Comparison and synergistic effect of imaging diagnosis by enhanced MRI, including dynamic study and calculation of apparent diffusion coefficient, and preoperative diagnosis by fine needle aspiration cytology

In 102 patients who performed contrast―enhanced MRI and underwent surgery for a tumor of the parotid gland, we compared the preoperative diagnoses made by fine needle aspiration cytology（FNAC）and imaging diagnoses made by enhanced MRI, including a dynamic study and calculation of the apparent diffusion coefficient（ADC）. In contrast―enhanced MRI, the ADC values of pleomorphic adenomas were significantly higher than those of Warthin's tumors. In addition, the ADC values of carcinomas were significantly lower than those of pleomorphic adenomas and significantly higher than those of Warthin's tumors. The patterns of the time―signal intensity curve in the dynamic study were as follows: persistent pattern in 23 cases, washout pattern in 38 cases, and the plateau pattern in 41 cases. Contrast―enhanced MRI was performed in 102 cases and a pathological diagnosis was available for 85 cases. The diagnostic accuracy rate of contrast―enhanced MRI in the 85 cases for which a pathological diagnosis was available was 82.3%（70 cases/ 85 cases）, 70 cases with the correct diagnosis was 68.6%（70 cases/102 cases）in which contrast―enhanced MRI was performed. FNAC was performed in 93 cases and pathological diagnosis was available for 46 cases. The diagnostic accuracy rate of FNAC in the 46 cases for which a pathological diagnosis was available was 84.7%（39 cases/46 cases）. 39 cases with the correct diagnosis was 41.9%（39 cases/93 cases）of cases in which FNAC was performed. There were 34 cases in which the preoperative diagnosis made by FNAC and that made by MRI were in agreement and the diagnostic accuracy rate in them was 94.1%（32 cases/34 cases）.