Imaging is essential in assessing patients with Crohn's disease, and it provides important and complementary information to the clinical and endoscopic findings. Patients can be accurately phenotyped and complications identified.

Crohn's disease and ulcerative colitis in humans and paratuberculosis in domestic and wild ruminants can be defined as chronic regional intestinal inflammatory diseases (CRIID). This review is a literature overview on these diseases in humans, non-human primates, dogs, cats, rabbits, equids and ruminants with a focus on pathological and microbiological features aimed identifying common characteristics that could lead to a unified pathological classification for a better understanding of their mechanisms and causes. The result is a framework of inflammatory forms throughout the different species indicative of common mechanisms of the slow infection type characterized by a time course varying from weeks to months or even years, and where the inflammatory component would be more prominent in the intestinal interphase between host and environment and be morphologically characterized by an infiltrate ranging from lymphoplasmacytic to histiocytic. This should provide new insights for causation demonstration and therapeutic approaches in human IBD.

We have previously recognized segmental sigmoid polyps as an indicator of a fistula from Crohn's ileitis to the sigmoid or the proximal rectum. In the course of this study, we realized that many patients with this fistula had no sigmoid polyps, but the sigmoid was the site of marked inflammation and early or late stricture formation. Furthermore, in some patients with a stricture, the fistula was not recognized until the surgeon (or the pathologist) dissected an inflammatory peri-ileal and/or a perisigmoidal mass.In this study, we have sought to clarify the sequence of events by focusing on the segmental inflammation and the stricturing of the sigmoid so that its significance can be recognized as a local complication of the ileitis and the progression of its severity as opposed to arising sui generis.

From our database of >3000 patients with inflammatory bowel disease at Lenox Hill Hospital, we identified 45 patients with Crohn's ileitis and ileosigmoid fistula (ISF): 24 had segmental sigmoid polyps and 18 had segmental inflammatory sigmoid strictures. The fistula was first seen by imaging in 36 patients, but not until resection by the surgeon or dissection by the pathologist in 7 patients.

The method of diagnosis for the initial recognition of the ISF and the sigmoid stricture is presented in Table 1. In 36 of the 45 cases, the ISF was recognized by radiologic imaging. In total, 31 of the 36 cases required surgical intervention, not because of the fistula, but because of small-bowel obstruction due to the ileitis. In 7 of the 31 (22%) cases, the fistula was recognized only by dissection of the inflammatory ileosigmoid mass by the surgeon or examination of the surgical specimen by the pathologist. The sequence of events from the originating ileitis to the ISF to the segmental sigmoid polyposis and stricture, with the resulting sigmoid obstruction, is shown in Figures 1A-E.

We emphasize the natural history of the ISF so that its recognition will lead to earlier medical management of the originating ileitis. Furthermore, it adds evidence of the recognition that the causative agent of Crohn's disease is carried by the fecal stream.

Crohn's disease of the foregut is more common than previously recognized, with up to 40% of patients with Crohn's disease in the distal intestine also having evidence of foregut disease. Esophageal disease is best managed medically with proton pump inhibition, steroids, thiopurines, methotrexate, and anti-tumor necrosis factor-α biologic medications. Esophageal strictures are dealt with using endoscopic dilation. Surgery is generally reserved of resistant strictures or esophageal fistulas. Patients with gastroduodenal disease more commonly come to surgery. The most commonly performed operations for gastroduodenal Crohn's disease are intestinal bypass or strictureplasty. The concomitant use of vagotomy remains controversial.

The advent of cross-sectional enterography has revolutionized small-bowel imaging, providing comprehensive, reproducible evaluation of CD and its complications. Continued collaboration between radiologists and gastroenterologists is critical to ensure further progress toward the common goals of classifying disease activity, predicting response to treatment, and appropriate triage to medical versus surgical therapy.

In the last decade, multiple imaging technologies have been developed that improve visualization of the mucosal, mural, and perienteric inflammation associated with inflammatory bowel diseases. Whereas these technologies have traditionally been used to detect and stage suspected enteric inflammation, we review new, emerging roles in detecting clinically occult inflammation (in asymptomatic patients) and inflammatory complications, predicting response prior to therapy, assessing response after therapy, and enteric healing. We compare the relative performance of these technologies in detecting inflammation, focusing on their advantages and disadvantages and how they might complement each other. We also discuss their potential benefits for patients and clinical trials, reviewing technologic developments and areas of research that could provide important insights into the pathophysiology of inflammatory bowel diseases-related enteric inflammation.

Inflammatory bowel disease basically consists of two entities: ulcerative colitis (UC) and Crohn's disease (CD). Both processes are characterized by chronic inflammation of the intestine, which in the case of CD may affect the entire digestive tract. We present the case of a young man who was diagnosed with esophageal CD after presenting dysphagia and odynophagia. Intestinal involvement was subsequently found. Esophageal involvement is infrequent and as the first manifestation of CD it is extremely rare. It should, however, be borne in mind in patients with esophageal ulcerations without symptoms or endoscopic signs compatible with peptic etiology, even though other indications of inflammatory disease are absent.

Historically, Crohn's disease of the esophagus, stomach, and duodenum has been reported only rarely. With more frequent use of upper endoscopy, however, upper gastrointestinal involvement has been found to be more common than previously suspected. The surgeon with an interest in Crohn's disease needs to be familiar with all areas that are potentially affected in this perplexing and sometimes devastating disease. This article examines the literature on foregut Crohn's and discusses the incidence, clinical manifestations, diagnosis, medical management, surgical indications, and operative techniques.

Recurrence of Crohn's disease frequently occurs after surgery. A randomized controlled trial was performed to determine if mesalamine is effective in decreasing the risk of recurrent Crohn's disease after surgical resection is performed.

One hundred sixty-three patients who underwent a surgical resection and had no evidence of residual disease were randomized to a treatment group (1.5 g mesalamine twice a day) or a placebo control group within 8 weeks of surgery. The follow-up period was a maximum of 72 months.

The symptomatic recurrence rate (symptoms plus endoscopic and/or radiological confirmation of disease) in the treatment group was 31% (27 of 87) compared with 41% (31 of 76) in the control group (P = 0.031). The relative risk of developing recurrent disease was 0.628 (90% confidence interval, 0.40-0.97) for those in the treatment group (P = 0.039; one-tail test) using an intention-to-treat analysis and 0.532 (90% confidence interval, 0.32-0.87) using an efficacy analysis. The endoscopic and radiological rate of recurrence was also significantly decreased with relative risks of 0.654 (90% confidence interval, 0.47-0.91) in the effectiveness analysis and 0.635 (90% confidence interval, 0.44-0.91) in the efficacy analysis. There was only one serious side effect (pancreatitis) in subjects in the treatment group.

Mesalamine (3.0 g/day) is effective in decreasing the risk of recurrence of Crohn's disease after surgical resection is performed.

Two patients presented to their clinicians with bowel complaints thought to be suggestive of Crohn's disease. The patients were sent for radiological studies to confirm that diagnosis. The radiologic findings in both patients were thought to be consistent with Crohn's disease, although not classical. No further diagnostic studies were initially undertaken. Each patient suffered small bowel obstruction and at surgery each was found to have a mucinous adenocarcinoma of the ileocecal valve. No evidence of Crohn's disease was found. At pathologic examination some interesting characteristics of the tumors were observed, which perhaps accounted for the misdiagnosis of Crohn's disease. It also was evident that the clinical information supplied to the radiologist may have influenced the radiologic interpretations. These cases stress the importance of obtaining tissue diagnoses in situations where radiographic findings are consistent but atypical with the clinical diagnosis of Crohn's disease.

A study has been made of 93 Japanese patients with Crohn's disease who had not undergone bowel resection at the time of diagnosis during the years 1969 to 1983. Ninety had longitudinal ulcers or a cobblestone appearance or both of the small intestine or colon or both on double contrast barium examination. The incidence of longitudinal ulcers in the small intestine was significantly higher than in the colon (P less than 0.001). Conversely the incidence of cobblestoning was higher in the colon than in the small intestine (P = 0.065). In patients with longitudinal ulceration, there was significantly lower Crohn's disease activity index (CDAI), ESR, and C-reactive protein. Patients with cobblestoning had a significantly higher CDAI, ESR and C-reactive protein, and significantly lower values of albumin, cholesterol in serum, serum iron, haemoglobin, and relative body weight. Our findings indicate that cobblestoning closely correlates with the disease activity of Crohn's disease, and that longitudinal ulceration has a negative correlation. Moreover, our results suggest that the high incidence of cobblestoning and low incidence of longitudinal ulcers in the colon and the reverse in the small intestine reflects the fact that colonic involvement renders the disease more severe than small intestine involvement only.

Twenty patients with Crohn's disease were treated with parenteral nutrition (PN). The indication for PN was a bodyweight of less than 80% ideal bodyweight and/or a Crohn's disease activity index (CDAI) above 150 despite conventional therapy. A complete nutrition solution containing per litre 150 g glucose, 50 g sorbitol, 50 g amino acids, 50 g fat, electrolytes, trace elements and vitamins was infused via a central venous catheter to provide 72 kcal per kg bodyweight and day. No other medications were given during the study. The patients were randomized into two groups: both groups received PN in identical fashion. Group 1 was not allowed to eat or drink to reach total bowel rest; Group 2 ate formula diets and low residue diet ad libidum in addition to PN. Criteria for the nutritional status were bodyweight, serum albumin, prealbumin and hemoglobin and for disease activity the CDAI. Mean duration of treatment was 28 days in group 1 and 33.5 days in group 2. At the beginning both groups were comparable with respect to disease activity, nutritional status and extent of Crohn's disease. At the end of the study nutritional status was improved (increase of bodyweight and prealbumin) and disease activity was decreased by therapy in both groups with no significant difference between the two regimens. We conclude that PN improves the nutritional status and reduces the activity of Crohn's disease. The combination of PN and total bowel rest resulted in the same improvement as with PN alone. Total bowel rest is therefore unnecessary, when PN is given in patients with Crohn's disease.

The course of all 113 patients with Crohn's disease whose initial procedure involved an anastomosis operated upon from 1942 to 1972 was followed through 1980. The calculated cumulative 30-year total mortality was 23.4%, 16.7% disease-related. The cumulative recurrence rate was 29% at five years, 52% at ten years, 64% at 15 years and 84% at 25 years, with no important differences between disease locations and types of operation. Sex, age, duration, granulomas, enteral or perirectal fistulas and length of the resection, the disease, and the proximal resection margin had no significant influence on the rates of development of recurrent disease or on functional outcome. By far the most common site of recurrence was the neo-terminal ileum, but in ileocolitis compared with ileitis, recurrence was 5.2 times more likely (p = 0.0001) to involve the adjacent or remote colon as well. Moreover, only 1/63 ileitis patients eventually required ileostomy, whereas 15/47 patients with ileocolitis or colitis ultimately required this procedure (p less than 0.001). The current status of the patients was excellent or good in 64% and unwell or dead related in 24%. Urolithiasis developed in 19%.

Six female patients are described with a fulminant onset of Crohn's's disease involving the whole of the colon. The initial picture resembled that of an acute infectious diarrhea, but rapid clinical deterioration with pronounced weight loss, major anal complications, toxic megacolon, and erythema nodosum necessitated reappraisal of the diagnosis. Extensive endoscopy and multiple biopsies confirmed the diagnosis of pancolitis in all patients. Only one patient needed resection. Recognition of such fulminant onset as a distinct clinical modality in Crohn disease of the colon and starting treatment immediately upon diagnosis is probably important in preventing the development of a critical clinical situation.

The radiographic manifestations of idiopathic ulcerative colitis and Crohn's disease of the colon have been extensively reviewed and are well known. The increasing use of primary double-contrast barium enemas in patients with inflammatory bowel disease has led to enthusiastic reports concerning the differentiation of ulcerative colitis and Crohn's disease. Typically, in ulcerative colitis there is a continuous, diffuse granular mucosal pattern, with or without superadded ulceration; in contrast, Crohn's colitis is characterised by discrete ulcers with intervening normal mucosa. In this paper the occurrence of continuous diffuse mucosal granularity in Crohn's disease of the colon is described. Four selected cases are used as illustrative examples to emphasise the non-specific nature of this particular finding. Caution must be exercised in attributing specific mucosal patterns to the various forms of infectious and non-infectious colitis.

Although the radiographic manifestations of Crohn's disease of the colon have been extensively reviewed, few reports specifically illustrate the evolution of discrete mucosal ulcers in this disease. There is, moreover, some controversy concerning the nature and significance of small or so-called aphthous ulcers in the pathogenesis of Crohn's colitis. In this study, results from sequential primary double-contrast barium enemas performed over a 5-year period in 21 patients with proven Crohn's colitis were reviewed. A localized segment of colon showing discrete mucosal ulcers was selected for analysis and comparison in serial examinations. The radiographic appearances and course of these discrete mucosal ulcers are described and illustrated.

Postoperative films of 150 patients operated upon for Crohn's disease were reviewed with regard to postoperative abnormalities in the new distal ileum. The lesions were always located in the most aboral part of the ileum. In patients with persistent colonic disease the ileal lesions were apparently the result of a spread of colonic lesions. In many of the remaining patients there was strong evidence that recurrent disease was representative of persistent disease.

Posteroperative films of 114 patients subjected to a primary operation for Crohn's disease were reviewed with special regard to postoperative lesions in the colon. Recurrence in the colon was in 13 patients of 16 due to an exacerbation of the disease in segments left behind at operation. Recurrence in the new distal ileum in addition to persistent colonic disease occurred in 11 patients of 12. This was probably due to the operative connection of the ileum to a diseased colon.

Preoperative films of 176 patients operated upon for Crohn's disease were reviewed and compared with microscopic findings in the resected specimens in order to assess the accuracy of the radiographic techniques used. It was found that a diagnosis of the presence and the extent of the disease was often dependent on the demonstration of minor mucosal ulcers and less marked submucosal edema. These lesions were not adequately demonstrated by any of the techniques used for small bowel examination, but were consistently revealed by the double-contrast technique used for examination of the colon.

To better define the course of Crohn's disease, certain clinical, laboratory, and radiological features were studied prospectively in a representative group of 25 patients at intervals of up to 77 months. Eleven variables of potential use in assessing the course were analyzed for clinician preference, and the statistical relationship of one variable, the Crohn's disease activity index, to the other 10 was determined. Modest improvement was documented in three clinical variables, as well as in anemia, serum albumin, intestinal protein loss, and radiological extent of disease. Variables most frequently ranked high as reflections of the course of Crohn's disease were hematocrit and extent of disease, followed by body weight, stools per day, B12 absorption, serum albumin, and intestinal protein loss. The highest intervariable correlation was between improvement in protein loss and decrease in radiological extent (r = 0.75).

Eight cases of pseudopolyposis occurring in Crohn's colitis are described. Emphasis is placed on the variability of the lesions. Four of the cases demonstrate localized giant pseudopolyposis which has until recently been regarded mainly as a complication of ulcerative colitis.

Our regional experience in the state of Connecticut indicates that Crohn's disease is being overdiagnosed. Six patients with disorders mimicking regional enteritis are presented, one of whom had an atypical clinical course and the remainder had atypical therapeutic responses. The radiologist should be aware of clinical responses and make reassessments if necessary, in order not to overlook surgically treatable conditions.

In patients with Crohn's disease, early or localized lesions of the colon, termed 'focal granulomatous colitis', may give rise to small and often relatively inconspicuous nodular or tumor-like contour defects in conventional barium enema studies. This radiologic sign, first illustrated by Ettinger [7], has received scant attention in the literature. The present communication is intended to re-emphasize the radiologic appearances of focal granulomatous (Crohn's) colitis in conventional barium enema examinations, provide pathologic correlation, and illustrate by selected case reports the clinical significance of recognizing this particular radiologic abnormality.

Regional enteritis in children may affect the small bowel without involvement of the terminal ileum. We have noted this distribution of disease in 4 of 20 consecutive cases of Crohn's disease. The clinical and radiologic features of these 4 patients are reported together with a review of similar observations in the literature.

Tuberculosis continues to be a major health problem in India. Our experience of 102 cases of gastrointestinal tract tuberculosis is presented. Eighty-one of these patients experienced obstructive symptoms, 62 had radiographic evidence of intestinal obstruction, and four had bowel perforation. Lymphadenopathy was present in 16 patients and pulmonary tuberculosis in 28. The commonest sites of bowel involvement were ileo-caecal, ileum and ascending colon. Duodenal lesions were seen in three cases and in another three there was isolated appendicular involvement. Right hemicolectomy was necessary in 55 of the 74 patients who had surgical exploration. Histopathological reports were available in 88 subjects. The various radiographic manifestations of tuberculosis of the bowel are discussed. Radiologically and sometimes even on histopathology, differentiation of ileo-caecal tuberculosis from Crohn's ileo-colitis may prove impossible.

Aphthoid ulceration is a strong indication and the earliest radiographic sign of Crohn's colitis. These small discrete ulcers were found by double contrast barium enema examination in 40 out of 91 patients with Crohn's colitis. Seen en face each ulcer appears as a central fleck of barium surrounded by a translucent halo set amidst a patch of normal mucosa. Their detection gives a more accurate assessment of the extent of disease. This information is required in order to plan medical or surgical treatment and can only be provided by meticulous double contrast examination or colonoscopy. Aphthoid ulceration has been demonstrated prior to the onset of bowel symptoms, and several years before the advent of severe colonic disease. The appearance of aphthoid ulcers in established quiescent disease has been observed to herald a relapse. The radiographic demonstration of the evolution of ulceration, which is illustrated, closely reflects what is seen on macroscopic examination of excised specimens and explains the characteristic patchiness and discontinuity of disease.

The role of the double-contrast enema (DCE) remains contraversial since no controlled comparison between the barium enema (BE) and the DCE has been performed. As a result of our experience with routine use of the DCE, we believe that it is the most sensitive technique for the detection of polypoid, annular, and inflammatory lesions in the colon. There are many commonly held myths and misconceptions regarding the DCE and these are discussed and refuted. The advantages of the DCE over the BE are discussed and illustrated.