Major salivary gland ultrasonography and sonoelastography in the diagnosis of Sjögren's syndrome

The aim of our study is to determine of a new semi-quantitative scoring system based on typical ultrasonographic changes and to evaluate ultrasound elastography of the major salivary glands in the diagnosis of Sjögren?s syndrome.Fifty eight patients with Sjögren?s syndrome were selected according to the. American-European Consensus Group Classification criteria. Twenthy five healthy volunteers involved in this study. All patients were evaluated with B-mode, color Doppler US and elastography by using Hitachi EUB 7500 digital ultrasound equipment. All the participiants were female. Five Ultrasound parameters were assessed; echogenicity, inhomogeneithy, number of hypoechogenic areas-hyperechogenic reflections, clearness of the borders and vascularity of the major salivary glands. A novel semi-quantitative US score (0-12) for the sum of these parameters were assigned and its diagnostic accuracy evaluated. At the same time all patients underwent real-time qualitative ultrasound elastography, images were scored on colour-scaled elastograms in the terms of their stiffness relative to adjacent soft tissues. Strain ratio of the glands was measured three times and mean strain ratio values were calculated for all glands.All five parameters that contains typical ultrasonographic and vascularity changes were significantly associated with Sjögren?s syndrome except parenchymal echocenicity for submandibulary gland. The patients with Sjögren syndrome had significantly higher scores than control group (p<0,05). Area under the receiver operating characteristics curve (AUC-ROC) for mean total score was highly significant (AUC ROC for submandibulary gland 0,85±0,04 %95 CI 0,78-0,94, for parotid gland 0,80±0,05 %95 CI 0,71-0,90 p<0,001). Setting the cut-off Ultrasound score at 4 resulted in the best ratio of spesificity to sensitivity (sensitivity 72%, spesificity 73% for submandibulary gland and sensitivity 76%, spesificity %68 for parotid gland), with a positive predictive value %72 for submandibulary gland and %72 for parotid gland, a negative predictive value %72 for submandibulary and %76 for parotid gland.On real-time elastography, the patients with Sjögren?s syndrome had significantly higher scores than control group (p<0,001) with sensitivity 88%, specificity 64% for submandibulary gland and sensitivity 72%, specificity 67% for parotid gland. Area under the receiver operating characteristics curve (AUC-ROC) for strain index ratio was highly significant (AUC ROC for submandibulary gland 0,86±0,04, for parotid gland 0,80±0,05 p<0,001). Setting the cut-off point at 1,55 for submandibulary gland and at 2,45 for parotid gland had the best specifity to sensitivity ratio (sensitivity 83%, specificity 88% for submandibulary gland and sensitivity 83%, specificity 92% for parotid gland). However, there wasn?t highly concordance between sonoelastographic data and typical ultrasonographic changes.Major salivary gland ultrasonography is a promising technique that can be used as a practical alternative to the other metods in the classification of Sjögren?s syndrome. Sonoelastography has the potential to aid diagnosis of major salivary gland involvement of Sjögren?s syndrome by increasing the specificity. Measuring the strain index may be useful as a complementery technique as its high specificitiy, sensitivity,and pozitive and negative predictive value.Key words: Ultrasonography, elastography, major salivary gland, Sjögrens?s syndrome