IN-VIVO MR DETERMINATION OF WATER DIFFUSION-COEFFICIENTS AND DIFFUSION ANISOTROPY - CORRELATION WITH STRUCTURAL ALTERATION IN GLIOMAS OF THE CEREBRAL HEMISPHERES

PURPOSE: To determine whether a relationship exists between water diff usion coefficients or diffusion anisotropy and MR-defined regions of n ormal or abnormal brain parenchyma in patients with cerebral gliomas. METHODS: In 40 patients with cerebral gliomas, diffusion was character ized in a single column of interest using a motion-insensitive spin-ec ho sequence that was applied sequentially at two gradient strength set tings in three orthogonal directions. Apparent diffusion coefficients (ADCs) were derived for the three orthogonal axes at 128 points along the column. An average ADC and an index of diffusion anisotropy (IDA = diffusion coefficient(max-min)/diffusion(mean)) was then calculated f or any of nine MR-determined regions of interest within the tumor or a djacent parenchyma. RESULTS: In cerebral edema, mean ADC (all ADCs as 10(-7) cm(2)/s) was 138 +/- 24 (versus 83 +/- 6 for normal white matte r) with mean IDA of 0.26 +/- 0.14 (versus 0.45 +/- 0.17 for normal whi te matter). Solid enhancing central tumor mean ADC was 131 +/- 25 with mean IDA of 0.15 +/- 0.10. Solid enhancing tumor margin mean ADC was 131 +/- 25, with IDA of 0.25 +/- 0.20. Cyst or necrosis mean ADC was 2 35 +/- 35 with IDA of 0.07 +/- 0.04. CONCLUSION: In cerebral gliomas A DC and IDA determinations provide information not available from routi ne MR imaging. ADC and IDA determinations allow distinction between no rmal white matter, areas of necrosis or cyst formation, regions of ede ma, and solid enhancing tumor. ADCs can be quickly and reliably charac terized within a motion-insensitive column of interest with standard M R hardware.