Multidetector Computed Tomography Myocardial Perfusion Imaging During Adenosine Stress

Objectives: The purpose of this study is to validate the accuracy of multidetector computed tomography (MDCT) to measure differences in regional myocardial perfusion during adenosine stress in a canine model of left anterior descending (LAD) artery stenosis, during first-pass, contrast-enhanced helical MDCT. Background: Myocardial perfusion imaging by MDCT may have significant implications in the diagnosis and treatment of coronary artery disease. Methods: Eight dogs were prepared with a LAD stenosis, and contrast-enhanced MDCT imaging was performed 5 min into adenosine infusion (0.14 to 0.21 mg/kg/min). Images were analyzed using a semiautomated approach to define the regional signal density (SD) ratio (myocardial SD/left ventricular blood pool SD) in stenosed and remote territories, and then compared with microsphere myocardial blood flow (MBF) measurements. Results: Mean MBF in stenosed versus remote territories was 1.37 ± 0.46 ml/g/min and 1.29 ± 0.48 ml/g/min at baseline (p = NS) and 2.54 ± 0.93 ml/g/min and 8.94 ± 5.74 ml/g/min during adenosine infusion, respectively (p < 0.05). Myocardial SD was 92.3 ± 39.5 HU in stenosed versus 180.4 ± 41.9 HU in remote territories (p < 0.001). There was a significant linear association of the SD ratio with MBF in the stenosed territory (R = 0.98, p = 0.001) and between regional myocardial SD ratio and MBF <8 ml/g/min, slope = 0.035, SE = 0.007, p < 0.0001. Overall, there was a significant non-linear relationship over the range of flows studied (LR chi-square [2 degrees of freedom] = 31.8, p < 0.0001). Conclusions: Adenosine-augmented MDCT myocardial perfusion imaging provides semiquantitative measurements of myocardial perfusion during first-pass MDCT imaging in a canine model of LAD stenosis.