The current status of multidetector row CT and three-dimensional imaging of the small bowel

Since its introduction into clinical use in the late 1970s, CT has made spectacular technologic advancements. These advancements have dramatically improved the detection and characterization of a wide variety of small bowel pathology and, today, CT is considered to play a crucial role in the evaluation of the small intestine. Early scanners acquired scan data relatively slowly, requiring 15 seconds to obtain a single 10-mm slice with at least a 60-second reconstruction time. Although oral and intravenous (IV) CT contrast agents were available, long acquisition and reconstruction times resulted in significant respiratory and motion artifact, and limited resolution of the small intestine and bowel wall. At that time, the small bowel series still played the dominant role in radiologic imaging of the small intestine. The introduction of spiral (helical) CT in the late 1980s revolutionized CT imaging of the gastrointestinal tract by allowing for faster scanning, thinner collimation (3-5 mm) and faster reconstruction times, as well as volume acquisition. For the first time, CT did not consist of merely a series of slices, but rather as a complete volume of information. This paradigm shift led to the introduction of three-dimensional (313) imaging, which greatly expanded the clinical role of CT. Thus, CT began to play a more serious role in evaluation of gastrointestinal tract pathology, although barium studies were still the first line of imaging for most indications. Today, multidetector row CT (MDCT) represents the latest technical advancement in CT scanning and has completed the evolution from a slice-based to a volume-based technique. Eight-detector row scanners are now widely available and allow four slices to be obtained in less than 500 milliseconds with thinner collimation (0.5-1.0 . mm). Thirty-two-detector row CT scanners are now being introduced and will offer at least a threefold increase in speed and a doubling of resolution compared with current systems. The availability of MDCT and advancements in 3D CT imaging systems have greatly expanded the role of CT in evaluation of suspected small bowel pathology. Applications that were once routinely performed with barium studies (eg, the evaluation of suspected small bowel obstruction) or angiography (eg, the evaluation of mesenteric ischemia) now have been replaced with CT scans. At this time, CT is considered a first-line modality for the evaluation of a wide variety of small bowel diseases. This article discusses the current role of MDCT and 3D imaging in the detection and characterization of small bowel pathology, including mesenteric ischemia, Crohn's disease, small bowel obstruction, and neoplasms.