Considerations when measuring myocardial perfusion reserve by cardiovascular magnetic resonance using regadenoson

Abstract

BackgroundAdenosine cardiovascular magnetic resonance (CMR) can accurately quantify myocardial perfusion reserve. While regadenoson is increasingly employed due to ease of use, imaging protocols have not been standardized. We sought to determine the optimal regadenoson CMR protocol for quantifying myocardial perfusion reserve index (MPRi) – more specifically, whether regadenoson stress imaging should be performed before or after rest imaging.MethodsTwenty healthy subjects underwent CMR perfusion imaging during resting conditions, during regadenoson-induced hyperemia (0.4 mg), and after 15 min of recovery. In 10/20 subjects, recovery was facilitated with aminophylline (125 mg). Myocardial time-intensity curves were used to obtain left ventricular cavity-normalized myocardial up-slopes. MPRi was calculated in two different ways: as the up-slope ratio of stress to rest (MPRi-rest), and the up-slope ratio of stress to recovery (MPRi-recov).ResultsIn all 20 subjects, MPRi-rest was 1.78 ± 0.60. Recovery up-slope did not return to resting levels, regardless of aminophylline use. Among patients not receiving aminophylline, MPRi-recov was 36 ± 16% lower than MPRi-rest (1.13 ± 0.38 vs. 1.82 ± 0.73, P = 0.001). In the 10 patients whose recovery was facilitated with aminophylline, MPRi-recov was 20 ± 24% lower than MPRi-rest (1.40 ± 0.35 vs. 1.73 ± 0.43, P = 0.04), indicating incomplete reversal. In 3 subjects not receiving aminophylline and 4 subjects receiving aminophylline, up-slope at recovery was greater than at stress, suggesting delayed maximal hyperemia.ConclusionsMPRi measurements from regadenoson CMR are underestimated if recovery perfusion is used as a substitute for resting perfusion, even when recovery is facilitated with aminophylline. True resting images should be used to allow accurate MPRi quantification. The delayed maximal hyperemia observed in some subjects deserves further study.Trial registrationClinicalTrials.gov NCT00871260

Clinical Quantification of Myocardial Blood Flow Using PET: Joint Position Paper of the SNMMI Cardiovascular Council and the ASNC

“…Importantly, if regadenoson is used, reversal with 150 mg of aminophylline may not be sufficient to restore resting perfusion conditions. 55 More data are needed before a transition to routine stress-only imaging for quantitative PET MBF imaging can be recommended. Table 1 lists doses of clinically used PET radiotracers for MBF imaging.…”

Myocardial perfusion reserve and global longitudinal strain as potential markers of coronary allograft vasculopathy in late-stage orthotopic heart transplantation

“…Lastly, in our vCMR protocol, imaging was first performed under hyperemic conditions, while resting perfusion evaluation was performed after the reversal of hyperemia with aminophylline. Although this sequence has been shown to underestimate MPR [53], this is unlikely to have impact on our results since this protocol was used in all patients and controls. In our MPR calculations, we used the upslope technique rather than a fully quantitative technique involving deconvolution, which could have been more accurate.…”

Cardiac Mri Assessment of Myocardial Perfusion

“…CMR quantitative perfusion data is now available in various populations (syndrome X) [27], various myocardial regions (subepicardium vs subendocardium) [28], using different techniques (manual vs automatic) [29], and with different vasodilator agents (adenosine and regadenoson [30]).…”