COMPUTER-ASSISTED IMAGE-PROCESSING FOR QUANTITATIVE MEASUREMENTS OF FRACTIONAL BONE AREA - A METHODOLOGIC STUDY

The purpose of this study was to evaluate a method for computer-assist ed image processing to assess quantitatively fractional bone volume in sections of bone biopsies (part I). A second purpose was to apply thi s method in an experimental study to determine bone loss by measuring fractional bone area in sections of calvarial bone of gastrectomized r ats and to compare this with a control group. Stained paraffin section s of skull bone of young rabbits (part I) and rats (part II) were exam ined. The histologic sections were placed on a microscope. A video cam era was connected to the microscope, and the image transferred to a di splay monitor connected to a PC with dedicated software, performing th e measurements. In the first part of the study tests of the reproducib ility of the method were performed. The influence of factors such as e xternal illumination and light intensity in the microscope was evaluat ed by measuring the same area several times at different times (= diff erent illumination) and at different microscope light intensity levels . The automatic method was compared with a manual method, using a Merz grid but automatically calculated. The difference between the means o f the manual and automatic measurements was determined with the paired t test. In the second part of the study the unpaired t test was used to determine the differences between the control group and experimenta l group, both for the manually and the automatically measured values. The data of this study indicate that the automatic image processing me thod is an efficient tool for determining bone loss by measuring bone area to estimate fractional bone volume in histologic sections. Howeve r, the quality of the histologic sections is of paramount importance f or precise measurements.