Evaluation of three analysis methods for Tc MDP SPECT scintigraphy in the diagnosis of unilateral condylar hyperplasia.

The aims of the study were to evaluate the diagnostic accuracy and utility of the mean region of interest (ROI) and mean and maximum volume of interest (VOI) analysis methods for Tc MDP SPECT scintigraphy in the diagnosis of active unilateral condylar hyperplasia (UCH). Inactive UCH (n=43) and active UCH (n=8) patients, and patients without condylar hyperplasia (controls, n=41) were analyzed. Inter-observer agreement was good for all methods. Condylar uptake was not normally distributed, with a longer right tail in UCH patients compared to control patients. Receiver operating characteristic curve analysis indicated that the ROI method was slightly superior to both VOI methods for the diagnosis of active UCH (area under the curve=0.866, 0.811, and 0.817, and J=0.642, 0.596, and 0.573, respectively). The 'traditional' 55% cut-off value proved optimal for ROI and mean VOI methods, but a cut-off of 56.125% was optimal for maximum VOI. Sensitivity was 88% for all three methods using these cut-off values, while specificity was 77%, 65%, and 70% for mean ROI, mean VOI, and maximum VOI, respectively. These results indicate that corrective surgery for negative scan patients can be performed without delay, with an error rate of only 3%, but not in positive scan patients.