Differentiating benign and malignant salivary gland tumours: diagnostic criteria and the accuracy of dynamic contrast enhanced MRI with high temporal resolution.
OBJECTIVE To determine the optimal diagnostic criterion of dynamic contrast enhanced MRI (DCE MRI) for predicting salivary gland malignancy using a dynamic sequence with high temporal resolution, as well as the accuracy of this technique. METHODS The DCE MRI findings of 98 salivary gland tumours (74 benign and 24 malignant) were reviewed. MR images were sequentially obtained at 5 s intervals for 370 s. Two parameters, peak time and washout ratio (WR) were determined from the time signal intensity curve. The optimal thresholds of these parameters for differentiating benign and malignant tumours were determined, along with the diagnostic accuracy of the criterion using these thresholds. RESULTS A peak time of 150 s and a WR of 30% were identified as optimal thresholds. As the criterion for malignancy, the combination of peak time <150 s and WR <30% provided a sensitivity of 79% (19/24) specificity of 95% (70/74) and an overall accuracy of 91% (89/98) Three of the five false negative cases were malignant lymphomas of the parotid gland. CONCLUSION Peak time <150 s with WR <30% comprised the optimal diagnostic criterion in predicting salivary gland malignancy, providing a sensitivity of 79% and specificity of 95% The use of high temporal resolution might improve the accuracy of DCE MRI. ADVANCES IN KNOWLEDGE Although several studies have reported the usefulness of DCE MRI in the differential diagnosis of salivary gland tumours, the specific diagnostic criteria employed have differed widely. We determined the optimal criterion and its accuracy using a dynamic sequence with high temporal resolution.
The British journal of radiology