Novel Detection of Pleomorphic Adenomas via Analysis of 68 Ga-DOTATOC PET/CT Imaging.

Simple Summary: We present in this study novel data which demonstrates that the most common type of tumor of the salivary glands may be accurately diagnosed using a specific type of radiological imaging. This may be used to help discriminate this tumor or recurrent versions of it amid various types of benign and malignant tumors. Furthermore, this data suggest that new avenues of minimally invasive therapy may be viable for these tumors and potentially even malignant versions of these tumors and should be examined in further studies. Introduction: Currently, the diagnosis of salivary gland tumors using imaging techniques is unreliable. Methods: In this monocentric retrospective study, we examined patients who received a ⁶⁸Ga-DOTATOC PET/CT and subsequently underwent a salivary gland tumor resection between 1 January 2010 and 31 December 2021. PET/CT image assessment was compared with somatostatin receptor (SSTR) expression and histology. Results: Thirteen patients (five pleomorphic adenoma (PA) and eight other parotid lesions (OPL)) received a ⁶⁸Ga-DOTATOC PET/CT. Imaging displayed strong focal tracer uptake in all PA except for one with strong tumor to background discrimination. PA revealed higher SUVmax, SUVmean, liver and blood pool quotients than those of Warthin tumors (WT) and of OPL. In comparison to the contralateral parotid, SUVmax (p = 0.02), SUVmean (p = 0.02), liver quotient (p = 0.03) and blood pool quotient (p = 0.03) were all significantly higher. In contrast, WT and OPL showed in relation to the contralateral parotid no significant differences of SUVmax (WT p = 0.79; OPL p = 0.11), SUVmean (WT p = 1.0; OPL p = 0.08), liver quotient (WT p = 0.5; OPL p = 0.08) and blood pool quotient (WT p = 0.8; OPL p = 0.19). Two PA and one granuloma were not available for examination. In the immunohistochemal analysis, all PA demonstrated the highest intensity of SSTR2 expression (grade 3). Furthermore, PA had a high percentage of cells expressing SSTR2 (20%, 80% and 55%). Conclusions: A strong tracer uptake in PA was shown in ⁶⁸Ga-DOTATOC PET/CT. This may allow physicians to utilize radioligated somatostatin analogue PET CT/MR imaging to accurately diagnose PA. Additionally, it may be possible in the future to treat the PA with a noninvasive peptide receptor radionuclide therapy or with somatostatin analogues. [ABSTRACT FROM AUTHOR]