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Distinguishing Benign from Malignant Bowel Obstruction in Patients with Malignancy: Findings at MR Imaging¹

¹ From the Sharp Memorial Hospital and Sharp Departments of Radiology (R.N.L., S.C.C.) and Surgical Oncology (R.B.), and Sharp and Children’s MRI Center (R.N.L., S.C.C.), 7901 Frost St, San Diego, CA 92123. Received June 19, 2002; revision requested August 9; revision received September 27; accepted November 22. Address correspondence to R.N.L.

View larger version (137K): [in a new window]   Figure 1. MR image of a patient with colon cancer who previously underwent radiation therapy and who now has bowel obstruction. Transverse gadolinium-enhanced spoiled gradient-echo MR image (165/2.1; flip angle, 70°) shows segmental mural thickening (arrows) measuring approximately 1 cm and enhancement of all visualized pelvic bowel. No obstructing mass was present. Findings correlate with radiation enteritis. Both observers correctly predicted benign bowel obstruction.

View larger version (138K): [in a new window]   Figure 2a. MR images of a patient with treated ovarian cancer. (a) Coronal gadolinium-enhanced spoiled gradient-echo MR image (140/2.1; flip angle, 70°) shows a bulky abdominal mass (arrows) producing bowel obstruction. The confluent abdominal mass involves the peripancreatic and portal regions superiorly and the small-bowel mesentery inferiorly. (b) Transverse gadolinium-enhanced spoiled gradient-echo MR image (140/2.1; flip angle, 70°) depicts a tumor mass (arrows) at the point of bowel obstruction. Other images (not shown) depicted bulky peritoneal tumor and a transition point in bowel dilatation. Both observers correctly predicted malignant bowel obstruction. Findings were confirmed at surgery.

View larger version (155K): [in a new window]   Figure 2b. MR images of a patient with treated ovarian cancer. (a) Coronal gadolinium-enhanced spoiled gradient-echo MR image (140/2.1; flip angle, 70°) shows a bulky abdominal mass (arrows) producing bowel obstruction. The confluent abdominal mass involves the peripancreatic and portal regions superiorly and the small-bowel mesentery inferiorly. (b) Transverse gadolinium-enhanced spoiled gradient-echo MR image (140/2.1; flip angle, 70°) depicts a tumor mass (arrows) at the point of bowel obstruction. Other images (not shown) depicted bulky peritoneal tumor and a transition point in bowel dilatation. Both observers correctly predicted malignant bowel obstruction. Findings were confirmed at surgery.

View larger version (126K): [in a new window]   Figure 3. MR image of a patient with treated cervical cancer and high-grade bowel obstruction. Transverse gadolinium-enhanced spoiled gradient-echo MR image (140/2.1; flip angle, 70°) shows marked bowel distention and an obstructing 3-cm mass (arrows) in the right lower quadrant. Gadolinium enhancement improves the conspicuity of the obstructing tumor. Focal mural thickening was better depicted on adjacent images (not shown). Enhancing peritoneal tumor (arrowheads) is present in the lower abdomen and pelvis. Metastatic cervical cancer producing bowel obstruction was confirmed at surgery. Both observers correctly predicted malignant bowel obstruction.

View larger version (101K): [in a new window]   Figure 4a. MR images of a patient with a history of rectal cancer and who now has abdominal pain and bowel obstruction. (a) Transverse gadolinium-enhanced spoiled gradient-echo MR image (165/2.1; flip angle, 70°) through the middle of the abdomen depicts focal mural thickening (arrows) involving an 8-cm segment of the transverse colon. No obstructing mass was present. (b) Coronal gadolinium-enhanced spoiled gradient-echo MR image (160/2.1; flip angle, 70°) depicts mural thickening of the transverse colon (white arrows). Additionally, note the focal mural thickening (black arrow) of the gastric antrum. Findings correlate with surgically proven serosal metastases from the patient’s rectal cancer. Both observers correctly predicted malignant bowel obstruction.

View larger version (163K): [in a new window]   Figure 4b. MR images of a patient with a history of rectal cancer and who now has abdominal pain and bowel obstruction. (a) Transverse gadolinium-enhanced spoiled gradient-echo MR image (165/2.1; flip angle, 70°) through the middle of the abdomen depicts focal mural thickening (arrows) involving an 8-cm segment of the transverse colon. No obstructing mass was present. (b) Coronal gadolinium-enhanced spoiled gradient-echo MR image (160/2.1; flip angle, 70°) depicts mural thickening of the transverse colon (white arrows). Additionally, note the focal mural thickening (black arrow) of the gastric antrum. Findings correlate with surgically proven serosal metastases from the patient’s rectal cancer. Both observers correctly predicted malignant bowel obstruction.

View larger version (143K): [in a new window]   Figure 5. MR image of a patient with treated colon cancer and partial bowel obstruction. Transverse gadolinium-enhanced spoiled gradient-echo MR image (165/2.1; flip angle, 70°) shows segmental mural thickening (arrows), which involved a 15-cm segment of the distal ileum without an obstructing mass. Both observers incorrectly predicted benign obstruction on the basis of the segmental (>10 cm) length of bowel wall thickening and absence of an obstructing mass.

View larger version (152K): [in a new window]   Figure 6. MR image of a woman with a 3-year history of ovarian cancer and who now has bowel obstruction. Transverse gadolinium-enhanced spoiled gradient-echo MR image (165/2.1; flip angle, 70°) shows enhancing dilated small bowel (arrows) with mild mural thickening but no obstructing mass. Both observers correctly predicted benign bowel obstruction. The patient’s bowel obstruction resolved, and she has remained tumor free for 5 years without additional treatment. Bowel wall enhancement is a nonspecific finding seen in both malignant and benign bowel obstruction.

View larger version (176K): [in a new window]   Figure 7. MR image of a patient with a history of lymphoma who now has abdominal pain and bowel obstruction. Coronal fat-suppressed gadolinium-enhanced spoiled gradient-echo MR image (140/2; flip angle, 70°) shows marked segmental mural thickening (arrows) and enhancement of the descending colon. No obstructing mass was present. Pseudomembranous colitis was confirmed with endoscopy and clinical evaluation, with a positive cytotoxicity test for toxin B. Both observers correctly predicted benign bowel obstruction.

View larger version (134K): [in a new window]   Figure 8a. MR images of a patient with colon cancer who previously underwent colectomy and who now has acute small-bowel obstruction. (a) Coronal and (b) transverse gadolinium-enhanced spoiled gradient-echo MR images (165/2.1; flip angle, 70°) show markedly dilated small bowel (long arrows in a and white arrows in b) with mild diffuse mural thickening (short arrows in a) and mural enhancement. In the pelvis, the transverse image (b) shows mesenteric infiltration and tethering (black arrow) of the dilated small bowel, without evidence of an obstructing mass. Mild peritoneal enhancement was noted on other images (not shown). Findings at surgery confirmed small-bowel obstruction due to adhesions. Both observers correctly predicted benign bowel obstruction.

View larger version (139K): [in a new window]   Figure 8b. MR images of a patient with colon cancer who previously underwent colectomy and who now has acute small-bowel obstruction. (a) Coronal and (b) transverse gadolinium-enhanced spoiled gradient-echo MR images (165/2.1; flip angle, 70°) show markedly dilated small bowel (long arrows in a and white arrows in b) with mild diffuse mural thickening (short arrows in a) and mural enhancement. In the pelvis, the transverse image (b) shows mesenteric infiltration and tethering (black arrow) of the dilated small bowel, without evidence of an obstructing mass. Mild peritoneal enhancement was noted on other images (not shown). Findings at surgery confirmed small-bowel obstruction due to adhesions. Both observers correctly predicted benign bowel obstruction.

View larger version (146K): [in a new window]   Figure 9. MR image of patient with treated ovarian cancer and bowel obstruction. Transverse gadolinium-enhanced spoiled gradient-echo MR image (165/2.1; flip angle, 70°) shows pelvic ascites (A) and an enhancing mass (arrows) invading a 10-cm segment of the sigmoid colon. The presence of the mass confirms malignant obstruction. Both observers correctly predicted malignant bowel obstruction.