Perianal fistulas: use of MR imaging for diagnosis.

PURPOSE

To evaluate use of magnetic resonance (MR) imaging with saline solution as contrast agent in diagnosis of perianal fistulous disease.

MATERIALS AND METHODS

Spin-echo intermediate-, T2-, and T1-weighted images were obtained before and after instillation of saline solution into anal fistulas in 12 of 16 consecutive patients. In four patients without secretory fistulas, images were obtained without contrast enhancement.

RESULTS

Fistulous tracts were found in 13 patients, fluid cavities in 13, secondary fibrotic tracts in two, and normal perirectal tissue in one. The extent of fistulas and fluid collections was better delineated or more conspicuous on contrast-enhanced images in eight and 10 examinations, respectively, in part due to expansion of collapsed portions of the fistulous system. T2-weighted images were sufficient for diagnosis.

CONCLUSION

MR imaging with saline solution as contrast agent may improve visualization of fistulas and their relationship to normal anatomic structures in patients with complex fistulous systems with relatively sparse secretion.