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PURPOSE The characterization and differentiation of central nervous system (CNS) lymphoma has important diagnostic, therapeutic, and prognostic significance. The purpose of this study is to characterize the diffusion-weighted imaging (DWI) and MR spectroscopic (MRS) findings in CNS lymphoma. MATERIALS AND METHODS Twenty consecutive patients (male [ n= 12], female [ n= 8]) with histopathologically proven CNS lymphoma were retrospectively evaluated during this study from July 2005 to April 2007. Patients included immunocompromised ( n= 9) and immunocompetent ( n= 11) individuals. MR Imaging (pretreatment n= 13), pre- and post-treatment ( n= 7) included DWI ( n= 20) (b = 1000s/mm2) and ADC (apparent diffusion coefficient) maps of all patients. MRS was performed ( n= 10) with PRESS (point-resolved spectroscopy) sequence (multivoxel n= 8, single voxel n= 2) with a TE of 144 msec. All patients were histopathologically confirmed to have lymphoma by biopsy. RESULTS Areas of restricted diffusion were observed in 90 % ( n= 18/20) on pretreatment scans. The diffusion restriction was variable on post-treatment scans. Median metabolite ratios in 10 patients were Cho/Cr- 2.12, NAA/Cho - .49, and NAA/Cr - 1.64. Presence of lactate or lipid was noted in 90 % ( n= 9/10). Sites of lesion location were subcortical white matter ( n= 6), basal ganglia ( n= 4), corpus callosum ( n= 3), extra-axial space including cavernous sinus ( n= 5), cerebellum ( n= 1), and lateral ventricle ( n= 1). CONCLUSION Restricted diffusion is a consistent imaging finding in CNS lymphoma in immunocompetent patients. Spectroscopy is helpful in initial imaging diagnosis and post-treatment surveillance. These lesions are usually paraventricular in location. MR imaging appearances differ among immunocompetent and immunosuppressed individuals in most cases. [ABSTRACT FROM AUTHOR]

We studied four patients with diabetes mellitus and chronic renal failure who developed sudden choreic movement disorders. The clinical manifestations, laboratory findings, MR imaging findings, and clinical outcome in each patient were evaluated. All four patients had long-term diabetes mellitus and severe azotaemia. Brain MR findings consisted of bilateral symmetric basal ganglia lesions, with decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images. All three patients who underwent diffusion-weighted MR imaging (DWI) showed signal intensities similar to those of the surroundings in regions corresponding to increased signal intensity on T2-weighted images, with slightly increased apparent diffusion coefficient (ADC) values. Two of the patients showed small focal areas of restricted diffusion within the basal ganglia lesions. After haemodialysis, follow-up MR imaging in all patients demonstrated that the basal ganglia lesions had regressed markedly, with some residual changes. The movement disorders also improved in all patients. A syndrome associated with acute bilateral basal ganglia lesions in diabetic uraemic patients is rare, with reversible changes demonstrated by clinical and imaging findings. DWI showed that the bilateral basal ganglia lesions in this syndrome were primarily vasogenic in origin, although there were small foci of cytotoxic oedema within the lesions. [ABSTRACT FROM AUTHOR]

Due to its complementary information to standard morphological imaging, functional renal magnetic resonance imaging is a rapid growing field of radiology. This pictorial essay provides a comprehensive overview of state-of-the-art functional renal imaging techniques including renal magnetic resonance angiography, first pass renal perfusion, assessment of renal function, blood-oxygen level dependent imaging of the kidneys and diffusion-weighted imaging of the kidneys including diffusion-tensor imaging of the kidneys. Basic technical concepts for all sequences are laid out. As renal perfusion imaging becomes a clinical routine examination, particular attention is given to renal perfusion measurements and the potential postprocessing approaches. Advantages and drawbacks of the published methods are illustrated. Future applications of functional renal imaging are presented. [ABSTRACT FROM AUTHOR]

We examined MRI of two patients with progressive multifocal leukoencephalopathy (PML), including diffusion-weighted imaging (DWI), with calculation of apparent diffusion coefficients (ADC). The pathology findings of one patient were compared with those of MRI. The lesions had different ADC and DWI appearances, depending on the stage of the disease. Newer lesions and the advancing edge of large lesions had normal-to-low ADC and gave high signal on DWI. Older lesions and the centre of large lesions had increased ADC and gave low signal. High signal on DWI and low ADC mark the regions of active infection and cell swelling, distinguishing them from areas of reparative gliosis. [ABSTRACT FROM AUTHOR]