Radiology: Volume 254: Number 3—March 2010

CT Colonography after Metallic Stent Placement for Acute Malignant Colonic Obstruction

Eun-Young Cha, MD Seong Ho Park, MD Seung Soo Lee, MD Jin Cheon Kim, MD Chang Sik Yu, MD Seok-Byung Lim, MD Sang Nam Yoon, MD Yong Moon Shin, MD Ah Young Kim, MD Hyun Kwon Ha, MD

Purpose: To evaluate the feasibility of using computed tomographic (CT) colonography for preoperative examination of the proximal colon after metallic stent placement in patients with acute colon obstruction caused by colorectal cancer.

Materials and Methods: Institutional review board approval was obtained, and pa­tient informed consent was waived. Fifty patients (mean age ± standard deviation, 58.5 years ± 11.7), who dem­onstrated no postprocedural complication after success­ful placement of self-expandable metallic stents to treat acute colon obstruction caused by cancer, underwent CT colonography 1-43 days (median, 5 days) after stent placement. CT colonography was performed after cathar­tic preparation by using magnesium citrate (n = 20) or sodium phosphate (n = 3), combined with oral bisacodyl, or by using polyethylene glycol (n = 27). Fecal/fluid tag­ging was achieved by using 100 mL of meglumine diatri-zoate. The colon was distended by means of pressure-monitored C02 insufflation. The sensitivity and specificity of CT colonography in evaluating the colon proximal to the stent and CT colonography-related complications were assessed. The 95% confidence intervals (CIs) were calcu­lated for proportional data.

Results: Per-lesion and per-patient sensitivities of CT colonogra­phy for lesions 6 mm or larger in diameter in the colon proximal to the stent were 85.7% (12 of 14 lesions; 95% CI: 58.8%, 97.2%) and 90% (nine of 10 patients; 95% CI: 57.4%, 99.9%), respectively. CT colonography depicted all synchronous cancers (two lesions) and advanced ad­enomas (five lesions). Per-patient specificity for lesions 6 mm and larger in the proximal colon was 85.7% (18 of 21 patients; 95% CI: 64.5%, 95.9%). CT colonography did not generate any false diagnosis of synchronous cancer. False-positive findings at CT colonography did not result in a change in surgical plan for any patients. No CT colonography-associated stent dislodgment/migration or colonic perfora­tion occurred in any patient (95% CI: 0%, 6.2%).

Conclusion:CT colonography is a safe and useful method for preop­erative examination of the proximal colon after metallic stent placement in patients with acute colon obstruction caused by cancer.