ABSTRACT
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.
ABSTRACT
<p><b>BACKGROUND</b>Functional magnetic resonance imaging (fMRI) has become a powerful tool for tracking human brain activity in vivo. This technique is mainly based on blood oxygenation level dependence (BOLD) contrast. In the present study, we employed this newly developed technique to characterize the neural representations of human portraits and natural sceneries in the human brain.</p><p><b>METHODS</b>Nine subjects were scanned with a 1.5 T magnetic resonance imaging (MRI) scanner using gradient-recalled echo and echo-planar imaging (GRE-EPI) pulse sequence while they were visually presented with 3 types of white-black photographs: natural scenery, human portraits, and scrambled nonsense pictures. Multiple linear regression was used to identify brain regions responding preferentially to each type of stimulus and common regions for both human portraits and natural scenery. The relative contributions of each type of stimulus to activation in these regions were examined using linear combinations of a general linear test.</p><p><b>RESULTS</b>Multiple linear regression analysis revealed two distinct but adjacent regions in both sides of the ventral temporal cortex. The medial region preferentially responded to natural scenery, whereas the lateral one preferentially responded to the human portraits. The general linear test further revealed a distribution gradient such that a change from portraits to scenes shifted areas of activation from lateral to medial.</p><p><b>CONCLUSIONS</b>The boundary between portrait-associated and scenery-associated areas is not as clear as previously demonstrated. The representations of portraits and scenes in ventral temporal cortex appear to be continuous and overlap.</p>
Subject(s)
Adult , Female , Humans , Male , Magnetic Resonance Imaging , Regression Analysis , Temporal LobeABSTRACT
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