tract (Proteus, Klebsiella, E. coli). * Medical treatment is usually initiated without imaging studies.

Answer 38

Fig. 3 The early morphologic alterations of renal parenchyma determined by tuberculosis. The fundamental calyceal alterations in renal tuberculosis: calyceal erosion (a), medullary necrosis (b), papillary necrosis (c), and infundibular stricture without (d) or with hydrocalyx (e) https://radiologykey.com/renal-infections-and-renal-fungal-infections/

Answer 39

**_Gross description Collecting Duct Carcinoma_** * Infiltrative, firm gray or white mass * Centered in the medulla but often involving both cortex and medulla * Tumor size range from 2.5 - 12 cm (mean 5 cm) * Hemorrhage, necrosis and cystic changes are common * May have satellite nodules and renal vein invasion * Often infiltrates perirenal and renal sinus fat **Collecting duct carcinoma (CDC) of the kidney, also known as Bellini duct carcinoma, is an extremely rare variant of renal cell carcinoma (RCC), accounting for 0.4–1.8% of all RCCs (1).** By CT, the lesions are medullary in location and have an infiltrative appearance. The reniform contour of the kidney is maintained. By renal angiography, the tumors are usually hypovascular. By MR imaging, the tumors are hypointense on T2W images.In contrast to the considerably more common variants of RCC, arising from the convoluted tubules of the renal cortex, **CDC is derived from the renal medulla,** possibly from the **distal collecting ducts of Bellini** (1–3). Approximately four decades ago, Mancilla-Jimenez et al(4) first observed the atypical hyperplasia of the adjacent collecting ducts epithelium in three cases of papillary RCC. Therefore, the authors speculated that a few papillary RCCs may derive from the epithelium of the collecting ducts. Until 1979, the term Bellini duct carcinoma was presented by Cromie et al(5) It is worth noting that CDC has other synonyms besides Bellini duct carcinoma, including medullary renal carcinoma, distal nephron carcinoma and distal renal tubular carcinoma. In 1997, in accordance with the morphological aspect and chromosome of the primary renal cancer, five histologic types was defined in the Heidelberg classification (6), including the conventional, chromophobe, papillary, collecting duct and unclassifiable carcinoma. CDC is characterized by a tremendously aggressive phenotype. Patients with CDC usually have metastatic diseases at the time of presentation. Radical nephrectomy is the basis of therapy. Several systemic treatment protocols, including chemotherapy, radiotherapy and immunotherapy have been considered. However, these treatments do not produce a favorable response in the majority of CDC patients, and ~70% of patients succumb due to CDC progression within 2 years of diagnosis. In general, CDC is considered to have a poor prognosis and early diagnosis is likely the only factor leading to a prolonged survival for patients (7). However, due to the rarity of this tumor and the lack of clinical awareness, no reliable diagnostic protocol has been established. To achieve an improved understanding of CDC and diagnosis, the present study analyzed the imaging features of six CDC patients treated in Jinling Hospital, Clinical school of Medical College, Nanjing University (Nanjing, China), between June 2007 and October 2012.

Answer 40

Emphysematous Pyelonephritis * Most commonly caused by gram-negative bacteria in patients with DM; * less commonly in nondiabetics with obstruction. * Spectrum includes: * Emphysematous pyelonephritis: * gas in renal parenchyma and collecting system. * **Mortality: 60%–80%.** * Emphysematous pyelitis: * gas in collecting system (“air pyelogram”). * **Mortality: 20%.** * **Case Discussion** * Case courtesy of Dr Ian Bickle, Radiopaedia.org, rID: 32755 * Extensive bilateral renal stone disease. * Obstructing ureteric stone in the distal right ureter causing a mild nephrohydroureter. * Gas in both kidneys and large volume gas in the right retroperitoneum as well as in the right ureter. * Advanced case of emphysematous pyelonephritis. The vast majority occur in those with diabetes mellitus and/or urolithiasis. * In this case it is present bilaterally and on the right has perforated the renal capsule to extend in the most profound fashion into the retroperitoneum. This is termed class 4: the highest class of the disease. * In fact, the gas serves to illustrate the anatomy of the retroperitoneal spaces and confines of Gerota's fascia.

Answer 41

Perinephric Abscess Results most commonly from high-grade ureteral obstruction and infected kidney. Nonrenal causes include: 1. Duodenal perforation, 2. Diverticular abscess, 3. Crohn disease, 4. Infected pancreatic fluid collections, and 5. Spinal TB, which may spread and cause perirenal as well as psoas abscess. Treatment is with percutaneous drainage. * Case discussion: * **Xanthogranulomatous pyelonephritis with perinephric abscess** * Case courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org, rID: 16883 * A thick walled collection measuring 11 x 8 x 11.7 cm extends from the perinephric space through the pararenal space and into the abdominal wall. The left kidney is displaced anteriorly and measures 12.2 cm. It contains a large staghorn calculus. The parenchyma is thinned with decreased enhancement and extensive rounded radiolucencies. Fat stranding throughout the retroperitoneum. There is mild dilatation and inflammatory stranding of the left ureter; however, no obstructing lesion is identified. Bladder content is hyperdense, thought to relate to previous CT study. * The right kidney measures 12.5 cm and contains simple cysts. Splenomegaly - the spleen measures 17 x 6.5 x 11 cm. No focal lesion. What appear to be loops of small bowel are seen in the pouch of Douglas. * The pancreatic duct is dilated (5 mm), however, no intra- or extra-hepatic biliary dilatation is seen. Pancreatic duct dilatation appears to extend to the ampulla without an obstructing lesion identified. * Gallbladder and adrenals are unremarkable. No free intraperitoneal gas or fluid. Lung bases are clear. * No aggressive bony lesions. Right hip prosthesis with associated artifact noted. No CT evidence of osteomyelitis/discitis. * This case demonstrates typical appearances of xanthogranulomatous pyelonephritis complicated by a large perinephric abscess. The abscess was drained before nephrectomy and yielded Proteus mirabilis. * Gross pathology image courtesy of Dr Alpha.Tsui, Royal Melbourne Hospital. * Films obtained following perinephric abscess drainage. Large staghorn calculus with several noncontiguous large calculi filling dilated renal calyces in the left kidney. The left renal shadow is enlarged. Pigtail drainage catheter projects over the left inferior pole, compatible with abscess drainage catheter. No right-sided renal tract or ureteric calculi. Hyperdense faecal material in the left-sided colon and rectum compatible with mixed enteric contrast.

Answer 42

Location: three narrow sites in the ureter at which calculi often lodge 1. PUJ: junction of renal pelvis and ureter proper 2. At crossing of ureter with iliac vessels 3. UVJ: insertion of ureters into bladder

Answer 43

Causes of Renal Papillary Necrosis * Ischemic necrosis * DM * Chronic obstruction, calculus * Sickle cell disease * Analgesics * Necrosis caused by infections * TB * Fungal Renal Abscess and Papillary Necrosis 46-year-old woman with history of multiple prior UTIs, presented with renal abscess. (A) Coronal excretory phase CT shows renal abscess (blue arrow). (B) Axial excretory phase soft tissue window and (C) wide window images, as well as (D) coronal MIP image show dilated blunted upper pole calix (red arrow) with multiple collections of contrast in “ball on tree” appearance (yellow arrows) representing papillary necrosis. Wide window and MIP images better demonstrate contrast collections than soft tissue window. https://www.ctisus.com/responsive/learning/exhibit/genitourinary/311982

Answer 44

Dual energy CT: * Acquisition of CT data from two different energy spectra. * Most urinary calculi, regardless of composition, appear as opaque densities by conventional CT. * In dual energy CT, the differences in x-ray attenuation properties at high and low kVp allow more accurate renal stone differentiation between uric acid- and calcium-containing stones. * Stones that appear more dense on water decomposition images than iodine decomposition images have a significant uric acid component. [https://www.auntminnie.com/index.aspx?sec=ser&sub=def&pag=dis&ItemID=88958](https://www.auntminnie.com/index.aspx?sec=ser&sub=def&pag=dis&ItemID=88958)

Answer 45

Treatment Options 1. Small renal calculi (\<2.5 cm): extracorporeal lithotripsy 2. Large renal calculi (\>2.5 cm): percutaneous removal 3. Upper ureteral calculi: extracorporeal lithotripsy 4. Lower ureteral calculi: ureteroscopy

Answer 46

1. Medullary Sponge Kidney 2. Benign Renal Tubular Ectasia 3. Cacchi-Ricci Disease

Answer 47

“Purse-string” stenosis of renal pelvis Genitourinal TB

Answer 48

Renal calculi can be detected by US: * hyperechoic focus (calculus), * posterior shadowing; * calculi 3 mm or less may not be detected.

Answer 49

Types * Focal type (lobar nephronia) * Diffuse type: more severe and extensive

Answer 50

Most common pathogen is Escherichia coli. Less common organisms include other gram-negative bacteria: * Proteus, * Klebsiella, * Enterobacter, * Pseudomonas, * Neisseria , and * Trichomonas vaginalis.

Answer 51

Imaging Features of Replacement Lipomatosis * Enlarged renal outline, fatty lucent mass, and staghorn calculus * IVP shows poorly functioning or nonfunctioning kidney. * On US, kidney is enlarged but has a preserved shape. Residual hypoechoic renal parenchymal rim is surrounded by hyperechoic areas of fatty proliferation in both renal hilum and perinephric space. * CT is the imaging modality of choice to best demonstrate fatty characteristics.

Answer 52

Causes of Cortical nephrocalcinosis * Chronic glomerulonephritis * Cortical necrosis (because of ischemia) * Pregnancy * Shock * Infection * Toxins: methoxyflurane, ethylene glycol * AIDS-related nephropathy * Glomerular sclerosis * Punctate calcifications MAI * Rejected renal transplants * Chronic hypercalcemia * **Oxalosis (Case)** * Alport syndrome _Primary hyperoxaluria_ Case contributed by Dr Hala Maher * Presentation * End-stage renal disease associated with ascites and respiratory and liver failure. * Bilateral increased renal density associated with central displacement of the bowel due to ascites. * Also diffuse sclerosis of the ribs and upper limbs bones along with rugger jersey spine are noted * Bilaterally increased bone density showing heterogenous osteosclerosis along with extraosseous calcifications that extend at the medial aspect of the left carpometacarpal regions. * Both kidneys showing a marked echogenic cortex with strong posterior shadowing denoting diffuse calcifications that suggest bilateral nephrocalcinosis. * Case Discussion * This chronic complicated case was initially misdiagnosed as a congenital nephrocalcinosis with renal osteodystrophy due to end-stage renal disease. This results in a secondary (and potentially eventually a tertiary) hyperparathyroidism causing a generalised bony abnormality accompanied by extraosseous calcifications. Ascites was iatrogenic and due to peritoneal dialysis. * Yet, after reviewing the laboratory history of this child we found that there is a congenital disorder of oxalate metabolism. It is a rare condition and following chronic dialysis, the bone oxalosis mimics secondary hyperparathyroidism radiologically. However; the lab results of this child show a markedly elevated PTH 146 pg/mL (normal 15-65 pg/mL) denoting secondary hyperparathyroidism. * https://radiopaedia.org/cases/primary-hyperoxaluria

Answer 53

Other Renal Abnormalities 1. Acute tubular necrosis (ATN) 2. Interstitial nephritis 3. Focal nephrocalcinosis 4. Infection: * Cytomegalovirus (CMV), * aspergillus, * toxoplasmosis, * Pneumocystis jiroveci Frenkel 1999, * histoplasmosis, * Mycobacterium avium-intracellulare (MAI) 5. Tumors: * increased incidence of RCC, * lymphoma, * Kaposi sarcoma (KS)

Answer 54

Spectrum of renal injury in trauma: * Renal infarction * Segmental branch * Vascular pedicle avulsion * Hemorrhage (renal laceration, rupture) * Intraparenchymal * Extraparenchymal * Ruptured collecting system

Answer 55

Imaging Features * Bilateral, stippled calcification of medullary pyramids * Calcifications may extend peripherally. * US: hyperechoic medulla Case Discussion * Medullary nephrocalcinosis. * An infant suspected to have Liddle's syndrome, screened for nephrocalcinosis. * Case courtesy of Dr Hani Makky Al Salam, Radiopaedia.org, rID: 9899

Answer 56

Sites of Involvement 1. Renal 2. Ureteral 3. Bladder 4. Seminal vesicles (SVs) 5. epididymis

Answer 57

Imaging Features * Imaging studies (IVP, CT, US) are normal in 75%. * In the remaining 25%, there are nonspecific findings: * Renal enlargement (edema) * Loss of the corticomedullary differentiation (edema) * IVP findings: * Delay of contrast excretion * Narrowing of collecting system (edema) * Striated nephrogram * Ridging of uroepithelium * Areas of decreased perfusion by contrast-enhanced CT * Focal areas of hypodensity in lobar nephronia * Complications: abscess, scarring Case courtesy of Dr Gagandeep Singh, Radiopaedia.org, rID: 6628

Answer 58

Parenchyma * Parenchymal calcifications, 70% * Calcification may take on multiple forms: * curvilinear, * mottled, or * amorphous; * **“putty kidney”** results when calcification has homogeneous, ground-glass appearance. * Papillary necrosis; papillae may be irregular, necrotic, or sloughed * Tuberculoma * Parenchymal scarring, 20% Case courtesy of Associate Professor Natalie Yang, Radiopaedia.org, rID: 9933 Case courtesy of Dr Hani Makky Al Salam, Radiopaedia.org, rID: 17281 The upper and lower poles of the right kidney are largely replaced by a well-defined hypodense lesions with small specks of calcification, the overall contour of the right kidney is preserved except for some distortion seen at the upper pole. Path proven renal tuberculosis.

Answer 59

**Renal Papillary Necrosis** * Enlargement (early) * Small collection of contrast medium extends outside the interpapillary line in partial necrosis. * Contrast may extend into central portion of papilla in “medullary type” RPN. * Eventually contrast curves around papilla from both fornices, resulting in **“lobster-claw”** deformity. * Sequestered, sloughed papillae cause filling defects in collecting system: **“ring sign.”** * Tissue necrosis leads to blunted or **clubbed calyces.** * Multiple papillae affected in 85%. Rim like calcification of necrotic papilla occurs. **Ball-on-tee appearance:** Contrast material filling central excavations in the papilla of the interpolar region gives ball-on-tee appearance. **Lobster claw sign:** Excavation extending from the caliceal fornices produces the lobster claw deformity. **Signet ring sign:** The necrotic papillary tip may remain within the excavated calyx, producing the signet ring sign when the calyx is filled with contrast material. **Club shaped saccular calyx:** Due to sloughed papilla http: //learningradiology.com/archives05/COW%20165-Papillary%20Necrosis/papnecrosiscorrect.htm https: //epomedicine.com/wp-content/uploads/2016/10/renal-papillary-necrosis-patterns.jpg

Answer 60

Obstruction of Collecting System Causes 1. Calculi 2. Tumor 3. Previous surgery (ligation, edema, clot)

Answer 61

Calculi * Incidence: 5% of population; 20% at autopsy. * Recurrence of stone disease, 50%. * Symptoms in 50% of patients during first 5 years of stone presence.

Answer 62

**_Pyonephrosis_** Infected renal collecting system usually because of obstruction, calculi, 50% \> tumor strictures \> postoperative strictures. Penicillin and other antibiotics are sufficient in 35% of cases; remainder of patients require nephrectomy (depending on underlying cause). US * Best study to differentiate pyonephrosis from uninfected hydronephrosis * Echoes within collecting system * Urine/debris levels * Dense shadowing because of gas in collecting system * Poor through-transmission

Answer 63

Replacement Lipomatosis * Also known as replacement fibrolipomatosis, replacement represents extreme form of renal sinus lipomatosis in which infection, long-term hydronephrosis, and calculi are associated with severe renal parenchymal atrophy. * Calculi and inflammation are present in \>70% of cases. * Case courtesy of Dr Prashant Mudgal, Radiopaedia.org, rID: 67434 * Case Discussion * Replacement lipomatosis or fibrolipomatosis is an extremely rare condition, characterised by fibro-fatty proliferation of renal sinus tissue and replacement of normal renal parenchyma with fibrous and adipose tissue. * This particular patient has type-II diabetes mellitus and chronic nephropathy with longstanding left sided obstructive uropathy. * Pre-existing obstructive uropathy is associated with 70% cases of replacement lipomatosis of kidney 1. * Usually the condition is unilateral, but can occur bilaterally 2. * There is complete loss of normal architecture and shape of left kidney, with extreme parenchymal atrophy and fibrosis. Marked fatty proliferation is seen in renal sinus, hilum and perinephric space forming an encapsulated mass measuring 13.4 x 12.2 cm. A large staghorn calculus measuring 35 x 26 mm is seen in left renal parenchyma. In the setting of obstructive uropathy, imaging features are suggestive of replacement lipomatosis of kidney. * Right kidney appears normal.

Answer 64

and soft tissue rim sign

Answer 65

* IVP * Delayed and persistent nephrogram because of ureteral obstruction (pic 1) * Column of opacified urine extends in ureter from renal pelvis to lodged calculus (diminished or absent peristalsis). * Ureter distal to calculus is narrowed (edema, inflammation); may create false impression of stricture. * Ureter proximal to calculus is minimally dilated and straightened: columnization; degree of dilatation has no relation to stone size. (pic two) * “Steinstrasse:” several calculi are bunched up along the ureter (common after lithotripsy). * Halo appearance (edema) around distal ureter may resemble appearance of ureterocele (pseudoureterocele) or bladder carcinoma. Thickness of radiolucent halo of pseudoureterocele is typically \>2 mm as opposed to ureterocele. * Case discussion: * In the initial scout image there is a normal gas pattern. A safety pin and a clip from prior prostate surgery overlie the pelvis. The patient has a history of urolithiasis, but no renal or ureteral calculi were detected on this radiograph. * On the IVP images (including obliques), intravenous contrast concentrates in the left kidney and then travels through the left collecting system normally. Contrast concentrates more slowly in the right kidney and there is no opacification of the right collecting system. On the 20 min post-void image there is opacification of the right kidney (delayed nephrogram), still without any contrast in the collecting system, compatible with high-grade obstruction of the right collecting system. * Case courtesy of Dr Matt A. Morgan, Radiopaedia.org, rID: 41778pseudoureterocele is typically \>2 mm as opposed to ureterocele. * Case courtesy of Dr Bruno Di Muzio, Radiopaedia.org, rID: 31797

Answer 66

collecting duct renal cell carcinoma (Bellini duct): \<1% often younger patients worst prognosis 5

Answer 67

**_Emphysematous pyelonephritis and pyonephrosis_** CT * Best study to show cause and level of obstruction, as well as complications * Dilated collecting system * Allows detection of perinephric or renal abscess Case courtesy of Dr Ian Bickle, Radiopaedia.org, rID: 29648 * Left hydronephrosis due to an obstructing ureteric stone. * Additional renal stones. * Perinephric fat stranding and thickening of Gerota's fasica. * Air in the renal cortex and collection system.

Answer 68

Size * Early, kidneys are enlarged * Later, kidneys are small * Autonephrectomy (nonfunctioning kidney)

Answer 69

“Sterile pyuria” refers to increased urinary white blood cell count (WBC) without being able to culture pathogens. Common causes of sterile pyuria: 1. Tuberculosis (TB) 2. Fungal infections 3. Interstitial nephritis 4. Glomerulonephritis

Answer 70

Predisposing conditions: 1. Calyceal diverticula, 2. Crohn disease, 3. some diversions, 4. stents, 5. renal tubular acidosis, 6. hypercalcemia, 7. hypercalciuria.

Answer 71

* **_DDxs for replacement lipomatosis_** * **XGP** * (on IVP only), * CT can aid in differentiating XGP because CT shows attenuation values of –5 to +15 HU in XGP, in contrast to replacement lipomatosis where the fatty tissues measure –100 HU. * **fat-containing tumors** such as * AMLs, * lipoma, and * liposarcoma * Fat-containing tumors usually produce a mass effect and show renal function, unlike replacement lipomatosis.

Answer 72

Tuberculosis * The genitourinary (GU) tract is the second most common site of tuberculous involvement after the lung. * GU disease is typically due to hematogenous spread. * Clinical findings include history of pulmonary TB, pyuria, hematuria, and dysuria. Case Discussion * Case courtesy of Associate Professor Natalie Yang, Radiopaedia.org, rID: 9933 * Shrunken right kidney with extensive amorphous calcification. * This case demonstrates endstage renal tuberculosis (also known as TB autonephrectomy) resulting in the so-called putty kidney.

Answer 73

Interventional procedures * Aspiration for culture and sensitivity (definitive diagnostic study) * Penicillin * Formal antegrade pyelography should be deferred to a second visit so as not to cause sepsis. Case courtesy of Dr Ian Bickle, Radiopaedia.org, rID: 29648 Nephrostomy tube insertion for obstructed septic renal tract. A pyonephrosis was confirmed.

Answer 74

Collecting system * Blunting of forniceal angles * Dilatation of ureter and pelvis * decreased or absent peristalsis * Backflow

GENITOURINARY IMAGING 3 Flashcards

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