Retrospective comparison study between SPECT bone scintigraphy and serial radiograph tracing for assessment of growth in patients with condylar hyperplasia

Abstract

The comparison of serial radiographs and clinical photographs is considered the current accepted standard in diagnosing active condylar hyperplasia in patients with facial asymmetry. Recently, Single-Photon Emission Computed Tomography (SPECT) had been touted as the alternative method. SPECT can be interpreted using three reported methods: “Absolute Difference in Uptake”, “Uptake Ratio”, and “Relative Uptake”. SPECT findings were compared against those from serial comparisons of radiographs and clinical photographs taken at time of SPECT, and those a year later; and the sensitivities and specificities determined. Of 200 scans evaluated, 34 patients were found to have active growth from serial growth assessment. When compared, the three methods obtained sensitivity and specificity values of between 32.4 to 67.6%, and 36.1 to 78.3%, respectively. Analysis using Receiver Operating Characteristic (ROC) curves revealed Areas Under Curve (AUC) of less than 0.58. The average age of patients with active growth was 18.6 years (SD 2.8 years), and the average growths in the anteroposterior, vertical, and transverse directions were 0.94mm (SD 0.91mm), 0.88mm (SD 0.86mm), and 1.4mm (SD 0.66mm), respectively. With such low sensitivity and specificity values, it is not justifiable to use SPECT in place of serial growth assessment for determination of condylar growth statuses.