Screening of patients after colectomy: virtual colonography

Current status on performance of CT colonography and clinical indications

CT colonography (CTC) is a robust and reliable imaging test of the colon. Accuracy for the detection of colorectal cancer (CRC) is as high as conventional colonoscopy (CC). Identification of polyp is size dependent, with large lesions (≥10mm) accurately detected and small lesions (6-9mm) identified with moderate to good sensitivity. Recent studies show good sensitivity for the identification of nonpolypoid (flat) lesions as well. Current CTC indications include the evaluation of patients who had undergone a previous incomplete CC or those who are unfit for CC (elderly and frail individuals, patients with underlying severe clinical conditions, or with contraindication to sedation). CTC can also be efficiently used in the assessment of diverticular disease (excluding patients with acute diverticulitis, where the exam should be postponed), before laparoscopic surgery for CRC (to have an accurate localization of the lesion), in the evaluation of colonic involvement in the case of deep pelvic endometriosis (replacing barium enema). CTC is also a safe procedure in patients with colostomy. For CRC screening, CTC should be considered an opportunistic screening test (not available for population, or mass screening) to be offered to asymptomatic average-risk individuals, of both genders, starting at age 50. The use in individuals with positive family history should be discussed with the patient first. Absolute contraindication is to propose CTC for surveillance of genetic syndromes and chronic inflammatory bowel diseases (in particular, ulcerative colitis). The use of CTC in the follow-up after surgery for CRC is achieving interesting evidences despite the fact that literature data are still relatively weak in terms of numerosity of the studied populations. In patients who underwent previous polypectomy CTC cannot be recommended as first test because debate is still open. It is desirable that in the future CTC would be the first-line and only diagnostic test for colonic diseases, leaving to CC only a therapeutic role.

Contrast-enhanced CT colonography with 64-slice MDCT compared to endoscopic colonoscopy in the follow-up of patients after colorectal cancer resection

BACKGROUND

Seventy percent of newly diagnosed colorectal cancer cases are potential candidates for curative surgery, but after resection, in 30%, the tumor will recur. Postoperative follow-up includes endoscopic colonoscopy (EC) and computed tomography (CT). There have been only a few publications on the use of contrast-enhanced CT colonography (CECTC) in the follow-up of these patients.

METHODS

Twenty-nine consecutive patients after resection of colorectal cancer underwent CECTC and EC on the same day. CECTC studies were reviewed for identification of strictures, recurrence, polyps and metastases.

RESULTS

The anastomosis was identified in 96% of patients on CECTC and in 82% on endoscopic colonoscopy. One stricture was identified by both techniques. One extraluminal recurrence was depicted only on CECTC. Sensitivity in detecting polyps was per polyp 93% and per patient 100%.

CONCLUSION

CECTC performed on a 64-slice multidetector CT is reliable in imaging the postoperative colon for the follow-up of patients after resection of colorectal cancer.