Objective To investigate the relationship among early parenchymal enhancement,post- gadolinium(Gd)hyperintense middle cerebral artery(HMCA),and subsequent hemorrhagic transformation (HT)in patients with hyperacute ischemic stroke.Methods Twenty-four consecutive patients with ischemic stroke who underwent MRI within 6 h[(4.3?1.4)h]of symptom onset were retrospectively reviewed.All of these patients underwent at least one follow-up MRI or non-enhanced CT study at 2 to 7 days.Post-Gd T_1WI were analyzed for parenchymal enhancement and hyperintense MCA.Gradient echo MRI and CT were used for assessment of HT.Results Ten patients developed HT on follow-up imaging (hemorrhagic group).Early parenchymal enhancement was found in 6 patients with HT(P

Objective To evaluate the CT and MRI characteristics of Primary Central Nervous System Lymphoma(PCNSL)in immunocompetent patients,and enhance its diagnosis level.Methods CT and MRI data of 20 patients with PCNSL confirmed by histo-pathology were analyzed retrospectively.MRI scans were performed with and without Gadolinium contrast.Two of them had contrast-enhanced CT scan;six had CT scan without contrast administration;1 had CT scan with both non-contrast and contrast enhancement.Re- suits Totally,38 lesions were found in all patients:14 lesions of them were single and 24 lesions were found in 6 patients.Generally,the lesions were located in the surface and/or midline of the brain.The signal features and density were similar to meningioma,and strongly enhancing after contrast administration.Thirty-six of the 38 lesions had spicular sign peripheral to the lesion.Conclusion Although the manifestations of the PCNSL are variety,there are still many characteristics in the medical imaging,especially in the locations,the signal features,and spicular sign in the edge of the lesions after contrast material injection.