title: Central nervous system lymphoma characterization by diffusion-weighted imaging and MR spectroscopy.
abstract: OBJECTIVE
  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.
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Neuroradiology, Mount Sinai Medical Center, New York, NY, USA. ttz100@yahoo.com
authors.forename: T Thomas
authors.initials: TT
authors.lastname: Zacharia
authors.forename: Meng
authors.initials: M
authors.lastname: Law
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Naidich
authors.forename: Norman E
authors.initials: NE
authors.lastname: Leeds
mesh_terms: D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001706:Biopsy; D001921:Brain / Q000473:pathology; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007121:Immunocompetence; D007165:Immunosuppression Therapy; D007294:Inositol / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D016483:Lymphoma, AIDS-Related / Q000175:diagnosis / Q000473:pathology / Q000628:therapy; D016393:Lymphoma, B-Cell / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D016399:Lymphoma, T-Cell / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D001224:Aspartic Acid; D019344:Lactic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline