Differentiation between benign and malignant meningiomas using diffusion and perfusion MR imaging.

The purpose of the study was to investigate the utility of diffusion-weighted (DW) and perfusion-weighted (PW) MR imaging to differentiate benign and malignant meningiomas which were verified histologically. A total of 29 patients with meningiomas (22 benign and 7 malignant) underwent conventional, perfusion and diffusion MR imaging. Conventional MRI revealed the ordinary signs of tumor. The absolute apparent diffusion coefficient (ADC) and normalized ADC (NADC) ratio, maximal relative cerebral blood volume (rCBV) and the corresponding relative mean time to enhance (rMTE) in both tumour parenchyma and peritumoral edema were measured. The mean ADC of malignant meningiomas (0.64±0.12 x 10(-3) mm(2)/s) was significantly lower compared with benign meningiomas (0.89±0.09 x 10(-3) mm(2)/s; P<.0001). Mean NADC ratio in the malignant group (0.93±0.18) was also significantly lower than in the benign group (1.29±0.12; P<.0001). The mean maximal rCBV values of benign and malignant meningiomas were 7.18±4.12 and 6.01±3.89, in the tumour parenchyma, and 1,07±0,95 and 3,85±1,41 in the peritumoral edema. The mean rMTE values were 1.14±0.23 and 1.24±0.27, in the tumour, and 0.88±0.24 and 1.21±0.31, in the peritumoral edema. The differences in rCBV and rMTE values between benign and malignant meningiomas were not significant (P>0.05) in the tumour parenchyma, but both were significant (p<0.05) in the peritumoral edema. Diffusion and perfusion MR imaging are useful in the preoperative differentiation between benign and malignant meningiomas.