Value of apparent diffusion coefficient and magnetic resonance spectroscopy in the identification of various pathological subtypes of parotid gland tumors

Abstract

Background and purpose: Pre-operative imaging has a major role in surgical planning of parotid gland tumors. Aim: To assess the role of the combined techniques of ADC generated from DWI and MR spectroscopy in identification of various pathological subtypes of parotid gland tumors. Patients and methods: Prospective study was conducted on 25 patients with primary parotid tumors (11 males, 14 females, age ranged 22–79 years with mean of 53.4 ± 13.6 years). DWI and MRS were performed for all patients and the results were correlated with histopathological findings. Results: The 18 (72%) benign and 7 (28%) malignant tumors consisted of 11 pleomorphic adenomas, 7 Warthin tumors, and 7 malignant tumors. The mean ADC value for pleomorphic adenomas was 1.89 ± 0.18 × 10−3 mm2/s, for Warthin tumors was 0.92 ± 0.22 × 10−3 mm2/s, and for the malignant tumors was 1.03 ± 0.13 × 10−3 mm2/s, significant difference was seen between benign and malignant tumors (P = 0.037). The mean values of Cho/Cr ratios were 3.37 ± 0.78, 5.9 ± 1.75 and 1.72 ± 0.41, for pleomorphic adenomas, Warthin tumors, and malignant tumors, respectively. Difference was significant between benign and malignant tumors (P = 0.001). Conclusion: DWI and MRS are useful noninvasive diagnostic modalities in identification of various pathological subtypes of parotid tumors.

Keywords

• Parotid
• Diffusion
• ADC
• MR spectroscopy