Diffusion-weighted MRI: a new tool for the diagnosis of fistula in ano.
OBJECTIVE
To retrospectively determine the additional value of diffusion-weighted magnetic resonance imaging (MRI) to T2-weighted imaging in the evaluation of anal fistulae in comparison with gadolinium (Gd)-enhanced imaging.


METHODS
Thirteen patients (mean age, 35.2 years) with 20 anal fistulae were included. The protocol consisted of fat-suppressed T2-weighted fast spin-echo, diffusion-weighted single-shot echo-planar (b factors 0 and 800 s/mm(2)), and fat-suppressed Gd-enhanced T1-weighted gradient echo sequences. Two radiologists evaluated images in consensus.


RESULTS
Eighteen (90%) fistulae were detected on T2-weighted images, and 19 (95%) and 19 (95%) were detected on diffusion-weighted and T2-weighted images combined and on Gd-enhanced and T2-weighted images combined, respectively. There was no statistically significant difference in sensitivity of the techniques (P > 0.5 for all comparison pairs). Confidence scores with diffusion-weighted and T2-weighted images combined or those with Gd-enhanced and T2-weighted images combined were significantly greater than those with T2-weighted images alone (P = 0.0047 and 0.014, respectively).


CONCLUSIONS
Diffusion-weighted MRI of anal fistulae is a useful sequence and can be a helpful adjunct to T2-weighted imaging, especially in patients with risk factors for contrast agents.
Department of Radiology, University of Chicago, Chicago, Illinois 60637, USA. mhori@radiol.med.osaka-u.ac.jp
Masatoshi
M
Hori
Aytekin
A
Oto
Sarah
S
Orrin
Kenji
K
Suzuki
Richard L
RL
Baron
D000328:Adult; D003287:Contrast Media / Q000494:pharmacology*; D003424:Crohn Disease / Q000175:diagnosis* / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011871:Radiology / Q000379:methods*; D012003:Rectal Fistula / Q000175:diagnosis* / Q000473:pathology; D015203:Reproducibility of Results; D012107:Research Design; D012189:Retrospective Studies
D003287:Contrast Media