Cardiac Magnetic Resonance Methods Research Articles

CMR Mapping: The 4th-Era Revolution in Cardiac Imaging.

Cardiac magnetic resonance (CMR) imaging has witnessed substantial progress with the advent of parametric mapping techniques, most notably T1 and T2 mapping. These advanced techniques provide valuable insights into a wide range of cardiac conditions, including ischemic heart disease, cardiomyopathies, inflammatory cardiomyopathies, heart valve disease, and athlete's heart. Mapping could be the first sign of myocardial injury and oftentimes precedes symptoms, changes in ejection fraction, and irreversible myocardial remodeling. The ability of parametric mapping to offer a quantitative assessment of myocardial tissue properties addresses the limitations of conventional CMR methods, which often rely on qualitative or semiquantitative data. However, challenges persist, especially in terms of standardization and reference value establishment, hindering the wider clinical adoption of parametric mapping. Future developments should prioritize the standardization of techniques to enhance their clinical applicability, ultimately optimizing patient care pathways and outcomes. In this review, we endeavor to provide insights into the potential contributions of CMR mapping techniques in enhancing the diagnostic processes across a range of cardiac conditions.

Potential of non-contrast stress T1 mapping for the assessment of myocardial injury in hypertrophic cardiomyopathy

BackgroundIschemia of the hypertrophied myocardium due to microvascular dysfunction is related to a worse prognosis in hypertrophic cardiomyopathy (HCM). Stress and rest T1 mapping without contrast agents can be used to assess myocardial blood flow. Herein, we evaluated the potential of non-contrast stress T1 mapping in assessing myocardial injury in patients with HCM. MethodsForty-five consecutive subjects (31 HCM patients and 14 control subjects) underwent cardiac magnetic resonance (CMR) at 3T, including cine imaging, T1 mapping at rest and during adenosine triphosphate (ATP) stress, late gadolinium enhancement (LGE), and phase-contrast (PC) cine imaging of coronary sinus flow at rest and during stress to assess coronary flow reserve (CFR). PC cine imaging was performed on 25 subjects (17 patients with HCM and 8 control subjects). Native T1 values at rest and during stress were measured using the 16-segment model, and T1 reactivity was defined as the change in T1 values from rest to stress. ResultsATP stress induced a significant increase in native T1 values in both the HCM and control groups (HCM: p < 0.001, control: p = 0.002). T1 reactivity in the HCM group was significantly lower than that in the control group (4.2 ± 0.3% vs. 5.6 ± 0.5%, p = 0.044). On univariate analysis, T1 reactivity correlated with native T1 values at rest, left ventricular mass index, and CFR. Multiple linear regression analysis demonstrated that only CFR was independently correlated with T1 reactivity (β = 0.449; 95% confidence interval, 0.048–0.932; p = 0.032). Furthermore, segmental analysis showed decreased T1 reactivity in the hypertrophied myocardium and the non-hypertrophied myocardium with LGE in the HCM group. ConclusionsT1 reactivity was lower in the hypertrophied myocardium and LGE-positive myocardium compared to non-injured myocardium. Non-contrast stress T1 mapping is a promising CMR method for assessing myocardial injury in patients with HCM.Trial registration Retrospectively registered.

Age- and Sex-Specific Characteristics of Right Ventricular Compacted and Non-compacted Myocardium by Cardiac Magnetic Resonance.

The age and sex-specific characteristics of right ventricular compacted (RV-CMi) and RV-trabeculated myocardial mass (RV-TMi) and the determinants of RV myocardium are less well-studied; however, in different conditions, these might provide additional diagnostic information. We aimed to describe the age- and sex-specific characteristics of RV-CMi, RV-TMi, and RV volumetric and functional parameters and investigate the determinants of RV myocardial mass with cardiac magnetic resonance (CMR). Two hundred healthy Caucasian volunteers free of known cardiovascular or systemic diseases were prospectively enrolled in this study. Four different age groups were established with equal numbers of males and females: Group A (n = 50, 20-29 years, mean age: 24.3 ± 3.2 years), Group B (n = 50, 30-39 years, mean age: 33.6 ± 2.6 years), Group C (n = 50, 40-49 years, mean age: 44.7 ± 2.7 years), and Group D (n = 50, ≥50 years, mean age: 55.1 ± 3.9 years). Left ventricular (LV) and RV volumetric, functional, CMi, and TMi values were measured with a threshold-based post-processing CMR method. The volumetric parameters, RV-CMi, and RV-TMi values were larger, and the ejection fraction (EF) was lower in males. The RV-CMi did not correlate with age in either of the sexes, while the RV-TMi decreased with age in females but remained stable in males. The RV-TMi and RV-CMi correlated positively with RV volumetric parameters, the LV-CMi, the LV-TMi, and each other in both sexes. LV-TMi, LV-CMi, RV end-systolic volume, and sex were independent predictors of RV-TMi. Understanding the characteristics of RV-trabeculated and RV-compacted myocardium might have additive value in diagnosing different conditions with RV hypertrophy or hypertrabeculation.

Abstract 10016: Potential of Stress T1 Mapping for Detection of Microvascular Dysfunction Without Contrast Agents

Introduction: Ischemia of hypertrophic myocardium due to microvascular dysfunction is related to worse prognosis in hypertrophic cardiomyopathy (HCM). Stress T1 mapping is a novel cardiac magnetic resonance (CMR) method without contrast agents to be able to assess myocardial blood flow. Hypothesis: We assessed the hypothesis that stress T1 mapping can detect microvascular dysfunction in HCM patients. Methods: Forty-one consecutive subjects without history of coronary artery disease (mean age : 60±3 years, 25 HCM patients, 10 concentric left ventricular hypertrophy (LVH) patients and 6 control subjects) underwent CMR at 3T including cine imaging, rest and adenosine stress T1 mapping, and late gadolinium enhancement (LGE). Native and stress T1 values were measured as an averaged T1 values in the septum of 3 short-axis slices of base-to-apex left ventricle myocardium and T1 reactivity (ΔT1) was calculated as follows: ΔT1 (%) = (T1stress - T1rest)/T1rest х 100. Thirteen HCM patients underwent phase-contrast imaging of coronary sinus flow during rest and adenosine stress to assess coronary flow reserve (CFR). Results: Native T1 values in HCM patients (1271±12ms) showed no significant differences compared with LVH (1225±13ms, p=0.0877) and control subjects (1243±8ms, p=0.534), but ΔT1 in HCM patients (4.00±0.36%) was significantly lower than that in control subjects (5.97±0.41%, p=0.0272), but not in LVH patients (4.95±0.29%, p=0.265, Figure 1). In HCM patients, native T1 values and ΔT1 showed no significant differences between LGE-positive (n=19) and LGE-negative (n=6) groups (native T1: 1274±15ms vs. 1260±20ms, p=0.632, ΔT1: 4.55±0.79% vs. 3.82±0.41%, p=0.394). A moderate positive correlation between ΔT1 and CFR was seen (β=0.697, p=0.0398). Conclusions: T1 reactivity (ΔT1) was reduced in HCM patients compared to control subjects. Stress T1 mapping is a promising CMR method for the assessment of microvascular dysfunction without contrast agents.

‘Weighing up the Load’ – A Comparison of Cardiac Magnetic Resonance Methods to Assess Valvulo-Arterial Load in Patients with Aortic Stenosis

Background and Aim: The left ventricle (LV) faces a dual afterload in patients with aortic stenosis (AS) – both from the valve and vasculature. Together they form the global LV load. Two cardiac magnetic resonance (CMR) techniques have been described to quantify global LV load: (1) valvulo-arterial impedance instantaneous (ZVA-INS) and (2) valvulo-arterial load (VAL). The purpose of this study was to evaluate concordance (if any) between ZVA-INS and VAL. Methods: Twenty AS patients were compared (80 ± 9 years; 12 males; 80% severe). Aortic flow velocity data was obtained during breath-hold using through-plane PC Qflow imaging. ZVA-INS was determined as the relationship of aortic pressure and maximum aortic valve (AV) gradient to ascending aorta flow velocity in the time domain. VAL was determined as the relationship of aortic pressure to ascending aorta flow velocity in the frequency domain. Values from both methods were compared against total arterial compliance (TAC). Results: Global LV load was significantly higher when assessed by ZVA-INS (3990±1795 dynes.s.cm³) than VAL (946±318 dynes.s.cm³) (R=0.941; R²=0.886; F=109.2; P&lt;0.01) due to the addition of maximum AV gradient. VAL was linearly related to TAC with no significant difference (R=0.313; R²=0.098; F=1.413; P=0.256). Conclusion: This study presents the first direct comparison of CMR methods to assess global LV load in patients with AS. We conclude a significant difference between ZVA-INS and VAL, but not between VAL and TAC. This relationship is most likely due to the addition of maximum AV gradient.

Efficacy of Novel Noncontrast Cardiac Magnetic Resonance Methods in Indicating Fibrosis in Hypertrophic Cardiomyopathy.

Objective In hypertrophic cardiomyopathy (HCM), myocardial fibrosis is routinely shown by late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR) imaging. We evaluated the efficacy of 2 novel contrast-free CMR methods, namely, diffusion-weighted imaging (DWI) and feature-tracking (FT) method, in detecting myocardial fibrosis. Methods This cross-sectional study was conducted on 26 patients with HCM. Visual and quantitative comparisons were made between DWI and LGE images. Regional longitudinal, circumferential, and radial strains were compared between LGE-positive and LGE-negative segments. Moreover, global strains were compared between LGE-positive and LGE-negative patients as well as between patients with mild and marked LGE. Results All 3 strains showed significant differences between LGE-positive and LGE-negative segments (P < 0.001). The regional longitudinal and circumferential strain parameters showed significant associations with LGE (P < 0.001), while regional circumferential strain was the only independent predictor of LGE in logistic regression models (OR: 1.140, 95% CI: 1.073 to 1.207, P < 0.001). A comparison of global strains between patients with LGE percentages of below 15% and above 15% demonstrated that global circumferential strain was the only parameter to show impairment in the group with marked myocardial fibrosis, with borderline significance (P=0.09). A review of 212 segments demonstrated a qualitative visual agreement between DWI and LGE in 193 segments (91%). The mean apparent diffusion coefficient was comparable between LGE-positive and LGE-negative segments (P=0.51). Conclusions FT-CMR, especially regional circumferential strain, can reliably show fibrosis-containing segments in HCM. Further, DWI can function as an efficient qualitative method for the estimation of the fibrosis extent in HCM.

Performance of CMR Methods for Differentiating Acute From Chronic MI

ObjectivesThe purpose of this study was to assess the performance of cardiac magnetic resonance (CMR) methods for discriminating acute from chronic myocardial infarction (MI). BackgroundAlthough T2-weighted CMR is thought to be accurate in differentiating acute from chronic MI, few studies have reported on diagnostic accuracy, and these generally compared extremes in infarct age (e.g., <1 week old vs. more than 6 months old) and did not evaluate other CMR methods that could be informative. MethodsA total of 221 CMR studies were performed at various time points after ST-segment elevation myocardial infarction in 117 consecutive patients without a history of MI or revascularization enrolled prospectively at 2 centers. Imaging markers of acute MI (<1 month) were T2 hyperintensity on double inversion recovery turbo spin echo (DIR-TSE) images, microvascular obstruction (MO) on delayed-enhancement CMR, and focally increased end-diastolic wall thickness (EDWT) on cine-CMR. ResultsThe prevalence of T2-DIR-TSE hyperintensity decreased with infarct age but remained substantial up to 6 months post-MI. In contrast, the prevalence of both MO and increased EDWT dropped sharply after 1 month. T2-DIR-TSE sensitivity, specificity, and accuracy for identifying acute MI were 88%, 66%, and 77% compared with 73%, 97%, and 85%, respectively, for the combination of MO or increased EDWT. On multivariable analysis, persistence of T2-hyperintensity in intermediate-age infarcts (1 to 6 months old) was predicted by larger infarct size, diabetes, and better T2-DIR-TSE image quality score. For infarct size ≥10% of the left ventricle, a simple algorithm incorporating all CMR components allowed classification of infarct age into 3 categories (<1 month old, 1 to 6 months old, and ≥6 months old) with 80% (95% confidence interval: 73% to 87%) accuracy. ConclusionsT2-DIR-TSE hyperintensity is specific for infarcts <6 months old, whereas MO and increased EDWT are specific for infarcts <1 month old. Incorporating multiple CMR markers of acute MI and their varied longevity leads to a more precise assessment of infarct age.

Phenotyping patterns of left ventricular remodeling and hypertrophy in systemic hypertension by cardiac magnetic resonance (CMR)

Methods Consecutive patients referred from our tertiary hypertension clinic, who underwent CMR at 1.5T, were included. Exclusion criteria included patients with clinical or CMR evidence of concomitant pathology (e.g. moderate-severe aortic stenosis) which may confound remodeling/hypertrophy pattern. Indexed LVM (iLVM), including papillary muscle mass by blood pool thresholding, indexed LV enddiastolic volume (iEDV) and ejection fraction (EF) were calculated using established CMR methods and normalized to body surface area. Values out-with the 95 th confidence intervals of established CMR normal reference values were considered abnormal. Mass : volume ratio (M/ V) >1.12 for men and >1.14 for women was defined as abnormal, in accordance with previous literature. The phenotypes of ventricular remodeling and hypertrophy were defined as either normal, concentric remodeling, asymmetric remodeling, concentric hypertrophy, asymmetric hypertrophy, eccentric hypertrophy or decompensation depending on the constellation of iLVM, iEDV, M/V, asymmetric thickness (>13mm and >1.5 fold opposing wall) and EF Results One hundred and twenty three (n=123) patients were analysed. The prevalence of different phenotypical responses were as follows: normal (42.3%), concentric remodeling (6.5%), asymmetric remodeling (5.7%), concentric hypertrophy (12.2%), asymmetric hypertrophy (17.9%) eccentric hypertrophy (8.9%) and decompensation (6.5%). The demographic and CMR characteristics of the different types of remodeling and hypertrophy are described in Figure 1. There was no predilection of remodeling/hypertrophic pattern according to hypertension type. 12.2% of our cohort had normal iLVM but demonstrated concentric/asymmetric remodeling. Subgroup analysis by remodeling (n=15) versus hypertrophy (n=22) revealed no significant difference in age (62±9.4 vs 55.1±12.4 years, p=0.0598), gender (% male 74.4% vs 68.2%, p=0.999), BMI (30.9±3.0 vs 30.1±4.9 kg/m 2 , p=0.5836), degree of hypertension (SBP 179.9±31.3 vs 176.8±24.7 mmHg, p=0.7407 and DBP 98.4±11.4 vs 95.7±14.8 mmHg, p=0.5557) or prevalence of potentially remodeling modifying medication (ACEi/ARB 80.0% vs 77.3%, p=0.999). Conclusions Varied CMR patterns of LV remodeling/hypertrophy occur in hypertensive patients with no predilection demonstrated in subgroup analysis. CMR-derived iLVM is increasingly used an end-point for clinical trials in hypertension. Our data suggest that patterns of LV remodeling/ hypertrophy should also be taken into account to avoid misclassifying patients with normal iLVM (but abnormal ventricles due to remodeling) together with patients with normal iLVM and truly normal ventricles.

ACCURACY AND REPRODUCIBILITY OF RV VOLUMES MEASUREMENTS BY CMR USING SHORT AXIS VS LONG AXIS FOUR CHAMBER VIEWS IN PATIENTS AND RV PHANTOMS

Cardiac magnetic resonance (CMR) is the reference standard for right ventricular (RV) volume and function assessment. A stack of short-axis slices (SAX) is routinely used to measure RV volumes but basal slice selection is challenging due to tricuspid annular plane excursion. Long-axis views offer a clearer view of the tricuspid and pulmonary valve planes, eliminating the need for cross-referencing; yet, there is significant partial-volume variability due to large areas of tangential subendocardial borders not perpendicular to the plane. We assessed inter-reader agreement between two CMR Methods for measurement of RV volumes in patients. We also assessed agreement between CMR derived RV volumes and physical volume measurement obtained from explanted animal hearts. The study was conducted in both patients undergoing a clinically indicated scan (n=50), and in explanted pig hearts (n=10). The RV of explanted pig heart was injected with a plastic mold (Reprosil) and its reference volume was measured using water displacement. For patients and molds, the RV was imaged with a full stack of slices covering the heart in SAX and in 4-chamber long axis view (4ch). RV volumes were traced, from both imaging planes, by 2 readers for the patient data and 2-4 readers for the explant data. Inter-reader agreement of the RV volumes was assessed for SAX and 4ch using concordance correlation coefficients and Bland-Altman limits of agreement. For patients, SAX and 4ch had excellent inter-reader agreement with SAX having a slightly higher coefficient (Table). For explants, the inter-reader agreement was poor in comparison to patient data, with 4ch being the most reproducible method. When comparing CMR derived volumes to the reference volume of the molds, SAX views had the smallest limits of agreement, closely followed by 4ch. However both SAX and 4ch views overestimated the volume by about 4ml (Image). SAX is the most widely used and most accurate imaging plane for measurements of RV volumes, while inter-reader agreement is excellent for both SAX and 4ch. Both SAX and 4ch mildly overestimate RV volumes. The different morphology of the porcine heart and the challenges of tracing a still image may explain the poor inter-reader agreement for measuring the volume of explanted RV molds.View Large Image Figure ViewerDownload (PPT)

38 T1 and T2 Mapping Have Higher Diagnostic Accuracy for the Ischaemic Area-at-risk in Nstemi Patients Compared with Dark Blood Imaging

BackgroundT1 and T2 cardiac magnetic resonance (CMR) mapping methods have shown promise for infarct characterisation in patients with acute ST-elevation myocardial infarction (STEMI). Non-ST elevation MI is typically a sub-acute...

T1 and T2 Mapping have a higher diagnostic accuracy for the ischaemic area-at-risk in NSTEMI patients compared with dark blood imaging

Background T1 and T2 cardiac magnetic resonance (CMR) mapping methods have shown promise for infarct characterisation in patients with acute ST-elevation myocardial infarction (STEMI). Non-ST elevation MI is typically a sub-acute problem with infarct characteristics that are less readily defined. We prospectively studied the diagnostic accuracy of two novel (T1, T2 mapping) and one established (T2 STIR) CMR methods for imaging the ischaemic area-at-risk (AAR) in patients with a recent NSTEMI. Methods NSTEMI patients underwent contrast-enhanced CMR at 3.0 Tesla (T) after percutaneous coronary intervention. The presence/extent of infarction was assessed with late gadolinium enhancement imaging (Gadovist, 0.1 mmol/kg). The infarct-related territory (IRA) was identified independently using a combination of angiographic, ECG and clinical findings. AAR was assessed with T1, T2 and T2 STIR methods by 2 observers who were blind to all of the clinical data. Comparisons were made between CMR and clinical findings. Results Seventy-three NSTEMI patients (mean age 57 ± 10 yrs, 78% male) underwent 3.0 T MRI. The mean infarct size was 5.5 ± 7.2% of left ventricular (LV) volume. The AAR T1 and T2 times were 1323 ± 68 ms and 57 ± 5 ms, respectively. The extent of AAR (% of LV volume) estimated with T1 (15.8 ± 10.6%) and T2 maps (16.0 ± 11.8%) was similar (p = 0.838), and moderately well correlated (r = 0.82, p Mean AAR estimated with T2 STIR (7.8 ± 11.6%) was lower than that estimated with T1 (p The IRA was correctly identified in 52 patients (71%) when with T1 CMR, 56 (77%) with T2 CMR, and 32 (44%) with T2 STIR CMR. The diagnostic accuracies of T1 and T2 CMR for identification of the IRA were similar (p = 0.125) whereas T1 CMR and T2 CMR had higher diagnostic accuracy vs. T2 STIR (both p Conclusion T1 and T2 maps have higher diagnostic accuracy than T2 STIR maps, implying superior clinical utility with T1 and T2 CMR for infarct characterisation in NSTEMI patients.

Geometry-independent inclusion of basal myocardium yields improved cardiac magnetic resonance agreement with echocardiography and necropsy quantified left-ventricular mass

Left-ventricular mass (LVM) is widely used to guide clinical decision-making. Cardiac magnetic resonance (CMR) quantifies LVM by planimetry of contiguous short-axis images, an approach dependent on reader-selection of images to be contoured. Established methods have applied different binary cut-offs using circumferential extent of left-ventricular myocardium to define the basal left ventricle (LV), omitting images containing lesser fractions of left-ventricular myocardium. This study tested impact of basal slice variability on LVM quantification. CMR was performed in patients and laboratory animals. LVM was quantified with full inclusion of left-ventricular myocardium, and by established methods that use different cut-offs to define the left-ventricular basal-most slice: 50% circumferential myocardium at end diastole alone (ED50), 50% circumferential myocardium throughout both end diastole and end systole (EDS50). One hundred and fifty patients and 10 lab animals were studied. Among patients, fully inclusive LVM (172.6±42.3g) was higher vs. ED50 (167.2±41.8g) and EDS50 (150.6±41.1g; both P<0.001). Methodological differences yielded discrepancies regarding proportion of patients meeting established criteria for left-ventricular hypertrophy and chamber dilation (P<0.05). Fully inclusive LVM yielded smaller differences with echocardiography (Δ=11.0±28.8g) than did ED50 (Δ=16.4±29.1g) and EDS50 (Δ=33.2±28.7g; both P<0.001). Among lab animals, ex-vivo left-ventricular weight (69.8±13.2g) was similar to LVM calculated using fully inclusive (70.1±13.5g, P=0.67) and ED50 (69.4±13.9g; P=0.70) methods, whereas EDS50 differed significantly (67.9±14.9g; P=0.04). Established CMR methods that discordantly define the basal-most LV produce significant differences in calculated LVM. Fully inclusive quantification, rather than binary cut-offs that omit basal left-ventricular myocardium, yields smallest CMR discrepancy with echocardiography-measured LVM and non-significant differences with necropsy-measured left-ventricular weight.

Assessment of Left Atrial Volume by Magnetic Resonance in Patients with Permanent Atrial Fibrillation. The Short-axis Method vs. the Single Plane Area-length Method

Background: Atrial fibrillation (AF) is associated with enlargement of the left atrium (LA). The LA volume can be assessed by cardiac magnetic resonance (CMR). The standard CMR method for measuring the LA volume is the short- axis (SA) method, which is time consuming, hence little useful in the clinical setting. For this reason more simplified methods have been developed to assess the LA volume. Objective: To compare the standard SA method and the simplified single plane area-length (AL) method for measurements of the LA volume in patients with permanent AF. Methods and Results: CMR was performed in 34 patients with permanent AF. CMR was conducted with the steady-state free precession (SSFP) technique TrueFISP. LA volumes were measured using the single plane AL method and the SA method. A good and statistically significant correlation was found between the two methods. The Pearson's correlation coefficients for LA maximal volume (LAmax) and LA minimal volume (LAmin) were 0.92, p<0.0001 and 0.91, p<0.0001, respectively. The single plane AL method underestimated LA volumes compared to the SA method (LAmax: 143 ± 35 ml vs. 149 ml ± 38, p=0.046, LAmin: 124 ml ± 30 vs. 130 ml ± 34, p=0.014). Intra- and interobserver agreement was inferior for the single plane AL method. Conclusion: Measurements of LA volumes by the SA method and the single plane AL methods correlate closely in patients with permanent AF. However, the single plane AL method underestimates the LA volume and the reproducibility is inferior compared to the SA method.

Left Ventricular Stroke Volume Quantification by Contrast Echocardiography – Comparison of Linear and Flow‐Based Methods to Cardiac Magnetic Resonance

Echocardiography (echo)-quantified LV stroke volume (SV) is widely used to assess systolic performance after acute myocardial infarction (AMI). This study compared 2 common echo approaches - predicated on flow (Doppler) and linear chamber dimensions (Teichholz) - to volumetric SV and global infarct parameters quantified by cardiac magnetic resonance (CMR). Multimodality imaging was performed as part of a post-AMI registry. For echo, SV was measured by Doppler and Teichholz methods. Cine-CMR was used for volumetric SV and LVEF quantification, and delayed-enhancement (DE) CMR for infarct size. Overall, 142 patients underwent same day echo and CMR. On echo, mean SV by Teichholz (78±17mL) was slightly higher than Doppler (75±16mL; Δ=3±13mL; P=0.02). Compared to SV on CMR (78±18mL), mean difference by Teichholz (Δ=-0.2±14; P=0.89) was slightly smaller than Doppler (Δ=-3±14; P=0.02), but limits of agreement were similar between CMR and echo methods (Teichholz: -28, 27mL, Doppler: -31, 24mL). For Teichholz, differences with CMR SV were greatest among patients with anteroseptal or lateral wall hypokinesis (P<0.05). For Doppler, differences were associated with aortic valve abnormalities or root dilation (P=0.01). SV by both echo methods decreased stepwise in relation to global LV injury as assessed by CMR-quantified LVEF and infarct size (P<0.01). Teichholz and Doppler calculated SV yield similar magnitude of agreement with CMR. Teichholz differences with CMR increase with septal or lateral wall contractile dysfunction, whereas Doppler yields increased offsets in patients with aortic remodeling.

Diagnostic Performance of Dark-Blood T2-Weighted CMR for Evaluation of Acute Myocardial Injury

We compared the image quality and diagnostic performance of 2 fat-suppression methods for black-blood T2-weighted fast spin-echo (FSE), which are as follows: (a) short T1 inversion recovery (STIR; FSE-STIR) and (b) spectral adiabatic inversion recovery (SPAIR; FSE-SPAIR), for detection of acute myocardial injury. Edema-sensitive T2-weighted FSE cardiac magnetic resonance (CMR) imaging is useful in detecting acute myocardial injury but may experience reduced myocardial signal and signal dropout. The SPAIR pulse aims to eliminate artifacts associated with the STIR pulse. A total of 65 consecutive patients referred for CMR evaluation of myocardial structure and function underwent FSE-STIR and FSE-SPAIR, in addition to cine and late gadolinium enhancement (LGE) CMR. T2-weighted FSE images were independently evaluated by 2 readers for image quality and artifacts (Likert scale of 1-5; best-worst) and presence of increased myocardial signal suggestive of edema. In addition, clinical CMR interpretation, incorporating all CMR sequences available, was recorded for comparison. Diagnostic performance of each T2-weighted sequence was measured using recent (<30 days) troponin elevation greater than 2 times the upper limit of normal as the reference standard for acute myocardial injury. Of the 65 patients, there were 21 (32%) with acute myocardial injury. Image quality and artifact scores were significantly better with FSE-SPAIR compared with FSE-STIR (2.15 vs 2.68, P < 0.01; 2.62 vs 3.05, P < 0.01, respectively). The sensitivity, specificity, positive predictive value, and negative predictive value for acute myocardial injury were as follows: 29%, 93%, 67%, and 73% for FSE-SPAIR; 38%, 91%, 67%, and 75% for FSE-STIR; 71%, 98%, 94%, and 88% for clinical interpretation including LGE, T2, and wall motion. There was a statistically significant difference in sensitivity between the clinical interpretation and each of the T2-weighted sequences but not between each T2-weighted sequence. Although FSE-SPAIR demonstrated significantly improved image quality and decreased artifacts, isolated interpretations of each T2-weighted technique demonstrated high specificity but overall low sensitivity for the detection of myocardial injury, with no difference in accuracy between the techniques. However, real-world interpretation in combination with cine and LGE CMR methods significantly improves the overall sensitivity and diagnostic performance.

Characteristics and clinical associations of late gadolinium enhanced cardiovascular magnetic tesonance in lamin A/C, cardiac troponin T and myosin binding protein C gene mutation related cardiomyopathies

Background Dilated cardiomyopathy (DCM) is a common cause of heart failure (HF) and the most common diagnosis in patients referred for cardiac transplantation. Genetic studies in DCM have identified mutations in over 30 genes. To date, there is only scarce data regarding the interdependencies between the various genotypes and their impact on cardiac morphology and myocardial tissue appearance. Since non-contrast cardiac magnetic resonance (CMR) is considered the reference method for morpho-functional analysis and late gadolinium enhanced (LGE) CMR method of choice for myocardial tissue assessment, we sought to investigate the characteristics of LGE in asymptomatic and symptomatic carriers of known cardiomyopathy mutations and their clinical associations.

MR Cine DENSE Dyssynchrony Parameters for the Evaluation of Heart Failure: Comparison With Myocardial Tissue Tagging

We sought to assess the effectiveness of automated mechanical dyssynchrony (MD) parameters based on regional heterogeneity of strain (circumferential [CURE], longitudinal [LURE], and radial uniformity ratio estimates) relative to parameters based on regional time to peak contraction with cardiac magnetic resonance (CMR) cine DENSE (Displacement Encoding with Stimulated Echoes) validated with myocardial tissue tagging (MTT) strain data. Dyssynchrony measures based on the Fourier transformation (FT) of regional strain, such as CURE (previously evaluated in cardiac resynchronization therapy candidates), directly assess MD and yield straightforward global dyssynchrony indexes; however, performance relative to the 12-segment standard deviation of time to peak strain (SD12) or maximal regional delay in time to peak strain is unknown. Cine DENSE and MTT were obtained with CMR (1.5-T Siemens Avanto, Siemens, Erlangen, Germany) in 13 canines: 3 normal control subjects, 5 with tachycardia pacing-induced heart failure (HF) and left bundle branch ablation (LBBB-HF), and 5 with HF and narrow QRS (NQRS-HF). Strain and dyssynchrony parameters were determined with both CMR methods. Both HF groups had reduced peak strains and left ventricular ejection fraction compared with normal cases. There was strong agreement between cine DENSE and MTT on the basis of intraclass correlation coefficients (CURE: 0.99, 95% CI: 0.96 to 1.00; LURE: 0.92, 95% CI: 0.77 to 0.98; circumferential strain [E(CC)]: 0.95, 95% CI: 0.72 to 0.99; longitudinal strain [E(LL)]: 0.82, 95% CI: 0.42 to 0.97). The FT-based metrics (scale 0 to 1), in particular CURE, discriminated highly between LBBB-HF and NQRS-HF groups (median difference): CURE: 0.60, 95% CI: 0.43 to 0.76; LURE: 0.39, 95% CI: 0.19 to 0.58; radial uniformity ratio estimate: 0.22, 95% CI: 0.04 to 0.40). In contrast, relative confidence intervals for group differences in time-to-peak parameters were wide, indicating less consistent discrimination (median difference): SD12-E(CC): 52.5, 95% CI: -4.0 to 109.2; SD12-E(LL): 40.9, 95% CI: -5.3 to 87.1; SD12-radial strain: 42.0, 95% CI: 0.4 to 83.6). Correlations between FT-based and time-to-peak parameters were significant (CURE/SD12-E(CC): r = -0.62, p = 0.03; LURE/SD12-E(LL): r = -0.76, p = 0.005) but not as tight as correlations between time-to-peak parameters. Automated FT-based circumferential, radial, and longitudinal dyssynchrony measures compare favorably with time-to-peak parameters. Cine DENSE was effective for this application and validated with MTT. Further clinical evaluation in cardiac resynchronization therapy candidates with CMR or other imaging modalities is warranted.

CMR Imaging Assessing Viability in Patients With Chronic Ventricular Dysfunction Due to Coronary Artery Disease: A Meta-Analysis of Prospective Trials

The purpose of this study was to compare the diagnostic accuracy of cardiac magnetic resonance (CMR) assessing myocardial viability in patients with chronic left ventricular (LV) dysfunction due to coronary artery disease using 3 techniques: 1) end-diastolic wall thickness (EDWT); 2) low-dose dobutamine (LDD); and 3) contrast delayed enhancement (DE). CMR has been proposed to assess myocardial viability over the past decade. However, the best CMR strategy to evaluate patients being contemplated for revascularization has not yet been determined. Some centers advocate DE CMR due to its high sensitivity to identify scar, whereas others favor the use of LDD CMR for its ability to identify contractile reserve. A systematic review of MEDLINE, Cochrane, and Embase for all the prospective trials assessing myocardial viability in subjects with chronic LV dysfunction using CMR was performed using a standard approach for meta-analysis for diagnostic tests and a bivariate analysis of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). A total of 24 studies of CMR evaluating myocardial viability with 698 patients fulfilled the inclusion criteria. Eleven studies used DE, 9 studies used LDD, and 4 studies used EDWT. Our meta-analysis indicates that among CMR methods, DE CMR provides the highest sensitivity as well as the highest NPV (95% and 90%, respectively) for predicting improved segmental LV contractile function after revascularization, followed by EDWT CMR, whereas LDD CMR demonstrated the lowest sensitivity/NPV among all modalities. On the other hand, LDD CMR offered the highest specificity and PPV (91% and 93%, respectively), followed by DE CMR, whereas EDWT showed the lowest of these parameters. DE CMR provides the highest sensitivity and NPV, whereas LDD CMR provides the best specificity and PPV. In light of these findings, integrating these 2 methods should provide increased accuracy in evaluating patients with chronic LV dysfunction being considered for revascularization.

Cardiac magnetic resonance imaging and its electrocardiographs (ECG): tips and tricks

All cardiac magnetic resonance (CMR) techniques aim to create still depictions of a dynamic and ever-adapting organ. Most CMR methods rely on cardiac gating to capture information during fleeting periods of relative cardiac quiescence, at end diastole or end systole, or to acquire partial images throughout the cardiac cycle and average these signals over several heart beats. Since the inception of clinical CMR in the early 1980s, priority has been given to improving methods for image gating. The aim of this work is to provide a basic understanding of the ECG acquisition, demonstrate common ECG-related artifacts and to provide practical methods for overcoming these issues. Meticulous ECG preparation is essential for optimal CMR acquisition and these techniques must be adaptable to the individual patient.

Importance of standardized assessment of late gadolinium enhancement for quantification of infarct size by cardiac magnetic resonance: implications for comparison with electrocardiogram

Background Cardiac magnetic resonance (CMR) is currently considered the reference standard for in vivo assessment of myocardial infarction (MI). There is, however, no international consensus on how MI quantification from CMR should be performed. The aim of this study was to test how previously published manual quantification of MI using CMR images compares with MI quantification using a semiautomated, validated method and how this impacts the relationship with MI size estimated by 12-lead electrocardiogram (ECG). Methods Twenty-five patients, from a previously published cohort, were included in the study. All patients had presented with clinical signs of acute coronary syndrome 6 to 12 months before undergoing a CMR examination. The patients had a standard 12-lead ECG recorded at the time of the CMR examination. The previously reported manually quantified MI size was compared with MI size determined using a semiautomated method validated by computer phantom data, experimental in vivo and ex vivo data, and patient data. The MI sizes from the 2 CMR approaches were then compared with the ECG-estimated MI size. Results There was a strong correlation between MI size determined with the 2 CMR methods ( r 2 = 0.94, P < .001). There was, however, a systematic overestimation of MI size of approximately 50% by the previously published manually quantified MI size compared with the semiautomated method. This affected the comparison with estimated MI size by ECG, which showed a significant underestimation of MI size compared with manual CMR measurements, but no bias compared with the semiautomated CMR method. Conclusions Manual quantification of MI size by CMR can differ significantly from semiautomated, validated methods taking partial volume effects into account and can lead to erroneous conclusions when compared with ECG.