Evaluation of Cardiac Cone–Beam Single Photon Emission Computed Tomography Using Observer Performance Experiments and Receiver Operating Characteristic Analysis

Abstract

Single photon emission computed tomography (SPECT) with a cone-beam collimator improves the trade-off between detection efficiency and spatial resolution for cardiac imaging. However, acquisitions using orbits where the focus remains in a plane do not provide sufficient data for exact reconstruction. In the current study the authors evaluate the clinical utility of planar-orbit cone-beam SPECT in detecting a simple myocardial defect. Observer performance experiments compared high-resolution cone-beam with same-resolution parallel-hole and fan-beam collimator designs in myocardial defect detection using a computer-simulated cardiac model. The uptake of Thallium-201 in the myocardium and other tissue organs was modeled by a mathematical three-dimensional upper torso phantom from which physically realistic projections were simulated. Eight observers viewed reconstructed transaxial images from the three collimator designs and indicated the certainty with which they detected a Gaussian-shaped defect at a specified location. The area under the receiver operating characteristic curve indicated that the cone-beam design, regardless of slice position, was superior to the fan-beam, which in turn was superior to the parallel-hole design for the specified detection task. The observer study demonstrated that reconstruction artifacts resulting from insufficient data sampling do not hinder obtaining improved diagnostic information from planar-orbit cone-beam cardiac SPECT images compared to conventional cardiac SPECT using parallel-hole and fan-beam collimators.