Chemical shift MR images of the parotid gland in Sjögren's syndrome utilizing low-field MR system comparison with MR sialography and salivary secretion function.

PURPOSE

To compare chemical shift imaging and MR sialography in patients with Sjögren's syndrome utilizing a low (0.3 Tesla) magnetic field.

METHODS

We retrospectively evaluated 8 controls (16 glands) and 30 patients (60 glands) with parotitis of Sjögren's syndrome. MR images were obtained with a 0.3 Tesla system (HITACHI MRP-7000, Hitachi, Ltd., Tokyo, Japan) with a coil for the temporomandibular joint. MR sialography was graded according to the grading system established for conventional sialography. The signal decrease rate between in- and opposed-phase images, and the standard deviation (S.D.) of the parotid parenchymal signal in opposed-phase images were measured.

RESULTS

MR sialography and chemical shift images were obtained in 38 and 46 glands, respectively. MR sialography was graded as 0 in 15, 1 in 12, 2 in 4, and 3 in 5 glands. The mean signal decrease rate in in/opposed phase was 37.6%, and the mean S.D. of the parotid parenchymal signal in the opposed-phase images was 655.9. The salivary secretion function was related to heterogeneity on opposed phase (r=-0.3) but not to MR sialography grading.

CONCLUSION

Heterogeneity on opposed-phase images assessable with a low-field magnet system may be a useful parameter to add in the evaluation of Sjögren's parotitis.