Myocardial Perfusion Cardiovascular Magnetic Resonance Research Articles

Fully automated pixel-wise quantitative CMR-myocardial perfusion with CMR-coronary angiography to detect hemodynamically significant coronary artery disease.

We applied a fully automated pixel-wise post-processing framework to evaluate fully quantitative cardiovascular magnetic resonance myocardial perfusion imaging (CMR-MPI). In addition, we aimed to evaluate the additive value of coronary magnetic resonance angiography (CMRA) to the diagnostic performance of fully automated pixel-wise quantitative CMR-MPI for detecting hemodynamically significant coronary artery disease (CAD). A total of 109 patients with suspected CAD were prospectively enrolled and underwent stress and rest CMR-MPI, CMRA, invasive coronary angiography (ICA), and fractional flow reserve (FFR). CMRA was acquired between stress and rest CMR-MPI acquisition, without any additional contrast agent. Finally, CMR-MPI quantification was analyzed by a fully automated pixel-wise post-processing framework. Of the 109 patients, 42 patients had hemodynamically significant CAD (FFR ≤ 0.80 or luminal stenosis ≥ 90% on ICA) and 67 patients had hemodynamically non-significant CAD (FFR ˃ 0.80 or luminal stenosis < 30% on ICA) were enrolled. On the per-territory analysis, patients with hemodynamically significant CAD had higher myocardial blood flow (MBF) at rest, lower MBF under stress, and lower myocardial perfusion reserve (MPR) than patients with hemodynamically non-significant CAD (p < 0.001). The area under the receiver operating characteristic curve of MPR (0.93) was significantly larger than those of stress and rest MBF, visual assessment of CMR-MPI, and CMRA (p < 0.05), but similar to that of the integration of CMR-MPI with CMRA (0.90). Fully automated pixel-wise quantitative CMR-MPI can accurately detect hemodynamically significant CAD, but the integration of CMRA obtained between stress and rest CMR-MPI acquisition did not provide significantly additive value. • Full quantification of stress and rest cardiovascular magnetic resonance myocardial perfusion imaging can be postprocessed fully automatically, generating pixel-wise myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) maps. • Fully quantitative MPR provided higher diagnostic performance for detecting hemodynamically significant coronary artery disease, compared with stress and rest MBF, qualitative assessment, and coronary magnetic resonance angiography (CMRA). • The integration of CMRA and MPR did not significantly improve the diagnostic performance of MPR alone.

Malperfusion in dilated cardiomyopathy: One more link in the pathologic chain?

Dilated cardiomyopathy (DCM) is considered the primary non-ischemic heart disease, but there are controversial data regarding the microcirculatory disturbance in these patients. While the major epicardial vessels are always intact in these patients, the malperfusion of the myocardium of the left ventricle (LV) may be present, and the role of this malperfusion in the progression of the disease is not clear. The non-invasive echocardiographic assessment of the coronary blood flow reveals that it may be increased at rest and decreased during pharmacological stress, leading to a decreased coronary flow reserve.1 Beyond echocardiographic studies, microvascular dysfunction in DCM has been previously investigated with various imaging modalities. Bietenbeck M. et al. performed the quantitative myocardial first-pass perfusion cardiovascular magnetic resonance (CMR) imaging and coronary sinus flow measurements at rest and during maximal vasodilatation which is a well-validated approach for the quantification of global myocardial blood flow in CMR. The blood flow parameters were reduced at rest and during stress in both groups of patients with DCM and hypertrophic cardiomyopathy.2 Interestingly, in another study, it was shown that myocardial blood flow assessed by the CMR in DCM could be elevated at rest with a substantial decrease during the stress-test with adenosine. This corresponds well with the previous echocardiographic findings and also can reflect the possible stress-induced stunning instead of chronic hypoperfusion in DCM.3 Another promising in microcirculation evaluation, though not a fully available modality, is PET. In a study by Yamaguchi et al., the authors observed the regional 18-fluorodesoxiglucose uptake in all patients with ischemic cardiomyopathy in the fasting state, while patients with DCM showed variable patterns of uptake. Nevertheless, when going to glucose loading state, the DCM patients demonstrated mostly non-reversing patterns of uptake, which allows PET to distinguish DCM from ischemic cardiomyopathy.4 (99 m)Tc-methoxy-isobutyl-isonitrile and (123)I-15-(p-iodophenyl)-3(R,S)-methylpentadecanoic acid dual single photon emission computed tomography also provides valuable data on perfusion-metabolism mismatches, which carry the prognostic role in DCM.5 Myocardial contrast echocardiography (MCE) being a more simple, bedside method has been previously found to be helpful in differentiating the DCM and ischemic heart disease in patients with acute onset of heart failure.6 However, another group of authors has the confronting results: the contrast replenishment rate was similar in patients with coronary artery disease and without it.7 In this issue of the Journal of Clinical Ultrasound Sha Tang et al, for the first time the MCE was combined with speckle tracking strain analysis in a layer-specific manner in patients with DCM and compared with the same parameters in healthy volunteers.8 While the poor global and regional LV systolic function assessed by speckle tracking strain in DCM patients in comparison to healthy subjects is awaited, the authors performed the comprehensive analysis of the interaction between segmental parameters by dividing the myocardium into standard segments plus three layers in each segment. Therefore, the data on gradients in strain and perfusion parameters becomes the mainstay of this study. The idea of layer-specific strain analysis is not new, but still can be regarded as a pure experimental method with no clinical implication. For example, in the work by Nagata Y et al. the authors offer Endo/Epi strain ratio for gradient assessment.9 Therefore, the authors demonstrated an interesting correlation between MCE perfusion and longitudinal function at rest in DCM patients with the diffuse pattern of impairment in all segments and layers. Considering the aforementioned CMR-based and PET-based studies, which showed a substantial decrease in coronary flow reserve between rest and stress, the MCE with pharmacological stress could be the rational development of basic ideas, presented in this study. Moreover, the dynamic nature of MCE can give the opportunity for dynamic malperfusion assessment in patients with DCM during stress. In addition, new insights into the pathophysiology of DCM may provide the basis for new clinical trials of various agents, intended to restore the damaged microcirculatory link in the chain of global LV deterioration. The authors have nothing to disclosure. Open Access funding enabled and organized by Projekt DEAL. Not applicable.

Abnormal left ventricular subendocardial perfusion and diastolic function in women with obesity and heart failure and preserved ejection fraction

Purpose– Coronary microvascular dysfunction (CMD) is common in patients with heart failure with preserved ejection fraction (HFpEF) and obesity. Stress cardiovascular magnetic resonance (CMR) has been proposed as a non-invasive tool for detection of CMD. The aim of this study was to determine relationship between CMD and diastolic function in patients with HFpEF using a novel CMR technique.Methods– Patients with obesity and HFpEF without epicardial coronary artery disease (CAD) underwent Doppler echocardiography to measure diastolic function, followed by vasodilator stress CMR, using a single bolus, dual sequence, quantitative myocardial perfusion mapping to measure myocardial blood flow (MBF) at rest and at peak hyperemia. With this, myocardial perfusion reserve (MPR), global stress endocardial-to-epicardial (endo:epi) perfusion ratio, and total ischemic burden (IB, defined as myocardial segments with MBF < 1.94 mL/min/g) were calculated. Results are reported as median and interquartile range.Results– Nineteen subjects were enrolled (100% female, 42% Black). Median age was 64 [56–72] years. Global stress MBF was 2.43 ml/min/g [2.16–2.78] and global myocardial perfusion reserve (MPR) was 2.34 [2.07–2.88]. All had an abnormal subendocardial perfusion with an endo:epi of less than 1 (0.87 [0.81–0.90]). Regional myocardial hypoperfusion was detected in 14 (74%) patients with an IB of 6% [0-34.4]. Endo:epi ratio significantly correlated with IB (R=-0.510, p = 0.026) and measures of diastolic function (R = 0.531, p = 0.019 and R=-0.544, p = 0.014 for e’ and E/e’ respectively).Conclusion– Using a novel quantitative stress CMR myocardial perfusion mapping technique, women with obesity and HFpEF were found to have patterns of abnormal subendocardial perfusion which significantly correlated with measures of diastolic dysfunction.

Sex- and age-specific normal values for automated quantitative pixel-wise myocardial perfusion cardiovascular magnetic resonance.

Recently developed in-line automated cardiovascular magnetic resonance (CMR) myocardial perfusion mapping has been shown to be reproducible and comparable with positron emission tomography (PET), and can be easily integrated into clinical workflows. Bringing quantitative myocardial perfusion CMR into routine clinical care requires knowledge of sex- and age-specific normal values in order to define thresholds for disease detection. This study aimed to establish sex- and age-specific normal values for stress and rest CMR myocardial blood flow (MBF) in healthy volunteers. A total of 151 healthy volunteers recruited from two centres underwent adenosine stress and rest myocardial perfusion CMR. In-line automatic reconstruction and post processing of perfusion data were implemented within the Gadgetron software framework, creating pixel-wise perfusion maps. Rest and stress MBF were measured, deriving myocardial perfusion reserve (MPR) and were subdivided by sex and age. Mean MBF in all subjects was 0.62 ± 0.13 mL/g/min at rest and 2.24 ± 0.53 mL/g/min during stress. Mean MPR was 3.74 ± 1.00. Compared with males, females had higher rest (0.69 ± 0.13 vs. 0.58 ± 0.12 mL/g/min, P < 0.01) and stress MBF (2.41 ± 0.47 vs. 2.13 ± 0.54 mL/g/min, P = 0.001). Stress MBF and MPR showed significant negative correlations with increasing age (r = -0.43, P < 0.001 and r = -0.34, P < 0.001, respectively). Fully automated in-line CMR myocardial perfusion mapping produces similar normal values to the published CMR and PET literature. There is a significant increase in rest and stress MBF, but not MPR, in females and a reduction of stress MBF and MPR with advancing age, advocating the use of sex- and age-specific reference ranges for diagnostic use.

How to do quantitative myocardial perfusion cardiovascular magnetic resonance.

How to do quantitative myocardial perfusion cardiovascular magnetic resonance.

2D high resolution vs. 3D whole heart myocardial perfusion cardiovascular magnetic resonance.

AimsDevelopments in myocardial perfusion cardiovascular magnetic resonance (CMR) allow improvements in spatial resolution and/or myocardial coverage. Whole heart coverage may provide the most accurate assessment of myocardial ischaemic burden, while high spatial resolution is expected to improve detection of subendocardial ischaemia. The objective of this study was to compare myocardial ischaemic burden as depicted by 2D high resolution and 3D whole heart stress myocardial perfusion in patients with coronary artery disease.Methods and resultsThirty-eight patients [age 61 ± 8 (21% female)] underwent 2D high resolution (spatial resolution 1.2 mm2) and 3D whole heart (in-plane spatial resolution 2.3 mm2) stress CMR at 3-T in randomized order. Myocardial ischaemic burden (%) was visually quantified as perfusion defect at peak stress perfusion subtracted from subendocardial myocardial scar and expressed as a percentage of the myocardium. Median myocardial ischaemic burden was significantly higher with 2D high resolution compared with 3D whole heart [16.1 (2.0–30.6) vs. 13.4 (5.2–23.2), P = 0.004]. There was excellent agreement between myocardial ischaemic burden (intraclass correlation coefficient 0.81; P < 0.0001), with mean ratio difference between 2D high resolution vs. 3D whole heart 1.28 ± 0.67 (95% limits of agreement −0.03 to 2.59). When using a 10% threshold for a dichotomous result for presence or absence of significant ischaemia, there was moderate agreement between the methods (κ = 0.58, P < 0.0001).Conclusion2D high resolution and 3D whole heart myocardial perfusion stress CMR are comparable for detection of ischaemia. 2D high resolution gives higher values for myocardial ischaemic burden compared with 3D whole heart, suggesting that 2D high resolution is more sensitive for detection of ischaemia.

Use of quantitative cardiovascular magnetic resonance myocardial perfusion mapping for characterization of ischemia in patients with left internal mammary coronary artery bypass grafts

BackgroundQuantitative myocardial perfusion mapping using cardiovascular magnetic resonance (CMR) is validated for myocardial blood flow (MBF) estimation in native vessel coronary artery disease (CAD). Following coronary artery bypass graft (CABG) surgery, perfusion defects are often detected in territories supplied by the left internal mammary artery (LIMA) graft, but their interpretation and subsequent clinical management is variable.MethodsWe assessed myocardial perfusion using quantitative CMR perfusion mapping in 38 patients with prior CABG surgery, all with angiographically-proven patent LIMA grafts to the left anterior descending coronary artery (LAD) and no prior infarction in the LAD territory. Factors potentially determining MBF in the LIMA–LAD myocardial territory, including the impact of delayed contrast arrival through the LIMA graft were evaluated.ResultsPerfusion defects were reported on blinded visual analysis in the LIMA–LAD territory in 27 (71%) cases, despite LIMA graft patency and no LAD infarction. Native LAD chronic total occlusion (CTO) was a strong independent predictor of stress MBF (B = − 0.41, p = 0.014) and myocardial perfusion reserve (MPR) (B = − 0.56, p = 0.005), and was associated with reduced stress MBF in the basal (1.47 vs 2.07 ml/g/min; p = 0.002) but not the apical myocardial segments (1.52 vs 1.87 ml/g/min; p = 0.057). Extending the maximum arterial time delay incorporated in the quantitative perfusion algorithm, resulted only in a small increase (3.4%) of estimated stress MBF.ConclusionsPerfusion defects are frequently detected in LIMA–LAD subtended territories post CABG despite LIMA patency. Although delayed contrast arrival through LIMA grafts causes a small underestimation of MBF, perfusion defects are likely to reflect true reductions in myocardial blood flow, largely due to proximal native LAD disease.

Automated Segmental Analysis of Fully Quantitative Myocardial Blood Flow Maps by First-Pass Perfusion Cardiovascular Magnetic Resonance.

First pass gadolinium-enhanced cardiovascular magnetic resonance (CMR) perfusion imaging allows fully quantitative pixel-wise myocardial blood flow (MBF) assessment, with proven diagnostic value for coronary artery disease. Segmental analysis requires manual segmentation of the myocardium. This work presents a fully automatic method of segmenting the left ventricular myocardium from MBF pixel maps, validated on a retrospective dataset of 247 clinical CMR perfusion studies, each including rest and stress images of three slice locations, performed on a 1.5T scanner. Pixel-wise MBF maps were segmented using an automated pipeline including region growing, edge detection, principal component analysis, and active contours to segment the myocardium, detect key landmarks, and divide the myocardium into sectors appropriate for analysis. Automated segmentation results were compared against a manually defined reference standard using three quantitative metrics: Dice coefficient, Cohen Kappa and myocardial border distance. Sector-wise average MBF and myocardial perfusion reserve (MPR) were compared using Pearson’s correlation coefficient and Bland-Altman Plots. The proposed method segmented stress and rest MBF maps of 243 studies automatically. Automated and manual myocardial segmentation had an average (± standard deviation) Dice coefficient of 0.86 ± 0.06, Cohen Kappa of 0.86 ± 0.06, and Euclidian distances of 1.47 ± 0.73 mm and 1.02 ± 0.51 mm for the epicardial and endocardial border, respectively. Automated and manual sector-wise MBF and MPR values correlated with Pearson’s coefficient of 0.97 and 0.92, respectively, while Bland-Altman analysis showed bias of 0.01 and 0.07 ml/g/min. The validated method has been integrated with our fully automated MBF pixel mapping pipeline to aid quantitative assessment of myocardial perfusion CMR.

One-step anatomic and function testing by cardiac CT versus second-line functional testing in symptomatic patients with coronary artery stenosis: head-to-head comparison of CT-derived fractional flow reserve and myocardial perfusion imaging.

CT-QFR is a novel coronary computed tomography angiography (CTA)-based method for on-site evaluation of patients with suspected obstructive coronary artery disease (CAD). We aimed to compare the diagnostic performance of CT-QFR with myocardial perfusion scintigraphy (MPS) and cardiovascular magnetic resonance (CMR) as second-line tests in patients with suspected obstructive CAD after coronary CTA. A paired analysis of CT-QFR and MPS or CMR, with an invasive FFR-based classification as reference standard was carried out. Symptomatic patients with >50% diameter stenosis on coronary CTA were randomised to MPS or CMR and referred for invasive coronary angiography. The rate of coronary CTA not feasible for CT-QFR analysis was 17%. Paired patient-level data were available for 118 patients in the MPS group and 113 in the CMR group. Patient-level diagnostic accuracy was better for CT-QFR than for both MPS (82.2% [95% CI: 75.2-89.2] vs 70.3% [95% CI: 62.0-78.7], p=0.029) and CMR (77.0% [95% CI: 69.1-84.9] vs 65.5% [95% CI: 56.6-74.4], p=0.047). Following a positive coronary CTA and with the intention to diagnose, CT-QFR, CMR and MPS were equally suitable as rule-in and rule-out modalities. The diagnostic performance of CT-QFR as a second-line test was at least similar to MPS and CMR for the evaluation of obstructive CAD in symptomatic patients presenting with ≥50% diameter stenosis on coronary CTA.

Quantitative cardiovascular magnetic resonance myocardial perfusion mapping to assess hyperaemic response to adenosine stress.

Assessment of hyperaemia during adenosine stress cardiovascular magnetic resonance (CMR) remains a clinical challenge with lack of a gold-standard non-invasive clinical marker to confirm hyperaemic response. This study aimed to validate maximum stress myocardial blood flow (SMBF) measured using quantitative perfusion mapping for assessment of hyperaemic response and compare this to current clinical markers of adenosine stress. Two hundred and eighteen subjects underwent adenosine stress CMR. A derivation cohort (22 volunteers) was used to identify a SMBF threshold value for hyperaemia. This was tested in a validation cohort (37 patients with suspected coronary artery disease) who underwent invasive coronary physiology assessment on the same day as CMR. A clinical cohort (159 patients) was used to compare SMBF to other physiological markers of hyperaemia [splenic switch-off (SSO), heart rate response (HRR), and blood pressure (BP) fall]. A minimum SMBF threshold of 1.43 mL/g/min was derived from volunteer scans. All patients in the coronary physiology cohort demonstrated regional maximum SMBF (SMBFmax) >1.43 mL/g/min and invasive evidence of hyperaemia. Of the clinical cohort, 93% had hyperaemia defined by perfusion mapping compared to 71% using SSO and 81% using HRR. There was no difference in SMBFmax in those with or without SSO (2.58 ± 0.89 vs. 2.54 ± 1.04 mL/g/min, P = 0.84) but those with HRR had significantly higher SMBFmax (2.66 1.86 mL/g/min, P < 0.001). HRR >15 bpm was superior to SSO in predicting adequate increase in SMBF (AUC 0.87 vs. 0.62, P < 0.001). Adenosine-induced increase in myocardial blood flow is accurate for confirmation of hyperaemia during stress CMR studies and is superior to traditional, clinically used markers of adequate stress such as SSO and BP response.

Gadobutrol-Enhanced Cardiac Magnetic Resonance Imaging for Detection of Coronary Artery Disease

BackgroundGadolinium-based contrast agents were not approved in the United States for detecting coronary artery disease (CAD) prior to the current studies. ObjectivesThe purpose of this study was to determine the sensitivity and specificity of gadobutrol for detection of CAD by assessing myocardial perfusion and late gadolinium enhancement (LGE) imaging. MethodsTwo international, single-vendor, phase 3 clinical trials of near identical design, “GadaCAD1” and “GadaCAD2,” were performed. Cardiovascular magnetic resonance (CMR) included gadobutrol-enhanced first-pass vasodilator stress and rest perfusion followed by LGE imaging. CAD was defined by quantitative coronary angiography (QCA) but computed tomography coronary angiography could exclude significant CAD. ResultsBecause the design and results for GadaCAD1 (n = 376) and GadaCAD2 (n = 388) were very similar, results were summarized as a fixed-effect meta-analysis (n = 764). The prevalence of CAD was 27.8% defined by a ≥70% QCA stenosis. For detection of a ≥70% QCA stenosis, the sensitivity of CMR was 78.9%, specificity was 86.8%, and area under the curve was 0.871. The sensitivity and specificity for multivessel CAD was 87.4% and 73.0%. For detection of a 50% QCA stenosis, sensitivity was 64.6% and specificity was 86.6%. The optimal threshold for detecting CAD was a ≥67% QCA stenosis in GadaCAD1 and ≥63% QCA stenosis in GadaCAD2. ConclusionsVasodilator stress and rest myocardial perfusion CMR and LGE imaging had high diagnostic accuracy for CAD in 2 phase 3 clinical trials. These findings supported the U.S. Food and Drug Administration approval of gadobutrol-enhanced CMR (0.1 mmol/kg) to assess myocardial perfusion and LGE in adult patients with known or suspected CAD.

Comparison of quantitative flow ratio and fractional flow reserve with myocardial perfusion scintigraphy and cardiovascular magnetic resonance as reference standard. A Dan-NICAD substudy

Quantitative flow ratio (QFR) and fractional flow reserve (FFR) have not yet been compared head to head with perfusion imaging as reference for myocardial ischemia. We aimed to compare the diagnostic accuracy of QFR and FFR with myocardial perfusion scintigraphy (MPS) or cardiovascular magnetic resonance (CMR) as reference. This study is a predefined post hoc analysis of the Dan-NICAD study (NCT02264717). Patients with suspected coronary artery disease by coronary computed tomography angiography (CCTA) were randomized 1:1 to MPS or CMR and were referred to invasive coronary angiography with FFR and predefined QFR assessment. Paired data with FFR, QFR and MPS or CMR were available for 232 vessels with stenosis in 176 patients. Perfusion defects were detected in 57 vessel territories (25%). For QFR and FFR the diagnostic accuracy was 61% and 57% (p = 0.18) and area under the receiver operating curve was 0.64 vs. 0.58 (p = 0.22). Stenoses with absolute indication for stenting due to diameter stenosis > 90% by visual estimate were not classified as significant by either QFR or MPS/CMR in 21% (7 of 34) of cases. The diagnostic performance of QFR and FFR was similar but modest with MPS or CMR as reference. Comparable performance levels for QFR and FFR are encouraging for this pressure wire-free diagnostic method.

392Systematic review and meta-analysis on the diagnostic accuracy for the detection of relevant coronary artery stenosis of vasodilator myocardial perfusion CMR and dobutamine stress echocardiography

Abstract Background Relevance of coronary artery stenosis in patients with stabile coronary artery disease (SCAD) is defined by myocardial ischemia due to flow limitation. While FFR-guided treatment of SCAD is a class IA recommendation. The initial risk stratification with detection of relevant CAD can be facilitated by several myocardial imaging methods without any preference mentioned in current guidelines. Objectives This study aimed to systematically assess and to compare the diagnostic accuracy of vasodilator myocardial perfusion cardiovascular magnetic resonance imaging (pCMR) and dobutamine stress echocardiography (DSE) for the non-invasive detection of relevant SCAD through a meta-analysis, to enable an evidential preference in risk stratification. In contrast to previously published work, this meta-analysis explicitly included only studies with rigorous eligibility criteria and a narrowly prespecified definition of their invasive reference tests. Selection criteria A study was included if (1) CCA or FFR was used as a reference standard for diagnosing relevant SCAD, defined as &gt;70% stenosis or a value &lt;0.80 on FFR recordings, respectively; (2) sufficient data to permit analysis and to reconstruct contingency tables (explicitly true-positive, false-positive, false-negative and true-negative findings) was provided; (3) there was a minimal sample size of 20 patients; (4) assessment of myocardial perfusion reserve was performed using vasodilators adenosine or regadenoson for pCMR, and dobutamine used for echocardiography; and (5) the studies were of prospective design. Data collection and analysis: From the 5,634 studies identified, 1,306 relevant articles were selected after title screening. Just 47 fulfilled all inclusion criteria on full-text review, resulting in a total sample size of 4,742 patients. Data extraction was performed for each study by two reviewers independently.Pooled analysis was performed based on a random effects models. Results The sensitivity, specificity and diagnostic odds ratio (DOR) for pCMR were 0.88 (95% confidence interval (CI): 0.85–0.90), 0.84 (95% CI: 0.81–0.87), and 38 (95% CI: 29–49), and for DSE 0.72 (95% CI: 0.61–0.81), 0.89 (95% CI: 0.83–0.93), and 20 (95% CI: 9–46), respectively. Post-test probability was augmented by positive (likelihood ratio) LR of 5.5 (95% CI: 4.7–6.5) and negative LR of 0.14 (95% CI: 0.12–0.18) based on Bayes' theorem, as compared to LR of 6.3 (95% CI: 3.8, 10.4) and negative LR of 0.31 (95% CI: 0.21, 0.46) for DSE. The size of the prediction region on the hierarchical summary receiver operating characteristic (HSROC) plot for pCMR (0.29; 95% CI 0.11–0.77) was significantly smaller compared to the one of DSE (1.07; 95% CI 0.27–4.19; p&lt;0.01). Forrest plot pCMR Conclusion The results of this systematic review and meta-analysis show that pCMR is characterized by a superior diagnostic test accuracy of relevant SCAD compared to DSE and that it can refine the post-test probability of SCAD. Acknowledgement/Funding European Heart Academy of the European Society of Cardiology

Automatic myocardial ischemic lesion detection on magnetic resonance perfusion weighted imaging prior perfusion quantification: A pre-modeling strategy

Even if cardiovascular magnetic resonance (CMR) perfusion imaging has proven its relevance for visual detection of ischemia, myocardial blood flow (MBF) quantification at the voxel observation scale remains challenging. Integration of an automated segmentation step, prior to perfusion index estimation, might be a significant reconstruction component that could allow sustainable assumptions and constraint enlargement prior to advanced modeling. Current clustering techniques, such as bullseye representation or manual delineation, are not designed to discriminate voxels belonging to the lesion from healthy areas. Hence, the resulting average time–intensity curve, which is assumed to represent the dynamic contrast enhancement inside of a lesion, might be contaminated by voxels with perfectly healthy microcirculation.This study introduces a hierarchical lesion segmentation approach based on time–intensity curve features that considers the spatial particularities of CMR myocardial perfusion. A first k-means clustering approach enables this method to perform coarse clustering, which is refined by a novel spatiotemporal region-growing (STRG) segmentation, thus ensuring spatial and time–intensity curve homogeneity.Over a cohort of 30 patients, myocardial blood flow (MBF) measured in voxels of lesion regions detected with STRG was significantly lower than in regions drawn manually (mean difference = 0.14, 95% CI [0.07, 0.2]) and defined with the bullseye template (mean difference = 0.25, 95% CI [0.17, 0.36]). Over the 90 analyzed slices, the median Dice score calculated against the ground truth ranged between 0.62 and 0.67, the inclusion coefficients ranged between 0.62 and 0.76 and the centroid distances ranged between 0.97 and 3.88 mm. Therefore, though these metrics highlight spatial differences, they could not be used as an index to evaluate the accuracy and performance of the method, which can only be attested by the variability of the MBF clinical index.

Cardiology update 2ndquarter

This update includes some landmark trials which were published in the last 3 months. Myocardial perfusion cardiovascular magnetic resonance imaging has shown some initial promise in trials, rivaroxaban reduced thromboembolic events in heart failure with coronary artery disease, drug-coated balloons show superiority to bare metal stents in patients with high bleeding risk, and various studies are also published to improve cardiac resynchronization therapy pacemaker response.

Reduced global myocardial perfusion reserve in DCM and HCM patients assessed by CMR-based velocity-encoded coronary sinus flow measurements and first-pass perfusion imaging.

Coronary microvascular dysfunction (CMD) is an independent predictor of poor prognosis in patients suffering from dilative or hypertrophic cardiomyopathy (DCM/HCM). To assess CMD, quantitative myocardial first-pass perfusion (1P) cardiovascular magnetic resonance (CMR) can be performed. Coronary sinus flow (CSF) measurements at rest and during maximal vasodilatation are an alternative and well-validated approach for the quantification of global myocardial blood flow (MBF) in CMR. Global myocardial perfusion reserve (MPR) was used to compare both methods, 1P and CSF. This measure reflects the ratio of myocardial blood flow during maximal coronary vasodilatation over rest. 1P-MPR and CSF-MPR were calculated in 17 HCM patients, 14 DCM patients and 16 controls, who underwent a stress CMR study to rule out obstructive coronary artery disease. All patients were examined on a 1.5-T system and the study protocol comprised both, first-pass myocardial perfusion imaging (MPI) and velocity-encoded (VENC) phase-contrast imaging of CSF during rest and adenosine stress. 1P-MPR was significantly decreased only in HCM patients compared to controls (1.14 vs. 1.43, p = 0.045) whereas CSF-MPR was significantly reduced in both patient groups, HCM and DCM, compared to controls (2.38 and 2.07 vs. 3.18, p = 0.041 and p = 0.032). CSF-MBF at maximal stress was significantly lower in HCM and DCM patients compared to the control group (0.11 and 1.23 vs. 1.58ml/min/g, p = 0.008 and p = 0.040). A moderate but significant correlation between CSF-MPR and 1P-MPR was observed (r = 0.39, p = 0.011). A negative correlation between LV wall thickness and CSF-MBF at rest and stress was found in the DCM group using VENC-based CSF measurements (r=- 0.64, p = 0.013 and r=- 0.69, p = 0.006)-but not using 1P-MPI. Post-proceeding analysis regarding 1P-MPR and CSF-MPR measurements required 20.1 and 6.5min, respectively (p < 0.001). The presence of microvascular disease can be non-invasively and quickly detected by VENC-based CSF-MPR measurements during routine stress perfusion CMR in both HCM and DCM patients. Compared to conventional 1P-MPI, VENC-based CSF-MPR is particularly useful in DCM patients with thinned ventricular walls.

Quantitative Myocardial Perfusion Imaging Versus Visual Analysis in Diagnosing Myocardial Ischemia: A CE-MARC Substudy

ObjectivesThis study sought to compare the diagnostic accuracy of visual and quantitative analyses of myocardial perfusion cardiovascular magnetic resonance against a reference standard of quantitative coronary angiography. BackgroundVisual analysis of perfusion cardiovascular magnetic resonance studies for assessing myocardial perfusion has been shown to have high diagnostic accuracy for coronary artery disease. However, only a few small studies have assessed the diagnostic accuracy of quantitative myocardial perfusion. MethodsThis retrospective study included 128 patients randomly selected from the CE-MARC (Clinical Evaluation of Magnetic Resonance Imaging in Coronary Heart Disease) study population such that the distribution of risk factors and disease status was proportionate to the full population. Visual analysis results of cardiovascular magnetic resonance perfusion images, by consensus of 2 expert readers, were taken from the original study reports. Quantitative myocardial blood flow estimates were obtained using Fermi-constrained deconvolution. The reference standard for myocardial ischemia was a quantitative coronary x-ray angiogram stenosis severity of ≥70% diameter in any coronary artery of >2 mm diameter, or ≥50% in the left main stem. Diagnostic performance was calculated using receiver-operating characteristic curve analysis. ResultsThe area under the curve for visual analysis was 0.88 (95% confidence interval: 0.81 to 0.95) with a sensitivity of 81.0% (95% confidence interval: 69.1% to 92.8%) and specificity of 86.0% (95% confidence interval: 78.7% to 93.4%). For quantitative stress myocardial blood flow the area under the curve was 0.89 (95% confidence interval: 0.83 to 0.96) with a sensitivity of 87.5% (95% confidence interval: 77.3% to 97.7%) and specificity of 84.5% (95% confidence interval: 76.8% to 92.3%). There was no statistically significant difference between the diagnostic performance of quantitative and visual analyses (p = 0.72). Incorporating rest myocardial blood flow values to generate a myocardial perfusion reserve did not significantly increase the quantitative analysis area under the curve (p = 0.79). ConclusionsQuantitative perfusion has a high diagnostic accuracy for detecting coronary artery disease but is not superior to visual analysis. The incorporation of rest perfusion imaging does not improve diagnostic accuracy in quantitative perfusion analysis.

Simultaneous multi slice (SMS) balanced steady state free precession first-pass myocardial perfusion cardiovascular magnetic resonance with iterative reconstruction at 1.5\xa0T

BackgroundSimultaneous-Multi-Slice (SMS) perfusion imaging has the potential to acquire multiple slices, increasing myocardial coverage without sacrificing in-plane spatial resolution. To maximise signal-to-noise ratio (SNR), SMS can be combined with a balanced steady state free precession (bSSFP) readout. Furthermore, application of gradient-controlled local Larmor adjustment (GC-LOLA) can ensure robustness against off-resonance artifacts and SNR loss can be mitigated by applying iterative reconstruction with spatial and temporal regularisation. The objective of this study was to compare cardiovascular magnetic resonance (CMR) myocardial perfusion imaging using SMS bSSFP imaging with GC-LOLA and iterative reconstruction to 3 slice bSSFP.MethodsTwo contrast-enhanced rest perfusion sequences were acquired in random order in 8 patients: 6-slice SMS bSSFP and 3 slice bSSFP. All images were reconstructed with TGRAPPA. SMS images were also reconstructed using a non-linear iterative reconstruction with L1 regularisation in wavelet space (SMS-iter) with 7 different combinations for spatial (λσ) and temporal (λτ) regularisation parameters. Qualitative ratings of overall image quality (0 = poor image quality, 1 = major artifact, 2 = minor artifact, 3 = excellent), perceived SNR (0 = poor SNR, 1 = major noise, 2 = minor noise, 3 = high SNR), frequency of sequence related artifacts and patient related artifacts were undertaken. Quantitative analysis of contrast ratio (CR) and percentage of dark rim artifact (DRA) was performed.ResultsAmong all SMS-iter reconstructions, SMS-iter 6 (λσ 0.001 λτ 0.005) was identified as the optimal reconstruction with the highest overall image quality, least sequence related artifact and higher perceived SNR. SMS-iter 6 had superior overall image quality (2.50 ± 0.53 vs 1.50 ± 0.53, p = 0.005) and perceived SNR (2.25 ± 0.46 vs 0.75 ± 0.46, p = 0.010) compared to 3 slice bSSFP. There were no significant differences in sequence related artifact, CR (3.62 ± 0.39 vs 3.66 ± 0.65, p = 0.88) or percentage of DRA (5.25 ± 6.56 vs 4.25 ± 4.30, p = 0.64) with SMS-iter 6 compared to 3 slice bSSFP.ConclusionsSMS bSSFP with GC-LOLA and iterative reconstruction improved image quality compared to a 3 slice bSSFP with doubled spatial coverage and preserved in-plane spatial resolution. Future evaluation in patients with coronary artery disease is warranted.

Fully automated, inline quantification of myocardial blood flow with cardiovascular magnetic resonance: repeatability of measurements in healthy subjects

BackgroundNon-invasive assessment of myocardial ischaemia is a cornerstone of the diagnosis of coronary artery disease. Measurement of myocardial blood flow (MBF) using positron emission tomography (PET) is the current reference standard for non-invasive quantification of myocardial ischaemia. Dynamic myocardial perfusion cardiovascular magnetic resonance (CMR) offers an alternative to PET and a recently developed method with automated inline perfusion mapping has shown good correlation of MBF values between CMR and PET. This study assessed the repeatability of myocardial perfusion mapping by CMR in healthy subjects.MethodsForty-two healthy subjects were recruited and underwent adenosine stress and rest perfusion CMR on two visits. Scans were repeated with a minimum interval of 7 days. Intrastudy rest and stress MBF repeatability were assessed with a 15-min interval between acquisitions. Interstudy rest and stress MBF and myocardial perfusion reserve (MPR) were measured for global myocardium and regionally for coronary territories and slices.ResultsThere was no significant difference in intrastudy repeated global rest MBF (0.65 ± 0.13 ml/g/min vs 0.62 ± 0.12 ml/g/min, p = 0.24, repeatability coefficient (RC) =24%) or stress (2.89 ± 0.56 ml/g/min vs 2.83 ± 0.64 ml/g/min, p = 0.41, RC = 29%) MBF. No significant difference was seen in interstudy repeatability for global rest MBF (0.64 ± 0.13 ml/g/min vs 0.64 ± 0.15 ml/g/min, p = 0.80, RC = 32%), stress MBF (2.71 ± 0.61 ml/g/min vs 2.55 ± 0.57 ml/g/min, p = 0.12, RC = 33%) or MPR (4.24 ± 0.69 vs 3.73 ± 0.76, p = 0.25, RC = 36%). Regional repeatability was good for stress (RC = 30–37%) and rest MBF (RC = 32–36%) but poorer for MPR (RC = 35–43%). Within subject coefficient of variation was 8% for rest and 11% for stress within the same study, and 11% for rest and 12% for stress between studies.ConclusionsFully automated, inline, myocardial perfusion mapping by CMR shows good repeatability that is similar to the published PET literature. Both rest and stress MBF show better repeatability than MPR, particularly in regional analysis.

Diagnostic performance of static single-scan stress perfusion cardiac computed tomography in detecting hemodynamically significant coronary artery stenosis: a comparison with combined invasive coronary angiography and cardiovascular magnetic resonance-myocardial perfusion imaging.

Background Non-invasive anatomical and physiological evaluations of coronary artery disease (CAD) may be obtained with static single-scan stress perfusion cardiac computed tomography (SSPCT). Purpose To determine the diagnostic performance of static SSPCT for identifying hemodynamically significant CAD. Material and Methods This prospective study included 29 patients with suspected or known CAD who underwent static SSPCT, cardiovascular magnetic resonance myocardial perfusion imaging (CMR-MPI), and invasive coronary angiography (ICA). CT was performed as follows: (i) coronary calcium scan; (ii) static SSPCT for both coronary artery (coronary CT angiography [CCTA]) and myocardial perfusion (perfusion CT [PCT]) during adenosine infusion; (iii) late-phase scan. The diagnostic performance of CCTA alone, PCT alone, and SSPCT for the detection of a hemodynamically significant CAD (a perfusion defect in a vascular territory subtended by a coronary vessel with ≥ 50% stenosis) was compared with that of combined ICA/CMR-MPI representing the standard of reference. Results Twenty-three (79%) patients and 47 (54%) vascular territories manifested ischemia-causing coronary stenoses by combined ICA/CMR-MPI. The per-vessel sensitivity, specificity, positive and negative predictive values, and area under the receiver operating characteristic curve (AUC) of the SSPCT were 92%, 88%, 90%, 90%, and 0.90, respectively, compared to those of the combined ICA/CMR-MPI. These values for the CCTA alone were 96%, 63%, 75%, 93%, and 0.79, respectively; and the values for the PCT alone were 94%, 83%, 86%, 92%, and 0.88, respectively. The AUC of SSPCT was significantly ( P = 0.013) higher than that of the CCTA alone. Conclusion Static SSPCT may facilitate detection of hemodynamically significant CAD.