Adenosine stress 64- and 256-row detector computed tomography angiography and perfusion imaging: a pilot study evaluating the transmural extent of perfusion abnormalities to predict atherosclerosis causing myocardial ischemia

Abstract

Background: Multidetector computed tomography coronary angiography (CTA) is a robust method for the noninvasive diagnosis of coronary artery disease. However, in its current form, CTA is limited in its prediction of myocardial ischemia. The purpose of this study was to test whether adenosine stress computed tomography myocardial perfusion imaging (CTP), when added to CTA, can predict perfusion abnormalities caused by obstructive atherosclerosis.

Methods and results: Forty patients with a history of abnormal single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) underwent adenosine stress 64-row (n=24) or 256-row (n=16) detector CTP and CTA. A subset of 27 patients had invasive angiography available for quantitative coronary angiography. CTA and quantitative coronary angiography were evaluated for stenoses > or =50%, and SPECT-MPI was evaluated for fixed and reversible perfusion deficits using a 17-segment model. CTP images were analyzed for the transmural differences in perfusion using the transmural perfusion ratio (subendocardial attenuation density/subepicardial attenuation density). The sensitivity, specificity, positive predictive value, and negative predictive value for the combination of CTA and CTP to detect obstructive atherosclerosis causing perfusion abnormalities using the combination of quantitative coronary angiography and SPECT as the gold standard was 86%, 92%, 92%, and 85% in the per-patient analysis and 79%, 91%, 75%, and 92% in the per vessel/territory analysis, respectively.

Conclusions: The combination of CTA and CTP can detect atherosclerosis causing perfusion abnormalities when compared with the combination of quantitative coronary angiography and SPECT.

Figure 1

CT imaging protocols for 64- and 256-detector CT.

Figure 2

Left ventricular segmentation of CTP images. A through C, 16-segment analysis of the subendocardial, midmyocardial, and subepicardial layers, excluding only the most distal apex.

Figure 3

Relative frequency distribution plot (solid line) of the transmural perfusion ratio (x-axis) measurements in patients with no obstructive atherosclerosis determined with invasive coronary angiography (n=224 myocardial segments). Dotted line represents the normal distribution.

Figure 4

Bland-Altman Plot demonstrating the agreement in the measurement of the TPR between observer A and observer B on the rest (A) and stress (B) images.

Figure 5

TPR versus percent diameter stenosis on QCA performed on invasive coronary angiograms in patients with stenoses ≥30%.

Figure 6

Images from 64-row detector CTP. A, Partially reversible perfusion deficit in the territory of the LAD and a primarily fixed perfusion deficit in the inferior wall on radionuclide myocardial perfusion imaging with increased subdiaphragmatic tracer uptake (stress, upper panels; rest, lower panels). B and C, Adenosine stress CTP shows a dense perfusion deficit in the LAD territory, as well as a subendocardial perfusion deficit in the inferior and lateral walls. D, Invasive coronary angiogram demonstrates a left-dominant system with a totally occluded LAD (black arrow) as well as intermediate and high-grade stenoses in a large ramus intermedius, the body of the left circumflex, an the ostium of the obtuse marginal artery (white arrows).

Figure 7

Images from 256-row detector CTP. A, Partially reversible perfusion deficit in the inferior and inferolateral wall on radionuclide MPI in this patient with exertional angina (stress, upper panels; rest, lower panels). Rest (B) and stress (C) CTP imaging shows a reversible subendocardial perfusion deficit in the inferior and inferolateral walls. Noninvasive angiography confirms a significant stenoses (white arrows) in the proximal right coronary artery (D and E) and the proximal left circumflex artery (F).