Diagnostic value of dynamic contrast-enhanced MRI in the salivary gland tumors

SummaryTo evaluate the diagnostic value of dynamic contrast-enhanced MRI (DCE-MRI) in salivary gland tumors, thirty-five patients (47 lesions) who underwent MR examinations and were histopathologically diagnosed with salivary gland tumors in Okayama University Hospital, between April 1998 and March 2005, were entered in the present study. The parameters included CImax300 or CImax600, which was the contrast index (CI) at maximal contrast enhancement upon 300 s or 600 s, and Tmax, which was the time that corresponded to the CImax300. Washout ratio (WR300 or WR600) was defined as follows: CImax300 − CI300s/CImax300 or CImax600 − CI600s/CImax600 × 100 (%), where CI300 or CI600 was the CI at 300 s or 600 s after contrast medium administration.We obtained the following results from the analysis of DCE-MRI parameters; (a) The salivary gland tumors were categorized into three CI curve types according to Tmax and WR300; Pleomorphic adenoma; Tmax > 210 s and WR300 < 10%, Warthin tumor; Tmax < 60 s and WR300 > 40%, and malignant tumor; 60 s < Tmax < 210 s and 10% < WR300 < 30%; (b) On the basis of the relationship between Tmax and CImax or WR, all pleomorphic adenomas were successfully differentiated from Warthin tumor lesions. Of the 20 pleomorphic adenomas, 18 (90.0%) were successfully differentiated from malignant tumors. All Warthin tumor lesions were successfully differentiated from pleomorphic adenomas and malignant tumors. Of 12 the malignant tumors, 11 (91.7%) were successfully differentiated from pleomorphic adenomas. All malignant tumors were successfully differentiated from Warthin tumors.Thus, DCE-MRI parameters are useful in diagnosing salivary gland tumors on the basis of the combined assessment of Tmax and CImax or WR.