Quantitative Myocardial Perfusion with 2D and 3D Sequences Alternating Every Heartbeat

PurposeTo evaluate a myocardial perfusion acquisition that alternates 2D simultaneous multi-slice (SMS) and 3D stack-of-stars (SoS) acquisitions each heartbeat. MethodsA hybrid saturation recovery radial 2D SMS and a saturation recovery 3D SoS sequence were created for the quantification of myocardial blood flow (MBF). Initial studies were done to study the effects of using only every other beat for the 2D SMS in two subjects, and for the 3D SoS in two subjects. Alternating heartbeat 2D SMS and 3D SoS were then performed in ten dog studies at rest, four dog studies at adenosine stress, and two human resting studies. 2D SMS acquisition acquired three slices and 3D SoS acquired six slices. An arterial input function (AIF) for 2D SMS was obtained using the first 24 rays. For 3D, the AIF was obtained in a 2D slice prior to each 3D SoS readout. Quantitative MBF analysis was performed for 2D SMS and 3D SoS separately, using a two-compartment model. ResultsAcquiring every-other-beat data resulted in 5-20% perfusion changes at rest for both 2D SMS and 3D SoS methods. For alternating acquisitions, 2D SMS and 3D SoS quantitative perfusion values were comparable for both the twelve rest studies (2D SMS: 0.68±0.15 vs 3D: 0.69±0.15 ml/g/min, p=0.85) and the four stress studies (2D SMS: 1.28±0.22 vs 3D: 1.30±0.24 ml/g/min, p=0.66).ConclusionEvery-other-beat acquisition changed estimated perfusion values relatively little for both sequences. 2D SMS and 3D SoS gave similar quantitative perfusion estimates when used in an alternating every-other-heartbeat acquisition. Such an approach allows consideration of more diverse perfusion acquisitions that could have complementary features, although testing in a cardiac disease population is needed.

Quantitative myocardial perfusion response to adenosine and regadenoson in patients with suspected coronary artery disease

Background The aim of the present study was to compare the quantitative flow responses of regadenoson against adenosine using cardiac 15O-water PET imaging in patients with suspected or known coronary artery disease (CAD). Methods Hyperemic myocardial blood flow (MBF) after adenosine and regadenoson was compared using correlation and Bland–Altman analysis in 21 patients who underwent rest and adenosine 15O-water PET scans followed by rest and regadenoson 15O-water PET scans. Results Global mean (± SD) MBF values at rest and stress were 0.92 ± 0.27 and 2.68 ± 0.80 mL·g·min for the adenosine study and 0.95 ± 0.29 and 2.76 ± 0.79 mL·g·min for the regadenoson study (P = 0.55 and P = 0.49). The correlations between global and regional adenosine- and regadenoson-based stress MBF were strong (r = 0.80 and r = 0.77). The biases were small for both global and regional MBF comparisons (0.08 and 0.09 mL·min·g), but the limits of agreement were wide for stress MBF. Conclusion The correlation between regadenoson- and adenosine-induced hyperemic MBF was strong but the agreement was only moderate indicating that established cut-off values for 150-water PET should be used cautiously if using regadenoson as vasodilator.

Quantitative myocardial perfusion SPECT/CT for the assessment of myocardial tracer uptake in patients with three-vessel coronary artery disease: Initial experiences and results

Background To evaluate quantitative myocardial perfusion SPECT/CT datasets for routine clinical reporting and the assessment of myocardial tracer uptake in patients with severe TVCAD. Methods MPS scans were reconstructed as quantitative SPECT datasets using CTs from internal (SPECT/CT, Q_INT) and external (PET/CT, Q_EXT) sources for attenuation correction. TPD was calculated and compared to the TPD from non-quantitative SPECT datasets of the same patients. SUVmax, SUVpeak, and SUVmean were compared between Q_INT and Q_EXT SPECT datasets. Global SUVmax and SUVpeak were compared between patients with and without TVCAD. Results Quantitative reconstruction was feasible. TPD showed an excellent correlation between quantitative and non-quantitative SPECT datasets. SUVmax, SUVpeak, and SUVmean showed an excellent correlation between Q_INT and Q_EXT SPECT datasets, though mean SUVmean differed significantly between the two groups. Global SUVmax and SUVpeak were significantly reduced in patients with TVCAD. Conclusions Absolute quantification of myocardial tracer uptake is feasible. The method seems to be robust and principally suitable for routine clinical reporting. Quantitative SPECT might become a valuable tool for the assessment of severe coronary artery disease in a setting of balanced ischemia, where potentially life-threatening conditions might otherwise go undetected.

Use of quantitative myocardial perfusion mapping by CMR for characterisation of ischaemia in patients post coronary artery bypass graft surgery

Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Background Quantitative myocardial perfusion mapping using Cardiac Magnetic Resonance (CMR) imaging is used for evaluation of ischaemia in the context of native vessel coronary disease, but its diagnostic performance in patients with grafts is not well established. Perfusion defects are often detected in these patients, but whether these are a consequence of a technical limitation (delayed contrast arrival from graft conduits) or a true reflection of reduced myocardial blood flow is unclear. Methods 39 patients undergoing stress perfusion CMR with previous coronary artery bypass graft (CABG) surgery, unobstructed left internal mammary artery (LIMA) grafts to the left anterior descending (LAD) artery on coronary angiography and no CMR evidence of prior LAD infarction were included. Myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) were evaluated with quantitative perfusion mapping and the factors determining MBF in the LIMA-LAD territory (AHA segments 1,2,7,8,13,14), including the impact of delayed contrast arrival through the LIMA graft were evaluated. Results In 28 out of 39 cases a myocardial perfusion defect was reported on visual assessment in LIMA-LAD myocardial territory, despite the presence of unobstructed LIMA graft and no LAD infarction. Chronic total occlusion (CTO) of the native LAD was an independent predictor of stress MBF (B=-0.36, p =0.027) and the strongest predictor of MPR (B=-0.55, p 0.005) within the LIMA-LAD myocardial territory after adjusting for age, left ventricular (LV) ejection fraction, and presence of diabetes. CTO of the native LAD was associated with a reduction in stress MBF in the basal myocardial segments (-0.57ml/g/min, p = 0.002) but had no effect on the MBF of apical segments (-0.31ml/g/min, p = 0.084). Increasing the maximum value for allowable arterial delay (TA) of contrast in the quantitative mapping algorithm resulted in a small increase in myocardial blood flow in the LIMA-LAD territory both at stress (0.07 ± 0.08ml/g/min, p < 0.001) and rest (0.06 ± 0.05ml/g/min, p < 0.001). Conclusions Perfusion defects detected in LIMA-LAD subtended territories are common despite graft patency. These defects are likely to represent genuine reduction in MBF, resulting from native LAD coronary occlusion. Prolonged contrast transit time associated with LIMA grafts results in small underestimation of MBF as measured by quantitative CMR perfusion mapping, but does not account for the degree of MBF reduction seen in these patients. Figure 1. Study patient with unobstructed LIMA to LAD graft and evidence of inducible perfusion defect in LIMA-LAD territories. (A): First pass perfusion CMR imaging. (B): Perfusion mapping showing reduced stress MBF in mid antero-septum (0.85ml/g/min) compared to the apical septum (1.65ml/g/min). (C): Late gadolinium enhancement showing no evidence of previous infarction. (D,E): Coronary angiography demonstrating unobstructed LIMA graft (D) and anastomosis site (E). Abstract Figure 1.

EANM procedural guidelines for PET/CT quantitative myocardial perfusion imaging

The use of cardiac PET, and in particular of quantitative myocardial perfusion PET, has been growing during the last years, because scanners are becoming widely available and because several studies have convincingly demonstrated the advantages of this imaging approach. Therefore, there is a need of determining the procedural modalities for performing high-quality studies and obtaining from this demanding technique the most in terms of both measurement reliability and clinical data. Although the field is rapidly evolving, with progresses in hardware and software, and the near perspective of new tracers, the EANM Cardiovascular Committee found it reasonable and useful to expose in an updated text the state of the art of quantitative myocardial perfusion PET, in order to establish an effective use of this modality and to help implementing it on a wider basis. Together with the many steps necessary for the correct execution of quantitative measurements, the importance of a multiparametric approach and of a comprehensive and clinically useful report have been stressed.