Diagnostic Radiology: Gastrointestinal and Hepatobiliary Imaging Niranjan Khandelwal, Veena Chowdhury, Arun Kumar Gupta, Deep Narayan Srivastava
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Part One
1Gastrointestinal Imaging: Imaging Techniques
2

Current Status of Conventional Techniques and Advances in GIT ImagingChapter One

Arun Kumar Gupta,
Atin Kumar,
Chandan Jyoti Das
 
INTRODUCTION
Gastrointestinal radiology has its true beginning less than a year after the exciting discovery of X-rays in 1895 and has been at the forefront of radiology, combining physiologic and anatomic informations right from its very inception. Over the years, with advances in instrumentation and techniques, gastrointestinal radiology has extended beyond conventional radiography, fluoroscopy and barium examinations. The imaging modalities of high resolution real time sonography, computerised tomography and to some extent magnetic resonance imaging have provided increasingly sophisticated and accurate diagnostic studies. However, these modalities have been primarily complementary to barium examinations and particularly helpful in assessing abnormalities of the wall and extraluminal spread of the disease. In spite of these high-tech modalities, barium contrast examination continued to be the best technique for evaluation of the mucosal surface of the gastrointestinal tract.1 With the availability of flexible oesophagoscopy, gastroduodenoscopy and colonoscopy instrumentations, endoscopy emerged as an initial technique in the late 1980s and early 1990s in patients with upper gastrointestinal or colonic symptoms with resultant decline in the number of barium contrast studies. With the advent of capsule endoscopy even small bowel endoscopic images can be obtained which were earlier inaccessible to the endoscopists.
 
Development of Gastrointestinal Radiology
On reviewing the history of development of gastrointestinal radiology, conventional radiography consisting mainly of X-ray abdomen, fluoroscopy and single contrast barium study was the mainstay of technique till 1950s. With the development of image intensifiers and refinement in barium preparations, double contrast barium study became popular in 1960s for detection of small ulcers, early carcinoma or small colonic polyps. In the mid-1970s, development of flexible endoscopes made it possible to visualise directly the lumina of esophagus, stomach, duodenum and colon with the added advantage of biopsy facility for the suspected lesion. Thus, the evaluation of esophagus, stomach and colon no longer remained a domain of the radiologist and even with further improvements in technique and barium preparation for double contrast technique, radiological evaluation was taken away to a large degree by the endoscopists by the close of 1980s. However, the radiologist continued to have a primary responsibility in the evaluation of small bowel because of its unique anatomy and location. The endoscopists did not find a place in small bowel evaluation except for few inches of jejunum through upper gastrointestinal endoscopy or terminal ileum through colonoscopy. But recently capsule endoscopy has emerged as a promising technique to visualize small bowel beyond the reach of fibreoptic endoscopes. However it has the disadvantages of long hours of patient 4preparation time, small bowel transit and subsequent analysis of images. Also when a pathology is visualized, localizing it to a particular segment of bowel can be a problem with capsule endoscopy images. When a barium meal follow through examination is performed for a specific clinical problem indicating small bowel disease, the yield of positive study is higher. Also, this study provides more physiologic information about the antegrade flow and the natural response of the bowel to fluid bolus. However, barium meal follow through study is a lengthy examination, carries high false negative rate due to overlapping of bowel loops, peristalsis and poor distensibility of the segments.
The technique of enteroclysis, a dedicated small bowel study was introduced by Miller in 1982 which represented a significant improvement in ease of performance, speed of examination, optimal visualisation of the mucosal surface pattern and relationship of adjacent loops (Fig. 1.1). This has been accepted as a perferred technique for morphological demonstration of small lesions with other imaging techniques of US and CT giving an added dimension which is usually complementary.
In 1980s, in addition to the widespread use of endoscopy for gastrointestinal tract evaluation, the major development that influenced gastrointestinal radiology was further improvement in US and CT techniques for visualisation of endoluminal, intramural and perienteric components of the disease process. US and CT definitely score over double contrast techniques in the evaluation of the inflammatory disease affecting small and large bowel and staging of neoplasm involving gastointestinal tract.2
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Fig. 1.1: Conventional small bowel enteroclysis showing normal distended jejunal and ileal loops
If the clinical history suggests primary mucosal disease process, barium study or endoscopy is an appropriate first choice but when the disease is suspected in which the information about extraluminal extension of the disease process is more critical than the changes in the mucosal surfaces, CT becomes the first investigation of choice.
With advances in CT technology, the role of CT has increased in evaluating patients with acute abdominal symptoms. CT can demonstrate intestinal and vascular changes and other ancillary abdominal features, hence it is considered the procedure of choice in clinically suspected intestinal obstruction or mesenteric ischaemia. Recently, MR imaging has also been reported to be comparable to CT in demonstrating these changes.
CT enteroclysis and more recently MR enteroclysis have emerged as techniques for small bowel imaging that combine advantages of barium enteroclysis with those of cross sectional imaging. Multidetector CT (MDCT) scanner with its capability of multiplanar reconstruction, can delineate the extent of the bowel disease and its complications. It can image the entire small and large bowel consistently which cannot be always achieved with barium study. MDCT is reliable, well tolerated, accurate and a fast imaging alternative technique to barium study for initial evaluation of small bowel and to assess extraenteric abnormalities especially in inflammatory bowel disease. The disadvantages of MDCT over barium study are increased radiation dose and the need for intravenous contrast. Nevertheless, information gained from MDCT justifies the increased radiation dose compared with barium study.3
Colonoscopy is a standard procedure for colonic evaluation both for diagnosis and biopsy as it visualises directly the mucosa and it may also be used in the treatment for removal of polyps. Virtual colonoscopy in recent years is emerging as a practical clinical technique for detection of colonic polyp or mass, both for colorectal cancer screening and for evaluation of patients with incomplete colonoscopy.4
Currently research is directed towards improving speed of image analysis, use of computer aided methods for detection of polyps, MR colonography, oral contrast tagging of faecal contents to avoid the need for rigorous bowel preparation, thereby improving patient compliance.
5
 
Conventional Techniques: Present Scenario
Since the year 2000, conventional radiological techniques for the evaluation of gastrointestinal tract have shown considerable decline. Plain radiograph of the abdomen has been limited mostly for bedside evaluation and for initial evaluation of abdominal distension for small bowel obstruction, intestinal ischaemia and perforation. In many centres CT is done as an initial technique replacing X-ray abdomen in acute abdominal conditions like acute appendicitis, intestinal obstruction, perforation, blunt trauma etc.
For evaluation of the esophagus, endoscopy is the first line investigation with fluoroscopic barium studies being complimentary for esophagitis and tumors. However the fluoroscopic barium studies still have a role in the assessment of motility disorders.
For evaluation of the stomach and the duodenum, fluoroscopic barium meal study is only complimentary to endoscopy for most cases of dyspepsia and abdominal pain. However it is superior to endoscopy for functional abnormalities like reflux, delayed emptying and submucosal masses and infiltrative processes. The barium/gastrograffin oral contrast study is also the technique of choice for evaluation in early postoperative period following gastric surgery, and in late postoperative period to define the anatomy.
For radiological evaluation of small bowel, enteroclysis has proven to a better technique than barium small bowel follow through examination.5,6 It has been well accepted that enteroclysis is the technique of choice for demonstration of proximal disease, skip lesions, subtle strictures and mucosal abnormalities. The conventional enteroclysis has the advantages of shorter examination time, better distension of small bowel and better visualization of pathology but has drawbacks of more radiologist time, greater technical skill, more radiation dose to patient and operator and patient discomfort. CT enteroclysis and MR enteroclysis in addition have the advantage of cross-sectional studies like evaluation of wall and adjacent structures. Small bowel follow through study has the advantages of patient preference, ease to perform and ability to judge transit time. However the drawback of inadequate distension of small bowel coupled with dilution of barium renders it less useful as compared to enteroclysis and more recently capsule endoscopy. Capsule endoscopy is being increasingly used in clinical practice to visualize lesions of small bowel.5,6 It is competing with enteroclysis as the modality of choice for evaluating small bowel. It has been shown to be very sensitive in detecting mucosal lesions and angiodysplasias but suffers from limitations of long hours of patient preparation time, small bowel transit and subsequent analysis of images. Other limitations include difficulty in localizing the pathology and inability to work in cases of intestinal obstruction. A small bowel follow through or enteroclysis may be required prior to capsule endoscopy in cases of clinical suspicion of small bowel obstruction.
Evaluation of colorectal diseases has been taken over by colonoscopy as an initial technique, double contrast barium enema being reserved as a second line of investigation in situtation with incomplete colonoscopy.7 Also barium contrast enema is preferred in patients with question of large bowel obstruction, need for localisation of colonic disease preoperatively or to assess the status of colon anastomosis.
 
Advances in GIT Imaging
In recent years, advances in imaging technology of US, CT and MRI have contributed significantly in the imaging of various gastrointestinal diseases. Much interest has been focused on CT enteroclysis in recent times to overcome the individual deficiencies of CT (no distention of the small intestine) and conventional enteroclysis (no extraluminal information). CT enteroclysis has become a successful alternative imaging method for small-bowel evaluation and is reported to be highly accurate in depicting mucosal abnormalities and extraintestinal complications in patients with inflammatory diseases of the intestine. MR Enteroclysis (MRE) has the dual advantage of MRI (excellent soft-tissue contrast and multiplanar imaging capabilities) and enteroclysis (enables optimal distention of the small bowel) and could be the optimal imaging method for evaluation of the bowel. With the availability of ultra fast sequences, robust breath-hold sequences and adequate use of contrast media, a combined morphologic and functional imaging method for the small bowel, has now become possible with MRE. PET-CT scan has been the latest addition to the armoury.8
 
Ultrasonography (US) in GIT
Earlier, the inherent bowel gas was considered as an obstacle to useful US imaging but recently its role in 6intrinsic gastrointestinal diseases has been well recognized. The development of endoscopic US (EUS) has rendered upper gastrointestinal tract amenable to US examination. Also EUS instrument incorporating biopsy channel within the endoscope is available for fine needle aspiration of intramural or extramural lesions under US guidance. Intraoperative US using high frequency transducers can provide similar degree of resolution as EUS techniques.
Technique of endosonography can stage the tumor by depicting all layers of bowel wall and it has become a practical technique for staging carcinoma of the esophagus and the stomach in many centers. Transrectal ultrasonography using a high frequency rotating transducer is a valuable method, permits staging of colorectal carcinoma which can be correlated well with endoscopy. Anal endosonography is a modification of transrectal sonography that provides radial images of the anal canal and its sphincters. It has proven to be particularly useful for mapping traumatic defects of the external anal sphincter in patients with faecal incontinence.
Sonoenteroclysis is a useful technique in the evaluation of small bowel.9 The diagnostic accuracy of sonoenteroclysis for detecting small bowel lesions is comparable to that of barium enteroclysis. This new, widely available, inexpensive, and undemanding technique can be used as an initial investigation in the evaluation of patients with small bowel disorders.9 The application of color Doppler imaging and power Doppler may allow differentiation of active bowel thickening (increased blood flow) from chronic wall thickening/fibrosis (no increased flow).10 Similarly, Doppler ultrasound can also demonstrate hemodynamic changes in patients with active IBD which are not present in those with quiescent disease.11 In a study by Hata12 et al, ultrasound had a reported sensitivity of 86% for CD and 89% for UC. Although recent work is promising, ultrasound continues to be very operator dependent and adversely affected by factors such as obesity and intraluminal gas.
 
CT Enteroclysis (Fig. 1.2)
CT depicts mural and extraluminal abnormalities and CT Enteroclysis combines the advantages of both CT with IV contrast and enteroclysis with enteral contrast.13 The contrast agent should allow imaging with homogeneous luminal enhancement, high contrast between the lumen and bowel wall, minimal mucosal absorption, absence of artifact formation, and without significant adverse effects. Enteral Contrast Agents can be neutral (0.5% methylcellulose, Water, Low density Barium (VoLumen and Polyethylene glycol) or positive (4-15% water soluble contrast, Dilute 6% Barium). Barium as contrast is preferred for CT Enterography and to demonstrate sinus tracts and fistulae. Patterns of abnormality that have to be observed on CT Enteroclysis are mural enhancement pattern (Target, homogenous, heterogeneous and diminished), length of involvement, degree of thickening, symmetric vs asymmetric thickening, location (proximal vs distal), location in the wall (mucosal/submucosal/serosal) and associated abnormalities in the mesenteric vasculature.
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Fig. 1.2: Coronal CT enteroclysis showing nodular normal distension of the small bowel
 
Technique of CT Enteroclysis
Fluoroscopic Phase–Small bowel catheter used (12 F Frekka tube 120 cm)-positioned to the left of midline OR in proximal descending duodenum to evaluate obscure GI bleed or anemia.
CT Phase–Infusion of 2.5 L water with methyl cellulose or dilute barium infused at 80-100 ml/min-rate, Infuse 1.5 L of water at 100 ml/min; 2 L for large patients or when colon evacuation is important followed by 1 ampoule Buscopan given IV and IV contrast (100ml/min). CT 7images are acquired at 50 sec delay in the late arterial/early portal venous phase. CT enteroclysis parameters for a 40 channel CT are source: 40 * 0.625 mm, reformat: 2.0 mm, width 1.0 mm reconstruction interval, window width = 360 HU and window level = 40HU (for negative contrast).
 
Indications
  • Unexplained GI bleed or anemia
  • Staging of known Crohn's disease
  • Unexplained pain abdomen with no e/o significant small bowel distension on plain X-rays
  • Alternate examination before/after capsule endoscopy or when CO2 double contrast Ba enteroclysis is not technically possible.
 
CT Enterography
CT enterography has rapidly gained acceptance as a method for visualizing the small bowel lumen, wall and mesentery for a variety of clinical indications like CD and vascular and neoplastic small bowel masses.14 CT enterography is similar to CT enteroclysis except for the fact that naso-jejunal tube is not used and only oral contrast is used to distend the small bowel loops. Patient preparation include nil per orally for 4 hrs prior to scan. Oral contrast of choice is 0.1% w/v barium solution mixed with sorbitol-attenuation 20 HU (volume-900– 1800 ml over 30 min to 2 hrs before CT) followed by 1 amp buscopan (i/m, i/v). Scanning techniques include single phase imaging in ”Enteric phase” with scan delay of 45 sec especially for evaluation of Crohn's disease and obstruction. Multiphasic imaging can also be performed with bolus triggered arterial phase with scan delay of 6 sec, enteric phase in 20-25 sec and delayed phase in 70-75 sec. This is important especially for obscure GI bleed.
 
MRI and MR Enteroclysis (MRE)
The mesenteric small bowel has remained a grey zone for enteroscopists despite the advances in various endoscopic techniques. MRE can be used as the initial imaging method for small-bowel diseases (Fig. 1.3). MRE has the potential to change the way how we assess the small bowel because of its capability to provide functional information, excellent soft-tissue contrast, and multiplanar imaging capabilities. TruFISP, HASTE, and post-gadolinium VIBE images can be employed in a comprehensive and integrated MRE examination protocol.15–17 Distention of the small-bowel lumen with methylcellulose solution and intravenously administered gadopentetate dimeglumine provides optimal contrast between the bowel wall and lumen. This technique enables optimal distention of the small bowel and facilitates identification of wall abnormalities resulting in accurate visualization of stenoses and obstructions. MRE scores over other imaging modalities because of its excellent soft-tissue contrast, direct multiplanar imaging capabilities, lack of ionizing radiation and functional information of disease activity. MRE has shown excellent correlation with conventional enteroclysis in grading small bowel obstruction, visualization of transmural and extramural pathology and also provides functional information regarding disease activity status. Although superficial abnormalities are better seen on conventional enteroclysis, the characteristic transmural abnormalities of Crohn's disease such as bowel wall thickening, linear ulcers, and cobblestoning are better seen with MRE, especially with the TrueFISP sequence. MRE is comparable to conventional enteroclysis in the detection of the number and extent of involved small bowel segments and in the delineation of stenosis or prestenotic intestinal dilatation. MRE findings correlate well with disease activity in both active and chronic form of Crohn's disease.
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Fig. 1.3: T2W MRI coronal view showing stricture at ileocecal junction (arrow) with proximal dilation in intestinal TB
 
PET-CT Enteroclysis and PET CT Colonography
Although CT enteroclysis and MR Enteroclysis provide excellent anatomical information, they fail to show the 8metabolic status of disease activity. Small intestinal endoscopic techniques such as capsule endoscopy and double balloon enteroscopy holds a lot of promise for evaluation of intestinal lumen. However, they fail to provide information on the intestinal wall and surrounding structures. Therefore, they are combined with a cross-sectional imaging technique such as CT enteroclysis or more often MR enteroclysis.18 Therefore, we conceptualized a fusion of a metabolic imaging technique like positron emission tomography (PET) and an anatomical imaging modality like CT enteroclysis to derive information both on the morphological details and the functional activity of the lesions at the same time. PET is now a well-established functional imaging technique and is widely used in the management of various cancers.19–21 Fusion of PET with CT (PET-CT) provides morphological localization of the metabolically active focus/foci. This technique exploits the property of viable malignant cells, which have higher uptake and metabolism of glucose.22 Increase in the glucose utilization is not specific for cancer cells, various cytokines and growth factors increase the affinity of glucose transporters for deoxyglucose in inflammatory conditions also.22 PET has been used for assessment of various inflammatory disorders and has shown encouraging results.23–25 The interpretation of abdominal PET images is often difficult due to physiologic uptake of FDG in a variety of abdominal/pelvic organs, which makes it difficult to distinguish normal from abnormal uptake. As the intestine remains in a collapsed state, the resolution of the intestine remains very poor on PET-CT. Therefore, distension of the intestine is required for better resolution on imaging.26 PET-CT scan can be acquired sixty minutes after intravenous injection of 10 mCi of IV 18 fluoro-deoxy-glucose (FDG) radiotracer injection and infusion of 2 l of 0.5% methylcellulose through a naso-jejunal catheter just before the study. We in a pilot study including 17 patients with inflammatory diseases of intestine such as intestinal tuberculosis and CD showed that as a single investigation, PET-CT enteroclysis detects a significantly higher number of lesions both in small and large intestine in comparison to that detected by conventional barium and colonoscopy combined together (Fig. 1.4). This technique is noninvasive, feasible and very promising.8 PET-CT enteroclysis may be used not only in the evaluation of IBD but also in the follow-up of patients non-invasively. PET-CT colonography is a similar technique like PET-CT enteroclysis and has the potential for non-invasive evaluation of patients with UC. PET-CT colonography is performed after ingestion of 2.5 liter of polyethylene glycol solution to distend colon and PET-CT scan was obtained 60 min after injection of 10 mCi of FDG. In an ongoing study, we found PET-CT colonography to be a novel non-invasive technique for assessment of disease extent in UC.27
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Fig. 1.4: PET-CT enteroclysis: Coronal PET-CT enteroclysis image in a patient with Crohn's disease showing diffuse uptake of FDG in small bowel (arrows) (For color version see plate 1)
 
NUCLEAR SCINTIGRAPHY
With the availability of radionuclide-labeled white blood cells (WBC) scintigraphy is quickly emerging as a promising technique for visualizing actively inflamed bowel. In the past, the major radionuclide used in evaluating patients with active IBD was gallium-67.28-30 Now-a-days new radionuclide like indium and technetium are used to label WBCs. In these studies, blood is removed from the patient and the white blood cells are separated and labeled, then reinjected. The radionuclide accumulates at sites of acute inflammation or infection. Imaging is performed at 6,12 and 24 hours and any focal bowel or intra-abdominal activity is suggestive of active inflammation/infection. Published literature shows good correlation between the results of indium-labeled white cell studies and colonoscopy, barium enema and clinical symptoms in patients with active IBD. 31–34 With the advent of selective radionuclide, the role of nuclear scintigraphy in the evaluation of patients with IBD is expanding. The 9strength of these radionuclides lies in the ability to screen patients for disease and to differentiate active from inactive disease. However, because of the limited spatial resolution and current difficulty in differentiating between inflammatory and infectious bowel diseases, the scintigraphy is used as a problem solving modality when other tests are equivocal.
Characteristic imaging finding of common bowel disorders are discussed below.
 
Tuberculosis
CT may show mural thickening of IC area-concentric, low density areas in the bowel wall, skip areas, enlarged mesenteric lymph nodes with central low attenuation areas and obstruction. CT or MR enteroclysis can delineate the stricture and MRE specifically can tell about the activity of the stricture (Fig. 1.3). In addition, extraluminal findings like lymph nodes and peritoneal involvement can be seen.
 
Crohn's Disease
Complications of CD like stricture and fistulas are well seen on enteroclysis. Strictures are reported to occur in 21% of patients with small bowel CD and may result in high grade bowel obstruction necessitating surgical intervention in some cases. Enteroclysis is useful in differentiating fibrotic strictures which may require surgery from active ulcerated stenotic disease and luminal narrowing as a result of spasm. Resistance to lumen distension during enteroclysis confirms the presence of a fibrous stricture. Fistulas in CD occur in 6–33% cases. Most commonly these are ileo-ileal or ileo-caecal and are often multiple.
Specific advantages of cross-sectional imaging include demonstration of the transmural extent of inflammation; skip lesions without significant severe stenosis, intraperitoneal or extraintestinal complications and in assessment of the disease activity. CT is the modality of choice for evaluation of the bowel although recently MRI has also been shown to be as effective. A prerequisite for optimal evaluation of the small bowel with CT or MRI is adequate distension of the bowel loops. This can be achieved by administering 1-2 liters of contrast orally or better still via a naso-jejunal catheter. Bowel wall thickening usually ranging from 1-2 cm is the most consistent feature of Crohn's disease on cross-sectional imaging. The number of lesions, presence of luminal narrowing, prestenotic dilatation and pseudodiverticulum formation are easily recognized on the cross-sectional images. Fibrofatty proliferation in the adjacent mesentery is commonly seen in Crohn's disease. Cross-sectional imaging modalities especially CT or MRI can also depict complications like abscesses close to the involved bowel and fistulous communication (with adjacent bowel, skin or urinary bladder) and also the blind ending sinus tracts. Small mesenteric lymph nodes ranging from 3–8 mm in size can be seen in Crohn's disease. Knowledge of the inflammatory activity of the disease is important to institute appropriate treatment. CT and MRI are very useful in this regard. The findings which suggest active disease include: thickened bowel wall with marked contrast enhancement (Fig. 1.5), mural stratification, pericolic or perienteric hypervascularity (Coomb's sign) (Fig. 1.6), hyperintensity of the bowel on T2 weighted images, lymph node enlargement and exramural complications such as phlegmon and abscess.
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Fig. 1.5: Crohn's disease: Contrast-enhanced T1W MRI shows marked enhancement and wall thickening of the rectosigmoid (arrow) with positive Coombs’ sign
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Fig. 1.6: Crohn's disease: Post Gad T1W coronal image showing enhancement of whole of small bowel
10
 
Imaging in Small Bowel Obstruction
Enteroclysis is the method of choice in low grade/intermittent obstruction, unsuspected closed loop obstruction, h/o laparotomy for malignancy, radiation enteropathy and strictures in Crohn's disease. Enteroclysis is contraindicated in acute and complete or high grade obstruction, suspicious strangulated obstruction and suspected perforation. CT has high sensitivity of 94-100% and accuracy of 90-95%. CT is the method of choice in acute, complete obstruction, adynamic ileus, prolonged high grade obstruction, suspicion of strangulation, and suspicion of inflammatory process (Figs 1.7 and 1.8). Common extrinsic causes include adhesions, closed loop obstruction, strangulation (circumferential wall thickening with increased attenuation, target sign, congestion/hemorrhage in the mesentery, pneumatosis intestinalis and ascites), hernias and tumors (carcinoid, lymphoma, peritoneal carcinomatosis, and diverticulitis). Intrinsic causes include adenocarcinoma, inflammatory conditions (Tuberculosis, CD), radiation enteropathy and intussusception.
 
Mesenteric Ischemia
Mesenteric ischemia results from major artery occlusion (SMA) or mesenteric vein thrombosis. Plain X-rays may show thickened valvulae conniventes, dilated gas filled bowel loops, thickening of bowel wall, thumb printing and occasionally air in intestinal wall/hepatic veins. Barium studies reveal thickened valvulae thumbprinting of mesenteric border, luminal narrowing and wall thickening with separation of bowel loops. CT findings include bowel wall thickening more than 8 mm, transmural infarction causing paper thin wall bowel dilatation, low density bowel wall, pneumatosis/portomesenteric venous gas complete absence of enhancement, mesenteric edema. Vascular findings include thrombus, embolus, vasculitis, dissection, aneurysm and venous thrombosis.
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Fig. 1.7: Intestinal obstruction: Coronal CT enteroclysis showing multiple stenoses of jejunal loop with gross dilatation of intervening jejunal loops in a case of adhesion
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Fig. 1.8: Intestinal obstruction: Coronal CT enteroclysis showing gross dilatation of jejunal loops in a case of adhesion
 
Neoplasms Malignant
Forty percent of malignant small bowel tumors are adenocarcinomas. Barium shows narrowing and CT may show eccentric focal mass, circumferential asymmetric thickening and metastasis to lymph node and mesentery. Lymphoma is equally common. Barium may show aneurysmal, constrictive, nodular, ulcerative, mesenteric and endoexoenteric type of lesions. CT may show circumferential wall thickening, cavitary and mesenteric lymph nodal masses. Bulky, eccentric lesion with calcification, significant enhancement with IV contrast and metastasis to liver, omentum may be seen in 11leiomyosarcoma. Carcinoid may show characteristic crowding of folds with kinking of bowel wall on barium studies. In CT, it appears as a mesenteric mass with curvilinear strands extending to bowel loops (Stellate appearance) with adenopathy, calcification and liver metastasis. Angiography may show stellate arterial configuration at tumor periphery.
 
CONCLUSIONS
Advances in imaging technology of US, CT and MRI provide a clear understanding of the true extent of a gastrointestinal lesion. The rapid dissemination of MDCT provides faster and more accurate imaging. With robust computer processing power and larger set of data storage capacity will make image rendering faster, simpler and more affordable. It is quite likely that gastrointestinal imaging will continue to expand till it reaches its zenith due to further technical advances. In conclusion, judicious use of available modalities may lead to timely and prompt diagnosis of various intestinal disorders.
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