Myocardial blood flow and myocardial flow reserve values in N-ammonia myocardial perfusion PET/CT using a time-efficient protocol in patients without coronary artery disease.

Background: Cardiac imaging by means of myocardial Positron Emission Tomography/Computed Tomography (PET/CT) is being used increasingly to assess coronary artery disease, to guide revascularization decisions with more accuracy, and it allows robust quantitative analysis of both regional myocardial blood flow (MBF) and myocardial flow reserve (MFR).Recently, a more time-efficient protocol has been developed in combination with a residual activity correction algorithm in which a stress acquisition is performed directly after completion of the rest acquisition to subtract remaining myocardial radioactivity.The objective of this study is to define flow values of myocardial blood flow (MBF) and Myocardial Flow Reserve (MFR) with N-ammonia (NH) myocardial perfusion PET/CT on patients without coronary artery disease using a time-efficient protocol, since reference values for this particular type of study are lacking in literature. In addition, we aim to determine the effect of the residual activity correction algorithm in this time-efficient protocol.

Results: A mean MBF in rest of 1.02 ± 0.22 ml/g/min, a mean MBF in stress of 2.54 ± 0.41 ml/g/min with a mean MFR of 2.60 ± 0.61 were measured. Female patients had a significant higher MBF in rest and stress, but lower MFR; a small but significant negative correlation was measured between age and MBF in stress and MFR. Residual activity correction had a significant effect resulting in a difference in global stress MBF before and after correction of 0.39 ± 0.13 ml/g/min.

Conclusions: This study established flow values for NH myocardial PET/CT with a time-efficient protocol, and established that MBF in stress corrected for residual activity is comparable with known reference values in normal studies without temporal overlap. Further validation of the technique could be of value, e.g. by comparison to standard imaging without temporal overlap, or validation against catheterization results.