Gastrointestinal (Part 1)

Your answer	Choice	Correct?	Score	Feedback	Correct answer
	A sleeve gastrectomy, with gastrojejunostomy and jejunojejunostomy		0
	Pancreaticoduodenectomy		0
	Gastrojejunostomy		0
	Hepaticojejunostomy		0
	A gastric pouch, with a gastrojejunostomy and jejunojejunostomy		0

Bariatric operations can be distinguished into restrictive, malabsorptive or combined. A restrictive operation is one restricting intake, such as a gastric band. Malabdorptive operations primarily reduce the guts ability to absorb nutrients, and an example of this is a Biliopancreatic Diversion. The most common example of a combined operation would be a Roux-en-Y gastric bypass.

In a Roux-en-y gastric bypass, the stomach is divided proximally, creating a small gastric pouch. The jejunum is then divided, and the distal end is brought up to join the gastric pouch, creating a gastrojejunostomy. Food content now passes through the small gastric pouch directly into the jejunum. The remianing proximal free end of the jejunum is then anastamosed to the distal jejunum, creating a jejunojejunostomy. This means the gastric and pancreatic secretions will join the ingested food further down the small bowel. The common limb (where ingested contets and digestive juices travel together) is long, and so this operation is mildly malabsorbative.

In contrast, a much less common operation is the Biliopancreatic Diversion with Duodenal Switch. This is a similar operation to the Roux-en-Y gastric bypass, but it excludes a lot more of the small intestine, meaning its malabsorbative effect is much greater. In this case, the stomach is not divided, but rather a sleeve gastrectomy is performed, where the greater curve is removed, reducing the stomachs overall capacity. This maintains the normal gastric outflow into the duodenum. The proximal duodenum is then divided and connected to the distal jejunum. The biliary-pancreatic limb is now connected to the distal jejunum, but because this is done more distally, the common limb in this operation is very short when compared with a Roux-en-Y bypass, meaning there is a much bigger malabsorbative effect.

Hepaticojejunostomies are where the biliary system is anastamosed to the jejunum to bypass a stricture/injury/malignancy in the distal ducts. A Pancreaticoduodenectomy (Whipple procedure), is often used for removing malignancies in the pancreatic head.

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	Nothing - Normal Liver		0
	Hepatic Steatosis		0
	Haemochromatosis		0
	Hepatitis		0
	Wilson’s Disease		0

These MRI findings are typical of Haemochromatosis. Iron deposition produces susceptibility artefact reducing signal on all MRI sequences, but especially T2 and Gradient Echo. This makes the liver look darker than skeletal muscle. In a normal liver the signal on in-phase and out-of-phase sequences is fairly equivalent. In diffuse hepatic steatosis (fatty infiltration), there is signal drop out on the out-of-phase sequences. The opposite is true for haemochromatosis, where the in-phase sequences (which are more susceprtible to T2* effects) demonstrate significant signal drop out when compared with the out-of-phase sequences.

Copper deposition in Wilson’s disease does not have a ferro-magnetic affect, and so does not cause signal drop-out. Acute hepatitis would not have this effect on these MRI sequences.

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	Acute myocardial infarction		0
	Open angle glaucoma		0
	Hyperthyroidism		0
	Prostatic enlargement		0
	Ulcerative colitis		0

Acute MI, Open angle glaucoma, Hyperthyroidism and Ulceratice Colitis are all classed as cautions.

Prostatic enlargement is a contraindication. Myasthenia gravis, toxic megacolon, paralytic ileus, closed angle glaucoma and pyloric stenosis are also contraindications.

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	Carcinoid		0
	FNH		0
	Phaeochromocytoma		0
	Pituitary Adenoma		0
	Medullary Thyroid Tumour		0

Carney’s triad is one of the Multiple Endocrine Neoplasia syndromes, and it is characterised by 3 tumours: GIST, Pulmonary Hamartomas (chondromas), and extra-adrenal phaeochromocytomas (also referred to as extra-adrenal paragangliogliomas). The calcification described within the lung nodule is characteristic of a pulmonary hamartoma.

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	Serous Cystadenoma		0
	Mucious Cystadenoma		0
	IPMT (Intraductal Papillary Mucinous Neoplasm)		0
	Pseudocyst		0
	Adenocarcinoma		0

Pancreatic pseudocysts are the most common cystic pancreatic lesion, and should always be considered in a patient with a history of pancreatitis (or the causes thereof). On CT they usually appear cystic with an enhancing wall, and can be very large. On MRI they are typically of homogenous T2 signal, and on MRI the presence of layering or dependent debris is highly specific. 50% of pseudocysts maintain a connection with the pancreatic duct and are therefore difficult to treat, as fluid can reaccumulate. Indications for treatment are infection, or mass effect from their potentially large size.

Worrying features which would point towards the other differentials are; internal septations, calcifications, central scars, a dilated pancreatic duct, solid enhancing components or an irregularly thickened wall. Mucinous cystic neoplasms (of which mucinous cystadenoma is a form) occur almost exclusively in women (99%).

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	Prominent arterial centrifugal filling		0
	Washout of contrast in the portal venous phase		0
	Early contrast enhancement around the periphery of the lesion		0
	Prominent arterial centripetal filling		0
	Heterogeneous enhancement in the delayed phase		0

Although contrast enhanced ultrasound may not currently be widely used, the principles of the enhancement patterns still apply. FNH is usually discovered incidentally, and is thought to represent benign proliferation of normal hepatocytes around a pre-existing AVM. This means that the lesion gets its blood supply from the hepatic artery, and therefore demonstrates arterial enhancement. This enhancement is classically centrifugal (from centre to periphery), starting within a central scar and radiating outwards through stellate arteries. There is often homogenous sustained enhancement of the mass in the portal venous phase (which on CT makes the lesion look isodense in the portal venous phase.) In young patients the differential is often that of an adenoma. Centripetal or mixed arterial enhancement is more common in adenoma. Adenomas also have a more mixed appearance in the portal venous phase, and can washout or show sustained enhancement.

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	Abdominoperineal Resection (AP resection)		0
	Anterior Resection		0
	Sigmoid colectomy		0
	Extended left hemicolectomy		0
	Hartmann Procedure		0

The Hartmann procedure involves resection of the rectosigmoid colon, with formation of a distal colostomy, and a rectal or colonic stump. This procedure is often performed instead of a primary anastamosis in patients who are at high risk of a leak. It allows time for the bowel to heal, before a ‘takedown’ is performed and the two ends of the bowel are anastomosed.

An AP resection involves removal of part of the sigmoid colon, the rectum and the anus, with formation of a permanent colostomy. An anterior resection involves resection of the recto-sigmoid colon, with anastomosis of the descending colon and rectum. A ‘low’ anterior resection involves resecting to a point further down the rectum. A sigmoid colectomy is where part or all of the sigmoid is removed, and the two ends are anastomosed. A left hemicolectomy is where the descending colon is removed and the transverse colon and sigmoid colon are anastomosed. The term ‘extended’ left and right hemicolectomy refer to where part of the transverse colon is also resected.

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	No follow-up		0
	Follow-up ultrasound in 3 months		0
	Follow-up ultrasound in 6 months		0
	Cross sectional imaging		0
	Referral for cholecystectomy		0

Gallbladder polyps are common (5% of people), and typically appear as non-shadowing immobile lesions attached to the gallbladder wall.

Although individual institutional practices may vary, a retrospective analysis in Radiology from 2011 did not find cancer in polyps less than 6mm. Their conclusion was that these small lesions should be left without follow-up. The presence of more than one lesion (as in this case) reduces the risk of malignancy even further. Single polyps that are larger than this should probably be followed up, and those greater than a centimetre may want to be considered for cholecystectomy.

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	Haemangioma		0
	Metastatic deposit		0
	Focal fatty sparing		0
	Focal hepatic steatosis		0
	Adenoma		0

Focal hepatic steatosis (focal fat deposition in the liver) is common, and is thought to be due to variations in the vascular supply to different areas of the liver. This is a classic location for such a finding. Its imaging appearances are also characteristic of fat, being hyperechoic on ultrasound and low attenuation on CT.

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	T2		0
	T1		0
	STIR		0
	T1 with contrast enhancement		0
	T1 with IV contrast enhancement and fat suppression		0

The best sequence for assessing a primary rectal tumour on MRI is currently high resolution T2 weighted imaging, orthogonal to the tumour plane. This sequence allows you to differentiate between tumours confined within the rectal wall, and those that extend beyond the muscularis propria.

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	Bechet Syndrome		0
	Polyarteritis Nodosa		0
	Microscopic Polyangitis		0
	Takayasu Arteritis		0
	Fibromuscular Dysplasia		0

Takayasu’s generally affects the large and medium vessels such as the aorta and its major branches. It has a strong female predominance (9:1) and a young age of onset. On CT there is wall thickening and enhancement early on, which progresses to stenosis/occlusion. There can be aneurysmal dilatation, and in the late stages the distal aorta can appear narrowed.

Polyarteritis Nodosa is a medium vessel vasculitis, with a characteristic finding of multiple aneurysm formation. These form after segmental weakening of the arterial wall due to inflammation. The symptoms are usually due to ischaemia and infarction of the affected organ. The renal arteries are most commonly involved, classically with multiple microaneurysms identified the kidney on angiography.

Fibromuscular dysplasia is a non-inflammatory vascular disease which commonly affects the renal arteries. It causes intermittent arterial stenosis and aneurysmal dilatation which gives a ‘string of beads’ appearance. It responds very well to angioplasty. Microscopic polyangitis is a small vessel vasculitis, and on angiography the tiny microaneurysms are not typically seen. Bechet’s is a vasculitis affecting multiple organ systems, but classically with a triad of oral and genital ulceration and uveitis. When it affects the GI tract, it causes large ulcerations, particularly in the terminal ileum.

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	Hepatic Artery		0
	Hepatic Veins		0
	Portal Vein		0
	Bile ducts		0
	Lymphatic drainage to the liver		0

The pattern of inhomegnous mottling of the liver, with reduced peripheral enhancement and caudate enlargement is typical of Budd-Chiari Syndrome (Hepatic vein occlusion). Clinically it can present acutely with abdominal pain, hepatomegaly and ascites, however with most patients it is slower onset, and can be painless. The lack of venous drainage causes the liver to become congested, which causes reduced (or reversed) portal venous flow. This means peripheral enhancement is reduced. The caudate lobe is often spared as it has seperate anastamoses to the IVC. Obviously the finding to look for on imaging is occlusion to the hepatic veins/IVC.

The other named structures, if occluded, would not typically give this assortment of findings.

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	Menetrier disease		0
	Mirrizi Syndrome		0
	Bouveret syndrome		0
	Gastric Lymphoma		0
	Zollinger-Ellison Syndrome		0

This is a case of Menetrier disease. This is a rare form of hypertrophic gastropathy, characterised by thickened gastric folds on imaging. It results in hyperproduciton of mucous with a resulting protein loosing enteropathy, as well as and hypo/achlorhydria (low or absent stomach acid production). The patient often has oedema, ascites and pleural effusions.

Gastric lymphoma can also present with thickened rugal folds, but would not classically result in a protein losing enteropathy or hypochlorhydria. Zollinger-Ellison syndrome is where a gastrinoma outside the stomach produces gastrin which increases stomach acid production (not reduces it). This condition can be associated with thickened gastric folds.

Bouveret syndrome is where a gallstone erodes through the gallladder and into the duodenum, where it lodges and causes obstruction. It most commonly occurs in elderly women. Mirrizi syndrome is where a large gallstone within the gallbladder causes extrinsic compression of the common bile duct.

Your answer	Choice	Correct?	Score	Feedback	Correct answer
	Takayasu Arteritis		0
	Polyarteritis Nodosa		0
	Microscopic Polyangitis		0
	Bechet Syndrome		0
	Fibromuscular Dysplasia		0

Polyarteritis Nodosa is a medium vessel vasculitis, with a characteristic finding of multiple aneurysm formation. These form after segmental weakening of the arterial wall due to inflammation. The symptoms are usually due to ischaemia and infarction of the affected organ. The renal arteries are most commonly involved, classically with multiple microaneurysms identified the kidney on angiography. As in this case, the GI tract is also commonly affected.

Takayasu’s generally affects the large and medium vessels such as the aorta and its major branches. It has a strong female predominance (9:1) and a young age of onset. On CT there is wall thickening and enhancement early on, which progresses to stenosis/occlusion. There can be aneurysmal dilatation, and in the late stages the distal aorta can appear narrowed.

Fibromuscular dysplasia is a non-inflammatory vascular disease which commonly affects the renal arteries. It causes intermittent arterial stenosis and aneurysmal dilatation which gives a ‘string of beads’ appearance. It responds very well to angioplasty. Microscopic polyangitis is a small vessel vasculitis, and on angiography the tiny microaneurysms are not typically seen. Bechet’s is a vasculitis affecting multiple organ systems, but classically with a triad of oral and genital ulceration and uveitis. When it affects the GI tract, it causes large ulcerations, particularly in the terminal ileum.

Your answer	Choice	Correct?	Score	Feedback	Correct answer
	Focal Nodular Hyperplasia		0
	Adenoma		0
	HCC		0
	Haemangioma		0
	Focal steatosis		0

This is most likely to be an adenoma. They are the most common focal liver lesion in young women who are on the oral contraceptive pill. They are usually hypoechoic on ultrasound, and their enhancement is variable (but tends towards centripetal or mixed filling pattern). FNH is another possibility, but the enhancement pattern is not characteristic, and the presence of the contraceptive pill makes adenoma more likely. HCC is unlikely in this age-group. Haemangiomas are usually hyperechoic on ultrasound (90%), though do often enhance from the outside inwards. Focal fat would also be hyperechoic, and would not enhance.