Medulloblastoma (MB) is a high-grade rare brain tumor in adults, with heterogeneous imaging features and variable enhancing patterns. Diffusion and spectroscopy multimodal imaging have already been described in adult MB, yet perfusion has not been explored. This study aimed to evaluate vascularity in adult classic and desmoplastic MB, using perfusion-weighted dynamic susceptibility contrast (DSC) MRI and histopathology.

Six histologically proved MB patients were classified as classic (n=3) and desmoplastic (n=3). DSC perfusion MRI was performed in three centers and retrospectively evaluated. Postprocessing included automatic arterial input function, motion and contrast leakage correction. Region of interest (ROI) delineation was performed on three perfusion slices to obtain a total of three cerebral blood volume ratios (rCBV) that were averaged to serve as the main rCBV. Permeability was evaluated on K2 maps.

Low rCBVs were observed in all cases (mean rCBV=1.19±0.39). rCBV values were lower than 2 for classic MB and lower than 1 for desmoplastic MB. All cases showed an increase of permeability on K2 maps.

Our preliminary results suggest that MB exhibits rCBV values close to 1 and increased permeability on DSC perfusion imaging, especially in desmoplastic cases, which could be explained by fibrous matrix. This type of perfusion pattern contrasts with those given by other enhancing subtentorial tumors such as metastasis, high-grade gliomas or hemangioblastomas.