Minho Park MD, Presenter: Nothing to Disclose

Sung Kyoung Moon, Abstract Co-Author: Nothing to Disclose

Seong Jin Park MD, PhD, Abstract Co-Author: Nothing to Disclose

Joo Won Lim, Abstract Co-Author: Nothing to Disclose

Dong Ho Lee MD, Abstract Co-Author: Nothing to Disclose

Young Tae Ko MD, PhD, Abstract Co-Author: Nothing to Disclose

To investigate the diagnostic performance of DWI in fistula-in-ano.

This study included 46 patients who underwent rectal MRI to evaluate fistula-in-ano from March 2011 to March 2012. A history of Crohn’s disease (CD) and fistulectomy were reviewed. Two radiologists retrospectively reviewed rectal MRI with consensus three times at 2-week intervals. The first review assessed the presence of perianal lesions, fistula type, and lesion conspicuity with T2WI. The second review assessed fistula conspicuity with CE-FS-T1WI and T2WI. The third assessed fistula conspicuity with DWI with a b-value of 1000 and T2WI. Lesion conspicuity was scored from 1 to 4 as follows: 1, unclear fistula tract; 2, visible fistula tract with unclear margin; 3, distinct fistula tract with partial obscuration; and 4, distinct fistula without obscuration. The lesion conspicuity was compared between CE-FS-T1WI and DWI using the Wilcoxon rank-sum test. Lesion conspicuity according to the clinical history was assessed using the Mann–Whitney U-test.

Of the 46 patients, 39 had perianal lesions in rectal MRI: 30 patients with CD and 9 without. Nine patients (23.1%) had fistulectomy histories. There were 14 complex fistulas (35.90%), 12 intersphincteric fistulas (30.76%), 5 trans-sphincteric fistulas (12.82%), 4 perianal abscesses (10.26%), and 4 anal fissures (10.26%). The mean lesion conspicuity score of T2WI, CE-FS-T1WI, and DWI with a b-value of 1000 was 3.11±0.689, 3.29±0.732, and 3.55±0.724, respectively. There was no significant difference between CE-FS-T1WI and DWI (p=0.096). Lesion conspicuity was significantly better with DWI than T2WI (p=0.010). With DWI, lesion conspicuity was significantly better in the patients with CD than those without CD (p=0.004).

The lesion conspicuity of DWI with a b-value of 1000 was similar to that of CE-FS-T1WI, and significantly better in the patients with CD.

DWI with a high b-value could help to inform clinicians about fistula shape and type.

Park, M, Moon, S, Park, S, Lim, J, Lee, D, Ko, Y, Rectal MRI of Fistula-in-ano: Diagnostic Values of Diffusion-weighted Imaging (DWI).  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13022162.html