CALCULATION OF APPARENT DIFFUSION-COEFFICIENTS (ADCS) IN BRAIN USING 2-POINT AND 6-POINT METHODS

We evaluated the relative accuracy of calculating apparent diffusion c oefficients (ADCs) of intracranial tissues using a two-paint versus a six-point regression technique. Echo planar diffusion-weighted MRI was performed at 1.5 T in three standard locations and in pathologic regi ons in 10 subjects using gradient strengths corresponding to b values of 1, 100, 200, 500, 800, and 1,000 s/mm(2). Estimation of ADCs was ma de using two methods: a nonlinear regression model using measurements from the full set of b values (six-point technique) and linear estimat ion using b values of 1 and 1,000 only (two-point technique). A high c orrelation between the two methods was noted (R-2 = 0.999), and the me an percentage difference was 0.84%. These results suggest there is lit tle error in estimating brain ADCs using a two-point technique.