The Role of Multiparametric Magnetic Resonance Imaging (MRI) (DWI and DCE-MRI) in Differentiating Parotid Tumors: A Retrospective Study of 42 Cases

Abstract

Background: Tumors of the parotid gland are complex. The surgical approach depends on the histology, location, and size of the tumor. Magnetic resonance imaging (MRI) is an important tool for accurate preoperative assessment of topography and infiltration; however, its role in pathological differentiation remains controversial.

Purpose: Our study aims to illustrate the results of MRI in parotid tumors and correlate them with histopathological findings.

Materials and Methods: A retrospective and analytical study was conducted on 42 patients with clinically suspected parotid tumors, collected over 12 years from 2011 to 2023. All patients underwent a multiparametric MRI protocol, including conventional sequences, diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) measurement, and dynamic contrast-enhanced (DCE-MRI) sequences. MRI results were then correlated with the definitive histopathological findings obtained after surgery. Statistical analysis was performed using SPSS software. The concordance between MRI and histology was assessed using the kappa coefficient.

Results: Histopathology revealed 31 benign tumors (73.8%), 5 malignant tumors (11.9%), and 6 pseudotumors (14.2%). For distinguishing benign from malignant tumors, MRI showed moderate agreement with histology (kappa = 0.58). However, excellent concordance was observed for specific diagnoses: pleomorphic adenoma (kappa = 0.85) and Warthin tumor (kappa = 0.91). Mean ADC values were significantly lower in malignant tumors compared to benign tumors (p < 0.05). Pleomorphic adenoma typically demonstrated a Type A dynamic enhancement curve, Warthin tumor a Type B curve, and mucoepidermoid carcinoma a Type C curve.

Conclusion: Multiparametric MRI with gadolinium enhancement and ADC assessment demonstrates high diagnostic accuracy for specific benign parotid tumors, particularly pleomorphic adenoma and Warthin tumor, despite a moderate overall performance in distinguishing benign from malignant lesions. These findings can guide surgeons in preoperative planning when specific benign entities are suspected.