Feasibility of adenosine stress cardiovascular magnetic resonance perfusion imaging in patients with MR-conditional transvenous permanent pacemakers and defibrillators

Background The use of stress perfusion-cardiovascular magnetic resonance (CMR) imaging remains limited in patients with implantable devices. The primary goal of the study was to assess the safety, image quality, and the diagnostic value of stress perfusion-CMR in patients with MR-conditional transvenous permanent pacemakers (PPM) or implantable cardioverter-defibrillators (ICD). Methods Consecutive patients with a transvenous PPM or ICD referred for adenosine stress-CMR were enrolled in this single-center longitudinal study. The CMR protocol was performed using a 1.5 T system according to current guidelines while all devices were put in MR-mode. Quality of cine, late-gadolinium-enhancement (LGE), and stress perfusion sequences were assessed. An ischemia burden of ≥ 1.5 segments was considered significant. We assessed the safety, image quality and the occurrence of interference of the magnetic field with the implantable device. In case of ischemia, we also assessed the correlation with the presence of significant coronary lesions on coronary angiography. Results Among 3743 perfusion-CMR examinations, 66 patients had implantable devices (1.7%). Image quality proved diagnostic in 98% of cases. No device damage or malfunction was reported immediately and at 1 year. Fifty patients were continuously paced during CMR. Heart rate and systolic blood pressure remained unchanged during adenosine stress, while diastolic blood pressure decreased (p = 0.007). Six patients (9%) had an ischemia-positive stress CMR and significant coronary stenoses were confirmed by coronary angiography in all cases. Conclusion Stress perfusion-CMR is safe, allows reliable ischemia detection, and provides good diagnostic value.

Human hyperpolarized [1-13C] pyruvate CMR and adenosine stress test

Background Hyperpolarized (HP) [1-13C]pyruvate cardiac magnetic resonance (CMR) imaging can visualize myocardial perfusion and metabolism beyound glucose uptake. Depending on the prevailing metabolic conditions, buid-up of either [1-13C]lactate or 13C-bicarbonate can be measured. The aim of the present study was to assess cardiac metabolism using HP [1-13C]pyruvate rest-stress CMR. Methods Six healthy volunteers underwent cine CMR and HP [1-13C]pyruvate CMR at rest and during an adenosine stress test. Signal from HP [1-13C]pyruvate and its downstream metabolites was measured at the mid-left-ventricle (LV) level. We did semi-quantitative assessment of first-pass myocardial [1-13C]pyruvate perfusion. Pressure-volume loops were assessed non-invasively. Results Myocardial [1-13C]pyruvate perfusion was significantly increased during stress with a reduction in time-to-peak from 6.2±2.8 sec to 2.7±1.3 sec, p=0.04. This higher perfusion was accompanied by an overall increased myocardial uptake and metabolism. The conversion rate constant (kPL) for lactate increased from 0.011±0.009 sec–1 to 0.020±0.010 sec–1, p=0.04. The pyruvate oxidation (kPB) increased from 0.004±0.004 sec–1 to 0.012±0.007 sec–1, p=0.008. This increase in oxidative metabolism was positively correlated with heart rate (R2=0.44, p=0.02). Conclusion We observed a significant increase in carbohydrate oxidation during cardiac stress in the healthy human heart. The present study forms the basis for comparisons in future research in patients with heart failure and coronary artery disease. HP [1-13C]pyruvate CMR could be a possible alternative to PET in the future. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Danish Heart FoundationIndependent Research Fund, Denmark Increased conversion rate of pyruvate Increased metabolite signal in LV

Quantification of myocardial ischemia and subtended myocardial mass at adenosine stress cardiac computed tomography. A feasibility study

Introduction Combination of computed tomography angiography (CTA) and adenosine stress CT myocardial perfusion (CTP) allows for coronary artery lesion assessment as well as myocardial ischemia. Nowadays, ischemia on CTP is assessed semi-quantitatively by visual analysis. The aim of this study was to fully quantify myocardial ischemia and the subtended myocardial mass on CTP. Methods We included 33 patients referred for a combined CTA and adenosine stress CTP with good or excellent imaging quality on CTP. Firstly, the coronary artery tree was automatically extracted from CTA and the relevant coronary artery lesions (≥50%) were manually defined (Fig. 1A). Secondly, epi- and endocardial contours along with CTP deficits were manually defined in short-axis images (Fig. 1D, 1E). Thirdly, a Voronoi-based algorithm was used to quantify the subtended myocardial mass (Fig. 1B). Fourthly, the perfusion defect and subtended myocardial mass were spatially registered to the CTA and measured in grams (Fig. 1F, 1C). Finally, this can be used to quantitatively correlate the perfusion defect to the subtended myocardial mass. Results Voronoi-based segmentation was successful in all cases. We assessed a total of 64 relevant coronary artery lesions. Average values for left ventricular mass, total subtended mass and perfusion defect mass were 118, 69 and 7 grams respectively. In 19/33 patients (58%) the total perfusion defect mass could be distributed over the relevant coronary artery lesion(s). Conclusions Quantification of myocardial ischemia and subtended myocardial mass using a Voronoi-based segmentation algorithm seem feasible at adenosine stress CTP and allows for quantitative correlation of coronary artery lesions to corresponding areas of myocardial hypoperfusion. FUNDunding Acknowledgement Type of funding sources: None. Figure 1

Quantification of myocardial ischemia and subtended myocardial mass at adenosine stress cardiac computed tomography: a feasibility study

Combination of coronary computed tomography angiography (CCTA) and adenosine stress CT myocardial perfusion (CTP) allows for coronary artery lesion assessment as well as myocardial ischemia. However, myocardial ischemia on CTP is nowadays assessed semi-quantitatively by visual analysis. The aim of this study was to fully quantify myocardial ischemia and the subtended myocardial mass on CTP. We included 33 patients referred for a combined CCTA and adenosine stress CTP protocol, with good or excellent imaging quality on CTP. The coronary artery tree was automatically extracted from the CCTA and the relevant coronary artery lesions with a significant stenosis (≥ 50%) were manually defined using dedicated software. Secondly, epicardial and endocardial contours along with CT perfusion deficits were semi-automatically defined in short-axis reformatted images using MASS software. A Voronoi-based segmentation algorithm was used to quantify the subtended myocardial mass, distal from each relevant coronary artery lesion. Perfusion defect and subtended myocardial mass were spatially registered to the CTA. Finally, the subtended myocardial mass per lesion, total subtended myocardial mass and perfusion defect mass (per lesion) were measured. Voronoi-based segmentation was successful in all cases. We assessed a total of 64 relevant coronary artery lesions. Average values for left ventricular mass, total subtended mass and perfusion defect mass were 118, 69 and 7 g respectively. In 19/33 patients (58%) the total perfusion defect mass could be distributed over the relevant coronary artery lesion(s). Quantification of myocardial ischemia and subtended myocardial mass seem feasible at adenosine stress CTP and allows to quantitatively correlate coronary artery lesions to corresponding areas of myocardial hypoperfusion at CCTA and adenosine stress CTP.

CT-derived characterization of pericoronary, paracardial and epicardial adipose tissue and its association with myocardial ischemia as assessed by adenosine stress CMR perfusion imaging

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Kaltenbach scholarship of the german heart foundation Background Increased attenuation of pericoronary adipose tissue (PCAT) around the right coronary artery (RCA) is a new imaging biomarker to detect coronary inflammation derived from routine coronary CT angiography (CTA) and has been shown to be associated with cardiac mortality. Increased volume of epicardial adipose tissue (EAT) has been reported be associated with myocardial ischemia. Purpose We aimed to investigate for the first time a potential association between CTA-derived PCAT measures and myocardial ischemia as assessed by adenosine stress CMR perfusion imaging. Methods In this single-centre study 109 stable individuals (mean age of 62 ± 11 years, 77% males) with coronary artery disease underwent CTA followed by adenosine stress CMR perfusion imaging to detect myocardial ischemia. PCAT CT attenuation (HU) and PCAT volume (cm³) was measured around the RCA (10 to 50 mm from RCA ostium), the proximal 40 mm of the left anterior descending artery (LAD) and the circumflex artery (LCX) using semi-automated software. Per patient PCAT CT attenuation was calculated as followed: (PCAT attenuation of RCA + LAD + LCX)/3). Non-contrast CT data sets were used for coronary calcium scoring and the quantification of EAT (located between the myocardial surface and the pericardium) and paracardial adipose tissue (PAT; intrathoracic and outside of the pericardium). Results Between patients with evidence of significant myocardial ischemia as assessed by adenosine stress CMR (n = 35) and patients without myocardial ischemia (n = 74) there was no significant difference in the PCAT CT attenuation of RCA (-85.3 vs. -85.7 HU, p = 0.87), LAD (-84.8 vs. -85.7 HU, p = 0.66) and LCX (-82.8 vs. -83.2 HU, p = 0.79) as well as in the per patient PCAT CT attenuation (-84.2 vs. -84.9 HU, p = 0.76). Neither did patients with myocardial ischemia within the RCA territory show increased RCA PCAT CT attenuation (-87.7 vs. -85.3 HU, p = 0.40); nor was such a relationship found for the territory of the LAD (-80.6 vs. 85.8 HU, p = 0.11) or LCX (-83.1 vs. -83.0 HU, p = 0.99). The CT attenuation of EAT (-77.9 vs. -78.7 HU, p = 0.65) and PAT (-89.9 vs. -90.0 HU, p = 0.93) did not differ significantly between patients with myocardial ischemia compared to patients without myocardial ischemia. Between patients with myocardial ischemia and patients without myocardial ischemia there was no significant difference in the volumes of EAT (118.1 vs. 110.6 cm³, p = 0.55), PAT (279.5 vs. 240.9 cm³, p = 0.20) and the per patient PCAT volume (1021.9 vs. 1015.5 cm³, p = 0.90). In logistic regression analysis the volume and CT attenuation of the different intrathoracic fat compartments PCAT, EAT and PAT were not independently associated with the presence of myocardial ischemia (n.s.). Conclusions In this single-centre study CTA-derived quantified CT attenuation and volume of PCAT, EAT and PAT were not associated with myocardial ischemia as assessed by adenosine stress CMR perfusion imaging.