Fat suppressed contrast enhanced MR imaging in the assessment of sacroiliitis.

OBJECTIVE

To investigate the role of Gd-DTPA enhancement in the diagnosis of sacroiliitis.

PATIENTS AND METHODS

Fifteen patients with definite sacroiliitis, five subjects from an 'equivocal group', and five controls were imaged with Fast STIR, T1-weighted with fat suppression (T1FS) before and after Gd-DTPA. The 'equivocal group' included those who had abnormally high signal on Fast STIR images only suggestive of early sacroiliitis. The enhancement factor was calculated for T1FS images. Patients graded their symptoms at the time of MR imaging. The extent of abnormal enhancement was defined as none, local, or extensive.

RESULTS

Fourteen patients with definite sacroiliitis and one patient from the 'equivocal group' demonstrated abnormal Gd-DTPA enhancement of their sacroiliac joints or adjacent subchondral marrow. Correlation between the patients' symptoms and maximal enhancement of the subchondral marrow was r = 0.75, P < 0.01, and the extent of abnormal enhancement was r = 0.68, P < 0.01.

CONCLUSION

Fat suppressed Gd-DTPA or Fast STIR images can be used to assess disease activity in patients with sacroiliitis. Abnormal Gd-DTPA enhancement in the 'equivocal group' is important additional evidence suggesting the diagnosis of early sacroiliitis.