A comparison of single-photon emission computed tomography and planar imaging for quantitative skeletal scintigraphy of the mandibular condyle.

A prospective study was designed to compare two methods of quantifying technetium-99m methylene diphosphonate uptake in the mandibular condyle. The standard technique expresses condylar activity as a ratio of condylar uptake to a reference (often the fourth lumbar vertebra) with planar scans (lateral images of the mandible). The experimental technique quantifies condylar activity as a ratio of condyle to clivus uptake with single-photon emission computed tomography (SPECT). The results of this study indicated that the uptake ratio of condyle/clivus by SPECT scintigram was positively correlated (p = 0.039) with the planar scan technique. The SPECT technique, similar to an axial computed tomography scan, was easier to perform with better reproducibility than the standard planar technique. In addition, activity in the clivus showed less variation than activity in the fourth lumbar vertebrae. With the development of normal uptake standards in the clivus, the SPECT technique may replace the planar image technique in nongrowing patients.