FAT-SUPPRESSED CONTRAST-ENHANCED MR-IMAGING IN THE ASSESSMENT OF SACROILIITIS

Objective: To investigate the role of Gd-DTPA enhancement in the diagn osis of sacroiliitis. Patients and methods: Fifteen patients with defi nite sacroiliitis, five subjects from an 'equivocal group', and five c ontrols were imaged with Fast STIR, T1-weighted with fat suppression ( T1FS) before and after Gd-DTPA. The 'equivocal group' included those w ho had abnormally high signal on Fast STIR images only suggestive of e arly sacroiliitis, The enhancement factor was calculated for T1FS imag es, Patients graded their symptoms at the time of MR imaging. The exte nt of abnormal enhancement mas defined as none, local, or extensive. R esults: Fourteen patients with definite sacroiliitis and one patient f rom the 'equivocal group' demonstrated abnormal Gd-DTPA enhancement of their sacroiliac joints or adjacent subchondral marrow, Correlation b etween the patients' symptoms and maximal enhancement of the subchondr al marrow was r = 0.75, P < 0.01, and the extent of abnormal enhanceme nt 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 sa croiliitis. Abnormal Gd-DTPA enhancement in the 'equivocal group' is i mportant additional evidence suggesting the diagnosis of early sacroil iitis.