Advances in clinical application of quantitative myocardial perfusion imaging

Abstract

See related article, pp. 670-680Myocardial perfusion imaging (MPI) is well-established and the most widely used noninvasive imaging method for the detection of myocardial ischemia. Numerous studies have shown that the diagnostic accuracy of MPI for the detection of angiographically significant coronary artery disease (CAD) is high and that normal MPI in patients with intermediate-to-high likelihood of CAD predicts a very low rate of cardiac death or nonfatal myocardial infarction (MI). These features make MPI a strong technique to guide selection of patients for revascularization.The standard interpretation of MPI is based on the assessment of relative myocardial perfusion defects. This method of defining regional reductions in uptake relative to the maximum in the left ventricle myocardium has some limitations in the detection of ischemia. In clinical scenarios, these shortcomings may arise particularly with patients who have multivessel disease. 1The relative assessment is based on the assumption that the region with the best perfusion is normal and can be used as a reference. Therefore, global reduction of myocardial perfusion due by diffuse microvascular disease or multivessel disease can lead to false negative result and underestimation of patient's risk. The balanced multivessel disease may be completely missed or sometimes only the territory supplied by the most severe coronary artery stenosis can be identified. This constitutes one of the major shortcomings of standard relative MPI.It is possible to make quantitative measurements of myocardial blood flow (MBF) and myocardial flow reserve (MFR) with the use of positron-emission tomography (PET). Owing to high temporal resolution and correction of photon attenuation PET provides accurate delineation of regional tracer kinetics, which are used in combination with validated tracer kinetic models to quantify MBF in mL/minute/g of tissue.Regional MBF and MFR in response to stressors are reduced in the myocardial regions subtended by the stenosed coronary artery and correlate with the severity of stenosis, measured by quantitative coronary angiography 2,3 and also with the pressure gradient induced by the stenosis. Thus, in patients with chronic stable angina and no previous history of MI, quantitative assessment of MBF and MFR allows determination of the functional significance of epicardial coronary lesions. However, these measures have not been widely integrated into clinical practice and there is limited data supporting incremental diagnostic utility of flow quantification in patients being assessed for myocardial ischemia.Recently, there has been growing interest in translation of quantitative flow and flow reserve using PET from mainly research tool to routine clinical practice. This is largely based on the recent growth in the number of hybrid PET and computed tomography (CT) systems, attributable primarily to their wide spread use in clinical oncology. Moreover, the generator produced flow tracer 82 Rubidium ( 82 Rb) has made perfusion imaging possible ...

Quantification of Myocardial Blood Flow in Absolute Terms Using 82Rb PET Imaging

“…Measuring myocardial blood flow (MBF) in absolute terms with PET is nowadays possible in clinical routine practice (1). These measurements at rest and under stress can be completed fast (2,3), and the reconstructed dynamic images can be analyzed in few minutes by the majority of the available software packages (4).…”

Mapping18F-FDG Kinetics Together with Patient-Specific Bootstrap Assessment of Uncertainties: An Illustration with Data from a PET/CT Scanner with a Long Axial Field of View

“…Further examination of the V b variable could be merited. Viability of conducting PET 15 O-H 2 O on this scanner was previously demonstrated (29). Note that some of the deviation in Table 3 may be related to scaling differences between the use of whole-blood activity as an AIF (like ours) and other analyses that used the arterial plasma activity time course as an AIF.…”