Feasibility of MDCT Colonography in ultra-low-dose technique in the detection of colorectal lesions: comparison with high-resolution video colonoscopy.
OBJECTIVE
The purpose of this study was to assess the feasibility of MDCT colonography in an ultra-low-dose technique in the detection of endoluminal colonic lesions compared with high-resolution video colonoscopy.


METHODS
After standard bowel cleansing, 137 patients (77 men, 60 women; mean [+/- SD] age, 57.1 +/- 11.3 years) underwent high-resolution video colonoscopy within 2 hr after ultra-low-dose MDCT colonography had been performed. Ultra-low-dose MDCT colonography was performed with patients in the supine position only using 10 mAs (effective weighted CT dose index, 0.94 mGy). After mathematic noise reduction by nonlinear gaussian filter chains, using dedicated software (ECCET), images were analyzed by two blinded observers in simultaneously displayed interactive 2D and 3D modes. Findings of ultra-low-dose MDCT colonography were compared with the results obtained with high-resolution video colonoscopy.


RESULTS
Calculated effective doses were 0.7 and 1.2 mSv for men and women, respectively. Ultra-low-dose MDCT colonography detected 84 (62%) of 135 lesions: 11 (78.6%) of 14 large polyps (> 10 mm), 12 (85.7%) of 14 medium polyps (9.9-5 mm), and 61 (57%) of 107 small polyps (< 5 mm). On a patient-by-patient basis, an overall sensitivity of 70.3% with a specificity of 80.8% was calculated. False-positive findings were seen mostly for small lesions (eight medium and 29 small lesions). Two of the three false-negative lesions were retrospectively detected in contrast-enhanced cleansing fluid; one was a flat lipoma not detectable on ultra-low-dose MDCT colonography.


CONCLUSIONS
Despite an effective dose of approximately 1 mSv, MDCT colonography using an ultra-low-dose technique performs as well as MDCT colonography with a standard dose, according to published data. After mathematic noise reduction, 82% of polyps larger than 5 mm can be detected.
Cohnen
Mathias
M
Institute of Diagnostic Radiology, University Hospital Duesseldorf, MNR-Klinik, Moorenstrasse 5, Duesseldorf 40225, Germany. cohnen@med.uni-duesseldorf.de
Vogt
Christoph
C
Beck
Andreas
A
Andersen
Kjel
K
Heinen
Wolfram
W
vom Dahl
Stephan
S
Aurich
Volker
V
Haeussinger
Dieter
D
Moedder
Ulrich
U
D003106:Colon / Q000473:pathology; D003111:Colonic Polyps / Q000175:diagnosis; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D012680:Sensitivity and Specificity