Objective: The purpose of this study was to develop a method for quantitative analysis of the sonographic features of parotid glands as a noninvasive tool for the diagnosis of Sjögren's syndrome.
Subjects and methods: Sonographic texture analyses were performed on the parotid glands of 44 patients with Sjögren's syndrome, 83 healthy volunteers, and 17 patients with chronic parotitis, using a fast Fourier transform program.
Results: Texture analysis of sonographic studies of the parotid gland using a Fourier transform showed that the sum of the normalized radial power spectrum in the low-spatial-frequency region (S value) of the parotid gland was significantly higher (p < .0001) in the patients with definite Sjögren's syndrome [6.70 +/- 2.13 (x10(5))] than in the 72 age-matched normal volunteers [3.25 +/- 1.08 (x10(5))]. However, patients with probable Sjögren's syndrome showed S values [3.92 +/- 1.88 (x10(5))] similar to those of the controls. On the other hand, SDs of the echo levels in the parotid gland showed significantly greater (p < .0001) values in patients with definite (4.63 1.07) and probable (4.53 1.47) Sjögren's syndrome than in the normal controls (3.30 0.76). Discriminant analysis showed that a combination of these two distinctive values increased diagnostic accuracy to 96.9%. Furthermore, S values and SDs correlated well with the qualitative grading of sonographic features and with the gradings of sialography.
Conclusion: The system we describe for texture analysis of sonographic images is useful in the diagnosis of Sjögren's syndrome.