Understanding the mechanisms that drive uncontrolled inflammation in Crohn's disease (CD) remains one of the most pressing challenges in contemporary experimental medicine. Recently, a three-phased view on the pathogenesis of CD was proposed in which following the breakdown of intestinal epithelial barrier function, CD patients fail to clear the resulting infectious debris, provoking subsequent immune responses. This view on CD is attractive in that it is testable and allows better diagnosis of disease if proven correct, apart from opening a window on new therapeutic horizons. Here we shall argue, however, that this scheme may be an oversimplification in that it ignores the genetic diversity of CD and thus does not fully take into account the nature of the intestinal epithelium, which appears a non-passive actor in this disease.

Enteroclysis is a minimally invasive radiographic examination of the small intestine. During the procedure, considerable radiation dose is delivered to the patients. This study intends to: (a) evaluate the radiation dose to the patient using thermoluminescent dosemeters (TLDs, according to the protocol used at Radiology Department, University Hospital of Larissa, Greece; (b) estimate the thyroid surface dose (TSD) and doses to some radiosensitive organs located in the irradiation field. A total of 46 patients was examined. Patients were divided into two groups according to the digital X-ray machine used. The mean entrance surface dose (ESD) was 601.2 ± 96.2 mGy and the mean fluoroscopy time was 8.5 ± 3 min, while the mean TSD was 0.34 ± 0.6 mGy. The ESD for group A was lower by 20 % than group B due to fluoroscopic mode used. The dose values were higher than those in the literature. A local diagnostic reference level was introduced for further patient dose optimisation.

The substantial morbidity and mortality associated with Crohn's disease underlines the importance of accurate assessment at presentation, during follow-up, when investigating complications, and when evaluating the response to therapeutic interventions. Accurate methods are required to quantify the severity and extent of disease.

With the introduction of new techniques to image the small bowel, there remains uncertainty about their role for diagnosing Crohn's disease.

To assess the sensitivity and specificity of capsule endoscopy (CE), CT enterography (CTE), ileocolonoscopy, and small-bowel follow-through (SBFT) in the diagnosis of small bowel Crohn's disease.

Prospective, blinded trial.

Inflammatory bowel disease clinic at an academic medical center.

Known or suspected Crohn's disease. Exclusion criteria included known abdominal abscess and non-steroidal anti-inflammatory drug (NSAID) use. Partial small-bowel obstruction (PSBO) at CTE excluded patients from subsequent CE.

Patients underwent all 4 tests over a 4-day period.

Sensitivity, specificity, and accuracy of each test to detect active small-bowel Crohn's disease. The criterion standard was a consensus diagnosis based upon clinical presentation and all 4 studies.

Forty-one CTE examinations were performed. Seven patients (17%) had an asymptomatic PSBO. Forty patients underwent colonoscopy, 38 had SBFT studies, and 28 had CE examinations. Small-bowel Crohn's disease was active in 51%, absent in 42%, inactive in 5%, and suspicious in 2% of patients. The sensitivity of CE for detecting active small-bowel Crohn's disease was 83%, not significantly higher than CTE (83%), ileocolonoscopy (74%), or SBFT (65%). However, the specificity of CE (53%) was significantly lower than the other tests (P < .05). One patient developed a transient PSBO due to CE, but no patients had retained capsules.

Use of a consensus clinical diagnosis as the criterion standard-but this is how Crohn's disease is diagnosed in practice.

The sensitivity of CE for active small-bowel Crohn's disease was not significantly different from CTE, ileocolonoscopy, or SBFT. However, lower specificity and the need for preceding small-bowel radiography (due to the high frequency of asymptomatic PSBO) may limit the utility of CE as a first-line test for Crohn's disease.

The purpose of this study was to compare MR enteroclysis (MRE) with conventional enteroclysis (CE) in patients with small intestinal Crohn's disease. Fifty-two consecutive patients with known or suspected Crohn's disease underwent MR and conventional enteroclysis, which was considered the gold standard. Eleven imaging features, classified in three groups, mucosal, transmural and extraintestinal, were subjectively evaluated by two experienced radiologists. MRE and CE were in full agreement in revealing, localizing and estimating the length of all involved segments of the small bowel. The sensitivity of MRE for the detection of superficial ulcers, fold distortion and fold thickening was 40, 30 and 62.5%, respectively. The sensitivity of MRE for the detection of deep ulcers, cobble-stoning pattern, stenosis and prestenostic dilatation was 89.5, 92.3, 100 and 100%, respectively. Additional findings demonstrated on MRE images included fibrofatty proliferation in 15 cases and mesenteric lymphadenopathy in 19 cases. MRE strongly correlates with CE in the detection of individual lesions expressing small intestinal Crohn's disease. It provides additional information from the mesenteries; however, its capability to detect subtle lesions is still inferior to conventional enteroclysis.

Postoperative recurrence of Crohn disease is a common problem. It has been assumed that the radiologic patterns are similar in de novo and recurrent ileal disease, but there has been little in the literature to actually confirm this belief.

We retrospectively reviewed the small bowel examinations of 105 consecutive patients with a proven diagnosis of Crohn disease: a control group of 47 patients with no prior surgery and a postoperative group of 58 patients with resections. Of the latter, 22 had ileocecal or ileocolonic resections and 36 patients had ileocecal or ileocolonic and extensive enteric resections. We examined the disease sites and compared the disease patterns in both groups.

Fifty-six of 58 (97%) postoperative patients had anastomotic recurrences with proximal extension from 3 to 25 cm, with a mean of 10.5 cm; none showed distal disease extension. Two (3%) had enteric recurrences with neoterminal ileal sparing. There were no statistically significant differences in the length of distal/terminal ileal disease and the frequency of skip lesions in de novo and recurrent disease. There were lower frequencies of mucosal thickening, ulceration/ulceronodular mucosa, sacculation, loop separation, sinuses, and masses and a higher frequency of strictures in recurrent disease than in de novo disease. There was also a lower frequency of ulceration or ulceronodular mucosa after extensive resection than after limited resection.

Postoperative patients with ileal Crohn disease show a marked preponderance for anastomotic recurrence with proximal disease extension. There are significant differences in disease patterns in patients with de novo and recurrent disease.

MR enteroclysis is becoming a very important imaging modality in the workup and follow-up of small bowel diseases. The technique has many advantages, including the absence of ionizing radiation, ability to control luminal distension, superior tissue characterization, multiplanar capabilities, and mural and extramural visualization. These capabilities can be obtained with a simple protocol showing excellent agreement with conventional enteroclysis. In 29 (18 with new or known Crohn's disease) of the 50 patients pathology was detected, with a very good clinical correlation. In 14 patients MR enteroclysis data altered the therapeutic strategy. This contributes to the acceptance of this modality as a primary tool in small bowel diseases.

Every single imaging finding that can be disclosed on conventional and MR enteroclysis was correlated with the Crohn's disease activity index (CDAI). Nineteen consecutive patients with Crohn's disease underwent colon endoscopy and both conventional and MR enteroclysis examinations. Seventeen MR imaging findings and seven conventional enteroclysis findings were ranked on a four-point grading scale and correlated with CDAI, with a value of 150 considered as the threshold for disease activity. Six patients had active disease in the colon according to colon endoscopy. In the remaining 13 patients, the presence of deep ulcers ( P=0.002), small bowel wall thickening ( P=0.022) and gadolinium enhancement of mesenteric lymph nodes ( P=0.014) identified on MR enteroclysis images were strongly correlated to disease activity. The product of deep ulcers and enhancement of lymph node ranks identified on MR enteroclysis were the optimum combination for discriminating active from non-active disease ( F-test: 55.95, P<0.001). Additionally, the ranking of deep ulcers on conventional enteroclysis provided statistically significant differences between active and non-active patients ( F-test: 14.12, P=0.004). Abnormalities strongly suggestive of active Crohn's disease can be disclosed on MR enteroclysis examinations and may provide pictorial information for local inflammatory activity.

This article has reviewed the imaging features that correspond to and support the classification of patients into clinical subtypes of Crohn's disease. One study showed that radiologic features on barium studies closely correlated with the Crohn's Disease Activity Index, and another study indicated that CT findings changed patient management in up to 29% of cases. Knowledge of the location, severity, and presence of complications assist in providing patients with appropriate treatment options. Reports of radiologic studies in Crohn's disease should include the presence or absence of imaging features that support these different subtypes. An additional advantage of the use of a reproducible imaging classification that emphasizes morphologic features would be improved comparison of the results of different investigators and treatment protocols. Whatever method of radiologic investigation is employed, it should be targeted to answer questions relevant to patient management. The imaging modalities used should be able to classify the small bowel Crohn's subtypes and should be reflected in the radiologists' reports.

Magnetic resonance (MR) enteroclysis imaging is emerging as a technique for evaluation of the small bowel in patients with Crohn disease. Administration of 1.5-2 L of isosmotic water solution through a nasojejunal catheter ensures distention of the bowel and facilitates identification of wall abnormalities. True fast imaging with steady-state precession (FISP), half-Fourier acquisition single-shot turbo spin-echo (HASTE), and postgadolinium T1-weighted three-dimensional fast low-angle shot sequences can be employed in a comprehensive and integrated MR enteroclysis examination protocol to overcome specific disadvantages of each of the sequences involved. Superficial abnormalities that are ideally delineated with conventional enteroclysis are not consistently depicted with MR enteroclysis. The characteristic transmural abnormalities of Crohn disease such as bowel wall thickening, linear ulcers, and cobblestoning are accurately shown with MR enteroclysis imaging, especially with the true FISP sequence. MR enteroclysis is comparable to conventional enteroclysis in the detection of the number and extent of involved small bowel segments and in the disclosure of luminal narrowing or prestenotic intestinal dilatation. The clinical utility of MR enteroclysis in Crohn disease has not been fully established. At present, the method may be used for follow-up studies of known disease, estimation of disease activity, and determination of the extramucosal extent and spread of the disease process.

This article reviews the radiologic and endoscopic diagnosis of Crohn's disease. Radiographic and endoscopic findings of Crohn's disease are discussed; a practical approach to the selection of radiologic modalities is presented; and the role of endoscopy in diagnosis and treatment is explained.

Preoperative diagnosis of primary small intestinal neoplasms can be a challenge for both clinicians and radiologists. As a result of their infrequent occurrence, they invariably present difficult problems in diagnosis and management. These problems are reflected mainly in the delayed treatment and a very poor prognosis for such malignant tumours. Their morphological changes, however, shown in enteroclysis and CT, correlate almost perfectly with the lesions identified in the gross pathological specimens. This ability to accurately image a small intestinal neoplasm, independently of its size, anatomical localization and growing tendency, represents a major improvement in the diagnosis and management of these neoplasms. This paper, based on a large series of patients with primary small intestinal neoplasms, focuses on the recognition of their detailed radiological appearances when evaluated by enteroclysis and CT.

In two patients with Crohn's disease, strictureplasties had been marked operatively by a metal clip, so that definitive location on subsequent small bowel examination was possible. Each strictureplasty presented radiologically as a short annular constriction with apparently shouldered edges and parallel lumen. Similar radiological features were found in five other patients with strictureplasties, suggesting that a pseudotumoral appearance is characteristic of strictureplasty. Attention is drawn to this finding to avoid confusion with malignancy.

In a retrospective study the radiological reports of small bowel enema (enteroclysis) examinations of 1465 patients were reviewed and compared with the subsequent clinical outcome, and where possible with findings at laparotomy. A sensitivity of 93.1% and a specificity of 96.9% was found, based on whether the small intestine was reported as normal or an abnormality was diagnosed to account for the patient's clinical presentation. The correct specific diagnosis was made in 67.5% of the examinations that were considered abnormal. We believe that these figures support the use of small bowel enema as the routine barium examination for suspected disorders of the small intestine.

We describe three patients with Crohn's disease of the small intestine with a polypoid configuration. In two patients, the polypoid masses were the only radiologic abnormalities and were suggestive of jejunoileal lymphoma and terminal ileal adenomas. The diagnosis of Crohn's disease was established only at laparotomy. In the third patient, a polypoid mass simulating a sessile adenoma was seen along with other typical features of ileitis and was recognized preoperatively as a manifestation of the ileitis. The resected ileal segments of all three patients showed mural thickening, luminal narrowing and distortion, and mucosal ulceration and fissuring. The asymmetry of the mural thickening and the resultant luminal narrowing simulated sessile polyps to which mucosal ulceration and fissuring gave a lobulated appearance.

The radiological features of small intestinal lymphoma are described in 11 patients examined using the small bowel enema technique. The signs include luminal narrowing with mucosal destruction and occasionally shouldering of the margins and stricture formation, broad based ulceration, cavitation, non-specific thickening of the valvulae conniventes, discrete intraluminal filling defects, and a mass. In one patient, small nodules were scattered throughout the small intestine. Aneurysmal dilatation of a segment of intestine was seen in one case and an extraluminal mesenteric mass in another. A combination of different signs was a frequent finding and multiple intestinal lesions were present in four cases. Predisposing factors were present in five cases including coeliac disease, chronic lymphatic leukaemia, immunoproliferative small intestinal (alpha-chain) disease and previous extraintestinal lymphoma. In another patient there was evidence of extraintestinal lymphoma at the time of presentation.

Fifty-nine patients with an ileostomy were studied who were examined by small bowel enema over a 10-year period. Twenty-two subsequently underwent surgery, nine for recurrent Crohn's disease, seven for obstruction due to adhesions or internal hernia and one for ovarian carcinoma. The remaining five patients with colonic Crohn's disease had panproctocolectomy or closure of the ileostomy. The small bowel enema is a reliable method for investigating the small intestine of patients with an ileostomy.

In a prospective, blinded study we investigated 30 patients with Crohn's disease (CD) and 27 normal controls by means of dynamic grey-scale ultrasound scan. Within a few weeks the patients were also examined by radiography of the small bowel. Of the 30 patients, 21 had CD lesion of the small bowel as judged by radiography. A target lesion at the ultrasound scan indicating thickened bowel wall was seen in 15 CD patients, of which 14 showed radiographic signs of CD in the ileum and/or right side of the large bowel, whereas one had normal radiographic findings. Seven patients out of 15 without sonographic changes had radiographic signs of CD. The patients with discrepancy between the two examinations could not be clinically characterized as an entity. None of the 27 normal controls showed signs of intestinal disease at the ultrasound examination. We conclude that dynamic grey-scale ultrasound examination is a new tool in depicting the CD lesion, but it does not seem to be able to replace the radiographic examination. However, it may find a place in the follow-up study of patients with known CD, thereby avoiding repeated radiographic examinations. Furthermore, the possibility of diagnosing abscesses and fistulae by sonography is well known and has relevance in CD.

The radiological features of five cases of primary adenocarcinoma of the jejunum are described and the differential diagnosis is discussed. Barium examination is the best method for detecting adenocarcinoma in the small intestine and angiography is useful for pre-operative assessment.

The radiological findings, using a single-contrast barium infusion technique, are described in a series of 13 patients with chronic radiation enteritis. The signs include evidence of submucosal thickening, single or multiple stenoses, adhesions and sinus or fistula formation. A combination of these signs characterises the condition. This technique is particularly suited to the investigation of radiation enteritis because of its ability to distend maximally the small intestine. A cause, stenosis and/or adhesions, was demonstrated in the eight of the 13 patients presenting with intermittent small-intestinal obstruction. Three patients had diarrhoea as their predominant complaint and a fistula was demonstrated in two.

Primary carcinoid tumours are rarely detected in the small intestine by conventional radiological methods. The radiological features are presented of 11 patients with primary small-intestinal carcinoids, in whom the tumour was demonstrated by the barium infusion technique. In four of these patients the site of the primary tumour was also demonstrated angiographically. We have found these methods valuable in identifying primary carcinoid tumours and consider them to be the investigations of choice in evaluating patients with suspected or established carcinoid syndrome.

Twenty-eight patients with inflammatory bowel disease were examined with ultrasound. When possible, maximum bowel wall thickness was measured and the site of any focal abnormality recorded. There were 19 patients with Crohn's disease and nine with ulcerative colitis. Bowel wall thickness ranged from 0.5-1.8 mm in the Crohn's group to 0.3-0.8 cm in the ulcerative colitis group. Following treatment, a measurable reduction in bowel wall thickness was demonstrated in 13 of the patients with Crohn's disease. No significant change in bowel wall thickness was detected in five of the patients with ulcerative colitis. The results echo the findings at double-contrast radiography and suggest a possible role for ultrasound in the assessment and follow-up of inflammatory bowel disease.

A method is described for consistently improving the quality of the small bowel barium follow-through by enhancement with an oral effervescent agent. With this method, although satisfactory double-contrast views of the whole small bowel were obtained in less than half the patients, satisfactory distension of the small-bowel loops was achieved in 96% of examinations.

A technique for performing small bowel enemas in children is described in detail and the results of using this technique reported. Minor modifications are necessary to the technique commonly used in adults; a softer tube is used and sedation given early and generously. It is stressed that the radiologist must control the sedation as well as the radiology.

During a two-year period 26 patients with suspected small bowel obstruction were examined by infusing barium into the small intestine. Mechanical obstruction was confirmed in 25 patients and the level of obstruction was shown in all except one who had carcinoma of the caecum. Surgery was avoided in nine patients-six of whom had Crohn's disease, two had adhesions and the investigation showed no abnormality in one patient. There were no complications associated with the examination or with the subsequent operation.

A prospective study was carried out to compare the radiological and pathological appearances of Crohn's disease of the small intestine. The X-ray examinations were carried out by infusing barium directly into the small intestine. Thirty-six patients who were operated on for Crohn's disease of the small intestine are included. There was excellent correlation between the radiological appearances and the findings at morbid anatomy.