FRACTAL ANALYSIS FOR CLASSIFICATION OF GROUND-GLASS OPACITY ON HIGH-RESOLUTION CT - AN IN-VITRO STUDY

Purpose: Fractal analysis based on the fractional Brownian motion mode l was applied to ground-glass opacity on high-resolution CT (HRCT) to investigate its usefulness in distinguishing ground-glass opacity caus ed by nonfibrotic disease processes and that caused by fibrotic diseas e processes, confirming pathology. Method: Twenty-one postmortem lungs inflated and fixed by Heitzman's method were evaluated. By correlatin g HRCT and pathology, the lungs were classified into nonfibrotic disea se processes and fibrotic disease processes, Fractal analysis based on the fractional Brownian motion model provides the parameter H, which is a statistical measure related to the psychophysical perception of r oughness, For regions of interest positioned over ground-glass opaciti es on HRCT, conventional statistics (mean value and SD) and the estima ted H values were calculated using a workstation. Results: Pathologica lly, 10 lung specimens were categorized as nonfibrotic disease process es and 11 as fibrotic disease processes. Whereas the conventional stat istics had considerable overlap in two disease processes, the overlapp ing was drastically reduced in the H values. The H values of fibrotic disease processes (mean +/- SD, 0.423 +/- 0.064) were significantly gr eater than those of nonfibrotic disease processes (0.297 +/- 0.036) (p < 0.001). Conclusion: Fractal analysis based on the fractional Browni an motion model may provide a new promising scheme for assessing groun d-glass opacity on HRCT caused by either nonfibrotic or fibrotic disea se processes.