Toluene abuse: Physical basis for hypointensity of the basal ganglia on T2-weighted MR images

PURPOSE: To explain the hypointensity in the basal ganglia on T2-weighted magnetic resonance (MR) images of brains of toluene abusers. MATERIALS AND METHODS: Eight patients with histories of toluene abuse underwent MR imaging. A bilayered model of dipalmitoylphosphatidylcholine (DPPC; 100 mmol/L concentration) and varying concentrations of toluene was formed. The DPPC control and toluene-mixed bilayers underwent MR imaging. T1 and T2 were measured as a function of toluene and lipid concentrations. RESULTS: T2- weighted images of patients who had abused toluene showed marked hypointensity in the thalami and moderate hypointensity in the basal ganglia. Measurements of the DPPC-toluene phantom indicated that toluene-tainted lipid bilayers dramatically shortened T2 and had little effect on T1. By comparison, DPPC itself had little discernible effect on either T1 or T2. CONCLUSION: This model suggests that partitioning of toluene into the lipid membranes of cells in cerebral tissue may be responsible for the hypointensity of basal ganglia noted on T2-weighted MR images of brains of toluene abusers.