MDCT of Small Bowel Obstruction: How Reliable Are Oblique Reformatted Images in Localizing Point of Transition?

Abstract

The goal of this study is to prospectively assess the additional value of oblique reformatted images for localizing POT, having surgery as a reference standard. Materials and Methods. 102 consecutive patients with suspected small bowel obstruction (SBO) underwent 64-slice multidetector row CT (MDCT) using surgical findings as reference standard. Two independent GI radiologists reviewed the CT scans to localize the exact POT by evaluating axial images (data set A) followed by axial, coronal, and oblique MPR images. CT findings were compared to surgical findings in terms of diagnostic performance. McNemar's test was used to detect any statistical difference in POT evaluation between datasets A and B. Kappa statistics were applied for measuring agreement between two readers. Results. There was a diagnostic improvement of 9.9% in the case of the less experienced radiologist in localizing POT by using oblique reformatted images. The more experienced radiologist showed diagnostic improvement by 12.9%.

Figure 1

Effect of oblique MPRs on confidence of radiologist in diagnosing point of transition.

Figure 2

CT scan of 48-year-old female with acute abdominal pain. (a) Axial and coronal CT images obtained with intravenous contrast agents show dilated small-bowel loops (red arrow heads and green circles). (b) Oblique reformation shows dilated small-bowel loops with a transition point (green arrow) in the midabdomen. Multiple small mesenteric lymph nodes also visualized (yellow circles).

Figure 3

CT scans in a 54-year-old woman with a two-month history of nausea and vomiting acutely presenting with worsening of symptoms. (a) Axial and coronal CT images obtained with intravenous contrast agent show herniated loops of small-bowel loops through a defect in anterior abdominal wall; however, the tract of bowel could not be completely elucidated on axial and coronal sections alone (yellow circles). (b) Oblique reformation exactly shows the outgoing and incoming loops of bowel with proximal dilated segments of bowel representing partial obstruction (blue circles and curved arrows).

Figure 4

Agreement between readers.