23.7b ) MRI Superior to CT in identifying intraductal lesions and their extent owing to its greater soft tissue contrast resolution. ERCP \200 ERCP may establish the diagnosis by obtain brushings, and intraductal biopsies. Therapeutic procedures, such as stent insertion to relieve biliary obstruction ma y be performed. EUS is sensitive for assessing loco-regional lymphadenopathy and biopsy. PET PET remains an emerging technique for staging cholangiocarcinoma. SUBASH KC/NMC-15TH/2014 CHOLANGIOCARCINOMA 371 Information for the radiologist Duration of symptoms with emphasis on features suggestive o f malignancy. Severity of obstructive jaundice is useful (degree of derangement LFTs). Sign s suggestive of cholangitis (raised WCC, CRP) should prompt urgent discussion with a view t o ERCP. (a) (b) Fig. 23.7 showing dilated intrahepatic ducts, secondary to a \201 lling defect within the duct, washings at ERCP con \201 rmed cholangiocarcinoma. a) Ultrasound image showing dilated intrahepatic ducts. b) Axial CT SUBASH KC/NMC-15TH/2014 372 CHAPTER 23 Gastrointestinal conditions Pancreatic cancer \200 Incidence: 11 \200 Risk factors include smoking, age, chronic pa ncreatitis, diabetes th commonest cancer in UK and rising. mellitus, obesity. 90 % are adenocarcinomas arising from pancreatic duct epithelium. 5-year survival <2 % . Clinical presentation Often present with advanced disease. 80 % of pancreatic tumors arise in the pancreatic head; classically present with painless obstructive jaundice (Courvoisier \200\231s law \200\224 if palpable gallbladder jaundice is unlikely due to gall- stones). Constitutional symptoms are common. Late onset diabetes and pancreatitis are recognized bu t infrequent presentations. TNM staging \200 T1: tumor limited to pancreas \211 2cm. \200 T2: tumor limited to pa ncreas > 2cm. \200 T3: tumor extends beyond the pancreas without involvement of the coeliac axis or superior mesenteric artery. T4: tumor involvement of the coeliac axis or superior mesenteric artery. N0: no regional lymph node metastasis. \200 N1: regional lymph node metastasis. \200 M0 : no distant spread. \200 M1: distant metastasis. Imaging Ultrasound Primary investigation in obstructive jaundice. The liver, biliary tree, and gallbladder are assessed for metastases, biliary duct dilatation, and for the exclusion of gallstones respectively. Views of the pancreas often limited. CT (Fig. Triple-phase CT of the pancreas is the modality of choice for detecting and stagin g pancreatic cancer. Useful in assessment of resectability (local invasion of major vascula r structures). Accurately identi \201 es loco-regional/ distant lymphadenopathy and metast atic disease. 23.8 ) MRI MRI similar performance as CT, better at characterization of small lesions and assessin g resectability. EUS Bene \201 t of enabling biopsy along with tumor staging. ERCP For stent insertion, brushings and cytology. PET Useful for lesion detection when CT not identi \201 ed mass, and detection of occult m etastases. SUBASH KC/NMC-15TH/2014 PANCREATIC CANCER 373 Information for the radiologist Clinical history and duration of symptoms are important wit h emphasis on features suggestive of malignancy. An indicator of the severity of obstruc- t ive jaundice is useful. Symptoms/signs and biochemical parameters (raised WCC, CRP) suggest ive of cholangitis should prompt urgent discussion with a view to ERCP. Fig. 23.8 \200\230double duct \200\231 dilatation, i.e. dilatation of the intra- and extra hepatic biliary tree, and pancreatic duct, secondary to a large low attenuation mass within the pancreas (arrowed). Coronal CT image from a patient with pancreatic cancer. The CT shows SUBASH KC/NMC-15TH/2014 374 CHAPTER 23 Gastrointestinal conditions Achalasia, hiatus hernia, and re \202 ux \200 Achalasia: oesophageal motility disorder w ith failure of relaxation of the lower oesophageal sphincter and disordered peristalsis. Hiatus hernia: protrusion of stomach into the thoracic cavity. Two types; sliding (commonest) and rolling. Gastro-oesophageal re \202 ux disease (GORD): range of symptoms caused by re \202 ux of g astric acid into the lower esophagus. Often secondary to lower oesophageal sphincter incomp etence. Clinical presentation Dif \201 cult to discriminate reliably between these diagnoses owing to cross- over in symptomatology. Heartburn, acid re \202 ux often worse after meals and on lying \202 at, dysphagia and chest pain are common. Dysphagia to solids/liquids with r egurgitation of food is suggestive of achalasia. Imaging Several imaging techniques available to aid diagnosis including endoscopy, barium s tudies, and radionuclide techniques. Oesophageal manometry and pH measurements are physiolo gical investigations, the latter of which is the gold standard for diagnosing oesophageal m otility disorders but is limited by invasiveness, time-consumption, and lack of availabilit y. Plain \201 lm Often incidental \201 nding. Retrocardiac soft tissue density suggestive of a hiatus hernia. Dilated esophagus may be seen in achalasia. air- \202 uid levels are Fluoroscopy (Fig. Double-contrast barium swallow is sensitive for investigation of oesopha- geal disorders and superior to endoscopy in identifying motility disorders. Accurate at id entifying achalasia ( \200\230bird \200\231s beak \200\231 appearance), classifying hernias and visualization of re \202 ux of barium. 23.9 ) Nuclear medicine Rarely used in assessment of motility disorders and GORD. Ingestion of 99m Tc radiolabelled foods/liquids. Information for the radiologist Features suggestive of malignancy, such as progressive dysp hagia, anorexia, weight loss, and anemia is essential. SUBASH KC/NMC-15TH/2014 ACHALASIA, HIATUS HERNIA, AND REFLUX 375 Fig. 23.9 tapering to a \200\230bird \200\231s beak \200\231 narrowing at the gastro-oesop hageal junction. Double-contrast swallow shows abnormal dilatation of the esophagus, SUBASH KC/NMC-15TH/2014 376 CHAPTER 23 Gastrointestinal conditions Appendicitis \200 Common cause of acute abdominal pain. \200 May require emergency surg ery to prevent complications of perforation and peritonitis. Clinical presentation \200 Highest incidence age 10 \200\22319 years. \200 Classical pr esentation (<50 % ) central abdominal pain migrating to right iliac fossa, accompanied by fever, anorexia, nausea, and vomiting. Presentation in the very young and the elderly may be less typical with a rapidly progressing course. Clinical signs: rebound tenderness, right iliac fossa tenderness (McBurney \200\231s point), Rovsing \200\231s sign (right iliac fossa pain on palpation of left iliac fossa). Imaging Plain \201 lm \200 Appendicolith seen in <10 % of cases. \200 Non-speci \201 c features include lumbar scoliosis concave to the right, loss of the right pro-peritoneal fat stripe or psoas shadow, and distal small bowel obstruction. Ultrasound \200 High-frequency linear probe using graded compression. \200 Highly opera tor dependant, most useful in the young/thin. \200 Classic \201 ndings are of a blind e nding, non-compressible tubular structure with diameter > 6mm and hyperaemia. Additional \201 ndings may include localized \202 uid collection or abscess and an appendicolith. Retro-caecal appendix may be dif \201 cult to identify. CT (Fig. Considered by many to be the gold standard investigation but used with caution in children and women of childbearing age due to radiation risks. CT features include a disten ded, enhancing appendix measuring diameter, lack of oral contrast in the appendiceal lumen and stranding of the peri-appendiceal fat. 23.10 ) > 6mm in Information for the radiologist \200 Clinical features of pyrexia and raised in \202 amm atory markers. \200 In females: last menstrual period and any gynecological symptoms. SUBASH KC/NMC-15TH/2014 APPENDICITIS 377 Fig. 23.10 appendicolith within. Note the peri-appendiceal in \202 ammatory changes. Coronal CT showing thickening of the wall of the appendix, and calci \201 ed SUBASH KC/NMC-15TH/2014 378 CHAPTER 23 Gastrointestinal conditions Cholecystitis/cholangitis \200 Gallstones are extremely common, especially in females. \200 Acute cholecystitis is in \202 ammation of the gallbladder secondary to gallstone impaction. Acute cholangitis is in \202 ammation of the biliary ducts secondary to ascending infection (Escherichia coli , Klebsiella spp., presence of biliary obstruction, a nd a potentially fatal condition. Enterococci) in the Clinical presentation \200 Acute cholecystitis: right upper quadrant pain (Murphy \200 \231s sign) right shoulder tip pain. Nausea and vomiting. Acute cholangitis: right upper quadrant pain, obstructive jaundice and rigors (Charcot \200\231s triad). Nausea and vomiting. Severe systemic upset not infrequent . Grossly deranged LFTs with high bilirubin and raised CRP/ESR. Imaging Ultrasound (Fig. Initial investigation for suspected gallbladder and biliary pathol ogy. Excellent for identi \201 cation of gallstones and con \201 rmation of cholecystitis and the presence of biliary duct dilatation. 23.11a ) MRI (MRCP) Non-invasive evaluation of biliary duct dilatation, strictures and intraductal \201 lling defects. Reserved for cases when clinical suspicion is high for gall- stone rel ated pathology but initial investigations are equivocal. Fluoroscopy (ERCP) Optimal therapeutic option in acute cholangitis. Assessment of biliary t ree and identi \201 cation of cause of obstruction and treatment with sphincter- otomy and stent insertion to relieve obstruction. CT (Fig. Reserved for atypical cases or when complications are suspected such as emphysemat ous cholecystitis. 23.11b ) Information for the radiologist Clinical history, relevant examination \201 ndings and su pportive biochemical \201 ndings (LFTs, raised WCC, CRP/ESR) are essential. Features sugg estive of cholangitis warrant urgent discussion with a view to ERCP. SUBASH KC/NMC-15TH/2014 CHOLECYSTITIS/CHOLANGITIS 379 (a) (b) Fig. 23.11 dependent stones (arrow), in a patient with marked tenderness (Murphy \200\231s sign positive). b) Axial CT of another patient showing thickened gall bladder wall, with ga s within (arrow), in keeping with emphysematous cholecystitis. Marked surrounding in \202 ammatory changes of the fat, and ascites around the liver. a) Ultrasound showing thickened gallbladder wall (asterisk), and SUBASH KC/NMC-15TH/2014 380 CHAPTER 23 Gastrointestinal conditions Stomach/duodenal ulceration Ulceration occurring within the acid environment of the stomach or duo- denum. Common in elderly. Duodenal ulcers Helicobacter pylori smoking, stress. > gastric ulcers. Risk factors: , drugs (aspirin, NSAIDs, steroids, bisphosphonate), Clinical presentation Gastric ulcers classically present with intermittent, burning epigast ric pain occurring shortly after meals with minimal relief by food or ant- acids. Duodenal ulceration typically causes pain before meals and at night, relieved by bland foods and alk alis such as milk. However, there is much symptom overlap and often ulcer type differentiat ion cannot be made on history alone. ALARM symptoms: haematemesis; swallowing dif \201 culties. anemia; loss weight; anorexia; recent onset; melaena/ Imaging OGD is the investigation of choice for diagnosing peptic ulcer disease. In addition to direct visualization, tissue biopsies can be taken to assess for H. pylori infection an d malignancy. Therapeutic intervention for bleeding ulcers is also commonly performed. Plain \201 lm Pneumoperitoneum if perforation has occurred. CT (Fig. Used for identi \201 cation of complications, such as abscess formation, detec- t ion of free gas. 23.12 ) Fluoroscopy Traditional test for ulceration was a barium study, but this has been super- se ded by endoscopy, which allows biopsy and direct visualization. Information for the radiologist A clear, concise history outlining pertinent risk factors, i.e. relevant medi- cations, concerning features such as anorexia or weight loss and sup- p ortive examination \201 ndings or biochemical derangement, i.e. microcytic anemia is idea l. In the acute situation, if a viscus perforation is suspected, clinical history and exami nation \201 ndings, relevant blood tests, i.e. serum lactate and plain radiograph \201 ndings are essential. SUBASH KC/NMC-15TH/2014 STOMACH/DUODENAL ULCERATION 381 Fig. 23.12 Coronal CT showing thickening of the distal stomach (arrow) with surrounding in \202 ammatory change, in a patient with a locally perforated peptic ulcer. SUBASH KC/NMC-15TH/2014 382 CHAPTER 23 Gastrointestinal conditions Crohn \200\231s disease Chronic recurrent in \202 ammatory condition of the GI tract of un known etiology, characterized by transmural in \202 ammation. Lesions may occur anywhere i n the GI tract but are most common in the small bowel (espe- cially the terminal ileum) and the colon. Discontinuous and asymmetric involvement is characteristic. The earliest pathol ogical feature is apthoid ulceration which progresses to frank ulceration. Complications in clude \201 stula formation, abscesses, and strictures. It may also cause complica- tions outside of the GI tract. Clinical presentation Peak incidence 15 \200\22325 years. A 2 age group. Onset may be insid ious. Chronic diarrhea which may be bloody, abdominal pain and weight loss are common prese nting symptoms. nd peak has been reported in the 50 \200\22380-year Complications \200 Hepatobiliary: hepatic steatosis, gallstones, primary sclerosing cholangitis. Pancreatitis. \200 Urinary tract: nephrolithiasis, enterovesical \201 stula. \200 Mus culoskeletal: arthritis. Imaging Imaging was traditionally by contrast studies (DCBE and SBFT), however these have b een replaced by non-ionizing investigations magnetic resonance enterography (MRE) and ultra sound. Ultrasound Thickened, hyperaemic small bowel loops, most useful in imaging young thin patie nts. MRE (Fig. Demonstrates disease distribution, activity, response to treatment, enteric and e xtra-enteric complications, e.g. perianal \201 stulae. 23.13 ) CT Used in acute presentations to detect complications, disease extent and detection of ext ra-enteric complications. Information for the radiologist Due to the nature of the disease, patients with Crohn \200 \231s disease are likely to undergo repeated examinations in the course of their treatment, and as a result investigations should only be performed when they will help guide manageme nt. SUBASH KC/NMC-15TH/2014 CROHN \200\231S DISEASE 383 (a) (b) Fig. 23.13 abnormal pelvic small bowel showing wall thickening, mucosal enhancement and eng orged vessels in keeping with active disease. a) Axial and b) coronal images from a MRE study. There is a loop of SUBASH KC/NMC-15TH/2014 384 CHAPTER 23 Gastrointestinal conditions Ulcerative colitis Relapsing and remitting continuous non-transmural in \202 ammation of t he rectum (proctitis 50 % ) and colon (left-sided 30 may be associated \200\230backwash ileitis \200\231 (in \202 ammation of the terminal ileum). Histological diagnosis from end oscopic biopsy. % ; pancolitis 20 % ), Clinical presentation \200 Gradual onset diarrhea. Abdominal pain is common. Systemic symptoms during attacks. Extra-enteric signs seen at imaging: arthritis, sacro-iliitis, ankylosing spondylitis, fatty liver, PSC, cholangiocarcinoma, amyloidosis. Complications: perforation, bleeding, toxic megacolon, venous thrombosis, colonic cancer (risk 15 % with pancolitis for 20 years). Imaging Imaging used in diagnosis, monitoring therapy response or complications. Plain \201 lm (Fig. Abdominal X-ray: acute setting only, looking for perforation, abnorma l dilatation (toxic megacolon > 6cm), thickening of bowel wall and thumb- printing (mucosal oedema). 23.14 ) CT In acute setting may be used to con \201 rm colitis and extent of disease. May help to differentiate causes of colitis. Demonstration of complications. MRI Used in some centers as an alternative to CT for imaging the colon. Useful in investiga ting speci \201 c complications, e.g. primary sclerosing cholangitis/ cholangiocarcinoma, sacro-iliitis. In pancolitis with an equivocal biopsy MRE can be used to help differentiate UC from Crohn \200\231s disease. Fluoroscopy DCBE contraindicated in the acute setting due to risk of perforation! Information for the radiologist \200 Clinical symptoms if primary presentation \200\224 therefore choice of most appropriate radiological investigation can be made. Information on any biopsy results. Relevant past medical history, e.g. coeliac disease. SUBASH KC/NMC-15TH/2014 ULCERATIVE COLITIS 385 SUBASH KC/NMC-15TH/2014 Fig. 23.14 Abdominal radiograph showing grossly thickened wall of the transverse colon, wit h characteristic \200\230thumb-printing \200\231. SUBASH KC/NMC-15TH/2014 386 CHAPTER 23 Gastrointestinal conditions Infective colitis Etiology: bacterial (Amoebiasis) and viral (herpes and in UK due to rise in foreign travel and use of broad-spectrum antibiotics (pseudomembranous colitis). (Salmonella, Shigella, Campylobacter, E. coli) , protozoal Cytomegalovirus) . Increasing incidence Clinical presentation Diarrhea, which may be bloody, non-speci \201 c abdominal pain, and pyrexia, associated with anorexia, malaise, and dehydration. Hypotension, tachycardia, and impaired renal function are indicators of severity. Imaging Stool MC&S is the investigation of choice for diagnosing infective colitis with blo od tests used to aid assessment of severity. Sigmoidoscopy/colon- oscopy are \201 rst-lin e imaging techniques, as they are more sensitive than radiological investigations for mucos al changes of ulceration and haemor- rhage, and to permit biopsy. Radiology is reserved for assessing the extent and severity of disease and to identify complications. Plain \201 lm Initial investigation for complications, e.g. colonic dilatation and toxic megacolon (fulminant colitis) or perforation. SUBASH KC/NMC-15TH/2014 CT (Fig. Disease extent can be appreciated on CT which may range from a local- ized process to a pancolitis. Toxic megacolon and colonic perforation can be accurately identi \201 ed in addition to further complications such as intra-abdominal collections and liver abscess es. 23.15 ) Ultrasound Alternative to CT for identi \201 cation of liver abscesses and performing per- cutaneous intervention. Identi \201 cation of bowel wall thickening may be possible. Information for the radiologist Stool specimen analysis is paramount. Results of additional investigations such as plain radiographs or colonoscopy. Reasons for further investiga- ti on need to be explained. Patients may need to be imaged at the end of the list due to the i nfection risk. SUBASH KC/NMC-15TH/2014 INFECTIVE COLITIS 387 Fig. 23.15 Axial CT showing diffusely thickened colon, in keeping with colitis in a patient with Clostridium dif \201 cile infection. SUBASH KC/NMC-15TH/2014 SUBASH KC/NMC-15TH/2014 388 CHAPTER 23 Gastrointestinal conditions Small bowel obstruction 20 % of acute surgical admissions. Subdivided into partial or comp lete, simple or strangulated. If not diagnosed promptly, vascular compromise can lead to bo wel ischaemia, with high mortality. The leading cause in developed countries is postoperati ve adhesions, other causes include hernia, tumor, in \202 ammatory bowel disease, and volv ulus. Clinical presentation Four cardinal features are pain, vomiting, distension and constipatio n Obstruction of bowel leads to proximal dilatation secondary to accu- mulation of gastroin testinal secretions and swallowed air. This leads to increased peristalsis both proximal an d distal to the obstruction, with initial frequent loose stools and \202 atus. Increasing small-bowel distension leads to increased intraluminal pressures. Vomiting occurs if obstr uction is proximal. Constipation occurs as normal transit of bowel contents is not possible (may be absent early). . Imaging Plain \201 lm \200 Abdominal x-ray (Fig. 23.16a ): dilated loops of small bowel ( > 2.5cm) air \202 uid levels, identi \201 ed by their central position and presence of valvula e conniventes. Gas trapped in the valvulae (string of pearls sign) may also be identi \201 ed. Depending on degree of obstruction, there may be paucity of gas throughout the colon. Cause/complications of SBO may be identi \201 ed, e.g. hernia, perforation, or ischaemia. SUBASH KC/NMC-15TH/2014 Erect CXR: if there is any suspicion of perforation. CT (Fig. Con \201 rms the presence, severity and cause of obstruction. Diagnosis is by ide ntifying dilated loops of small bowel and a transition point with col- lapsed loops of dist al bowel, excluding ileus. Complications of obstruction such as ischaemia or perforation ca n be identi \201 ed. 23.16b ) Information for the radiologist \200 Relevant medical history, e.g. previous operations, hernia. \200 Any clinical evidence of developing ischaemia? SUBASH KC/NMC-15TH/2014 SMALL BOWEL OBSTRUCTION 389 (a) SUBASH KC/NMC-15TH/2014 (b) Fig. 23.16 a) Abdominal X-ray showing gas- \201 lled loops of centrally-placed, dilated sm all bowel. b) Coronal CT showing dilated \202 uid- \201 lled small bowel loops, secondar y to an obstructed left inguinal hernia (arrow). SUBASH KC/NMC-15TH/2014 390 CHAPTER 23 Gastrointestinal conditions Large bowel obstruction Obstruction may be luminal, within the bowel wall or extraluminal. Left- sided obstruction > right. Common causes include tumor, abscess, diverticular disease, volvulus, and extrinsic compression from pelvic tumor. Clinical presentation Features of obstruction: pain, vomiting, distension, and constipation . These features may vary according to the location, age, underlying pathology, or presence of ischaemia. The more distal the obstruction, the longer the interval between onset of sy mptoms and appearance of nausea and vomiting. Imaging Plain \201 lm (Fig. Supine abdominal X-ray: dilated loops of gas- \201 lled larg e bowel, recognized by their peripheral position and presence of haustral folds. In a minor ity of patients the ileocaecal valve is competent and in spite of increasing colonic pressu re, the small bowel is not distended. When the valve is incompetent, the caecum and ascendi ng colon may not be distended and there may be marked small bowel distension. 23.17a ) CT (Fig. Con \201 rms the presence of a mechanical obstruction and to look for the underly ing cause. In the presence of a tumor it may be used to plan for surgical treatment. Compli cations of obstruction such as perforation or ischaemia can also be identi \201 ed. 23.17b ) SUBASH KC/NMC-15TH/2014 Fluoroscopy Water-soluble enema can be performed to con \201 rm the presence of mechanical obstruction/exclude pseudo-obstruction/ileus, role is second line to CT. although its Information for the radiologist \200 Relevant medical history, e.g. oncological disease/p revious sigmoid volvulus. Whether there is clinical evidence of developing ischaemia. SUBASH KC/NMC-15TH/2014 LARGE BOWEL OBSTRUCTION 391 (a) SUBASH KC/NMC-15TH/2014 (b) Fig. 23.17 a) Abdominal radiograph showing dilated loops of large and small bowel, secondar y to an obstructing distal colonic tumor. b) Coronal CT showing the obstructing tumor (arro w). SUBASH KC/NMC-15TH/2014 392 CHAPTER 23 Gastrointestinal conditions Paralytic ileus and pseudo-obstruction Paralytic ileus occurs when intestinal peristalsis c eases and there is an accumulation of \202 uid and gas in the bowel, leading to non-speci \201 c dilata- tion of both small and large bowel mimicking obstruction. Causes include p ostoperative ileus, electrolyte disturbance, and peritonitis. A localized small bowel ileus affecting only 1 or 2 adjacent loops ( \200\230sentinel loops \200\231) can occur in respo nse to a local in \202 ammatory process, such as acute pancreatitis. Pseudo-obstruction refers to large bowel distention resulting from chronic impairment of mo tility. Patients are usually elderly, often on anticholinergics. The degree of colonic dist ension may be severe enough to cause caecal perforation. Surgical intervention is occasiona lly necessary. Clinical presentation Paralytic ileus and pseudo-obstruction present with abdominal distens ion, usually without pain (unlike in mechanical obstruction). Patients may or may not conti nue to pass \202 atus and stool. Imaging Plain \201 lm (Fig. In paralytic ileus, distended small and large bowel loops are seen with the degree of distension varying from local dilatation of a short length of bowe l to distension of the entire intestine. When there is generalized bowel distension, the ap pearances cannot usually be distinguished on plain radiograph alone from low grade large bo wel obstruction. 23.18a ) SUBASH KC/NMC-15TH/2014 In pseudo-obstruction, the large bowel is dilated all the way to the rectum, and the small bowel may be distended as well. The caecum may exceed the critical di ameter of 9cm when perforation is imminent. CT (Fig. This is sometimes required to exclude mechanical obstruction and to prevent unnece ssary surgery. 23.18b ) Fluoroscopy Water-soluble enema may be required to exclude mechanical obstruc- tion, but CT is usually the preferred method of investigation. Information for the radiologist \200 Presenting symptoms and signs. \200 Any recent sur gery. SUBASH KC/NMC-15TH/2014 PARALYTIC ILEUS AND PSEUDO-OBSTRUCTION 393 (a) SUBASH KC/NMC-15TH/2014 (b) Fig. 23.18 a) Abdominal X-ray showing prominent gas- \201 lled loops of small bowel, with a normal gas pattern in the large bowel, in keeping with ileus. b) Coronal CT from the same patient showing \202 uid- \201 lled loops of small bowel, with no transition point to c ollapsed bowel. Normal feces and gas within the large bowel. This is in keeping with ileus. SUBASH KC/NMC-15TH/2014 394 CHAPTER 23 Gastrointestinal conditions Gastrointestinal perforation Complete penetration of the wall of the esophagus, stomach, or bowel, resulting in the intestinal contents in the thorax or abdomen, depending on the sit e of perforation. Potentially a surgical emergency. Intestinal per- foration results in bac terial contamination of the abdominal cavity, gastric perforation can lead to a chemical pe ritonitis. Causes: iatrogenic (following a procedure, e.g. endoscopy/colonoscopy), spontaneous (duoden al ulcer, appendicitis, diverticulitis, tumor), traumatic. Clinical presentation These depend on the site of perforation: \200 Chest pain/dysphagia (if oesophageal). \200 Severe abdominal pain/rigidity (due to peritonitis). \200 Sepsis (depending on organ which has perforated). Imaging Plain \201 lm \200 Erect CXR (Fig. 23.19 ): pneumoperitoneum or pneumomediastin um, pleural effusion, subcutaneous emphysema of the neck. Supine abdominal X-ray: Rigler \200\231s sign (gas on both sides of the bowel wall), or out lining of the falciform ligament. In infants, free gas collects centrally producing a round ed translucency (football sign). CT More sensitive at identifying free gas and suggesting its origin of free gas suggest per foration of large bowel, large amounts of \202 uid indicate a small bowel perforation. Ma y see oral contrast extravasation. SUBASH KC/NMC-15TH/2014 \200\224 large amounts Fluoroscopy Used less now as increased use of CT. Water soluble contrast studies: \200 Sw allow (for suspected oesophageal perforation). \200 Enema (for lower GI perforation/to ch eck anastomotic sites post lower GI surgery). Information for the radiologist \200 History of recent procedures, e.g. endoscopy. \200 Whether patient is able to take oral preparation (for CT). SUBASH KC/NMC-15TH/2014 GASTROINTESTINAL PERFORATION 395 SUBASH KC/NMC-15TH/2014 Fig. 23.19 Erect CXR showing free gas under the diaphragm in a patient with perforated duod enal ulcer. SUBASH KC/NMC-15TH/2014 396 CHAPTER 23 Gastrointestinal conditions Subphrenic abscess Majority occur following surgery, and high mortality associated with the se abscesses can be reduced by their early diagnosis and management. The subphrenic space e xtends from the diaphragm above to the transverse mesocolon below and can be divided into 2 : \200 Left subphrenic space: the commonest cause is following operation on the stomach, the tail of pancreas, the spleen, or splenic \202 exure of the colon. Right subphrenic space: common causes are perforating cholecystitis, perforated duodenal ulcer, and appendicitis. Clinical presentation Signs and symptoms are frequently non-speci \201 c and may include: \200 Swinging pyrexia, wasting, and anorexia. \200 Epigastric fullness and tenderness. \200 Shoulder pain (referred due to irritation of the phrenic nerve). \200 Persistent h iccups. Imaging Plain \201 lm \200 Erect CXR: pneumoperitoneum or a pleural effusion, elevation or tenting of the diaphragm, basal consolidation on side of abscess. Abdominal X-ray: gas/ \202 uid level adjacent to the diaphragm, an irregular SUBASH KC/NMC-15TH/2014 pocket of gas or a soft tissue mass. Secondary paralytic ileus may also be seen. Ultrasound (Fig. Particularly valuable in detection of gas-free abscesses, also used to gui de the insertion of a drain for treatment. 23.20a ) CT (Fig. Allows identi \201 cation of the abscess/assessment of the other abdominal organs or further collections. CT can also be used to guide drainage. 23.20b ) Information for the radiologist History/details of any previous operations, dates of previo us drainages, clotting result. SUBASH KC/NMC-15TH/2014 SUBPHRENIC ABSCESS 397 (a) SUBASH KC/NMC-15TH/2014 (b) Fig. 23.20 a) Ultrasound image showing \202 uid collection overlying the liver, beneath t he diaphragm (arrows). b) Coronal CT showing right-sided subphrenic abscess, seen as \202 uid attenuation below the diaphragm (arrows). SUBASH KC/NMC-15TH/2014 398 CHAPTER 23 Gastrointestinal conditions Diverticular disease Diverticula develop when the mucosa herniates through points of weak- ness in the muscle layers of the colon wall at sites of vascular penetration. \200 Divert iculosis = the presence of colonic diverticula. \200 Diverticulitis = when in \202 ammat ion is present. \200 Sigmoid colon is the most common site. Only 15 % of patients have right-sided diverticulosis. Clinical presentation Prevalence increases with age, although most remain asymptomatic. It is commonly an incidental \201 nding. Causes include changes in colonic wall resistance, disordered motility, and reduced dietary \201 bre intake. Imaging \200 Role is to establish the diagnosis, severity, and extent. \200 Con \201 r m active in \202 ammation in diverticulitis. \200 Identify any complications \200\224 abscess, perforation, \201 stula formation, hemorrhage. Fluoroscopy \200\224 barium enema \200 Traditional test, CT, however, now often \201 r st line. \200 Air/barium \201 lled outpouchings extending from the lumen. \200 Strict ure length and caliber malignant stricture must be excluded. Features in favor of diverticular stricture include: \200 Stricture > 10cm. \200 Intact mucosa. \200 Adjacent diverticula (may also coexist with tumor). \200 Smooth transitio n with normal colon cf. shouldered margins of SUBASH KC/NMC-15TH/2014 malignant stricture ( \200\230apple core lesion \200\231). CT (Fig. \200 Thickened bowel wall > 3mm, with in \202 ammation. \200 Abscess formatio n: gas/ \202 uid collection. \200 Free intraperitoneal air/localized locules \200 Fist ulation: 65 % of colovesical \201 stulae occur as a result of diverticular 23.21 ) = perforation. disease (differential diagnosis is malignancy and Crohn \200\231s disease). CT angiography is used in active bleeding. Information for the radiologist Accurate clinical history, with attention to features sugge sting bleeding, malignancy, \201 stula, etc. Sigmoidoscopy \201 ndings. SUBASH KC/NMC-15TH/2014 DIVERTICULAR DISEASE 399 Fig. 23.21 Axial CT image showing a length of thickened sigmoid colon, with diverticulitis, pericolonic in \202 ammatory change, and locules of pericolonic gas. SUBASH KC/NMC-15TH/2014 SUBASH KC/NMC-15TH/2014 400 CHAPTER 23 Gastrointestinal conditions Volvulus \200 Twisting of a segment of bowel with subsequent obstruction. The sigmoid colon and caecum are most commonly affected due to the long, mobile mesentery. Risk factors: increased age (caecal younger 30 \200\22360 years), chronic constipation, mental handicap, institutionalization. Clinical presentation \200 Sigmoid: lower abdominal pain and progressive abdominal disten sion, may be spontaneously relieved by passage of a large amount of \202 atus/ feces, may devel op complete obstruction. Caecal: symptoms are those of acute bowel obstruction including pain, distension, and vomiting. Treatment is with decompression via a rectal tube through the twisted segment (sigmoid), su rgical resection of redundant loop sometimes required. Unrelieved obstruction may lead to b owel infarction/perforation. Imaging Plain \201 lm \200 Sigmoid: bowel loop dilated to occupy the whole abdomen, wit h the appearance of an inverted \200\230U \200\231 (resembling a \200\230coffee bean \200\231). Sigmoid loop typically devoid of haustra, with apex on the left of the abdomen. Remaining large bowel is often dilated, which is not seen in caecal volvulus. SUBASH KC/NMC-15TH/2014 Caecal: caecum usually twists and inverts so the caecal pole occupies the left upper quadra nt. The attached gas- \201 lled appendix is sometimes seen. 1 or 2 haustral markings can s till be seen. Often marked gaseous or \202 uid distension of small bowel. The left colon is usually collapsed. CT Performed when clinical and plain \201 lm assessment is inconclusive. As well as the s igns previously described on plain \201 lm, the \200\230whirl sign \200\231 on CT re \202 ects the twisted bowel and mesentery, along with demonstration of complications such a s ischaemia and perforation. Fluoroscopy If diagnostic doubt, a water-soluble contrast enema can be performed (risk of p erforation contraindicates the use of barium). Features at the point of torsion include a s mooth, curved tapering of the colonic lumen to give a \200\230bird \200\231s beak appearan ce \200\231, although CT increasingly used as \201 rst line. Information for the radiologist \200 Presenting symptoms and signs, any clinical suspicio n of ischaemia. SUBASH KC/NMC-15TH/2014 VOLVULUS 401 SUBASH KC/NMC-15TH/2014 Fig. 23.22 Abdominal X-ray showing grossly dilated loop of large bowel within the left abdo men in a patient with sigmoid volvulus. SUBASH KC/NMC-15TH/2014 402 CHAPTER 23 Gastrointestinal conditions Intussusception Intussusception is the telescoping, or prolapse of one part of bowel into a n adjacent segment. The prolapsed segment is referred to as the intus- susceptum and the re ceiving segment is the intussuscipiens. The most common sites are ileo \200\223colic and il eo \200\223ileo \200\223colic. Clinical presentation Commonest in children 3 months \200\2233 years. Majority are idiopath ic with no lead point other than lymphoid hyperplasia. In adults 90 point including lymphom a, polyps, tumors, Meckel \200\231s diverticulum, etc. % have a lead- In children, presenting features are of intermittent colicky pain with drawing up of the legs with or without vomiting. The child may be completely well between e pisodes. Initially there may be watery stools but later the patient may pass blood and mucu s in the classically described \200\230redcurrant jelly stools \200\231. In late presentat ions, there may be features of bowel obstruction and shock, with possible ischaemia. In adu lts, abdominal pain, nausea and vomiting are common over weeks \200\223months. Imaging Plain \201 lm Abdominal X-ray normal in 50 (most commonly in the right upper quad rant) and air crescent sign out- lining the apex of the intussusceptum. % . Classic \201 ndings include a soft tissue mass SUBASH KC/NMC-15TH/2014 Ultrasound (Fig. First-line investigation for intussusception. Free \202 uid is a common \201 nding and does not preclude air enema. 23.23a ) CT (Fig. In adults, CT is usually the \201 rst investigation, and may reveal the lead poi nt. 23.23b ) Fluoroscopy Single contrast/air enema demonstrates the obstruction, and reduction with air enema is the mainstay of treatment in uncomplicated pediatric intussusception. Air reductio n should only be carried out in a center with pediatric surgery and the child must be adequ ately resuscitated and haemodynamically stable. An NG tube is advised to decompress the sto mach. Absolute contraindications are peritonism, perforation, or persisting shock. There is no role for this in adults. Information for the radiologist Predisposing conditions, duration of symptoms, and clinical condition of the patient. SUBASH KC/NMC-15TH/2014 INTUSSUSCEPTION 403 (a) SUBASH KC/NMC-15TH/2014 (b) Fig. 23.23 a) Ultrasound image showing \200\230donut \200\231 appearance in a 2-year-old w ith intussusception. b) Axial CT showing intussuscepting loop of bowel within the right \202 ank, giving the typical \200\230bowel within bowel \200\231 appearance. SUBASH KC/NMC-15TH/2014 404 CHAPTER 23 Gastrointestinal conditions Acute pancreatitis Around 80 % mild and self-limiting, 20 necrosis and marked systemic resp onse, may lead to multi organ failure. Causes : alcohol, gallstones, iatrogenic (post ERCP) , drugs, trauma, meta- bolic e.g. increased Ca pancreas), tumor, idiopathic. % severe, associated with pancreatic 2 + , infection, congenital (pancreas divisum/annular Pathophysiology: unregulated activation of pancreatic enzymes leads to autodigestion of the gland causing in \202 ammation and necrosis. Leakage of enzymes into the surrounding stru ctures causes local complications. Clinical presentation Epigastric/central abdominal pain. Vomiting. Imaging \200 Con \201 rm diagnosis and identify cause. \200 Assess severity of pancrea titis, progression and complications. \200 Guide interventional procedures, e.g. drainage of peripancreatic abscess. Ultrasound Detects gallstones. Pancreas often obscured by body habitus and bowel gas. CT (Fig. Triple phase CT is the imaging modality of choice. CT <72 hours may not re \202 e ct the true severity of pancreatitis, only used if diagnostic doubt. 23.24 ) SUBASH KC/NMC-15TH/2014 Mild May be normal/mild enlargement/in \202 ammation. Severe \200 Necrosis: non-enhancement of the gland. \200 Peripancreatic \202 uid coll ections. \200 Infection: may see locules of gas. \200 Pseudocyst: collection of secreti ons. Extra-pancreatic complications \200 Pleural effusions, ascites, pseudoaneurysm of SMA/spl enic artery, thrombosis SMV/splenic vein, secondary GI tract involvement. MRI Comparable to CT but CT usually more readily available/quicker test in ill patients. MR CP assesses integrity of the ducts as well as detect anatomical anomalies. Information for the radiologist Likely etiology, how far into the disease process, clinical signs of sepsis, clotting if need for intervention. SUBASH KC/NMC-15TH/2014 ACUTE PANCREATITIS 405 Fig. 23.24 Axial CT showing ill-de \201 ned in \202 ammation of the pancreatic head, and a large \202 uid-collection occupying the body of the pancreas, in keeping with a pseudoc yst. SUBASH KC/NMC-15TH/2014 SUBASH KC/NMC-15TH/2014 406 CHAPTER 23 Gastrointestinal conditions