Abstract
Simple SummaryMultiparametric magnetic resonance imaging gains recognition in the diagnostic algorithm of salivary gland tumors, providing data from different diffusion-weighted imaging (DWI) models and dynamic contrast enhanced sequences (DCE-MRI). The aim of this prospective study is to identify quantitative intravoxel incoherent motion and DCE-MRI parameters of the most frequent benign parotid tumors, pleomorphic adenomas and Warthin tumors, to compare their utility and diagnostic accuracy. With a precise pre-treatment diagnostic tool, patients can potentially avoid unnecessary diagnostic procedures and be offered optimal treatment. Aim: The aim of this prospective study is to identify quantitative intravoxel incoherent motion and dynamic contrast-enhanced magnetic resonance imaging parameters of the most frequent benign parotid tumors, compare their utility and diagnostic accuracy. Methods: The study group consisted of 52 patients with 64 histopathologically confirmed parotid focal lesions. Parametric maps representing apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (FP) and transfer constant (Ktrans), reflux constant (Kep), extra-vascular extra-cellular volume fraction (Ve), and initial area under curve in 60 s (iAUC) have been obtained from multiparametric MRI. Results: Statistically significant (p < 0.001) inter-group differences were found between pleomorphic adenomas (PA) and Warthin tumors (WT) in all tested parameters but iAUC. Receiver operating characteristic curves were constructed to determine the optimal cut-off levels of the most significant parameters allowing differentiation between WT and PA. The Area Under the Curve (AUC) values and thresholds were for ADC: 0.931 and 1.05, D: 0.896 and 0.9, Kep: 0.964 and 1.1 and Ve: 0.939 and 0.299, respectively. Lesions presenting with a combination of ADC, D, and Ve values superior to the cut-off and Kep values inferior to the cut-off are classified as pleomorphic adenomas. Lesions presenting with combination of ADC, D, and Ve values inferior to the cut-off and Kep values superior to the cut-off are classified as Warthin tumors. Conclusions: DWI, IVIM and quantitative analysis of DCE-MRI derived parameters demonstrated distinctive features of PAs and WT and as such they seem feasible in differentiation of benign parotid gland tumors.
Highlights
Three to six percent of tumors within the head and neck arise in the salivary glands [1], the majority within the parotid glands
Eighty-eight consecutive patients referred to The Department of Otolaryngology with major salivary gland nodules revealed in physical examination and/or in ultrasound underwent parametric magnetic resonance examination of the parotid glands in our institution between July 2020 and October 2021
Lesions presenting with combination of apparent diffusion coefficient (ADC), D, and volume fraction (Ve) values superior to the cutoff and Kep values inferior to the cut-off are classified as pleomorphic adenomas
Summary
Three to six percent of tumors within the head and neck arise in the salivary glands [1], the majority within the parotid glands. Up to 80% of tumors within the parotids are benign with the two most common types being Warthin tumors (WTs) and pleomorphic adenomas (PAs). Despite both being benign lesions, they present with different clinical course if left untreated. Malignant transformation is reported in 1.9–23.3% of untreated PAs, whereas it is less than 1% for WTs [1,2]. WTs can be surveilled if asymptomatic, while surgery is a method of treatment for pleomorphic adenomas. The aim of surgery is to obtain a complete resection with clear histopathological margins, as recurrence rate after enucleation in up to 50% [2,3].
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