0470: Ultrasound in Crohns Disease

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High-resolution ultrasonography has greatly improved the diagnostic potential of ultrasound in the assessment of inflammatory bowel disease. Ultrasonography is not only a method used by radiologists, but also a clinical tool that can be applied to evaluate patients with Crohn's disease: both for bed-side tentative diagnosis, pre-operative scanning, and for out-patient follow-up. This lecture reviews some of the principles, common findings and methods that can be used in ultrasonographic scanning of the GI tract in patients with Crohn's disease. Ultrasound of the GI tract has proved to be useful as an imaging modality in patients with symptoms or clinical signs that indicate inflammatory bowel disorder as well as for assessing the anatomical extension of Crohn's lesions at primary diagnosis. Mb. Crohn often starts with symptoms like abdominal pain, diarrhoea or weight loss. Ultrasonography is a very relevant method to rule out different causes of these symptoms and to detect changes compatible with Crohn's disease. A normal bowel wall is considered to have a wall thickness below 2-4mm, depending on the actual localisation. Typical ultrasound findings in Crohn's disease are: Increased GI-wall thickness most often seen in the distal ileum, dilated bowel loops, ulcerations or fistulas, abscesses, reduced motility, decreased Resistive Index, and in some cases ascites. In some cases, full endoscopic examination is not possible due to a stenotic GI segment, e.g. of the colon or pyloric ulceration leading to gastric retention. In such circumstances, transabdominal ultrasound can image the more central part of the intestines and give valuable information about the length of the stenotic part. Ultrasonic determination of the extent of the GI-wall affection will also aid in distinguishing between ulcerative colitis and Crohn's disease. Another indication is the ambulant follow-up of patients who have established Crohn's disease. High-frequency ultrasonography may play a key role in the detection of luminal and mesentery complications or for the evaluation of disease extension during a clinical flare-up. The patients can act as their own controls over time and the effect of treatment can be monitored by ultrasonography. The role of bowel ultrasound in the assessment of disease activity is controversial, but the use of Doppler RI and i.v. contrast agents has the potential to differentiate inflammatory from fibrotic intestinal strictures. Contrast-enhanced power Doppler ultrasound has high sensitivity and specificity in the detection and evaluation of inflammatory abdominal masses associated with Crohn's disease, and compares favourably with computed tomography. The spatial resolution and sensitivity of contrast-enhanced power Doppler ultrasound enables the detection of small inflammatory abdominal masses. The absence of radiation dose to the patient allows multiple and serial examinations to be undertaken. In conclusion, ultrasonography is a very useful clinical tool in the management of patients with Crohn's disease. New ultrasound technologies, such intravenous contrast agents, advanced Doppler methods, and elastography may further increase the diagnostic capability of GI ultrasonography.