Diagnostic Performance of 3D Bull's Eye Display of SPECT and Coronary CTA Fusion

Abstract

Objectives: The aim of this study was to develop a display method to describe the fusion data of myocardial perfusion single-photon emission computed tomography (SPECT) and coronary computed tomography angiography into a single image that we call fusion-based bull's eye (FBE). This study sought to show its generating process and evaluate its diagnostic performance.

Background: Three-dimensional (3D) display is mostly used when reviewing SPECT/coronary computed tomography angiography fusion images, although multidirection interpretation is required to sweep the entire heart. Bull's eye display of the fusion image will be useful in clinical practice.

Methods: FBE images were generated from the 3D fusion data by determining a cardiac axis, adding a cylindrical object around the aortic root, obtaining a panoramic image from circumferential data of the 3D images, and converting it into a polar coordinate display image. The diagnostic performances of SPECT, the conventional 3D fusion, and FBE as to the presence of hemodynamically relevant coronary vessels were compared in 39 patients with abnormal SPECT findings.

Results: The 3D fusion and FBE images were successfully obtained in all patients. Of an evaluated 105 coronary segments in 35 patients without coronary artery bypass grafting, SPECT showed 17 segments (16%) equivocal to determine hemodynamically relevant coronary vessels. FBE corrected the diagnoses of 5 segments, in which SPECT was false-negative in 2 or false-positive in 3, with only 2 equivocal segments (p = 0.0017). FBE also revealed 4 culprit lesions in all 4 patients with coronary artery bypass grafting. There were no discordances between FBE and the 3D fusion.

Conclusions: FBE had the same capacity as the 3D fusion to solve equivocal SPECT findings or correct the diagnoses in 24 of 109 (22%) coronary segments for culprit lesion detection. Although FBE requires manual generation process at present, it facilitates evaluation of myocardial perfusion and coronary anatomy with only 1 image.

Keywords: bull’s eye; coronary CT angiography; fusion imaging; myocardial perfusion SPECT.