Quantitative Cardiac Magnetic Resonance Research Articles

Advances in multimodality imaging and the application of new cardiac imaging technologies for radiation‐induced heart disease

AbstractRadiation‐induced heart disease (RIHD) is a heterogeneous, delayed, and potentially fatal adverse reaction to radiation that can damage all structures of the heart, including the pericardium, myocardium, coronary arteries, valves, and conduction system, leading to a series of diseases. Acute and chronic disease processes play a role in the development of RIHD, the onset times of which range from months to decades. However, the clinical manifestations of RIHD are usually insidious, overlap with several other diseases, and lack specificity. Cardiovascular imaging is essential for early diagnosis, follow‐up, and outcome assessment in patients with RIHD. This review first describes the pathogenesis and clinical manifestations of RIHD before providing an overview of the practical approaches and research advances in multimodal cardiovascular imaging in patients with RIHD, including echocardiography, cardiac magnetic resonance (CMR) and nuclear medicine, and cardiac computed tomography (CT). Then, the value of new cardiac imaging assessments for the early diagnosis of RIHD is described, particularly with relation to speckle‐tracking echocardiography, extracellular volume fraction assessment as a quantitative CMR technique, CMR myocardial strain assessment, positron emission tomography‐CT myocardial perfusion imaging, CT‐ECV, and CT strain assessment, amongst others. In addition, the advantages and disadvantages of each screening technique are compared with the aim of better guiding the follow‐up and diagnosis of subclinical RIHD and preventing cardiovascular events.

Abstract 17534: Safety and Feasibility of Adenosine Stress CMR for CAV Detection in Orthotopic Heart Transplant Recipients

Background: Stress perfusion cardiac magnetic resonance (CMR) imaging is recommended in international guidelines in class I in patients with known or suspected CAD. Patients undergoing cardiac transplantation (OHT) are at risk of developing cardiac allograft vasculopathy (CAV). Adenosine is relatively contraindicated after transplantation because of a presumed risk of atrioventricular block in denervated hearts. We sought to evaluate the safety and feasibility of adenosine stress CMR in patients with OHT and suspected CAV. Methods: In an outpatient cohort study, we measured the incidence of adverse effects of adenosine stress CMR in consecutive OHT recipients undergoing quantitative stress perfusion CMR for suspected CAV. We additionally stratified patients based on presence of significant CAV (grades 2-3 versus 0-1) on either invasive or computed tomography coronary angiography to evaluate potential CMR biomarkers of significant coronary disease in this population. Results: We identified 50 adenosine stress CMR studies performed in 45 individual patients at a median of 19 years after transplantation (IQR 4.7-24.4); 9% of studies were conducted within the first year post-transplantation. No life-threatening adverse events, brief or prolonged atrioventricular block or other arrythmias occurred after adenosine infusion. Significant myocardial ischemia (≥ 1.5 segments) was reported in 17% of patients. When stratified by CAV severity, stress MBF index, but not inducible ischemia on visual inspection, was found to significantly differentiate patients with severe CAV from those without significant coronary disease (ANOVA p = 0.028). Conclusion: Adenosine stress perfusion CMR is safe and feasible in OHT recipients. Quantitative measurement of stress MBF index may represent a promising marker of coronary disease with incremental value over qualitative assessment of ischemia, and should be evaluated in future studies.

Evaluation of Ischemia with No Obstructive Coronary Arteries (INOCA) and Contemporary Applications of Cardiac Magnetic Resonance (CMR).

Ischemia with no obstructive coronary arteries (INOCA) is a relatively newly discovered ischemic phenotype that affects patients similarly to obstructive coronary artery disease (CAD) but has a unique pathophysiology and epidemiology. Patients with INOCA present with ischemic signs and symptoms but no obstructive CAD seen on coronary CTA or invasive coronary angiography, which can assess epicardial vessels. The mechanisms of INOCA can be grouped into three endotypes: coronary microvascular dysfunction, epicardial coronary vasospasm, or a combination of both. Accurate and comprehensive assessment of both epicardial and microvascular disease in suspected cases of INOCA is crucial for providing targeted therapy and improving outcomes in this underrepresented population. This review aims to clarify the complex pathophysiology of INOCA, present an overview of invasive and non-invasive diagnostic methods, and examine contemporary approaches for coronary perfusion assessment using cardiac magnetic resonance (CMR). We also explore how recent advancements in quantitative CMR can potentially revolutionize the evaluation of suspected INOCA by offering a rapid, accurate, and non-invasive diagnostic approach, thereby reducing the alarming number of cases that go undetected.

Prognostic Value of Qualitative and Quantitative Stress CMR in Patients With Known or Suspected CAD

BackgroundRecent studies suggest that quantitative cardiac magnetic resonance (CMR) may have more accuracy than qualitative CMR in coronary artery disease (CAD) diagnosis. However, the prognostic value of quantitative and qualitative CMR has not been compared systematically. ObjectivesThe objective was to conduct a systematic review and meta-analysis assessing the utility of qualitative and quantitative stress CMR in the prognosis of patients with known or suspected CAD. MethodsA comprehensive search was performed through Embase, Scopus, Web of Science, and Medline. Studies that used qualitative vasodilator CMR or quantitative CMR assessments to compare the prognosis of patients with positive and negative CMR results were extracted. A meta-analysis was then performed to assess: 1) major adverse cardiovascular events (MACE) including cardiac death, nonfatal myocardial infarction (MI), unstable angina, and coronary revascularization; and 2) cardiac hard events defined as the composite of cardiac death and nonfatal MI. ResultsForty-one studies with 38,030 patients were included in this systematic review. MACE occurred significantly more in patients with positive qualitative (HR: 3.86; 95% CI: 3.28-4.54) and quantitative (HR: 4.60; 95% CI: 1.60-13.21) CMR assessments. There was no significant difference between qualitative and quantitative CMR assessments in predicting MACE (P = 0.75). In studies with qualitative CMR assessment, cardiac hard events (OR: 7.21; 95% CI: 4.99-10.41), cardiac death (OR: 5.63; 95% CI: 2.46-12.92), nonfatal MI (OR: 7.46; 95% CI: 3.49-15.96), coronary revascularization (OR: 6.34; 95% CI: 3.42-1.75), and all-cause mortality (HR: 1.66; 95% CI: 1.12-2.47) were higher in patients with positive CMR. ConclusionsThe presence of myocardial ischemia on CMR is associated with worse clinical outcomes in patients with known or suspected CAD. Both qualitative and quantitative stress CMR assessments are helpful tools for predicting clinical outcomes.

Prognostic Power of Quantitative Assessment of Functional Mitral Regurgitation and Myocardial Scar Quantification by Cardiac Magnetic Resonance.

The severity classification of functional mitral regurgitation (FMR) remains controversial despite adverse prognosis and rapidly evolving interventions. Furthermore, it is unclear if quantitative assessment with cardiac magnetic resonance can provide incremental risk stratification for patients with ischemic cardiomyopathy (ICM) or non-ICM (NICM) in terms of FMR and late gadolinium enhancement (LGE). We evaluated the impact of quantitative cardiac magnetic resonance parameters on event-free survival separately for ICM and NICM, to assess prognostic FMR thresholds and interactions with LGE quantification. Patients (n=1414) undergoing cardiac magnetic resonance for cardiomyopathy (ejection fraction<50%) assessment from April 1, 2001 to December 31, 2017 were evaluated. The primary end point was all-cause death, heart transplant, or left ventricular assist device implantation during follow-up. Multivariable Cox analyses were conducted to determine the impact of FMR, LGE, and their interactions with event-free survival. There were 510 primary end points, 395/782 (50.5%) in ICM and 114/632 (18.0%) in NICM. Mitral regurgitation-fraction per 5% increase was independently associated with the primary end point, hazards ratios (95% CIs) of 1.04 (1.01-1.07; P=0.034) in ICM and 1.09 (1.02-1.16; P=0.011) in NICM. Optimal mitral regurgitation-fraction threshold for moderate and severe FMR were ≥20% and ≥35%, respectively, in both ICM and NICM, based on the prediction of the primary outcome. Similarly, optimal LGE thresholds were ≥5% in ICM and ≥2% in NICM. Mitral regurgitation-fraction×LGE emerged as a significant interaction for the primary end point in ICM (P=0.006), but not in NICM (P=0.971). Mitral regurgitation-fraction and LGE are key quantitative cardiac magnetic resonance biomarkers with differential associations with adverse outcomes in ICM and NICM. Optimal prognostic thresholds may provide important clinical risk prognostication and may further facilitate the ability to derive selection criteria to guide therapeutic decision-making.

Comparison of the diagnostic accuracy of dynamic CT perfusion and cardiac CMR with quantitative perfusion: a subanalysis of ADVANTAGE II study

Abstract Funding Acknowledgements Type of funding sources: None. Background The ADVANTAGE II study has evaluated the performance of dynamic myocardial perfusion assessed by CT (CTP) in stented patient using ICA and in particular invasive coronary physiology (FFR and IMR) as gold-standard. Recently, quantitative myocardial blood flow (MBF) analysis using stress cardiac magnetic resonance (CMR) has been showed to detect obstructive coronary artery disease (CAD) and coronary microvascular dysfunction (CMD). In a substudy of ADVANTAGE II we aimed to evaluate the performance of quantitative stress CMR in comparison to CTP. Methods We present data from 39 subjects with clinically indicated ICA who underwent both vasodilator stress CMR using 1.5T MR scanner (General Electric) and dynamic stress myocardial CTP using a last generation scanner characterized by a 16-cm Z-axis coverage. In CMR Quantitative myocardial perfusion imaging was performed using the dual sequence technique (i.e. low-resolution slice for arterial input function and 2–3 short axis slices for myocardial perfusion). Resting MBF (rMBF), Stress MBF (sMBF), and myocardial perfusion reserve (MPR) were measured using Fermi deconvolution (Circle Cvi42). Quantitative perfusion results were displayed on color-encoded pixel-wise maps and on a 16-segment plot with segmental values listed. Results When FFR was used as gold standard the diagnostic accuracy of CTP was higher than those of CCTA (84.7% vs. 61.5%, p&amp;lt;0.001). When IMR was used as gold standard, diagnostic accuracy of CTP was higher than CCTA (82.9% vs. 59.3%, p&amp;lt;0.01, respectively). When the presence of at least one abnormal physiological parameter among FFR and IMR was used as gold standard, the diagnostic accuracy of CTP was higher than that of CCTA (90.8%vs 68%). Quantitative stress CMR using 2.2 ml/min/g as cut-off has a sensitivity of 83.3%, 77.7% and 100% vs QCA, FFR and IMR, respectively with higher performance of dynamic CTP in comparison to quantitative stress CMR. Conclusions In this substudy of ADVANTAGE II, we showed that global sMBF in MRI can accurately identify patients with CAD. Dynamic CTP seems to offer higher value of diagnostic performance in comparison to quantitative CMR that seems to be very promising, but more data are needed.

Quantitative cardiac MRI parameters for assessment of myocarditis in children and adolescents: a systematic review and meta-analysis

To evaluate the role of quantitative cardiac magnetic resonance imaging (CMRI) parameters in myocarditis, including acute and chronic myocarditis (AM and CM), for children and adolescents. PRISMA principles were followed. PubMed, EMBASE, Web of Science, Cochrane Library, and grey literature were searched. The Newcastle-Ottawa Scale (NOS) and the Agency for Healthcare Research and Quality (AHRQ) checklist were utilised for quality assessment. Quantitative CMRI parameters were extracted and a meta-analysis was performed in comparison with healthy controls. The overall effect size was measured as the weighted mean difference (WMD). Ten quantitative CMRI parameters of seven studies were analysed. Compared with the control group, the myocarditis group reported longer native T1 relaxation time (WMD=54.00, 95% confidence interval [CI]: 33.21,74.79, p<0.001), longer T2 relaxation time (WMD=2.13, 95% CI: 0.98, 3.28, p<0.001), increased extracellular volume (ECV; WMD=3.13, 95% CI: 1.34,4.91, p=0.001), elevated early gadolinium enhancement (EGE) ratio (WMD=1.47, 95% CI: 0.65,2.28, p<0.001), and increased T2-weighted ratio (WMD=0.43, 95% CI: 0.21,0.64, p<0.001). The AM group had longer native T1 relaxation times (WMD=72.02, 95% CI: 32.78,111.27, p<0.001), increased T2-weighted ratios (WMD=0.52, 95% CI: 0.21,0.84 p=0.001), and impaired left ventricular ejection fractions (LVEF; WMD=-5.84, 95% CI: -9.69, -1.99, p=0.003). Impaired LVEF (WMD=-2.24, 95% CI: -3.32, -1.17, p<0.001) was observed in the CM group. Statistical differences can be observed in some CMRI parameters between patients with myocarditis and healthy controls; however, apart from native T1 mapping, there were no large differences in other parameters between two groups, which may reveal the limited benefit of CMRI in assessing myocarditis in children and adolescents.

Cardioprotective effects of shock wave therapy: A cardiac magnetic resonance imaging study on acute ischemia-reperfusion injury.

Cardioprotection strategies remain a new frontier in treating acute myocardial infarction (AMI), aiming at further protect the myocardium from the ischemia-reperfusion damage. Therefore, we aimed at investigating the mechano-transduction effects induced by shock waves (SW) therapy at time of the ischemia reperfusion as a non-invasive cardioprotective innovative approach to trigger healing molecular mechanisms. We evaluated the SW therapy effects in an open-chest pig ischemia-reperfusion (IR) model, with quantitative cardiac Magnetic Resonance (MR) imaging performed along the experiments at multiple time points (baseline (B), during ischemia (I), at early reperfusion (ER) (∼15 min), and late reperfusion (LR) (3 h)). AMI was obtained by a left anterior artery temporary occlusion (50 min) in 18 pigs (32 ± 1.9 kg) randomized into SW therapy and control groups. In the SW therapy group, treatment was started at the end of the ischemia period and extended during early reperfusion (600 + 1,200 shots @0.09 J/mm2, f = 5 Hz). The MR protocol included at all time points LV global function assessment, regional strain quantification, native T1 and T2 parametric mapping. Then, after contrast injection (gadolinium), we obtained late gadolinium imaging and extra-cellular volume (ECV) mapping. Before animal sacrifice, Evans blue dye was administrated after re-occlusion for area-at-risk sizing. During ischemia, LVEF decreased in both groups (25 ± 4.8% in controls (p = 0.031), 31.6 ± 3.2% in SW (p = 0.02). After reperfusion, left ventricular ejection fraction (LVEF) remained significantly decreased in controls (39.9 ± 4% at LR vs. 60 ± 5% at baseline (p = 0.02). In the SW group, LVEF increased quickly ER (43.7 ± 11.4% vs. 52.4 ± 8.2%), and further improved at LR (49.4 ± 10.1) (ER vs. LR p = 0.05), close to baseline reference (LR vs. B p = 0.92). Furthermore, there was no significant difference in myocardial relaxation time (i.e. edema) after reperfusion in the intervention group compared to the control group: ΔT1 (MI vs. remote) was increased by 23.2±% for SW vs. +25.2% for the controls, while ΔT2 (MI vs. remote) increased by +24.9% for SW vs. +21.7% for the control group. In conclusion, we showed in an ischemia-reperfusion open-chest swine model that SW therapy, when applied near the relief of 50' LAD occlusion, led to a nearly immediate cardioprotective effect translating to a reduction in the acute ischemia-reperfusion lesion size and to a significant LV function improvement. These new and promising results related to the multi-targeted effects of SW therapy in IR injury need to be confirmed by further in-vivo studies in close chest models with longitudinal follow-up.

Translating principles of quality control to cardiovascular magnetic resonance: assessing quantitative parameters of the left ventricle in a large cohort

Cardiac magnetic resonance (CMR) examinations require standardization to achieve reproducible results. Therefore, quality control as known as in other industries such as in-vitro diagnostics, could be of essential value. One such method is the statistical detection of long-time drifts of clinically relevant measurements. Starting in 2010, reports from all CMR examinations of a high-volume center were stored in a hospital information system. Quantitative parameters of the left ventricle were analyzed over time with moving averages of different window sizes. Influencing factors on the acquisition and on the downstream analysis were captured. 26,902 patient examinations were exported from the clinical information system. The moving median was compared to predefined tolerance ranges, which revealed an overall of 50 potential quality relevant changes (“alerts”) in SV, EDV and LVM. Potential causes such as change of staff, scanner relocation and software changes were found not to be causal of the alerts. No other influencing factors were identified retrospectively. Statistical quality assurance systems based on moving average control charts may provide an important step towards reliability of quantitative CMR. A prospective evaluation is needed for the effective root cause analysis of quality relevant alerts.

Cardiovascular Magnetic Resonance Parametric Mapping Techniques for the Assessment of Chronic Coronary Syndromes.

The term chronic coronary syndromes encompasses a variety of clinical presentations of coronary artery disease (CAD), ranging from stable angina due to epicardial coronary artery disease to microvascular coronary dysfunction. Cardiac magnetic resonance (CMR) imaging has an established role in the diagnosis, prognostication and treatment planning of patients with CAD. Recent advances in parametric mapping CMR techniques have added value in the assessment of patients with chronic coronary syndromes, even without the need for gadolinium contrast administration. Furthermore, quantitative perfusion CMR techniques have enabled the non-invasive assessment of myocardial blood flow and myocardial perfusion reserve and can reliably identify multivessel coronary artery disease and microvascular dysfunction. This review summarizes the clinical applications and the prognostic value of the novel CMR parametric mapping techniques in the setting of chronic coronary syndromes and discusses their strengths, pitfalls and future directions.

Image resampling and discretization effect on the estimate of myocardial radiomic features from T1 and T2 mapping in hypertrophic cardiomyopathy

Radiomics is emerging as a promising and useful tool in cardiac magnetic resonance (CMR) imaging applications. Accordingly, the purpose of this study was to investigate, for the first time, the effect of image resampling/discretization and filtering on radiomic features estimation from quantitative CMR T1 and T2 mapping. Specifically, T1 and T2 maps of 26 patients with hypertrophic cardiomyopathy (HCM) were used to estimate 98 radiomic features for 7 different resampling voxel sizes (at fixed bin width), 9 different bin widths (at fixed resampling voxel size), and 7 different spatial filters (at fixed resampling voxel size/bin width). While we found a remarkable dependence of myocardial radiomic features from T1 and T2 mapping on image filters, many radiomic features showed a limited sensitivity to resampling voxel size/bin width, in terms of intraclass correlation coefficient (> 0.75) and coefficient of variation (< 30%). The estimate of most textural radiomic features showed a linear significant (p < 0.05) correlation with resampling voxel size/bin width. Overall, radiomic features from T2 maps have proven to be less sensitive to image preprocessing than those from T1 maps, especially when varying bin width. Our results might corroborate the potential of radiomics from T1/T2 mapping in HCM and hopefully in other myocardial diseases.

Assessment of Asymptomatic Severe Aortic Regurgitation by Doppler-Derived Echo Indices: Comparison with Magnetic Resonance Quantification.

Reliable quantification of aortic regurgitation (AR) severity is essential for clinical management. We aimed to compare quantitative and indirect echo-Doppler indices to quantitative cardiac magnetic resonance (CMR) parameters in asymptomatic chronic severe AR. Methods and Results: We evaluated 104 consecutive patients using echocardiography and CMR. A comprehensive 2D, 3D, and Doppler echocardiography was performed. The CMR was used to quantify regurgitation fraction (RF) and volume (RV) using the phase-contrast velocity mapping technique. Concordant grading of AR severity with both techniques was observed in 77 (74%) patients. Correlation between RV and RF as assessed by echocardiography and CMR was relatively good (rs = 0.50 for RV, rs = 0.40 for RF, p < 0.0001). The best correlation between indirect echo-Doppler and CMR parameters was found for diastolic flow reversal (DFR) velocity in descending aorta (rs = 0.62 for RV, rs = 0.50 for RF, p < 0.0001) and 3D vena contracta area (VCA) (rs = 0.48 for RV, rs = 0.38 for RF, p < 0.0001). Using receiver operating characteristic analysis, the largest area under curve (AUC) to predict severe AR by CMR RV was observed for DFR velocity (AUC = 0.79). DFR velocity of 19.5 cm/s provided 78% sensitivity and 80% specificity. The AUC for 3D VCA to predict severe AR by CMR RV was 0.73, with optimal cut-off of 26 mm2 (sensitivity 80% and specificity 66%). Conclusions: Out of the indirect echo-Doppler indices of AR severity, DFR velocity in descending aorta and 3D vena contracta area showed the best correlation with CMR-derived RV and RF in patients with chronic severe AR.

Stress myocardial blood flow reduced after severe COVID-19, not related to symptoms

Abstract Introduction Persistent cardiopulmonary symptoms after COVID-19 are reported in a large number of patients and the underlying pathology is still poorly understood. (1) Histopathologic studies revealed myocardial macrophage infiltrates in deceased patients, likely an unspecific finding of severe illness, and increased prevalence of micro- and macrovascular thrombi. (2) We examined whether microvascular perfusion, measured by quantitative cardiac magnetic resonance under vasodilator stress, was altered post COVID-19. Methods Our population consisted of 12 patients from the Pa-COVID-19-Study of the Charité Berlin, which received a cardiac MRI as part of a systematic follow up post discharge, 10 patients that presented at the German Heart Center Berlin with persistent cardiac symptoms post COVID-19 and 12 patients from the Kings College London referred for stress MRI and previous COVID-19. The scan protocol included standard functional, edema and scar imaging and quantitative stress and rest perfusion to assess both macro- and microvascular coronary artery disease. The pharmacological stress agent was regadenosone in 20 and adenosine in 13 of the patients. To control for the higher heart rate increase under regadenosone compared to adenosine, we calculated the myocardial blood flow per heartbeat (MBF_HRi) under stress. Results The median time between first positive PCR for COVID-19 and the CMR exam was 2 months (Range 0 to 12). None of the 33 patients exhibited signs of myocardial edema. One patient with a previous history of myocarditis had focal fibrosis. Three patients with known coronary artery disease showed ischemic Late Enhancement. Five patients had a small pericardial effusion; one of these four patients showed slight focal pericardial edema and LGE, consistent with mild focal pericarditis. Five Patients had a stress-induced focal perfusion deficit. Mean Stress MBF_HRi was 32.5±6.5 μl/beat/g. Stress MBF_HRi was negatively correlated with COVID-19 severity (rho=−0.361, P=0.039) and age (r=−0.452, P=0.009). The correlation with COVID-19 severity remained significant after controlling for age (rho=−0.390, P=0.027). There was no apparent difference in stress MBF_HRi between patients with and without persistent chest pain (34.5 vs. 31.5 μl/beat/g, P=0.229) Conclusion While vasodilator-stress myocardial blood flow after COVID-19 was negatively correlated to COVID-19 severity, it was not correlated to the presence of chest pain. The etiology of persistent cardiac symptoms after COVID-19 remains unclear. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Philips Figure 1. A) Quantitative regadenosone stress myocardial blood flow (MBF) map, medial short axis slice, in a patient with persistent cardiac symptoms after COVID-19. B) Boxplot of stress MBF per heart beat by COVID-19 severity, showing decreasing MBF with increasing COVID-19 severity.

Viability and functional recovery after chronic total occlusion percutaneous coronary intervention.

ObjectivesThis study evaluated myocardial viability as well as global and regional functional recovery after successful chronic coronary total occlusion (CTO) percutaneous coronary intervention (PCI) using sequential quantitative cardiac magnetic resonance (CMR) imaging.BackgroundThe patient benefits of CTO PCI are being questioned.MethodsIn a single high‐volume CTO PCI center patients were prospectively scheduled for CMR at baseline and 3 months after successful CTO PCI between 2013 and 2018. Segmental wall thickening (SWT) and percentage late gadolinium enhancement (LGE) were quantitatively measured per segment. Viability was defined as dysfunctional myocardium (<2.84 mm SWT) with no or limited scar (≤50% LGE).ResultsA total of 132 patients were included. Improvement of left ventricular ejection fraction was modest after CTO PCI (from 48.1 ± 11.8 to 49.5 ± 12.1%, p < 0.01). CTO segments with viability (N = 216, [31%]) demonstrated a significantly higher increase in SWT (0.80 ± 1.39 mm) compared to CTO segments with pre‐procedural preserved function (N = 456 [65%], 0.07 ± 1.43 mm, p < 0.01) or extensive scar (LGE >50%, N = 26 [4%], −0.08 ± 1.09 mm, p < 0.01). Patients with ≥2 CTO segments viability showed more SWT increase in the CTO territory compared to patients with 0–1 segment viability (0.49 ± 0.93 vs. 0.12 ± 0.98 mm, p = 0.03).ConclusionsDetection of dysfunctional myocardial segments without extensive scar (≤50% LGE) as a marker for viability on CMR aids in identifying patients with significant regional functional recovery after CTO PCI.

3D cardiac magnetic resonance stress-perfusion in elderly patients

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Swiss National Science Foundation Introduction Age related comorbidities and reduced compliance often limit ischaemia testing in elderly patients. Purpose To assessed the accuracy of 3D cardiac magnetic resonance (CMR) stress perfusion in the elderly population. Methods 56 patients aged ≥75 years underwent 3D CMR stress-perfusion and invasive coronary angiography with quantitative coronary angiography (QCA) and fractional flow reserve (FFR) as part of a multicenter study. The accuracy of 3D CMR stress-perfusion was compared to patients aged &amp;lt;75 years old (n = 360) using qualitative and quantitative imaging parameters. Results Sensitivity, specificity, positive and negative predictive values of qualitative 3D perfusion CMR were similar for both age groups in the detection of high-grade (≥50%) coronary stenosis on QCA and hemodynamically relevant (&amp;lt;0.8) stenosis on FFR, p &amp;gt; 0.05 all. Quantitative myocardial ischemia burden was larger in elderly patients (15% ± 17% vs. 9% ± 13%) with similarly high diagnostic accuracy of quantitative 3D CMR perfusion in both age groups to predict pathological FFR (AUC ≥75: 0.906; AUC &amp;lt;75: 0.866). Conclusions 3D CMR perfusion is well suited for myocardial ischaemia testing in the elderly patients with similarly high diagnostic accuracy as in younger individuals.

Advances in Myocardial Perfusion MR Imaging: Physiological Implications, the Importance of Quantitative Analysis, and Impact on Patient Care in Coronary Artery Disease.

Stress myocardial perfusion imaging (MPI) is the preferred test in patients with intermediate-to-high clinical likelihood of coronary artery disease (CAD) and can be used as a gatekeeper to avoid unnecessary revascularization. Cardiac magnetic resonance (CMR) has a number of favorable characteristics, including: (1) high spatial resolution that can delineate subendocardial ischemia; (2) comprehensive assessment of morphology, global and regional cardiac functions, tissue characterization, and coronary artery stenosis; and (3) no radiation exposure to patients. According to meta-analysis studies, the diagnostic accuracy of perfusion CMR is comparable to positron emission tomography (PET) and perfusion CT, and is better than single-photon emission CT (SPECT) when fractional flow reserve (FFR) is used as a reference standard. In addition, stress CMR has an excellent prognostic value. One meta-analysis study demonstrated the annual event rate of cardiovascular death or non-fatal myocardial infarction was 4.9% and 0.8%, respectively, in patients with positive and negative stress CMR. Quantitative assessment of perfusion CMR not only allows the objective evaluation of regional ischemia but also provides insights into the pathophysiology of microvascular disease and diffuse subclinical atherosclerosis. For accurate quantification of myocardial perfusion, saturation correction of arterial input function is important. There are two major approaches for saturation correction, one is a dual-bolus method and the other is a dual-sequence method. Absolute quantitative mapping with myocardial perfusion CMR has good accuracy in detecting coronary microvascular dysfunction. Flow measurement in the coronary sinus (CS) with phase contrast cine CMR is an alternative approach to quantify global coronary flow reserve (CFR). The measurement of global CFR by quantitative analysis of perfusion CMR or flow measurement in the CS permits assessment of microvascular disease and diffuse subclinical atherosclerosis, which may provide improved prediction of future event risk in patients with suspected or known CAD. Multi-institutional studies to validate the diagnostic and prognostic values of quantitative perfusion CMR approaches are required.

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

Abstract 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 &amp;lt; 0.001) and rest (0.06 ± 0.05ml/g/min, p &amp;lt; 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.

Regional Amyloid Burden Differences Evaluated Using Quantitative Cardiac MRI in Patients with Cardiac Amyloidosis.

ObjectiveThis study aimed to investigate the regional amyloid burden and myocardial deformation using T1 mapping and strain values in patients with cardiac amyloidosis (CA) according to late gadolinium enhancement (LGE) patterns.Materials and MethodsForty patients with CA were divided into 2 groups per LGE pattern, and 15 healthy subjects were enrolled. Global and regional native T1 and T2 mapping, extracellular volume (ECV), and cardiac magnetic resonance (CMR)-feature tracking strain values were compared in an intergroup and interregional manner.ResultsOf the patients with CA, 32 had diffuse global LGE (group 2), and 8 had focal patchy or no LGE (group 1). Global native T1, T2, and ECV were significantly higher in groups 1 and 2 than in the control group (native T1: 1384.4 ms vs. 1466.8 ms vs. 1230.5 ms; T2: 53.8 ms vs. 54.2 ms vs. 48.9 ms; and ECV: 36.9% vs. 51.4% vs. 26.0%, respectively; all, p < 0.001). Basal ECV (53.7%) was significantly higher than the mid and apical ECVs (50.1% and 50.0%, respectively; p < 0.001) in group 2. Basal and mid peak radial strains (PRSs) and peak circumferential strains (PCSs) were significantly lower than the apical PRS and PCS, respectively (PRS, 15.6% vs. 16.7% vs. 26.9%; and PCS, −9.7% vs. −10.9% vs. −15.0%; all, p < 0.001). Basal ECV and basal strain (2-dimensional PRS) in group 2 showed a significant negative correlation (r = −0.623, p < 0.001). Group 1 showed no regional ECV differences (basal, 37.0%; mid, 35.9%; and apical, 38.3%; p = 0.184).ConclusionQuantitative T1 mapping parameters such as native T1 and ECV may help diagnose early CA. ECV, in particular, can reflect regional differences in the amyloid deposition in patients with advanced CA, and increased basal ECV is related to decreased basal strain. Therefore, quantitative CMR parameters may help diagnose CA and determine its severity in patients with or without LGE.

High-Resolution Cardiac Magnetic Resonance Imaging Techniques for the Identification of Coronary Microvascular Dysfunction

ObjectivesThis study assessed the ability to identify coronary microvascular dysfunction (CMD) in patients with angina and nonobstructive coronary artery disease (NOCAD) using high-resolution cardiac magnetic resonance (CMR) and hypothesized that quantitative perfusion techniques would have greater accuracy than visual analysis. BackgroundHalf of all patients with angina are found to have NOCAD, while the presence of CMD portends greater morbidity and mortality, it now represents a modifiable therapeutic target. Diagnosis currently requires invasive assessment of coronary blood flow during angiography. With greater reliance on computed tomography coronary angiography as a first-line tool to investigate angina, noninvasive tests for diagnosing CMD warrant validation. MethodsConsecutive patients with angina and NOCAD were enrolled. Intracoronary pressure and flow measurements were acquired during rest and vasodilator-mediated hyperemia. CMR (3-T) was performed and analyzed by visual and quantitative techniques, including calculation of myocardial blood flow (MBF) during hyperemia (stress MBF), transmural myocardial perfusion reserve (MPR: MBFHYPEREMIA / MBFREST), and subendocardial MPR (MPRENDO). CMD was defined dichotomously as an invasive coronary flow reserve <2.5, with CMR readers blinded to this classification. ResultsA total of 75 patients were enrolled (57 ± 10 years of age, 81% women). Among the quantitative perfusion indices, MPRENDO and MPR had the highest accuracy (area under the curve [AUC]: 0.90 and 0.88) with high sensitivity and specificity, respectively, both superior to visual assessment (both p < 0.001). Visual assessment identified CMD with 58% accuracy (41% sensitivity and 83% specificity). Quantitative stress MBF performed similarly to visual analysis (AUC: 0.64 vs. 0.60; p = 0.69). ConclusionsHigh-resolution CMR has good accuracy at detecting CMD but only when analyzed quantitatively. Although omission of rest imaging and stress-only protocols make for quicker scans, this is at the cost of accuracy compared with integrating rest and stress perfusion. Quantitative perfusion CMR has an increasingly important role in the management of patients frequently encountered with angina and NOCAD.

Viability and functional recovery after chronic total occlusion percutaneous coronary intervention

Abstract Background Current guidelines advocate viability assessment to guide percutaneous coronary intervention (PCI) of chronic coronary total occlusions (CTO). Purpose Aim of the present study was to evaluate viability as well as global and regional functional recovery after successful CTO PCI using quantitative cardiac magnetic resonance (CMR) imaging. Methods 132 patients with sequential CMR at baseline and 3-months after successful CTO PCI were prospectively recruited between 2013 and 2018. Segmental wall thickening (SWT) and percentage late gadolinium enhancement (LGE) were quantitatively measured per segment. Viability was defined as dysfunctional myocardium (&amp;lt;2.84mm SWT) with no or limited scar (≤50% LGE). Results Significant improvements in left ventricular (LV) ejection fraction (from 48.1±11.8 to 49.5±12.1%, p&amp;lt;0.01), LV end-diastolic volume (from 99.1±31.8 to 95.7±30.2ml, p&amp;lt;0.01), and LV end-systolic volume (from 54.4±30.5 to 51.2±29.3ml, p&amp;lt;0.01) were observed after CTO PCI. CTO segments with viability (N=216, (31%)) demonstrated a significantly higher increase in SWT (0.80±1.39mm) compared to CTO segments with pre-procedural preserved function (N=456 (65%), 0.07±1.43mm, p&amp;lt;0.01) or extensive scar (LGE &amp;gt;50%, N=26 (4%), −0.08±1.09mm, p&amp;lt;0.01). Improvement in SWT was comparable between segments with viability if further stratified to 0, &amp;gt;0–25, and &amp;gt;25–50% hyperenhancement (p=0.94). Patients with ≥2 CTO segments viability showed more SWT increase in the CTO territory compared to patients with 0–1 segment viability (0.49±0.93 vs. 0.12±0.98mm, p=0.03). Conclusions Improvements in LV function and volumes were significant but modest following CTO PCI. Detection of dysfunctional myocardial segments without extensive scar (≤50% LGE) as a marker for viability may aid in identifying subjects with significant regional functional recovery after CTO PCI. Funding Acknowledgement Type of funding source: None