Is Single-Photon Emission Computed Tomography/Computed Tomography Superior to Single-Photon Emission Computed Tomography in Assessing Unilateral Condylar Hyperplasia?

Abstract

Single-photon emission computed tomography (SPECT) with technetium-99m diphosphates plays an important role in assessing unilateral condylar hyperplasia (UCH). The aim of this study was to evaluate whether quantification methods of SPECT plus CT (SPECT/CT) based on precise region-of-interest (ROI) drawings made under the guide of CT images were more accurate than conventional SPECT methods in the assessment of UCH growth. This study is a nonblinded retrospective case series. Patients with UCH who had undergone SPECT/CT were enrolled. CT images were used to guide ROI drawings around the anatomic contour of the affected and contralateral condyles on SPECT/CT images versus fixed ROIs on conventional SPECT images. Mean and maximum values within the ROIs were recorded to compute percentile ratios. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and receiver operating characteristic (ROC) curves were calculated separately for SPECT-based methods (SPECTaver, SPECTmax) and SPECT/CT methods (SPECTCTaver, SPECTCTmax). The area under the ROC curve of each method was calculated and compared pairwise. Fifty-six patients (30 patients with progressive and 26 patients with nonprogressive mandibular asymmetry) were evaluated. SPECTmax had the highest sensitivity of 83.3%, followed by SPECTCTmax, SPECTaver, and SPECTCTaver. In contrast, SPECTaver, SPECTCTmax, and SPECTmax had similar specificities, PPVs, and NPVs. Nonetheless, SPECTCTaver had the lowest specificity, PPV, and NPV among all methods. ROC analysis also showed similar diagnostic performances among SPECTaver, SPECTmax, and SPECTCTmax (P>.05) and poorer diagnostic performance of SPECTCTaver compared with the other 3 methods (P<.05). The method of using ROIs drawn around the contour of the condyle on SPECT/CT images does not show improved accuracy over conventional SPECT-fixed ROI methods in assessing UCH.