A method for the relative quantification of 99mTc-HM-PAO distribution in brain SPECT is described. The method, applied in 12 normal volunteers and 150 patients suffering from different cerebral diseases, uses circumferential profiles to quantify the relative radionuclide distribution in the brain tomograms as an angular function with the origin at the center of the brain slice. Abnormal 99mTc-HM-PAO distribution is evaluated by comparing the count content of symmetrical selected parts of the profile curve and comparing each patient's profile with the corresponding limits of normal ones, determined from the pooled profiles of 12 normal subjects. This computerized method allows an accurate, reproducible and objective assessment of the relative HM-PAO distribution in the brain.