[Value of MRI to evaluate extra-abdominal desmoid fibromatosis]

To describe the MR appearance of extra-abdominal desmoid fibromatosis, especially using sequences such as MR angiography, STIR and FAT SAT. Materials and methods. We reviewed retrospectively the MRI studies of 8 patients (4 men and 4 women) with histologically proved desmoid fibromatosis. In five patients the lesion corresponded to recurrent disease. Eleven MRI examinations were available (Siemens, Vision, 1.5T) including the following sequences: pre- and postcontrast T1 weighted (11 cases), STIR (9 cases), and MRA (3 cases). All lesions were imaged in at least two orthogonal planes. CT was available for 5 patients.

The lesions were localized to the girdles in 8 cases and to the upper extremity in 3 cases. Most lesions (10/11) were isointense to muscle on noncontrast T1W images and showed intense enhancement on postcontrast T1W images. All lesions (9/9) were hyperintense on STIR images.

A STIR sequence is useful as a first sequence to identify smaller lesions (usually recurrences) and to better adapt the FOV of following sequences, especially before administration of intravenous contrast. MR angiography may be valuable for surgical planning.