Session 10 Flashcards

Question

What mutations have been found in Colorectal Cancer?

Answer 1

* FAP Chromosome 5 * K or N Ras mutations (Cetuximab has no effect) * (17p) p53 loss/inactivation * (18q) DCC deletion * Braf

Answer 2

**Carcinoid tumour**: rare and unpredictable neuro-endocrine tumour * Slow growing, potentially malignant but their malignant potential depends on site. Can occur in the gut and elsewhere e.g. pancreas, biliary tract and lung. * Larger tumours in the appendix and ileum tend to spread to regional lymph nodes and the liver. Small tumours (less than 2cm in diameter) near the tip of the appendix rarely do so. * Because of the cells in which they arise, tumours produce hormones that may have local or systemic effects e.g. 5-HT (=\> diarrhoea and borborygymi due to stimulated contractility of the small intestine), ACTH (Cushing’s Syndrome) * Palliative treatment is usually given. Survival can be anything from 3 years to 30 years even if metastases are present. * *Lymphoma**: rare, may be primary or spread from elsewhere * *Smooth muscle / stromal tumours**: rare and unpredictable

Answer 3

**Morphology** * 2/3 in the head * Firm pale mass with a necrotic centre * May infiltrate adjacent structures e.g. the spleen **Histology:** * 80% are ductal adenocarcinomas * Well formed glands +/- mucin * Some acinar tumours contain zymogen granules * All types have poor prognosis

Answer 4

* The bile duct is blocked with only a small tumour, leading to jaundice and early presentation when the tumour is still treatable. * Quite good prognosis if detected early enough (curative surgery still possible)

Answer 5

* Rare * Insulinoma (tumour derived from Beta cells and secretes insulin) =\> Hypoglycaemia * Glycagonoma has a characteristic skin rash * Vasoactive Intestinal Peptideoma (VIPoma) leads to Werner Morrison Syndrome (chronic and profound watery diarrhoea with resultant dehydration, hypokalaemia, achlorhydria, acidosis, vasodilation, hypocalcaemia and hyperglycaemia) * Gastrinoma leads to Zollinger-Ellison Syndrome (gastrin-secreting tumour leads to GI mucosal ulceration)

Answer 6

Benign tumours are fairly rare * Hepatic adenoma * Bile duct adenoma / amartoma * Haemangioma Malignant * Hepatocellular carcinoma * Cholangiocarcinoma * Hepatoblastoma [\*] Commonest malignancy in the liver is a secondary tumour (metastatic deposit)

Answer 7

* Abdominal X-Ray * Erect chest X-Ray * Contrast Studies: Barium Swallow Barium enema Barium meal / follow through Water soluble contrast studies * Ultrasound * Cross-sectional imaging Computed Tomography Magnetic Resonance Imaging (MRI) * Angiograph [\*] The dose of radiation that these modalities give the patient, vary considerably. Ultrasound and MRI don’t use radiation while a CT scan can deliver a very high dose of radiation (up to 15x the dose of an abdominal X-ray). An abdominal X-ray has a significantly higher dose of radiation compared to a Chest X-ray.

Answer 8

* Carcinogenesis * Genetic * Developmental risk to foetus

Answer 9

[\*] Mainly used in the investigation of acute abdomen. [\*] Air under the diaphragm on an erect abdominal film indicates a perforated hollow viscus. [\*] Distended loops of small bowel of segments of colon may be seen. [\*] Retroperitoneal calcification may be present in chronic pancreatitis. [\*] Faecal loading can be seen in constipation. [\*] Projection – AP lying down

Answer 10

Any part of hollow tube visible if: * Gas filled * Low density gas acts as a contrast * Fully fluid filled NOT visible Transit time: * Slow = stomach (fluid +/- air) and colon (faeces +/- gas) * Fast: small bowel (so if we see gas in the normal bowel, this is abnormal!)

Answer 11

[\*] Contrast is used to define hollow viscera. Examples of contrast that is used include Barium and water soluble contrast (typically usuing iodine) [\*] Barium contrast studies include barium swallow, double contrast barium meal, small bowel follow-through, small bowel enema and barium enema. [\*] These studies are often performed after an overnight fast. [\*] Barium swallow: oesophagus is visualized as barium is swallowed in the upright and prone positions. Motility abnormalities as well as anatomical lesions can then be observed. Reflux of barium from the stomach into the oesophagus is observable when the patient is tipped head down. [\*] Double-contrast barium meal – this is performed to examine the stomach and duodenum. A small amount of barium is given together with effervescent granules or tablets to produce carbon dioxide so that a double contrast between air and barium is obtained. [\*] Small bowel follow-through – barium is swallowed and allowed to pass into the small intestine through the jejunum and into the ileum. This technique is useful to demonstrate the gross anatomy of the small intestine. [\*] Small bowel enema – a tube is passed through the duodenum and a large volume of dilute barium is introduced. This technique is useful where there is suspicion of obstruction, to evaluate the strictures. [\*] Barium enema – patients are given a low-fibre diet for 3 days and the colon thoroughly cleansed with oral laxative preparations. Barium and air are blown (insufflated) via a rectal catheter and double-contrast views are obtained of the entire colon.

Answer 12

[\*] Does not require radiation and is best for fluid-filled lesions. Use of sound waves to generate image (usually 2-18 MHz) [\*] Thickened bowel is visualized without mucosal detail. [\*] In acute abdomen, it can be used to diagnose acute cholecystitis, gallstones, aortic aneurysms or appendicitis. [\*] Cheap compared to CT and MRI [\*] Portable [\*] Highly user dependent [\*] Can be used to determine if a patient has Gallstones, or to see if the common bile duct is dilated (an indicator that there is an impacted gallstone in the duct). [\*] Abdominal ultrasound scan can also view the Liver and portal vein, even the Appendix. These scans are often difficult to interpret and the usefulness of a scan is often down to who is doing and interpreting the scan.

Answer 13

[\*] Computed Tomography: This technique demonstrates excellent definition of the anatomy. It can detect thickened bowel wall and gives god visualization of the mesentery, the retroperitoneal structures and the aorta. It can detect perforated viscus, subdiaphragmatic abscesses, extraluminal abscesses in appendicitis and divericulitis. Contrast extravasated from the gut lumen, as well as free air, can be detected. [\*] Magnetic Resonance Imaging: this technique has the advantage of using no ionising radiation. It is particularly useful in the evaluation of abscesses and fistulae in the perianal region. It is commonly used in hepatobiliary and pancreatic diseases.

Answer 14

[\*] This technique is to demonstrate the GI vascular system following puncture, catheterization and injection of a radio-opaque contrast medium into a blood vessel. This is useful for both bleeding and ischaemia. Various modalities are used to capture the images [\*] Isotope studies: Limited use now that CT and MRI are available. An intravenous isotope spreads throughout the bloodstream and soon dissipates into the tissues producing only a faint background on a gamma-camera. Active bleeding at a sufficient rate (from an ulcerated Meckel’s diverticulum or tiny colonic vascular malformation) produces a small pool of blood before the isotope leaves the bloodstream. [\*] The pool of isotope produces a patch of gamma-activity that may be picked up by the camera.

Answer 15

[\*] Abdominal X-Ray Features * Stomach * Small and Large Bowel * Soft tissues: liver, spleen, kidneys, psoas muscles, bladder, lung bases * Bones [\*] Any part of a hollow tube is visible on an X-ray if it is filled with gas (low density gas acts as a contrast) [\*] Fully fluid-filled lumens are not visible. [\*] You can visualize the stomach (if gas-filled) but most commonly an AXR is used to visualize the small bowel . [\*] GO OVER THE IMAGES IN BOTH LECTURES AND RADIOLOGYMASTERCLASS

Answer 16

[\*] Acute abdominal pain (not a true indication though) [\*] Small or large bowel obstruction [\*] Acute exacerbation of IBD [\*] Renal colic – however not all renal calculi can be seen on an AXR.

Answer 17

[\*] The small bowel: usually occupies a central position on the Abdominal X-ray and can display its circular folds ‘Valvulae comniventes’ which appear as lines that appear to cross the whole of the bowel lumen. Often not seen due to fast transit time. [\*] The large bowel: in contrast to the small bowel, this usually occupies a more peripheral position on the abdominal X-ray. It is often possible to see the Haustra on the X-ray which appear as incomplete lines going across the lumen. [\*] Transverse colon can hang down to the pelvis and is longer in females. Sigmid colon can also loop and is long. [\*] Faeces can also appear on the X-ray and this can look like clouds in the lumen – helps make large bowel visible.

Answer 18

[\*] Abnormal Gas Patterns on Abdominal X-Ray * Small and large bowel obstruction can be noted and follow the rule of 3/6/9 * The small bowel is said to be dilated when it is greater than 3cm diameter * The large bowel when it is greater than 6cm * The caecum (when the ileocaecal valve is working) is said to be dilated when it is greater than 9cm. When the ileocaecal value is competent, backflow of faeces and gas cannot occur so if there is an obstruction e.g. due to a malignancy, the faeces and gas can build up – patient requires surgery urgently. If the ileocaecal value is incompetent, the buildup of faeces in the small bowel leads to appearance of small dilated loops on an AXR. * This only applies when the X-ray shown is to scale!

Answer 19

* Small bowel obstruction usually presents with vomiting (early) and mild distension * Absolute constipation (not passing anything per rectum, even flatus) is a late feature. * You vomit early simply because the obstruction is nearer the mouth than a large bowel obstruction. For the same reason constipation is a late feature in small bowel obstruction. * There will be colicky pain that presents every 2-3 minutes.

Answer 20

* Adhesions (most common cause – e.g. after removal of gallbladder) * Hernias – Inguinal, Femoral, Incisional * Tumours * Inflammation

Answer 21

* Abdominal pain and distension with constipation as an early feature (nothing can pass into the rectum and out) * The pain is also colicky but not as frequent as small bowel obstruction (every 10-15 minutes). * Vomiting is a late feature of large bowel obstruction (it has further to travel to the mouth) and can be faeculant. [\*] Causes of Large Bowel Obstruction * Colorectal carcinoma * Diverticular stricture * Hernia * Volvulus * Pseudo-obstruction

Answer 22

* This is when a viscera twists around itself or more commonly when it twists around its mesentery. * Most common is a Sigmoid volvulus or more rarely Caecal volvulus * When this twisting occurs the enclosed loop of bowel dilates and is at risk of perforating or cutting of its blood supply (which runs in the mesentery) – potential venous occlusion. * The enclosed bowel loop dilates and there is risk of perforation and ischaemia (due to venous occlusion leading to decreased perfusion) * Sigmoid volvulus common, caecal uncommon * NB: not expected to interpret a volvulus on an abdominal X-ray

Answer 23

* Pancreatitis (chronic) * Aneurysms with calcification * Nodes * Bones * Artifact * Foreign body * Kidney stones * Organs/masses

Answer 24

* Mucosal thickening * Featureless colon * Bowel wall oedema – leading to thumb-printing appearance (oedematous, thickened haustra – most common cause is UC) [\*] Toxic Megacolon * Acute deterioration with ulcerative colitis or colitis * Colonic dilation * Oedema pseoudopolyps * Occasionally need surgical whole colon removal [\*] Lead Pipe Colon * Featureless colon * Loss of haustra due to chronic inflammation * Seen in chronic UC

Answer 25

[\*] Perforation: an erect CXR can be useful in diagnosing perforated bowel. This can be caused by: * Peptic ulcer * Diverticular disease * Tumour * Obstruction * Trauma * Iatrogenic [\*] The CXR needs to be erect because you are looking for the diaphragm to be elevated away from any other viscera (the liver on the right) by the presence of air/gas in the peritoneal cavity. [\*] The air/gas will rise to the top of the cavity and so the patient needs to be sat up for 10 minutes prior to the X-ray to ensure this happens. [\*] The peritoneal cavity only normally contains a small amount of fluid, so the presence of air/gas is abnormal and could be the result of a perforated bowel.

Answer 26

[\*] Abdominal CT: * High dose radiation * Good spatial resolution (poor contrast resolution vs MRI) * Use of IV or oral/rectal contrast * Can be done in a variety of anatomical planes * Quick [\*] MRI * No radiation * Good spatial and contrast resolution * Time consuming [\*] Magnetic Resonance Cholangio-Pancreatogram (MRCP) is an MRI scan that can visualize the Gallbladder and biliary tree [\*] REVISE LECTURE SLIDES, RADIOLOGY MASTERCLASS AND LOOK ON NETANATOMY!!

Answer 27

[\*] Endoscopic ultrasound can be used to stage oesophageal cancer – can determine whether patient needs surgery or not [\*] GI angiography can be used to detect bleeding ulcers [\*] GI stenting for oesophageal carcinomas and colorectal cancer – especially when patients inoperable tumours [\*] Biliary intervention – placement of catheters in the biliary system to bypass biliary obstructions and decompress the biliary system. Also placement of permanent indwelling biliary stents. [\*] Radiologically inserted gastrostomy – placement of a feeding tube percutaneously into the stomach and/or jejunum [\*] Cholecystostomy – placement of a tube into the gallbladder to remove infected bile in patients with cholecystitis who are free to frail or too sick or undergo surgery [\*] GO OVER THE IMAGING LECTURES!!!

Session 10 Flashcards

(51 cards)