Intravenous, contrast-enhanced MR colonography using air as endoluminal contrast agent: impact on colorectal polyp detection.
OBJECTIVE
To compare diagnostic accuracy and patient tolerance of MR colonography with intravenous contrast and luminal air (MRC) to conventional colonoscopy (CC).


METHODS
IRB approval and written informed consent were obtained. Forty-six patients, both screening and symptomatic, underwent MRC followed by CC. The MRC technique employed 3D T1W spoiled gradient echo sequences performed after the administration of gadopenetate dimeglumine, with parallel imaging. The diagnostic accuracy and tolerance of patients for MRC was compared to CC.


RESULTS
Twenty-four polyps were detected in eighteen patients with CC (5 polyps ≥ 10 mm, 4 polyps 6-9 mm, 15 polyps ≤ 5 mm). MRC was 66.7% (12/18) sensitive and 96.4% (27/28) specific for polyp detection on a per-patient basis. When analyzed by polyp size, sensitivity and specificity of MRC was 100% (5/5) and 100% (19/19), respectively, for lesions greater than 10mm, 100% (4/4) and 100% (20/20) for lesions 6-9 mm, and sensitivity of 20% (3/15) lesions less than 5mm. The sensitivity and specificity of MRC for detecting significant lesions (>6mm) was 100% (9/9) and 100% (15/15), respectively. Regarding tolerance of the exams, there were no significant differences between MRC and CC. Thirty-five percent (n=16) of patients preferred MRC as a future screening test compared to 33% (n=15) for CC.


CONCLUSIONS
MRC using air as an intraluminal contrast agent is a feasible and well-tolerated technique for detecting colonic polyps ≥ 6 mm in size. Further studies are warranted.
Department of Radiology, Beaumont Hospital, Beaumont Road, Dublin 9, Ireland. aoifekeeling@hotmail.com
Aoife N
AN
Keeling
Martina M
MM
Morrin
Charles
C
McKenzie
Richard J
RJ
Farrell
Sunil G
SG
Sheth
Long
L
Ngo
B Nicolas
BN
Bloch
Ivan
I
Pedrosa
Neil M
NM
Rofsky
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000388:Air; D003106:Colon / Q000473:pathology*; D003111:Colonic Polyps / Q000473:pathology*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D012002:Rectal Diseases / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D003287:Contrast Media