Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
RADIOLOGICAL EXAMINATION OF THE DIGESTIVE CANAL DEPARTMENT OF ONCOLOGY AND RADIOLOGY PREPARED BY I.M.LESKIV ANATOMIC AND FUNCTIONAL OF THE ESOPHAGUS The normal functions of the esophagus are simple - the transport of food from the pharynx to the stomach and the prevention of reflux of gastric contents. Disease processes that affect either function may result in profound clinical symptoms. Some important anatomic features of the esophagus are illustrated in next sl. The esophagus is a muscular tube that begins as a continuation of the pharynx at about the level of the sixth cervical vertebra. It is a relatively mobile structure, fixed only at its proximal and distal ends. The trachea lies immediately anterior to the esophagus from its origin in the neck to the tracheal bifurcation at the level of the fifth thoracic vertebra. The right and left recurrent laryngeal nerves ascend in grooves between the trachea and cervical esophagus, where they are vulnerable to involvement by proximal esophageal tumors. Also adjacent to the cervical esophagus are the right and left common carotid arteries and part of the thyroid gland. ANATOMIC AND FUNCTIONAL OF THE ESOPHAGUS Schematic Barium contrast examination of the normal esophagus reveals an indentation at the representation of the level of the fourth thoracic vertebra caused by the arch of the aorta. Just below the esophagus illustrating aortic arch, the anterior aspect of the esophagus may be narrowed slightly by the left some important main bronchus. Below the left main bronchus, the left atrium lies just anterior to the esophagus. Because of these intimate anatomic associations, any enlargement of the anatomic thyroid gland, carinal lymph nodes, or left atrium or aorta (aneurysm) can be relationships. recognized by characteristic impressions on the barium-filled esophagus. Attempts to correlate the structural features of the distal esophagus with its remarkable function have resulted in confusion regarding the anatomy of this segment. While the radiologist and physiologist can recognize a lower esophageal sphincter (LES), prosectors have searched in vain for a corresponding anatomic sphincter. The physiological LES corresponds roughly with the esophageal ampulla observed on barium contrast examinations. The fluoroscopist recognizes this area both by its ability to remain contracted at rest and to dilate more than the remainder of the esophagus when distended with barium. The proximal border of the ampulla is formed by a band of circular muscle called the upper. A ring or muscular ring. In some individuals, the radiologist may identify the lower esophageal mucosal ring (also known as the В ring or Schatzki ring), which marks the distal border of the ampulla. The muscular coat of the proximal third of the esophagus is comprised predominantly of striated muscle, while that of the distal two-thirds is largely smooth muscle. Therefore, the esophagus is vulnerable to diseases affecting either type of muscle. The vagus nerve innervates both the striated and the smooth muscle portions of the esophagus. Innervation to the distal esophagus and LES is carried in intramural nerve plexuses. Because of this intramural innervation, distal thoracic truncal vagotomy has little effect on distal esophageal function. The esophagus also receives fibers from cervical and thoracic sympathetic ganglia. The venous drainage of the distal esophagus is by way of the gastric veins into the portal vein; therefore, esophageal varices may develop as a consequence of portal hypertension. Unlike the rest of the gut, the esophagus has no serosal layer. Surgeons claim that this contributes to the difficulty of esophageal surgery. Lack of a restraining serosa may also contribute to the local invasiveness of esophageal carcinoma. CLINICAL ANATOMY OF THE STOMACH The size and shape of the stomach vary from moment to moment depending on the volume of its contents and on body posture. For clinical purposes, it is useful to divide this distensible organ into four anatomic regions. The cardia is the portion of the stomach immediately adjacent to the esophagus; the fundus is the region that rises above the cardia. The body of the stomach extends from the fundus to the incisura angularis, an indentation on the lesser curvature that is best appreciated by barium contrast examination. The antrum is the region beyond the incisura angularis where the stomach turns horizontally toward the pyloric sphincter. The histologist often can identify the anatomic region from which a gastric biopsy is obtained by the type of gastric glands present in the specimen. The cardiac region contains the cardiac glands, which are predominantly composed of mucous cells. The oxyntic glands are found in the fundus and body of the stomach and contain both chief (zymogen) cells, which secrete pepsinogens, and parietal (oxyntic) cells, which secrete hydrochloric acid and intrinsic factor. The gastric antrum contains the pyloric glands, which include endocrine cells that produce gastrin. The surgeon takes advantage of this relationship between gross and microscopic anatomy when designing an operation for peptic ulcer disease. For example, an antrectomy may be performed to remove the gastrin-secreting mechanism of the stomach. CLINICAL ANATOMY OF THE DUODENUM The duodenum may also be divided into four anatomic regions. The first portion of the duodenum extends posteriorly and superiorly from the pylorus to the first duodenal flexure; it is entirely intraperitoneal and normally assumes a characteristic conical shape when distended with barium (duodenal bulb). The second portion of the duodenum extends vertically downward from the first to the second duodenal flexure. Its medial wall is adjacent to the head of the pancreas, which when enlarged by carcinoma or pancreatitis, produces a tell tale impression on the barium-filled second duodenal portion. The ampulla of Vater, the intestinal opening of the major pancreatic duct and common bile duct, is located in this duodenal segment. The third portion is the horizontal segment situated just anterior to the inferior vena cava and aorta; the superior mesenteric artery and vein lie anterior to this duodenal segment. The fourth portion of the duodenum is the ascending segment that begins just to the left of the aorta. A fibromuscular ligament arising from the right cms of the diaphragm (ligament of Treitz) attaches to the small intestine at the duodenojejunal flexure, which delimits the end of the duodenum and the beginning of the jejunum. Except for a small segment near the duodenojejunal flexure, the second, third, and fourth portions of the duodenum are entirely retro-peritoneal. The duodenum is histologically distinguished from the remainder of the small intestine by the presence of Brunner’s glands in the duodenal submucosa; these glands secrete a viscous, highly alkaline fluid. The blood supply to the stomach and duodenum is generous. The stomach is supplied by large vessels arising from all branches of the celiac artery. The duodenum receives blood from the superior pancreaticoduodenal branches of the gastroduodenal artery and the inferior pancreaticoduodenal branches of the superior mesenteric artery. Not surprisingly, bleeding frequently accompanies ulceration of the stomach and duodenum. The vagal trunks applied to the anterior and posterior surfaces of the distal esophagus provide parasympathetic innervation to the entire stomach. These vagal trunks also give off hepatic branches and celiac branches that supply the small bowel and other abdominal viscera. This anatomic distribution is important to the surgeon who may wish to spare hepatic, celiac, or pyloric vagal branches when performing a selective or proximal gastric vagotomy for treatment of peptic ulcer disease. GENERAL ANATOMIC AND FUNCTIONAL OF THE SMALL INTESTINE The most remarkable feature of the small intestine is its enormous surface area, which is conferred not so much by its length as by its multitude of circumferential folds, villi, and microvilli. The anatomic regions of the small intestine, designated as duodenum, jejunum, and ileum, have no clear boundaries with respect to absorptive cell characteristics; functionally their similarities are greater than their differences. Indeed, regional specialization exists only with respect to vitamin B12 and conjugated bile salts, which are both absorbed preferentially in the distal ileum. Although absorption of all other nutrients appears to be greater in proximal sites, absorption takes place along the entire length of the intestine. In addition, the small intestine has an enormous reserve capacity and can fully compensate for losses of up to one-half its length. The intestine is more than a conduit for nutrients. Although most of the enzymatic digestion of carbohydrates, proteins, and lipids takes place in the small intestinal lumen before their uptake, optimum absorption of both protein and carbohydrate is closely linked to an ultimate phase of hydrolysis that occurs within the intestinal brush border. Dietary fat is digested in the lumen and not further hydrolyzed in the intestinal cells. However, within these cells, absorbed fat is resynthesized to complex lipids and combined with transport proteins for delivery into the lymph.The major manifestations of small intestinal diseases are malabsorption of nutrients and abnormalities in water and electrolyte transport. ANATOMIC AND FUNCTIONAL OF THE COLON The ileal effluent entering the colon consists of water, electrolytes, unabsorbed gastrointestinal secretions, cellular debris, and undigested food residue. The colon has no digestive function per se; its principal roles are to assist in maintaining the body’s electrolyte and water balance and to excrete the unabsorbed remains or feces by means of its absorptive, secretory, storage, and excretory functions. Sodium, chloride, and water are absorbed, and potassium and bicarbonate are secreted. The importance of the colon in sodium absorption is demonstrated by the fact that patients with an intact intestine can consume a low-sodium diet (10 mEq/day) for months without adverse effects, whereas individuals with ileostomy on a 10 mEq per day sodium diet develop symptoms and signs of sodium depletion within 3 to 5 days. Absorption and secretion of electrolytes and water occur principally in the right half of the colon; the ability of the colon to perform these functions decreases toward the rectum. The undigested food residue is primarily that portion of plant cells contained principally in cereals that consists of nonstarch polysaccarides and lignin (an aromatic polymer); the intestinal tract is devoid of enzymes to digest these substances known as dietary fiber. The nonstarch polysaccarides are degraded by colonic bacteria to short-chain fatty acids, other products, and gases (e.g., methane, carbon dioxide, and hydrogen), while the lignin remains practically intact. These products of bacterial degradation, except for the gases, give bulk to the stool by imbibing water and are laxative in effect. In the western world, the average normal fecal output is up to 200 gm per day and contains 100 to 150 ml of water, up to 5 mEq of sodium, 7 to 15 mEq of potassium, 2 mEq of chloride, and 3 mEq of bicarbonate. The normal colon has the capacity to absorb about 6 liters of water and about 800 mEq of sodium per day. The storage and excretory functions of the colon depend on coordinated colonic motor activity. Nonpropulsive, segmental contractions that probably produce the haustra move the bowel contents forward and backward over short segments of mucosa, thus enhancing absorption. Periodically, a peristalitic contraction propels the contents forward either for a short distance or on into the sigmoid colon or rectum. Distention of the rectum induces a desire to defecate, which can be overcome by voluntary contraction of the internal and external anal sphincters GAS PATTERNS NORMAL ABDOMINAL RADIOGRAPHS In the supine abdominal radiograph gas is normally present in the body of the stomach and in variable amounts in the transverse and other parts of the colon. It is also present in small amounts in the small intestine of adults. Normal gas-fluid levels are usually seen in the gastric fundus on erect radiographs and occasionally in the first part of the duodenum and in the caecum. In infants and children gaseous distension of the stomach and of the intestines is a common feature. In infants in particular this is largely due to swallowed air. Supine abdominal radiographs occasionally show apparent soft tissue masses in the gastric fundus or duodenal loop; these are well-recognised ‘pseudo-tumours’ and are due to normal fluid collections gravitating to these dependent areas. ABNORMAL GAS PATTERNS Abnormal gas patterns in abdominal radiographs may be conveniently classified into: excessive intestinal gas abnormal contour of gas-containing loops extraluminal gas. Excessive intestinal gas Causes Physiological Air-swallowing, usually in children Radiological features Non-specific gaseous distension. No consistent end-point to suggest obstruction Mechanical obstruction Small bowel, e.g. adhesions, hernia, Crohn’s disease Gaseous distension of loops of small bowel which lie centrally. Valvulae conniventes visible. Short fluid levels on erect film. Large bowel, e.g. carcinoma, diverticular disease with stricture Distension of peripherally situated large bowel, proximal to obstruction. Haustra visible. Longer fluid levels than in small bowel Volvulus of the caecum, sigmoid Specific radiological signs. Extremely dilated loops extending upwards from normal site of these structures to lie in upper quadrants. Very long fluid levels in erect film Non-mechanical obstruction (or pseudo-obstruction).Generalised ileus, e.g. following surgery, peritonitis, metabolic disorders Localised ileus, e.g. appendicitis, pancreatitis, abscess, ischaemia Large and small bowel distended. May resemble mechanical obstruction Single loop of dilated bowel (sentinel loop). Speckled gas in abscess Abnormal contour of gas-containing loops Causes Radiological features Crohn’s disease Affects small or large bowel, or both. Stricture may be visible, or irregularity of mucosa due to ulceration May show signs of obstruction or toxic megacolon (see below) Ulcerative colitis Narrowed, featureless empty colon. Pseudopolypi may be visible as filling defects. Gross dilatation - ‘toxic megacolon’ is a dangerous complication and predisposes to perforation Ischaemia Dilated bowel, thickened wall with areas of oedema ‘thumbprinting’. Ileus, with signs of obstruction Intrinsic masses Tumours and intussusception may be outlined by gas Displaced loops Large non-alimentary abdominal masses, e.g. enlarged spleen, may displace or indent gas-filled loops of otherwise normal bowel Extraluminal gas Causes Intraperitoneal Perforation of a hollow viscus Subphrenic abscess Radiological features Variable amounts of gas, from small crescent under diaphragm (erect film) to gross peritoneal distension Air-fluid level under diaphragm. Adjacent consolidation. Confirm with ultrasound lung base Linear streaks of gas in bowel wall. May coalesce or outline Bowel wall portal vein radicles Infarction, necrotising enterocolitis in infants Pneumatosis coli Blebs of gas in colon wall. Symptoms may mimic carcinoma. Usually elderly patient with airways obstruction Branching gas pattern in liver (bile ducts). Usually lie centrally Biliary tree in liver; gas in portal vein radicles extends more After sphincterotomy or anastomosis peripherally between biliary tree and bowel Erosion of gallstone into small bowel; Small bowel obstruction (‘gallstone ileus’) and opaque calculus may be visible in intestine with gas in biliary tree. Other erosion of duodenal ulcer into biliary causes listed do not cause intestinal obstruction tree; pancreatic neoplasm; gas-forming infection Gas may outline urinary bladder, ureters and collecting Genitourinary tract systems. Differential diagnosis: gas-forming infection in Fistula, e.g. trauma, postoperative, diabetic patients Crohn’s disease ABDOMINAL CALCIFICATION Many structures in the abdomen calcify, especially in older subjects; most of these are of no clinical significance. They include the walls of blood vessels, lymph nodes and costal cartilages. Calcification may also occur in pathological states but may be discovered coincidentally. Gallstones and prostatic calcification fall into this category. Those that are often associated with symptoms include calcified urinary calculi, pancreatic calcification in chronic pancreatitis, and calcification occurring in abdominal tumours RADIOLOGICAL EXAMINATION OF THE GASTROINTESTINAL TRACT Contrast studies of the gastrointestinal tract and endoscopic diagnostic techniques play complementary roles in the investigation of alimentary tract symptoms. How these different methods are deployed in different hospitals depends to a large extent on the availability and accessibility of endoscopy. Hospitals with comprehensive endoscopy facilities and ‘open access’ policies tend to use this technique as the first-line investigation in patients with gastrointestinal symptoms. This has been accompanied by a decline in the numbers of barium studies carried out in the same hospitals. In general, patients complaining of dysphagia can be investigated using either endoscopy or radiology: dyspepsia is investigated by endoscopy; colonic symptoms are investigated using barium techniques, followed by colonoscopy for further clarification and biopsy; upper gastrointestinal bleeding (haematemesis and melaena) is investigated with endoscopy; the small bowel is examined by means of a specialised barium technique. There will be many local variations in the way that some of these investigations are used. BARIUM EXAMINATIONS Barium sulphate suspensions are specially formulated for use in different parts of the alimentary tract. Whether they are taken orally or introduced through simall bowel or rectal tubes, they are accompanied by gas (carbon dioxide) releasing agents or air insuflation to produce what is known as air contrast or double contrast. This allows detection of small mucosal lesions as well as improving the accuracy of these techniques in detecting masses, polyps, strictures, infiltrations and surface erosions and ulceration. All barium examinations are carried out under fluoroscopic control to optimise mucosal barium coating and gaseous distension. Assessment of gut distensibility and motility can also be made during fluoroscopy. Biopsy techniques have been used in conjunction with barium studies of the oesophagus but have not gained widespread acceptance. Endoscopic ultrasound techniques are becoming established and have been shown to be useful in the oesophagus, stomach and rectum. Contrast examination of the small bowel will be discussed in a later section in this lecture. In this section it is appropriate to discuss radiology of the alimentary tract according to the clinical presentation - dysphagia, dyspepsia, bleeding, symptoms suggesting small bowel disease, and large bowel disorders. DYSPHAGIA This is a common symptom. Its radiological assessment often requires a rapid sequence of radiographs or video recording during fluoroscopy, so that the swallowing function can be studied in detail from the oropharynx to the gastric cardia. The common causes of dysphagia and their radiological features are summarised in Table Causes Radiological features Post-cricoid carcinoma Irregular narrowing; mass displacing larynx forwards Pharyngeal diverticulum Variable size, arising posteriorly Oesophageal web Characteristic appearance; associated with iron-deficiency anaemia Malignant stricture May be primary oesophageal cancer or invasion by bronchial or mediastinal tumour. Characteristic appearance - irregular narrowing, ‘shouldering’, partial or complete obstruction Stricture secondary to Reflux shown during fluoroscopy; mucosal ulceration, hiatus hernia; reflux oesophagitis and strictures tend to be smooth but may mimic carcinoma hiatus hernia complex Achalasia Miscellaneous causes: corrosive strictures Generalised motility defect with dysfunction of cardia causing obstruction and sometimes gross dilatation of oesophagus, with food and liquid residue Severe ulceration initially. Tendency to perforate moniliasis, herpes infection Opportunistic infection. Severe ulceration and pain systemic sclerosis Impaired peristalsis neurological disorders Swallowing difficulties with aspiration into lungs Dyspepsia This term is used to describe upper abdominal symptoms arising from a variety of different conditions. Epigastric pain, with or without a relationship to food, is an extremely common symptom. Peptic ulceralion, hiatus hernia with gastro-oesophageal reflux, gastric neoplasm and diseases of the biliary tract (e.g. gallstones) and pancreas (e.g. chronic pancreatitis, carcinoma) all tend to cause similar symptoms. It is possible to distinguish between these conditions to some extent on the basis of symptom complexes, particularly their relationship to meals. Persistence of symptoms despite adequate medical treatment, weight loss, vomiting, blood loss (haematemesis and melaena), persistent pain with radiation away from the typical site of peptic ulcer or gallstone pain are all features that give cause for concern. In this situation the patient should be investigated intensively, using endoscopy as the first investigation. If endoscopy is negative, radiological techniques, including plain abdominal radiographs, upper gastrointestinal barium studies and ultrasonography, are used, depending on the symptom complex. Ultrasonography is useful for the detection of biliary and pancreatic disease; CT may be added to complete the investigations by outlining areas not demonstrated by ultrasonography, e.g. the retroperitoneal planes.Uncomplicated dyspepsia which is short lived is usually managed conservatively (particularly in young adults) using one of the many anti-dyspepsia drug regimens. The decision to investigate this common problem depends on the availability of endoscopy services. There is, however, some debate about the appropriateness of the current widespread use of endoscopy in this particular clinical circumstance. Dyspepsia Cause Radiological features Oesophageal disease hiatus hernia complex Superfici.il mucosal ulceration in the oesophagus indicates oesophagitis. Reflux may be detected but barium studies are less sensitiv e than endoscopy or pH studies. Strictures may develop and may be indistinguishable from malignant strictures Gastric abnormalities ulceration Barium collection in crater. Radiating folds of mucosa to edge of crater. Surrounding deformity and oedema. Heal to form distinctive scars. May be malignant from outset. Careful endoscopic follow-up necessary, with biopsies Polip(s) Multiple polyps in body of stomach form part of chronic gastritis spectrum - usually hyperplastic in nature, and benign. Adenomatous polyps, usually in antrum, may be premalignant lesion(s). Should be removed. Other types of polyps may be part of familial polyposis syndromes Cancer Characteristic signs in advanced disease. Either ulcerating or polypoid, or mixture of both. Early or superficial cancers resemble benign ulcers but with specific signs such as ‘clubbed’ mucosal folds and geographical areas of very superficial ulceration Non-mucosal tumours Usually large and may have surface ulceration or excavation. Exogastric extension. May be leiomyoma, sarcoma or lymphoma Duodenal Characteristic ulcer craler(s) in first part of duodenum, with deformity. disease:e.g. alceration Atypical signs in Crohn’s disease and Zollinger-Ellison syndrome BARIUM MEAL The standard double-contrast study of the upper gastrointestinal tract includes views of the oesophagus, stomach and duodenum. The examination is carried out following a period of starvation; peristalsis is temporarily abolished using an injection of glucagon or an atropine-like agent. This enhances mucosal coating with barium suspension and allows detection of small mucosal lesions, e.g. erosions and polyps. The radiographs obtained are examined for evidence of ulceration, deformity, infiltration, stricture formation, external compression or displacement, and obstruction. Some of the radiological abnormalities that may be found are summarised in Table 5. The major advantage of endoscopy in the investigation of alimentary disorders is the ability of the operator to obtain biopsies of lesions or suspicious mucosal abnormalities. Sources of bleeding can also be identified accurately. Endoscopy is not without complications and it has been claimed that good barium studies are as accurate as endoscopy in the detection of significant lesions. What has become apparent over recent years is that many benign and malignant diseases of the gastrointestinal tract cause similar or identical radiological signs, and that some benign lesions become, or harbour, malignant disease. Disorders such as achalasia, peptic and corrosive strictures of the oesophagus, gastric ulcers and certain non-epithelial sub-mucosal tumours, such as leiomyomas, predispose to, or undergo, malignant transformation into malignant tumours. Therefore direct inspection of the lesions, obtaining biopsies where necessary, is an accepted way of following up some lesions such as gastric ulcers. It is also known that malignant ulcers undergo cyclical healing changes and may therefore mimic benign ulcers. Finally, benign ulcers may cause marked localised fibrosis and deformity when they heal. This change is usually permanent and should not be the sole justification for further follow-up using barium studies. GASTROINTESTINAL BLEEDING Bleeding may be the first manifestation and presenting feature of gastrointestinal disease. The clinical picture may vary from severe haematemesis to anaemia due to occult blood loss (e.g. cancer of the stomach or colon), melaena or frank rectal bleeding. Careful questioning may pin-point other symptoms, and clinical examination may reveal signs that help lo localise the cause of the bleeding. Very occasionally no cause is found after exhaustive investigation and these patients may require exploratory operations. Endoscopic techniques are the preferred method of investigation because the sources of bleeding, both in the upper gastrointestinal tract and in the colon, can be identified. Barium studies may show the causal abnormality but may also show unrelated diseases, which may cause confusion. Barium persisting in the alimentary tract may preclude the use of more effective investigations, such as isotope-labelled red blood cell scans or selective coeliac and mesenteric angiography, to localise sites of bleeding beyond the reach of diagnostic endoscopy, or when the latter is ‘negative’. Table 6 lists some causes of upper gastrointestinal bleeding and their radiological features. It is important to remember that bleeding may arise in the small bowel or in the caecum; these areas are not easily accessible during endoscopy. Further more, bleeding may be intermittent, and may vary in severity from sub-clinical to catastrophic and life threatening. All diagnostic methods are more accurate during active bleeding. Angiography must be carried out when bleeding is brisk (a rate of over 5 ml/min is often quoted); isotopelabelled red blood cell scans may detect slower rates of bleeding but are anatomically less precise. Selective coeliac and mesenteric angiography is time consuming and is rendered more difficult and hazardous if the patient’s general condition is deteriorating due to the rate of blood loss. The technique may show a vascular lesion or demonstrate extravasation of contrast medium into the bowel lumen. In a patient with portal hypertension it may be important to demonstrate the patency of the portal vein if shunt procedures are being considered. Delayed radiographs will demonstrate the venous phase of an angiogram and will outline draining and collateral veins. This technique has superseded the hazardous direct approach of splenoportography which involved direct needle puncture of the spleen. One cause of rectal bleeding, particularly in childhood, is a Meckel’s diverticulum. Because this contains gastric mucosa which ulcerates and bleeds, it is readily detectable using a technetium isotope scan. The ectopic gastric mucosa is shown as a localised area of increased isotope activity, usually lying centrally in the abdomen. Upper gastrointestinal bleeding Cause Radiological features Oesophagus Varices due to portal hypertension Serpiginous filling detects on barium studies of the lower oesophagus Mucosal tear following vomiting (MalloryWeiss lesion) Tears rarely shown radiologically. Endoscopy preferred Oesophagitis, .ill causes Stomach Endoscopy more sensitive. Barium studies may show ulceration Erosions Characteristic multiple ‘target’ lesions. Acute or chronic gastritis Ulcer, tumour, varices Duodenum Characteristic appearances. Varices here usually accompanied by varices in the oesophagus, though not invariable Ulceralion, invasion from adjacent tumour Characteristic findings in duodenal ulceration; signs of malignant infiltration also characteristic THE SMALL INTESTINE The usual indications for investigating the small intestine are: abdominal pain, weight loss, diarrhoea symptoms suggesting inflammatory disease; colicky abdominal pain, distension, vomiting - symptoms suggesting obstruction, which may be intermittent; anaemia, malabsorption - caused by a variety of small bowel disorders. Abdominal radiographs may show signs of small bowel obstruction but the cause may not be apparent. Evidence of inflammatory disease in the colon is helpful (Table 2). Small bowel contrast studies may be a continuation of a barium meal (a ‘follow-through’ study) although the high density barium contrast agent used specifically for doublecontrast studies of the oesophagus, stomach and duodenum may give poor images of the small bowel. F:or the small bowel a large volume of relatively low density (semitransparent) barium suspension is more appropriate. A more detailed study of the small bowel may be indicated if a follow-through examination is inconclusive; this consists of administering the barium suspension via a catheter introduced through the mouth into the proximal small intestine (small bowel enema, or enteroclysis). This method has some well-documented advantages but is more invasive. Fluoroscopy is used to determine the optimal infusion rate of contrast agent and allows ‘spot films’ of areas of interest to be obtained during the infusion. The radiological features of some common small bowel disorders are summarised in Table . Small bowel disorders Cause Radiological features Crohn’s disease Signs of bowel inflammation - characteristic fissuring or ‘rose-thorn’ ulcers, nodular or ‘cobble-stone’ mucosa, strictures, thickened bowel wall, adherence of adjacent loops, fistulae to adjoining structures, ‘skip’ lesions, dilated and obstructed loops of bowel, involvement of stomach, duodenum and colon. Terminal ileum is commonly affected, but disease may be extensive Obstruction due to causes other than inflammation Small bowel contrast studies usually localise site of obstruction provided proximal loops are not too distended. Adhesions produce characteristic deformities of affected loops, especially when using small bowel enema technique Malabsorphion problems, Coeliac syndrome causes non-specific dilatation of small other than those caused by. bowel loops in severe cases but small bowel biopsy is inflammatory disease much more specific. Jejunnl diverticulosis , blind loops, fislulae and strictures may all cause malabsorption and are detectable on contrast studies THE LARGE INTESTINE Symptoms such as alterecd bowel habit, rectal bleeding, abdominal pain, weight loss and anaemia may indicate serious colonic disease. Colonoscopy and barium studies are complementary and equally useful but their deployment depends to a large extent on the availability of colonoscopy services. Many clinicians use the barium enema as the first-line diagnostic investigation and either combine this with flexible fibreoptic sigmoidoscopy or reserve a full colonoscopy for those instances where a barium study is inconclusive or where a lesion shown radio-logically requires further direct examination and biopsy. Barium studies require full bowel preparation using one of a variety of cleansing techniques (faecal residue may mimic polyps or tumours). A double-contrast technique involves inflation of the colon using air or carbon dioxide, and peristaltic activity is temporarily abolished using a short-acting atropine-like pharmacological agent. Colonoscopv provides direct access to lesion- or suspicious areas of mucosa for biopsy: small polypoid lesions may be amenable to removal during the same diagnostic procedure. The examination may not be complete because in a significant proportion (10-30%) the caecum is not reached and there are also ‘blind’ spots at points of angulation of the colon. Advanced diverticular disease produces deformity and narrowing that is difficult to assess both in barium studies and during colonoscopy. Colonoscopy has a significantly higher risk of complications than barium enema, and the procedure is more time consuming. Table 8 summarises the radiological features of common disorders of the large intestine Common disorders of the large intestine Carcinoma: Most are irregular strictures with ‘shouldering’. Destroyed mucosal pattern, proximal dilatation and obstruction. Invasion of adjoining tissues and organs. May appear as polyp, usually more than 2 cm with complex surface pattern. Long-standing ulcerative colitis and familial polyposis coli are predisposing conditions. Diverticular disease: Multiple diverticula particularly in sigmoid region, but may be widespread. Narrowing and deformity. Common, so may coexist with cancer. May bleed or perforate, or form fistulae, e.g. with bladder. Ulcerative colitis: Diffuse, uniform fine ulceration; loss of haustra, giving featureless tubular colon. Toxic megacolon and carcinoma are complications. May only involve distal colon or rectum in some cases. Crohn’s disease: Areas of narrowing, deep ulceration, strictures. Perianal disease is common. Prone to form fistulae. Coexists with small bowel disease often. Ischaemic colitis: Cause of profuse bleeding and acute abdominal pain. Narrowing of lumen, often affecting localised segment, with mucosal oedema (‘thumb-printing’). Occasionally difficult to distinguish from Crohn’s disease Normal oesophagus, (a) Full of barium to show the smooth outline and indentation made by the aortic arch (arrow), (b) Film taken after the main volume of barium has passed, to show the parallel mucosal folds. Carcinoma of the oesophagus. The carcinoma is shown as a mass around the lumen of the oesophagus (arrow). Subcarinal nodes (N) are also present. Ao, descending aorta; RPA, right pulmonary artery . There is an irregular stricture with shouldering (arrow) at the upper end. Peptic stricture due to gastro-oesophageal reflux in a patient with a hiatus hernia. There is a short smooth stricture at the oesophagogastric junction with an ulcer crater within the stricture (arrow). Achalasia. The very dilated oesophagus containing food residues shows a smooth narrowing at its lower end. Leiomyoma There is an intramural filling defect in the eosophagus below the aortic arch (arrows). The sharp angle this makes with the wall of the oesophagus indicates that the filling defect is due to a mass arising in the wall of the oesophagus . There is a large filling defect in the stomach with smooth borders (outer arrows). An ulcer crater (central arrow) is present within the filling defect - a characteristic feature of a leiomyoma Oesophageal varices. Tortuous, worm-like filling defects are seen in the lower half of the oesophagus. Pharyngeal pouch (Zenker's diverticulum). The pouch is lying behind the oesophagus which is displaced forward. Duodenal diverticulum arising from the second part of the duodenum (arrows) Normal stomach and duodenum: double-contrast barium meal. On this supine view barium collects in the fundus of the stomach. The body and the antrum of the stomach together with the duodenal cap and loop are coated with barium and distended with gas. Note how the fourth part of the duodenum and duodenojejunal flexure are superimposed on the body of the stomach Carcinoma. There are a number of large filling defects in the antrum and body of the stomach Benign ulcer, (a) In profile the ulcer (arrow) projects from the lesser curve of the stomach, (b) En face the ulcer (arrow) is seen as a rounded collection of barium. Malignant ulcer. The ulcer (arrow) does not project from the lumen of the stomach. Note how the mucosal folds do not reach the ulcer crater. The stomach is narrowed by an extensive carcinoma converting it to a rigid tube with obliteration of mucosal folds. Gastric outlet obstruction. A carcinoma is causing narrowing of the antrum (arrow). The speckled appearance in the fundus of the enlarged stomach is due to food residues Erosive gastritis. The erosions appear on this double-contrast barium meal as many small collections of barium, some of which are arrowed, surrounded by a radiolucent halo of oedema. Hiatus hernia, Sliding: the fundus of the stomach and the gastro-oesophageal junction (arrow) have herniated through the oesophageal hiatus and lie above the diaphragm (dotted line) (a) Normal barium follow-through. The small intestine, ascending and transverse colon are filled with barium. The jejunum in the left side of the abdomen has a much more marked mucosal fold pattern than the ileum which is lying in the pelvis. When a peristaltic wave contracts the bowel the mucosal folds lie longitudinally (arrows). Note the way of measuring the diameter of the bowel. In the pelvis the loops overlap and details of the bowel become hidden, (b) Normal terminal ileum Normal small bowel enema. This technique gives good mucosal detail. The arrow points to the terminal ileum. Note that a tube has been passed through the stomach into the jejunum Dilatation from small bowel obstruction. The diameter of the bowel is greatly increased. The feathery mucosal pattern is lost and the folds appear as thin lines traversing the bowel, known as valvulae conniventes (arrows). Mucosal abnormality with infiltration of the bowel, in this case from oedema. The mucosal folds become thickened. Some of the thickened folds are arrowed Ulceration. Abnormal loops of bowel in Crohn's disease showing the ulcers as outward projections (arrows). Narrowing. There is a long irregular stricture (arrows) in the terminal ileum due to Crohn's disease. There is an abnormal mucosal pattern in the remainder of the terminal ileum. Note the contracted caecum - another feature of the disease Displacement. The small bowel is displaced around enlarged abdominal lymph nodes from a metastatic teratoma of the testis. Malrotation. The small bowel is situated in the right side of the abdomen. Later films showed the colon on the left side. Crohn's disease Diverticulosis. A number of diverticula of varying size are arising from the small bowel. Some of these are arrowed multiple small bowel diverticula a dilated loop cut off from the main stream of the bowel in which there is delayed filling and emptying (blind loop) Stricture. A short circumferential narrowing is seen in the sigmoid colon (arrow) from a carcinoma. Extrinsic compression. A narrowed length of sigmoid colon is seen caused by compression by an adjacent ovarian Extrinsic compression. An appendix abscess is compressing and narrowing the caecum. Filling defects. Lumps of faeces have caused smooth filling defects surrounded by barium. However, in the sigmoid colon there is a large filling defect with ill-defined edges (arrow). This is a carcinoma. A clean colon is essential for a satisfactory barium enema. Muscle hypertrophy and diverticula. Muscle hypertrophy gives the sigmoid colon a serrated appearance. Two small diverticula are arrowed Ulceration, (a) Single contrast. (b) Double contrast. In this case of ulcerative colitis the ulceration causes the normally smooth outline of the colon to be irregular. Ulcerative colitis. With long-standing disease the haustra are lost and the colon becomes narrowed and shortened coming to resemble a rigid tube. Reflux into the ileum through an incompetent ileocaecal valve has occurred. A). Crohn's disease. The mucosal pattern has a 'cobblestone' appearance due to criss-crossing fine ulceration. B). Crohn's disease - strictures. A long stricture is present in the transverse colon (between curved arrows) and a shorter one in (hesigmoid colon (between small arrows). In this case the outline of the strictures are irregular, due to ulceration. C). These two abnormal segments with normal intervening bowel are an example of skip lesions' - an important diagnostic feature of Crohn's a b c Diverticular disease. Numerous diverticula are seen as out-pouchings from the sigmoid colon Diverticular disease. A stricture is present (arrow). Although there is recognizable diverticular disease at both ends of the stricture, it is impossible to exclude definitely a carcinoma Polyps within the colon may be demonstrated as radiolucent filling defects displacing the contrast substance. Note stalk, which is well seen.