Initial experience of virtual touch tissue quantification in diagnosis of salivary glands in early stage of Sjögren′s syndrome

Abstract

Objective To investigate the usefulness of virtual touch tissue quantification (VTQ) of acoustic radiation force impulse (ARFI) elastography in the diagnosis of the early stage of Sjogren′s syndrome (SS) disease. Methods From January 2013 to April 2015, a total number of 44 SS patients who were confirmed by labial gland biopsy were enrolled in the study. All of them were referred by the First Affiliated Hospital of Medical College of Shantou University and the Central Hospital of Shantou. SS patients were further divided into two subgroups: 21 patients belonged to early group and 21 patients belonged to advanced group. Totally 45 healthy volunteers were enrolled by the First Affiliated Hospital of Medical College of Shantou University in this study. The parotid glands and submandibular glands of the SS patients and healthy volunteers were identified and VTQ measurements of shear wave velocity (SWV) were obtained. The difference of the SS patients and healthy volunteers salivary glands SWV value were measured using independent samples t-tests. Draw the VTQ technology in the diagnosis of early and advanced stage SS patients with parotid and submandibular glands of the receiver operating characteristic (ROC) curves. Results The mean SWVs of the SS submandibular and parotid glands were (2.44±0.48) m/s and (2.77±0.70) m/s; The mean SWVs of the healthy volunteers submandibular and parotid glands were (1.74±0.24) m/s and (1.77±0.28) m/s. The SWV in both submandibular and parotid glands are significantly higher in SS patients than in healthy volunteers, There was significant difference between these two groups (t values were 22.67, 19.92 respectively, both P<0.01). The mean SWVs of the early stages of SS submandibular and parotid glands were (2.42±0.37) m/s and (2.76±0.57) m/s; The mean SWVs of the advanced stages of SS submandibular and parotid glands were (2.47±0.34) m/s and (2.80±0.37) m/s. There was no significant difference between these two groups. In the use of VTQ technique to diagnose the submandibular glands of early stage SS patients, area under ROC was 0.997, with a cutoff value of 2.28 m/s, the sensitivity and specificity were 100% and 90.41%. To diagnose the parotid glands of early stage SS patients, area under ROC was 1.0, with a cutoff value of 2.27 m/s, the sensitivity and specificity were 100% and 95.89%. To diagnose the submandibular glands of advanced stage SS patients, area under ROC was 0.845, with a cutoff value of 2.30 m/s, the sensitivity and specificity were 73.76% and 92.59%. To diagnose the parotid glands of advanced stage SS patients, area under ROC was 0.836, with a cutoff value of 2.41 m/s, the sensitivity and specificity were 72.66% and 93.1%. Conclusions VTQ has higher accuracy in the assessment of early stage SS disease than conventional ultrasonography. But there was no significant difference between VTQ and conventional Ultrasonography in the evaluation of the advanced stage SS disease. Key words: Sjogren′s syndrome; salivary gland; acoustic radiation force impulse; virtual touch tissue quantification; Elastography