Proposal for a new staging system of Sjögren's syndrome using salivary gland SPECT/CT: comparison with Saxon test, MR sialography, and histopathological examination.

OBJECTIVES

Sjögren's syndrome causes dryness of the eyes and mouth due to destruction of glandular tissue. Single-photon emission computed tomography/computed tomography (SPECT/CT) is used to evaluate salivary gland function. This study aimed to quantitatively evaluate the stage of Sjögren's syndrome using SPECT/CT maximum standardized uptake value (SUVmax) by comparing the SUVmax with the Saxon test, magnetic resonance (MR) sialography stage, and histopathological grade.

METHODS

This study was conducted in 29 patients with Sjögren's syndrome who underwent the Saxon test, MR sialography, SPECT/CT, and histopathological examination. We compared the SPECT/CT SUVmax with the Saxon test, MR sialography stage, and histopathological grade to determine the stage of Sjögren's syndrome. We then calculated the cutoff value of SUVmax at pre-stimulation for the parotid glands in the early and late stages of Sjögren's syndrome.

RESULTS

The SUVmax for > 2 g per 2 min by the Saxon test was higher than that for ≤ 2 g per 2 min. The SUVmax for MR sialography stages 0-1 was higher than that for stages 2-4. The SUVmax for histopathological grades 0-2 was higher than that for grades 3-4. The cutoff value for early and late Sjögren's syndrome was 20.55 (sensitivity, 0.85; specificity, 0.67).

CONCLUSIONS

SPECT/CT is a highly suitable modality for quantitatively evaluating the stage of Sjögren's syndrome. Especially, the pre-stimulation SUVmax of the parotid glands serves as a valuable indicator for assessing Sjögren's syndrome stage and predicting prognosis.