title: Analysis of the utility of diffusion-weighted MRI and apparent diffusion coefficient values in distinguishing central nervous system toxoplasmosis from lymphoma.
abstract: BACKGROUND
  Toxoplasmosis and lymphoma are common lesions of the central nervous system in patients with AIDS. It is often difficult to distinguish between these lesions both clinically and radiographically. Previous research has demonstrated restricted diffusion within cerebral lymphomas and bacterial abscesses. However, little work has been done to evaluate the diffusion characteristics of toxoplasmosis lesions. This study was designed to explore further the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps and values in making the distinction between toxoplasmosis and lymphoma.
  
  
  METHODS
  The magnetic resonance imaging (MRI) studies of 36 patients, including 22 with toxoplasmosis (all of whom had AIDS) and 14 with lymphoma (8 of whom had AIDS), at two institutions were reviewed retrospectively. The characteristics of the lesions on DWI were evaluated, and the ADC ratios of the lesions were calculated and compared.
  
  
  RESULTS
  There was significant overlap of the ADC ratios of toxoplasma and lymphoma, most notably in the intermediate (1.0-1.6) range. There was variability in ADC ratios even among different lesions in the same patient. In only a minority of the lymphoma patients were the ADC ratios low enough to suggest the correct diagnosis.
  
  
  CONCLUSIONS
  Our study showed that toxoplasmosis exhibits a wide spectrum of diffusion characteristics with ADC ratios which have significant overlap with those of lymphoma. Therefore, in the majority of patients, ADC ratios are not definitive in making the distinction between toxoplasmosis and lymphoma.
authors.affiliation: Jackson Memorial Hospital, University of Miami, Miami, FL, USA.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Schroeder
authors.forename: M Judith Donovan
authors.initials: MJ
authors.lastname: Post
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Oschatz
authors.forename: Alfred
authors.initials: A
authors.lastname: Stadler
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Bruce-Gregorios
authors.forename: Majda M
authors.initials: MM
authors.lastname: Thurnher
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000175:diagnosis*; D001932:Brain Neoplasms / Q000175:diagnosis*; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D008223:Lymphoma / Q000175:diagnosis*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016781:Toxoplasmosis, Cerebral / Q000175:diagnosis*