Colorectal polyps: Detection with multi-slice CT colonography.
OBJECTIVE
To compare the performance of virtual and conventional colonoscopy for the detection of colorectal polyps using a multislice spiral CT scanner (MSCT).


METHODS
48 patients (20 women, 28 men, mean age 61.5 years) with clinical indication for conventional colonoscopy were prospectively studied using a MSCT (Somatom Volume Zoom, Siemens, Forchheim). Examination was performed after standard oral preparation for colonoscopy and colonic distension with room air and i. v. butylscopolamin. Images were obtained in prone and supine position using a detector configuration of 4 x 1 mm, a table feed of 5 mm/rotation at 140 mAs and 120 kV. Slice thickness and reconstruction increment were 3 and 1.5 mm, respectively. CT data were assessed by two blinded radiologists on a Vitrea workstation (Vital Images, USA) using a software with multiplanar and volume-rendering capabilities.


RESULTS
33 patients had normal findings on conventional colonoscopy. In 15 patients a total of 30 polyps and one carcinoma with stenosis were identified. MSCT-colonography identified the carcinoma and 23 polyps (77 %). 3 of 3 polyps were 10 mm or more (100 %), 6 of 7 were 5.1 to 9.9 mm (86 %) and 14 of 20 were 5 mm or smaller (70 %). There were 13 false positive findings for polyps (10 lesions < 6 mm in 5 patients) and no false positive finding of carcinoma.


CONCLUSIONS
MSCT colonography allows accurate detection of polyps larger than 10 mm. Compared to published results of single-slice CT, multislice CT colonography increases the rate of detection of small colorectal polyps in particular. However, false positive results still remain a problem.
Wessling
J
J
Department of Clinical Radiology, University of Muenster, Germany. weslingj@uni-muenster.de
Fischbach
R
R
Domagk
D
D
Lügering
N
N
Neumann
E
E
Heindel
W
W
D003108:Colonic Diseases / Q000000981:diagnostic imaging; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007415:Intestinal Obstruction / Q000000981:diagnostic imaging; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011237:Predictive Value of Tests; D014057:Tomography, X-Ray Computed