Clinical Value of Absolute Quantification of Myocardial Perfusion With ¹⁵ O-Water in Coronary Artery Disease

Abstract

Background-The standard interpretation of perfusion imaging is based on the assessment of relative perfusion distribution. The limitations of that approach have been recognized in patients with multivessel disease and endothelial dysfunction. To date, however, no large clinical studies have investigated the value of measuring quantitative blood flow and compared that with relative uptake. Methods and Results-One hundred four patients with moderate (30%-70%) pretest likelihood of coronary artery disease (CAD) underwent PET imaging during adenosine stress using 15 O-water and dynamic imaging. Absolute myocardial blood flow was calculated from which both standard relative myocardial perfusion images and images scaled to a known absolute scale were produced. The patients and the regions then were classified as normal or abnormal and compared against the reference of conventional angiography with fractional flow reserve. In patient-based analysis, the positive predictive value, negative predictive value, and accuracy of absolute perfusion in the detection of any obstructive CAD were 86%, 97%, and 92%, respectively, with absolute quantification. The corresponding values with relative analysis were 61%, 83%, and 73%, respectively. In region-based analysis, the receiver operating characteristic curves confirmed that the absolute quantification was superior to relative assessment. In particular, the specificity and positive predictive value were low using just relative differences in flow. Only 9 of 24 patients with 3-vessel disease were correctly assessed using relative analysis. Conclusions-The measurement of myocardial blood flow in absolute terms has a significant impact on the interpretation of myocardial perfusion. As expected, multivessel disease is more accurately detected. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00627172. (Circ Cardiovasc Imaging. 2011;4:678-684.)

Hybrid Imaging Using Quantitative H215O PET and CT-Based Coronary Angiography for the Detection of Coronary Artery Disease

“…Furthermore, generation of high-quality parametric perfusion images is now feasible (12). Nonetheless, relative flow imaging with H 2 15 O PET still faces many challenges, and studies investigating the additive value of quantitative MBF imaging, compared with relative flow PET are scarce (38). Clearly, more prospective studies are warranted to establish the clinical value of relative perfusion imaging with H 2 15 O as a perfusion tracer.…”

“…Nonetheless, several important issues remain to be addressed such as whether qualitative or quantitative PET (or their combination) conveys the best results because data on this topic are scarce (8,38). The results of prospective studies further exploring the diagnostic accuracy of PET/ CTCA are therefore eagerly awaited.…”

CT fractional flow reserve: the next level in non-invasive cardiac imaging

“…Similarly, in 101 patients with leftmain CAD on ICA, >40 % of patients had low-risk findings on MPI-SPECT [27]. The ability of MPI-PET to enable absolute measurements of myocardial blood flow improves its sensitivity in left-main or multivessel disease [29][30][31]. In 103 angina patients with an intermediate pre-test risk for CAD, absolute quantification of myocardial perfusion with PET outperformed relative assessment of myocardial perfusion with PET [30].…”

“…The ability of MPI-PET to enable absolute measurements of myocardial blood flow improves its sensitivity in left-main or multivessel disease [29][30][31]. In 103 angina patients with an intermediate pre-test risk for CAD, absolute quantification of myocardial perfusion with PET outperformed relative assessment of myocardial perfusion with PET [30]. The PPV improved from 61 % to 86 % and the NPV improved from 83 % to 97 % [30].…”

“…In 103 angina patients with an intermediate pre-test risk for CAD, absolute quantification of myocardial perfusion with PET outperformed relative assessment of myocardial perfusion with PET [30]. The PPV improved from 61 % to 86 % and the NPV improved from 83 % to 97 % [30]. The addition of wall motion abnormalities and a decrease in left ventricular ejection fraction during stress resulted in a modest improvement of the detection and exclusion of three-vessel or left-main disease [27,28,32].…”