MR enteroclysis

The low prevalence of small bowel disease and its nonspecific symptoms frequently cause delays in diagnosis and treatment. An accurate radiologic examination is important not only for recognition of small bowel disease but also to help reliably document normal morphology [1]. Enteroclysis is widely accepted as the method of choice for small bowel imaging [2-4], because enteroclysis provides optimal distention of the entire small bowel, functional information, and high spatial resolution. Enteroclysis, however, only provides indirect information of the small bowel wall and surrounding structures and suffers from problems with overlapping bowel loops. Additional cross-sectional imaging modalities (CT or MR imaging) may be required for accurate diagnosis and precise evaluation of the extent of extraluminal disease. CT enteroclysis was recently introduced to combine the advantages of enteroclysis and CT [5]. CT enteroclysis profits from excellent distention of the entire small bowel, which allows detection of small lesions in the bowel wall and improves the detection of low-grade partial small bowel obstruction (SBO) [5,6]. The disadvantages of CT enteroclysis are increased exposure of ionizing radiation, lack of functional information, lack of fluoroscopic control of the small bowel filling in the CT examination room, and poor soft tissue contrast. Because of its excellent soft tissue contrast and multiplanar imaging capabilities, MR imaging could be the optimal imaging method for evaluation of the small bowel. Long acquisition times, peristalsis, and respiratory motion artifacts, however, were severe limitations of MR imaging of the small bowel in the past and MR imaging was rarely used for evaluation of small bowel diseases [7-10]. Recently, because of the development of ultrafast sequences, there is increasing interest in small bowel evaluation with MR imaging [11-15]. Problems related to small bowel distention and to functional information, however, remain limitations of MR imaging of the small bowel. Collapsed bowel loops may hide or simulate small bowel disease [16,17]. Adequate distention of the entire small bowel is a key requirement of any small bowel imaging method (Fig. 1). Different methods have been used to achieve an adequate distention of the entire small bowel [18-32] for MR imaging. In the authors', opinion, enteroclysis is the only method that provides adequate distention of the entire small bowel in any patient. In addition, functional information is required to facilitate detection of even low-grade partial SBO, and to exclude small bowel disease reliably. MR enteroclysis was introduced to overcome the individual deficiencies of MR imaging and enteroclysis and to combine the advantages of both into one technique [17].