Evaluation of equine scintigraphic stifle scans

Evaluation of equine scintigraphic bone scans is carried out mostly by visual interpretation. By the use of ROI (regions of interest)-technique scintigraphic stifle scans were evaluated regarding possible significant differences between clinically healthy and pathological stifles. Certain regions of interest were measured quantitatively trying to determine reference ranges for the different regions. 207 stifles of 195 horses were examined and classified into three groups according to the clinical symptoms. For the quantitative evaluation of the lateral views 13 different regions of interest were appointed. One of these regions was located on the diaphysis of the tibia and served as reference region. Most of the ratios between the other regions and this reference region of the clinically healthy group show a strong dependence on age of the hones, decrease quickly until 5 years of age and then find their level. Significant differences between the clinically healthy and pathological stifles were found for 8 of the 12 regions. The results prove that the quantitative evaluation of stifle scintigraphy in horses cannot replace the visual examination of the scintigram. The scintigraphic examination is the only diagnostic procedure that gives early information about actual bone metabolism, but is too sensitive for providing useful reference ranges for the quantitative evaluation.