Pseudo-continuous arterial spin labeling MR images in Warthin tumors and pleomorphic adenomas of the parotid gland: qualitative and quantitative analyses and their correlation with histopathologic and DWI and dynamic contrast enhanced MRI findings

We investigated the correlation between tumor blood flow (TBF) and histopathologic features of Warthin tumors (WTs) and pleomorphic adenomas (PAs) to determine the TBF in the differential diagnosis of these tumors and evaluated how well pCASL-MRI can differentiate PAs from WTs compared to conventional MRI. The ADC, time intensity curve (TIC) pattern of dynamic contrast enhancement, and pCASL (visual assessment and TBF of the MR images of 10 WTs and 13 PAs) were reviewed. We compared the pCASL and ADC or TIC patterns in WT and PA images. Tissue sections were stained with CD34 to evaluate microvessel density (MVD). The TBF and MVD results were compared. The Mann-Whitney U test was used to compare the TBFs, ADCs, and MVDs of these tumors. The diagnostic accuracy was determined by analyzing the receiver operating characteristic curve. On visual assessment, the signal intensity was higher in all but three cases of WT. The TBF and MVD of the WTs were significantly higher (both, p < 0.01) than the PAs, and the ADC was significantly lower (p < 0.01). Many WTs had early enhancement of the TIC pattern and high washout; many PAs had gradual enhancement. The diagnostic accuracies of visual analysis, TBF, and ADC for differentiation between WTs and PAs were 91.3, 95.7, and 87.0%, respectively. The TBF were significantly higher in WTs than in PAs, and there was a positive correlation between TBF and MVD. Moreover, pCASL-MRI provides more accurate imaging than conventional MRI to differentiate WTs and PAs.