Is SPECT/CT Superior to SPECT in Assessing Unilateral Condylar Hyperplasia?

Publication date: Available online 21 February 2019

Source: Journal of Oral and Maxillofacial Surgery

Author(s): Pingan Liu, Jun Shi

Abstract

Purpose

Single-photon emission computed tomography (SPECT) imaging with technetium-99m-disphosphates plays an important role in assessing unilateral condylar hyperplasia. The aim of the study was to evaluate whether quantification methods of single-photon emission computed tomography/computed tomography (SPECT/CT) based on precise region of interest (ROI) drawings made under the guide of CT images are more accurate than conventional SPECT methods in the assessment of unilateral condylar hyperplasia (UCH) growth.

Methods

This study is a nonblinded, retrospective case series. Patients with UCH who had undergone SPECT/CT scans were enrolled. CT images were used to guide the ROI drawings around the anatomical contour of the affected and contralateral condyles in SPECT/CT while conventional SPECT used fixed ROIs. Both the mean and maximum values within the ROIs were recorded to compute the 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 curve (AUC) of the receiver operating characteristic (ROC) curve of each method was calculated and compared pairwise.

Results

Fifty-six patients total, including 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. Alternatively, 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 between SPECTaver, SPECTmax and SPECTCTmax (P>0.05) and poorer diagnostic performance of SPECTCTaver compared to the other three methods (P<0.05).

Conclusions

The method of using ROIs drawn around the contour of the condyle from SPECT/CT does not show improved accuracy over conventional SPECT-fixed ROI methods in assessing unilateral condylar hyperplasia.

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