Non-invasive assessment of heterogeneity of gliomas using diffusion and perfusion MRI: correlation with spatially...

Heterogeneity of gliomas challenges the neuronavigated biopsy and oncological therapy. Diffusion and perfusion magnetic resonance imaging (MRI) can reveal the cellular and hemodynamic heterogeneity of tumors. Integrated positron emission tomography (PET)/MRI is expected to be a non-invasive imaging approach to characterizing glioma.

To evaluate the value of apparent diffusion coefficient (ADC), cerebral blood volume (CBV), and spatially co-registered maximal standard uptake value (SUV_max) for tissue characterization and glioma grading.

Thirty-seven consecutive patients with pathologically confirmed gliomas were retrospectively investigated. The relative minimum ADC (rADC_min), relative maximal ADC (rADC_max), relative maximal rCBV (rCBV_max), the relative minimum rCBV (rCBV_min), and the corresponding relative SUVmax (rSUV_max) were measured. The paired t-test was used to compare the quantitative parameters between different regions to clarify tumor heterogeneity. Imaging parameters between WHO grade IV and grade II/III gliomas were compared by t-test. The diagnostic efficiency of multiparametric PET/MRI was analyzed by receiver operating characteristic (ROC) curve.

The values of rSUV_max were significantly different between maximal diffusion/perfusion area and minimum diffusion/perfusion area (P < 0.001/P < 0.001) within tumor. The values of rADC_min (P < 0.001), rCBV_max (P = 0.002), and corresponding rSUV_max (P = 0.001/P < 0.001) could be used for grading gliomas. The areas under the ROC curves of rSUV_max defined by rADC_min and rCBV_max were 0.89 and 0.91, respectively.

Diffusion and perfusion MRI can detect glioma heterogeneity with excellent molecular imaging correlations. Regions with rCBV_max suggest tissues with the highest metabolism and malignancy for guiding glioma grading and tissue sampling.