Diffusion- and Perfusion-Weighted Magnetic Resonance Imaging-An Alternative to Fine Needle Biopsy or Only an Adjunct Test in Preoperative Differential Diagnostics of Malignant and Benign Parotid Tumors?

PURPOSE: The role of dynamic magnetic resonance imaging (MRI) in the preoperative differential diagnostics of parotid tumors is unclear. The aim of this study was to compare the accuracy of dynamic MRI and routinely used fine needle biopsy examination in the preoperative differentiation of malignant and benign parotid tumors.

MATERIALS AND METHODS: The study included 100 consecutive patients with parotid tumors treated surgically at the authors' center. Accuracy of dynamic MRI and fine needle biopsy examinations in the differential diagnostics of malignant and benign lesions was verified against the gold standard (ie, final histologic diagnosis).

RESULTS: Based on histopathologic examination of surgical specimens, 19 tumors were eventually diagnosed as malignant lesions and 81 were diagnosed as benign. Preoperative fine needle biopsy examination yielded 9 true positive, 70 true negative, 11 false positive, and 10 false negative results, which corresponded to 47.4 and 86.4% sensitivity and specificity, respectively. The most commonly established preoperative diagnosis for 10 tumors that were misdiagnosed as benign based on examination of biopsy specimens was pleomorphic adenoma (n = 10). Dynamic MRI examination yielded 17 true positive, 81 true negative, 2 false negative, and 0 false positive results, which corresponded to 89.5% sensitivity and 100% specificity.

CONCLUSIONS: These results suggest that dynamic MRI is highly accurate in the detection of malignant parotid tumors. However, taking into account the high cost and limited availability of this examination, its logical application seems to be verification of preoperative diagnoses in patients whose fine needle biopsy examination turned out to be nondiagnostic or showed pleomorphic adenoma.