Various imaging modalities for the detection of salivary gland lesions: The advantages of Tl-201 SPET

The aim of this study was to compare dual-isotope (Tc-99(m) and Tl-201) SPE T imaging with computed tomography (CT) and magnetic resonance imaging (MRI ) in the differentiation of various lesions of the major salivary glands. T wenty-two patients underwent dual-isotope SPET imaging, of whom 12 also had CT and 15 also had an MRI study. The uptake ratio and retention index for Tc-99(m) and Tl-201 were calculated by drawing regions of interest on the i nvolved and normal glands. Both CT and MRI were interpreted by two radiolog ists. All malignant tumours were detected by all three modalities. Warthin' s tumours were detected by dual-isotope SPET imaging; however, MRI failed t o differentiate Warthin's tumour from pleomorphic adenoma. Of 13 other beni gn tumours, dual-isotope SPET correctly diagnosed 12. Of 16 tumours showing a cold defect on the Tc-99(m) images, parametric analysis with Tl-201 gave an accuracy of 94%, whereas CT gave an accuracy of 70-90%. MRI was 73-91% accurate in differentiating between benign (Warthin's) and malignant tumour s. We believe that dual-isotope SPET imaging (Tc-99(m) and Tl-201), togethe r with semi-quantitative analysis, is the method of choice for differentiat ing between various lesions of the major salivary glands. ((C) 2000 Lippinc ott Williams & Wilkins).