Comparison of CTAC and prone imaging for the detection of coronary artery disease using CZT SPECT

Abstract

Background: Cadmium-zinc-telluride (CZT) cameras have improved the evaluation of patients with chest pain. However, inferior/inferolateral attenuation artifacts similar to those seen with conventional Anger cameras persist. We added prone acquisitions and CT attenuation correction (CTAC) to the standard supine image acquisition and analyzed the resulting examinations.

Methods and results: Seventy-two patients referred for invasive coronary angiography (CAG), and who also underwent rest/stress myocardial perfusion imaging (MPI) on a CZT camera in the supine and prone positions plus CTAC imaging, to examine known or suspected CAD between April 2013 and March 2014 were included. A sixteen-slice CT scan acquired on a SPECT/CT scanner between rest and stress imaging provided data for iterative reconstruction. Sensitivity, specificity, accuracy, and positive and negative likelihood ratios (LRs) were calculated to compare MPI with CAG on a per-patient basis. Per-patient sensitivity, specificity, and accuracy of supine images to predict coronary abnormalities on CAG were 35% [95% confidence interval (CI) 19-52], 86% (95% CI 80-92), and 74% (95% CI 66-82); those of prone imaging were 65% (95% CI 45-81), 82% (95% CI 76-87), and 78% (95% CI 68-85); and those of CTAC were 59% (95% CI 41-71), 93% (95% CI 87-97), and 85% (95% CI 76-91), respectively.

Conclusions: Prone acquisition and CTAC images improve the ability to assess the inferior/inferolateral area.

Keywords: Coronary artery disease; Myocardial ischemia; Single-photon emission computed tomography.

Fig. 1

The combined MPI and CTAC protocol

Fig. 2

A 72-year-old man experiencing chest pain. CTAC images elucidated inferior ischemia that could not be seen on supine or prone images. CAG showed 90% stenosis of #4PL

Fig. 3

Changes in diagnosis when adding prone (a) and CTAC (b) images in each case