抄録
We introduce three-dimensional fractal analysis (3D-FA) to quantify the spatial heterogeneity of radioisotope on nuclear medicine images. We delineated SPECT images using four cut-off levels, ( % of the maximal voxel radioactivity), and measured the total number of voxels in the areas surrounded by the contours obtained with each cut-off level. We calculated fractal dimensions from the relationship between the total number of voxels and the cut-off levels transformed into natural logarithms. The fractal dimensions obtained from ventilation and cerebral blood flow SPECT images were well correlated with the obstructive impairment in pulmonary function tests and the cognitive impairment in neuropsychological tests.3D-FA may be an useful method for evaluating objectively the progression of emphysema and Alzheimer'disease.3D-FA is applicable for routine clinical use because it is simple and because the fractal dimensions can be calculated easily without using special software.
