Native T1 Mapping for the Diagnosis of Myocardial Fibrosis in Patients With Chronic Myocardial Infarction.

BACKGROUND: Myocardial fibrosis is a fundamental process in cardiac injury. Cardiac magnetic resonance native T1 mapping has been proposed for diagnosing myocardial fibrosis without the need for gadolinium contrast. However, recent studies suggest that T1 measurements can be erroneous in the presence of intramyocardial fat. OBJECTIVES: The purpose of this study was to investigate whether the presence of fatty metaplasia affects the accuracy of native T1 maps for the diagnosis of myocardial replacement fibrosis in patients with chronic myocardial infarction (MI). METHODS: Consecutive patients (n = 312) with documented chronic MI (>6 months old) and controls without MI (n = 50) were prospectively enrolled. Presence and size of regions with elevated native T1 and infarction were quantitatively determined (mean + 5SD) on modified look-locker inversion-recovery and delayed-enhancement images, respectively, at 3.0-T. The presence of fatty metaplasia was determined using an out-of-phase steady-state free-precession cine technique and further verified with standard fat-water Dixon methods. RESULTS: Native T1 mapping detected chronic MI with markedly higher sensitivity in patients with fatty metaplasia than those without fatty metaplasia (85.6% vs 13.3%) with similar specificity (100% vs 98.9%). In patients with fatty metaplasia, the size of regions with elevated T1 significantly underestimated infarct size and there was a better correlation with fatty metaplasia size than infarct size (r = 0.76 vs r = 0.49). In patients without fatty metaplasia, most of the modest elevation in T1 appeared to be secondary to subchronic infarcts that were 6 to 12 months old; the T1 of infarcts >12 months old was not different from noninfarcted myocardium. CONCLUSIONS: Native T1 mapping is poor at detecting replacement fibrosis but may indirectly detect chronic MI if there is associated fatty metaplasia. Native T1 mapping for the diagnosis and characterization of myocardial fibrosis is unreliable.

Assessment of myocardial lipomatous metaplasia using an optimized out-of-phase cine steady-state free-precession sequence: Validation and clinical implementation.

Myocardial lipomatous metaplasia, which can serve as substrate for ventricular arrhythmias, is usually composed of regions in which there is an admixture of fat and nonfat tissue. Although dedicated sequences for the detection of fat are available, it would be time-consuming and burdensome to routinely use these techniques to image the entire heart of all patients as part of a typical cardiac MRI exam. Conventional steady-state free-precession (SSFP) cine imaging is insensitive to detecting myocardial regions with partial fatty infiltration. We developed an optimization process for SSFP imaging to set fat signal consistently "out-of-phase" with water throughout the heart, so that intramyocardial regions with partial volume fat would be detected as paradoxically dark regions. The optimized SSFP sequence was evaluated using a fat phantom, through simulations, and in 50 consecutive patients undergoing clinical cardiac MRI. Findings were validated using standard Dixon gradient-recalled-echo (GRE) imaging as the reference. Phantom studies of test tubes with diverse fat concentrations demonstrated good agreement between measured signal intensity and simulated values calculated using Bloch equations. In patients, a line of signal cancellation at the interface between myocardium and epicardial fat was noted in all cases, confirming that SSFP images were consistently out-of-phase throughout the entire heart. Intramyocardial dark regions identified on out-of-phase SSFP images were entirely dark throughout in 33 patients (66%) and displayed an India-ink pattern in 17 (34%). In all cases, dark intramyocardial regions were also seen in the same locations on out-of-phase GRE and were absent on in-phase GRE, confirming that these regions represent areas with partial fat. In conclusion, if appropriately optimized, SSFP cine imaging allows for consistent detection of myocardial fatty metaplasia in patients undergoing routine clinical cardiac MRI without the need for additional image acquisitions using dedicated fat-specific sequences.

Cardiovascular magnetic resonance imaging in suspected cardiac tumour: a multicentre outcomes study.

AIMS: Cardiovascular magnetic resonance (CMR) imaging is a key diagnostic tool for the evaluation of patients with suspected cardiac tumours. Patient management is guided by the CMR diagnosis, including no further testing if a mass is excluded or if only a pseudomass is found. However, there are no outcomes studies validating this approach. METHODS AND RESULTS: In this multicentre study of patients undergoing clinical CMR for suspected cardiac tumour, CMR diagnoses were assigned as no mass, pseudomass, thrombus, benign tumour, or malignant tumour. A final diagnosis was determined after follow-up using all available data. The primary endpoint was all-cause mortality. Among 903 patients, the CMR diagnosis was no mass in 25%, pseudomass in 16%, thrombus in 16%, benign tumour in 17%, and malignant tumour in 23%. Over a median of 4.9 years, 376 patients died. Compared with the final diagnosis, the CMR diagnosis was accurate in 98.4% of patients. Patients with CMR diagnoses of pseudomass and benign tumour had similar mortality to those with no mass, whereas those with malignant tumour [hazard ratio (HR) 3.31 (2.40-4.57)] and thrombus [HR 1.46 (1.00-2.11)] had greater mortality. The CMR diagnosis provided incremental prognostic value over clinical factors including left ventricular ejection fraction, coronary artery disease, and history of extracardiac malignancy (P < 0.001). CONCLUSION: In patients with suspected cardiac tumour, CMR has high diagnostic accuracy. Patients with CMR diagnoses of no mass, pseudomass, and benign tumour have similar long-term mortality. The CMR diagnosis is a powerful independent predictor of mortality incremental to clinical risk factors.

Patients With Acute Myocarditis Following mRNA COVID-19 Vaccination.

Importance: Vaccine-associated myocarditis is an unusual entity that has been described for the smallpox vaccine, but only anecdotal case reports have been described for other vaccines. Whether COVID-19 vaccination may be linked to the occurrence of myocarditis is unknown. Objective: To describe a group of 7 patients with acute myocarditis over 3 months, 4 of whom had recent messenger RNA (mRNA) COVID-19 vaccination. Design, Setting, and Participants: All patients referred for cardiovascular magnetic resonance imaging at Duke University Medical Center were asked to participate in a prospective outcomes registry. Two searches of the registry database were performed: first, to identify patients with acute myocarditis for the 3-month period between February 1 and April 30 for 2017 through 2021, and second, to identify all patients with possible vaccine-associated myocarditis for the past 20 years. Once patients with possible vaccine-associated myocarditis were identified, data available in the registry were supplemented by additional data collection from the electronic health record and a telephone interview. Exposures: mRNA COVID-19 vaccine. Main Outcomes and Measures: Occurrence of acute myocarditis by cardiovascular magnetic resonance imaging. Results: In the 3-month period between February 1 and April 30, 2021, 7 patients with acute myocarditis were identified, of which 4 occurred within 5 days of COVID-19 vaccination. Three were younger male individuals (age, 23-36 years) and 1 was a 70-year-old female individual. All 4 had received the second dose of an mRNA vaccine (2 received mRNA-1273 [Moderna], and 2 received BNT162b2 [Pfizer]). All presented with severe chest pain, had biomarker evidence of myocardial injury, and were hospitalized. Coincident testing for COVID-19 and respiratory viruses provided no alternative explanation. Cardiac magnetic resonance imaging findings were typical for myocarditis, including regional dysfunction, late gadolinium enhancement, and elevated native T1 and T2. Conclusions and Relevance: In this study, magnetic resonance imaging findings were found to be consistent with acute myocarditis in 7 patients; 4 of whom had preceding COVID-19 vaccination. Further investigation is needed to determine associations of COVID-19 vaccination and myocarditis.

Epicardial Surface Area of Infarction: A Stable Surrogate of Microvascular Obstruction in Acute Myocardial Infarction.

BACKGROUND: Microvascular obstruction (MO) is a pathophysiologic complication of acute myocardial infarction that portends poor prognosis; however, it is transient and disappears with infarct healing. Much remains unknown regarding its pathophysiology and whether there are predictors of MO that could function as stable surrogates. We tested for clinical and cardiovascular magnetic resonance predictors of MO to gain insight into its pathophysiology and to find a stable surrogate. METHODS: Three hundred two consecutive patients from 2 centers underwent cardiovascular magnetic resonance within 2 weeks of first acute myocardial infarction. Three measures of infarct morphology: infarct size, transmurality, and a new index-the epicardial surface area (EpiSA) of full-thickness infarction-were quantified on delayed-enhancement cardiovascular magnetic resonance. RESULTS: Considering all clinical characteristics, only measures of infarct morphology were independent predictors of MO. EpiSA was the strongest predictor of MO and provided incremental predictive value beyond that of infarct size and transmurality (P<0.0001). In patients with 3-month follow-up cardiovascular magnetic resonance (n=81), EpiSA extent remained stable while MO disappeared, and EpiSA was a predictor of adverse ventricular remodeling. After 20 months of follow-up, 11 died and 1 had heart transplantation. Patients with an EpiSA larger than the median value (≥6%) had worse outcome than those with less than the median value (adverse events: 6.4% versus 1.9%, P=0.045). CONCLUSIONS: The EpiSA of infarction is a novel index of infarct morphology which accurately predicts MO during the first 2 weeks of MI, but unlike MO, does not disappear with infarct healing. This index has potential as a stable surrogate of the presence of acute MO and may be useful as a predictor of adverse remodeling and outcome which is less dependent on the time window of patient assessment.

ECG-gated MR angiography provides better reproducibility for standard aortic measurements.

OBJECTIVE: Cardiac motion and aortic pulsatility can affect the image quality of 3D contrast-enhanced MR angiography (CE-MRA). The addition of ECG gating improves image quality; however, no studies have directly linked image quality improvements to clinically used measures. In this study, we directly compared diameter measurements in the same patient from ECG-gated to non-gated CE-MRA to evaluate the impact of ECG gating upon measurement reproducibility. METHODS: Fifty-three patients, referred for thoracic aortic angiography, were enrolled and underwent both non-gated and ECG-gated CE-MRA. Two readers independently measured vessel diameter, image quality, and vessel sharpness at the sinus of Valsalva (SOV), sinotubular junction (STJX), ascending aorta (AAO), distal aortic arch (DLSA), and descending aorta (DAO). Measurement reliability and reproducibility were compared between methods. RESULTS: Image quality with ECG gating was rated significantly higher at the SOV (3.2 ± 0.9 vs 1.2 ± 1.0, p < 0.0001), STJX (3.4 ± 0.7 vs 1.8 ± 1.0, p < 0.0001), AAO (3.5 ± 0.6 vs 1.7 ± 1.1 p < 0.0001), DLSA (4.0 ± 0.1 vs 3.6 ± 0.7, p = 0.006), and DAO (4.0 ± 0.1 vs 3.4 ± 0.9 p < 0.0001) than for non-gated studies. Bland-Altman analyses demonstrated that inter- and intra-observer variability was significantly smaller for ECG-gated MRA at the SOV and AAO. For the non-gated images at the SOV, the 95% limits of agreement for both inter- and intra-observer variability exceeded the growth-rate cutoff for surgical repair (0.5 cm). At the DAO, variability was similar between the two techniques. CONCLUSION: ECG-gated CE-MRA resulted in improved reproducibility in aortic root and ascending aortic measurements. These data suggest that ECG-gated CE-MRA should be used for the serial assessment of the ascending thoracic aorta. KEY POINTS: • ECG-gated CE-MRA improves the reproducibility and repeatability of measurements of the ascending aorta. • With non-gated CE-MRA, pulsatile motion in the proximal aorta results in significant variability in measurement reproducibility.

Comparison of magnetization transfer-preparation and T2-preparation for dark-blood delayed-enhancement imaging.

Recently developed dark-blood techniques such as Flow-Independent Dark-blood DeLayed Enhancement (FIDDLE) allow simultaneous visualization of tissue contrast-enhancement and blood-pool suppression. Critical to FIDDLE is the magnetization preparation, which accentuates differences between myocardium and blood-pool. Here, we compared magnetization transfer (MT)-preparation and T2-preparation for use with FIDDLE. Variants of FIDDLE were developed with MT- or T2-preparation modules and tested in 35 patients (11 at 1.5 T, 24 at 3 T). Images were acquired with each FIDDLE variant in an interleaved fashion 10 minutes after gadolinium administration with otherwise identical acquisition parameters. Images were visually and quantitatively assessed for artifacts and differences in right ventricle to left ventricle (RV-to-LV) blood-pool suppression. Bright artifacts, reflecting incomplete blood-pool suppression, were frequently observed in the left atrium with T2-preparation FIDDLE at 1.5 and 3 T (82% and up to 100% of patients, respectively). MT-preparation FIDDLE resulted in fewer patients with artifacts (0% at 1.5 T, 22% at 3 T; P < .01). Left atrial blood-pool signal was significantly more homogeneous with MT-preparation than with T2-preparation at 1.5 and 3 T (P < .001 for all comparisons). Visibly different RV-to-LV blood-pool suppression was observed with T2-preparation in 36% of patients at 1.5 T and up to 94% at 3 T. In these patients, RV blood-pool signal was elevated, reducing the conspicuity of the myocardial-RV blood-pool border. Conversely, there were no visible differences in RV-to-LV blood-pool suppression with MT-preparation. Quantitative assessment of differences in blood-pool suppression and blood-pool artifacts was consistent with visual analyses. We conclude that for dark blood-blood delayed-enhancement imaging of the heart, MT-preparation results in fewer bright blood-pool artifacts and more uniform blood-pool suppression than T2-preparation.

Prevalence and Prognosis of Unrecognized Myocardial Infarction in Asymptomatic Patients With Diabetes: A Two-Center Study With Up to 5 Years of Follow-up.

OBJECTIVE: To determine the prevalence and prognostic significance of unrecognized myocardial infarction (MI) by delayed-enhancement MRI (DE-MRI) in asymptomatic patients with diabetes. RESEARCH DESIGN AND METHODS: In this prospective, two-center study of asymptomatic patients without known cardiac disease (n = 120), two prespecified cohorts underwent a research MRI: 1) a high-risk group with type 1 diabetes and chronic renal insufficiency (n = 50) and 2) an average-risk group with type 2 diabetes (n = 70). The primary end point was a composite of all-cause mortality and clinical MI. RESULTS: Overall, the prevalence of unrecognized MI was 19% by DE-MRI (28% high-risk group and 13% average-risk group) and 5% by electrocardiography. During up to 5 years of follow-up with a total of 460 patient-years of follow-up, the rate of death/MI was markedly higher in patients with diabetes with (vs. without) unrecognized MI (all 44% vs. 7%, high-risk group 43% vs. 6%, and average-risk group 44% vs. 8%; all P < 0.01). After adjustment for Framingham risk score, left ventricular ejection fraction, and diabetes type, the presence of unrecognized MI by DE-MRI conferred an eightfold increase in risk of death/MI (95% CI 3.0-21.1, P < 0.0001). Addition of unrecognized MI to clinical indices significantly improved model discrimination for adverse events (integrated discrimination improvement = 0.156, P = 0.001). CONCLUSIONS: Unrecognized MI is prevalent in asymptomatic patients with diabetes without a history of cardiac disease and confers a markedly increased risk of death and clinical MI.

Dark-Blood Delayed Enhancement Cardiac Magnetic Resonance of Myocardial Infarction.

OBJECTIVES: This study introduced and validated a novel flow-independent delayed enhancement technique that shows hyperenhanced myocardium while simultaneously suppressing blood-pool signal. BACKGROUND: The diagnosis and assessment of myocardial infarction (MI) is crucial in determining clinical management and prognosis. Although delayed enhancement cardiac magnetic resonance (DE-CMR) is an in vivo reference standard for imaging MI, an important limitation is poor delineation between hyperenhanced myocardium and bright LV cavity blood-pool, which may cause many infarcts to become invisible. METHODS: A canine model with pathology as the reference standard was used for validation (n = 22). Patients with MI and normal controls were studied to ascertain clinical performance (n = 31). RESULTS: In canines, the flow-independent dark-blood delayed enhancement (FIDDLE) technique was superior to conventional DE-CMR for the detection of MI, with higher sensitivity (96% vs. 85%, respectively; p = 0.002) and accuracy (95% vs. 87%, respectively; p = 0.01) and with similar specificity (92% vs, 92%, respectively; p = 1.0). In infarcts that were identified by both techniques, the entire length of the endocardial border between infarcted myocardium and adjacent blood-pool was visualized in 33% for DE-CMR compared with 100% for FIDDLE. There was better agreement for FIDDLE-measured infarct size than for DE-CMR infarct size (95% limits-of-agreement, 2.1% vs. 5.5%, respectively; p < 0.0001). In patients, findings were similar. FIDDLE demonstrated higher accuracy for diagnosis of MI than DE-CMR (100% [95% confidence interval [CI]: 89% to 100%] vs. 84% [95% CI: 66% to 95%], respectively; p = 0.03). CONCLUSIONS: The study introduced and validated a novel CMR technique that improves the discrimination of the border between infarcted myocardium and adjacent blood-pool. This dark-blood technique provides diagnostic performance that is superior to that of the current in vivo reference standard for the imaging diagnosis of MI.

The Prevalence, Correlates, and Impact on Cardiac Mortality of Right Ventricular Dysfunction in Nonischemic Cardiomyopathy.

OBJECTIVES: This study sought to determine the prevalence, correlates, and impact on cardiac mortality of right ventricular (RV) dysfunction in nonischemic cardiomyopathy. BACKGROUND: Current heart failure guidelines place little emphasis on RV assessment due to limited available data on determinants of RV function, mechanisms leading to its failure, and relation to outcomes. METHODS: We prospectively studied 423 patients with cardiac magnetic resonance (CMR). The pre-specified study endpoint was cardiac mortality. In 100 patients, right heart catheterization was performed as clinically indicated. RESULTS: During a median follow-up time of 6.2 years (interquartile range: 2.9 to 7.6 years), 101 patients (24%) died of cardiac causes. CMR right ventricular ejection fraction (RVEF) was a strong independent predictor of cardiac mortality after adjustment for age, heart failure-functional class, blood pressure, heart rate, serum sodium, serum creatinine, myocardial scar, and left ventricular ejection fraction (LVEF). Patients with the lowest quintile of RVEF had a nearly 5-fold higher cardiac mortality risk than did patients with the highest quintile (hazard ratio: 4.68; 95% confidence interval [CI]: 2.43 to 9.02; p < 0.0001). RVEF was positively correlated with LVEF (r = 0.60; p < 0.0001), and inversely correlated with right atrial pressure (r = -0.32; p = 0.001), pulmonary artery pressure (r = -0.34; p = 0.0005), transpulmonary gradient (r = -0.28; p = 0.006) but not with pulmonary wedge pressure (r = -0.15; p = 0.13). In multivariable logistic regression analysis of CMR, clinical, and hemodynamic data the strongest predictors of right ventricular dysfunction were LVEF (odds ratio [OR]: 0.85; 95% CI: 0.78 to 0.92; p < 0.0001), transpulmonary gradient (OR: 1.20; 95% CI: 1.09 to 1.32; p = 0.0003), and systolic blood pressure (OR: 0.97; 95% CI: 0.94 to 0.99; p = 0.02). CONCLUSIONS: CMR assessment of RVEF provides important prognostic information independent of established risk factors and LVEF in heart failure patients with nonischemic cardiomyopathy. Right ventricular dysfunction is strongly associated with both indices of intrinsic myocardial contractility and increased afterload from pulmonary vascular dysfunction.

Sources of variability in quantification of cardiovascular magnetic resonance infarct size - reproducibility among three core laboratories.

BACKGROUND: Acute myocardial infarct (AMI) size depicted by late gadolinium enhancement cardiovascular magnetic resonance (CMR) is increasingly used as an efficacy endpoint in randomized trials comparing AMI therapies. Infarct size is quantified using manual planimetry (MANUAL), visual scoring (VISUAL), or automated techniques using signal-intensity thresholding (AUTO). Although AUTO is considered the most reproducible, prior studies did not account for the subjective determination of endocardial/epicardial borders, which all methods require. For MANUAL and VISUAL, prior studies did not address how to treat intermediate signal intensities due to partial volume. METHODS: To assess sources of variability, AMI size was measured in 30 patients and 12 controls by 3 core-laboratories using 8 methods, each separated by more than 2 months time (n = 720 evaluations). The methods were: (1,2) AUTOSegment, AUTOFWHM (using Segment software or the full-width-at-half-maximum algorithm, respectively); (3,4) AUTO-UCSegment, AUTO-UCFWHM (user correction for endocardial border pixels, no-reflow, etc.); (5) MANUAL; (6) MANUAL-ISI (adjustment for intermediate signal-intensities); (7) VISUAL; (8) VISUAL-ISI. RESULTS: Mean infarct size varied between 16.8% and 27.2% of LV mass depending on method. Even automated techniques with no user interaction for infarct borders resulted in significant within-patient variability given the need to subjectively trace endocardial/epicardial contours. The coefficient-of-variation (CV) was 10.6% and 14.6% for AUTOSegment and AUTOFWHM, respectively. For manual and visual categories, reproducibility was improved when intermediate signal-intensities were considered (MANUAL-ISI vs MANUAL: CV = 8.3% vs 14.4%; p = 0.03; VISUAL-ISI vs VISUAL: CV = 8.4% vs 10.9%; p = 0.01). For AUTO-UCSegment, MANUAL-ISI, and VISUAL-ISI (best technique in each category) within-patient variability due to the quantification method was less than 10% of total variability, and the required sample sizes for detecting a 5% absolute difference in infarct size were 62, 63, and 62 patients, respectively. CONCLUSION: Among CMR core-laboratories, an important source of variability in infarct size quantification is the subjective delineation of endocardial/epicardial borders. When intermediate signal intensities are considered in manual planimetry and visual scoring, reproducibility and impact on sample size are similar to automated techniques.

Suppression of ghost artifacts arising from long T1 species in segmented inversion-recovery imaging.

PURPOSE: We demonstrate an improved segmented inversion-recovery sequence that suppresses ghost artifacts arising from tissues with long T1 ( > 1.5 s). THEORY AND METHODS: Long T1 species such as pericardial fluid can create bright ghost artifacts in segmented, inversion-recovery MRI because of oscillations in longitudinal magnetization between segments. A single dummy acquisition at the beginning of the sequence can reduce oscillations; however, its effectiveness in suppressing long T1 artifacts is unknown. In this study, we systematically evaluated several test sequences, including a prototype (saturation post-pulse readout to eliminate spurious signal: SPPRESS) in simulations, phantoms, and patients. RESULTS: SPPRESS reduced artifact signal 90% ± 25% and 74% ± 28% compared with Control and Single-Dummy methods in phantoms. SPPRESS performed well at 1.5 Tesla (T) and 3T, with steady-state free precession (SSFP) and fast low-angle shot (FLASH) readout, with conventional and phase-sensitive reconstruction, and over a range of physiologic heart rates. A review of 100 consecutive clinical cardiac MRI scans revealed large fluid collections (eg, regions with long T1 ) in 14% of patients. In a prospectively enrolled cohort of 16 patients with visible long T1 fluids, SPPRESS appreciably reduced artifacts in all cases compared with Control and Single-Dummy methods. CONCLUSION: We developed and validated a new robust method, SPPRESS, for reducing artifacts due to long T1 species across a wide range of imaging and physiologic conditions. Magn Reson Med 78:1442-1451, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Relationship of T2-Weighted MRI Myocardial Hyperintensity and the Ischemic Area-At-Risk.

RATIONALE: After acute myocardial infarction (MI), delineating the area-at-risk (AAR) is crucial for measuring how much, if any, ischemic myocardium has been salvaged. T2-weighted MRI is promoted as an excellent method to delineate the AAR. However, the evidence supporting the validity of this method to measure the AAR is indirect, and it has never been validated with direct anatomic measurements. OBJECTIVE: To determine whether T2-weighted MRI delineates the AAR. METHODS AND RESULTS: Twenty-one canines and 24 patients with acute MI were studied. We compared bright-blood and black-blood T2-weighted MRI with images of the AAR and MI by histopathology in canines and with MI by in vivo delayed-enhancement MRI in canines and patients. Abnormal regions on MRI and pathology were compared by (a) quantitative measurement of the transmural-extent of the abnormality and (b) picture matching of contours. We found no relationship between the transmural-extent of T2-hyperintense regions and that of the AAR (bright-blood-T2: r=0.06, P=0.69; black-blood-T2: r=0.01, P=0.97). Instead, there was a strong correlation with that of infarction (bright-blood-T2: r=0.94, P<0.0001; black-blood-T2: r=0.95, P<0.0001). Additionally, contour analysis demonstrated a fingerprint match of T2-hyperintense regions with the intricate contour of infarcted regions by delayed-enhancement MRI. Similarly, in patients there was a close correspondence between contours of T2-hyperintense and infarcted regions, and the transmural-extent of these regions were highly correlated (bright-blood-T2: r=0.82, P<0.0001; black-blood-T2: r=0.83, P<0.0001). CONCLUSION: T2-weighted MRI does not depict the AAR. Accordingly, T2-weighted MRI should not be used to measure myocardial salvage, either to inform patient management decisions or to evaluate novel therapies for acute MI.

Performance of CMR Methods for Differentiating Acute From Chronic MI.

OBJECTIVES: The purpose of this study was to assess the performance of cardiac magnetic resonance (CMR) methods for discriminating acute from chronic myocardial infarction (MI). BACKGROUND: Although 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. METHODS: A 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. RESULTS: The 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. CONCLUSIONS: T2-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.

Motion and flow insensitive adiabatic T2 -preparation module for cardiac MR imaging at 3 Tesla.

A versatile method for generating T2 -weighting is a T2 -preparation module, which has been used successfully for cardiac imaging at 1.5T. Although it has been applied at 3T, higher fields (B0 ≥ 3T) can degrade B0 and B1 homogeneity and result in nonuniform magnetization preparation. For cardiac imaging, blood flow and cardiac motion may further impair magnetization preparation. In this study, a novel T2 -preparation module containing multiple adiabatic B1 -insensitive refocusing pulses is introduced and compared with three previously described modules [(a) composite MLEV4, (b) modified BIR-4 (mBIR-4), and (c) Silver-Hoult-pair]. In the static phantom, the proposed module provided similar or better B0 and B1 insensitivity than the other modules. In human subjects (n = 21), quantitative measurement of image signal coefficient of variation, reflecting overall image inhomogeneity, was lower for the proposed module (0.10) than for MLEV4 (0.15, P < 0.0001), mBIR-4 (0.27, P < 0.0001), and Silver-Hoult-pair (0.14, P = 0.001) modules. Similarly, qualitative analysis revealed that the proposed module had the best image quality scores and ranking (both, P < 0.0001). In conclusion, we present a new T2 -preparation module, which is shown to be robust for cardiac imaging at 3T in comparison with existing methods.

Assessment of myocardial scarring improves risk stratification in patients evaluated for cardiac defibrillator implantation.

OBJECTIVES: We tested whether an assessment of myocardial scarring by cardiac magnetic resonance imaging (MRI) would improve risk stratification in patients evaluated for implantable cardioverter-defibrillator (ICD) implantation. BACKGROUND: Current sudden cardiac death risk stratification emphasizes left ventricular ejection fraction (LVEF); however, most patients suffering sudden cardiac death have a preserved LVEF, and many with poor LVEF do not benefit from ICD prophylaxis. METHODS: One hundred thirty-seven patients undergoing evaluation for possible ICD placement were prospectively enrolled and underwent cardiac MRI assessment of LVEF and scar. The pre-specified primary endpoint was death or appropriate ICD discharge for sustained ventricular tachyarrhythmia. RESULTS: During a median follow-up of 24 months the primary endpoint occurred in 39 patients. Whereas the rate of adverse events steadily increased with decreasing LVEF, a sharp step-up was observed for scar size >5% of left ventricular mass (hazard ratio [HR]: 5.2; 95% confidence interval [CI]: 2.0 to 13.3). On multivariable Cox proportional hazards analysis, including LVEF and electrophysiological-study results, scar size (as a continuous variable or dichotomized at 5%) was an independent predictor of adverse outcome. Among patients with LVEF >30%, those with significant scarring (>5%) had higher risk than those with minimal or no (≤5%) scarring (HR: 6.3; 95% CI: 1.4 to 28.0). Those with LVEF >30% and significant scarring had risk similar to patients with LVEF ≤30% (p = 0.56). Among patients with LVEF ≤30%, those with significant scarring again had higher risk than those with minimal or no scarring (HR: 3.9; 95% CI: 1.2 to 13.1). Those with LVEF ≤30% and minimal scarring had risk similar to patients with LVEF >30% (p = 0.71). CONCLUSIONS: Myocardial scarring detected by cardiac MRI is an independent predictor of adverse outcome in patients being considered for ICD placement. In patients with LVEF >30%, significant scarring (>5% LV) identifies a high-risk cohort similar in risk to those with LVEF ≤30%. Conversely, in patients with LVEF ≤30%, minimal or no scarring identifies a low-risk cohort similar to those with LVEF >30%.

Anatomic and clinical correlates of septal morphology in hypertrophic cardiomyopathy.

UNLABELLED: Aim The presence of septal hypertrophy in hypertrophic cardiomyopathy (HCM) is common. To date, there has been no accepted classification of septal morphology in HCM. Furthermore, the possible relationship between septal morphology and clinical features of HCM is undefined. METHODS AND RESULTS: Seventy-five consecutive adult patients with HCM were enrolled. Septal morphologies were retrospectively categorized into one of four patterns of hypertrophy based on transthoracic echocardiography. Left ventricular diastolic function by Doppler echocardiography and late gadolinium enhancement (LGE) by magnetic resonance imaging were assessed in all patients. Patients were followed for a mean of 45 ± 32 months. Catenoid septum was the most common morphologic subtype (46 of 75, 61%), followed by simple sigmoid (22 of 75, 29%), neutral (4 of 75, 5%), and apical (3 of 75, 4%). Inter-observer reproducibility of septal classifications was high (κ = 0.95). Patients with the catenoid subtype presented at a younger age, had worse diastolic function, and high rates of LGE. The presence of catenoid septal morphology was independently associated with LGE in multivariable logistic regression analysis. Implantable cardioverter-defibrillator implantation for prevention of sudden cardiac death occurred only in patients with this septal morphology. CONCLUSION: We propose a simple, reproducible classification system of patterns of septal hypertrophy in HCM. These patterns of hypertrophy are associated with significant differences in clinical, haemodynamic, and myocardial characteristics. Further studies are needed to evaluate the relationship between septal morphology and outcome or response to therapies in HCM.

Detection of myocardial damage in patients with sarcoidosis.

BACKGROUND: In patients with sarcoidosis, sudden death is a leading cause of mortality, which may represent unrecognized cardiac involvement. Delayed-enhancement cardiovascular magnetic resonance (DE-CMR) can detect minute amounts of myocardial damage. We sought to compare DE-CMR with standard clinical evaluation for the identification of cardiac involvement. METHODS AND RESULTS: Eighty-one consecutive patients with biopsy-proven extracardiac sarcoidosis were prospectively recruited for a parallel and masked comparison of cardiac involvement between (1) DE-CMR and (2) standard clinical evaluation with the use of consensus criteria (modified Japanese Ministry of Health [JMH] guidelines). Standard evaluation included 12-lead ECG and at least 1 dedicated non-CMR cardiac study (echocardiography, radionuclide scintigraphy, or cardiac catheterization). Patients were followed for 21+/-8 months for major adverse events (death, defibrillator shock, or pacemaker requirement). Patients were predominantly middle-aged (46+/-11 years), female (62%), and black (73%) and had chronic sarcoidosis (median, 7 years) and preserved left ventricular ejection fraction (median, 56%). DE-CMR identified cardiac involvement in 21 patients (26%) and JMH criteria in 10 (12%, 8 overlapping), a >2-fold higher rate for DE-CMR (P=0.005). All patients with myocardial damage on DE-CMR had coronary disease excluded by x-ray angiography. Pathology evaluation in 15 patients (19%) identified 4 with cardiac sarcoidosis; all 4 were positive by DE-CMR, whereas 2 were JMH positive. On follow-up, 8 had adverse events, including 5 cardiac deaths. Patients with myocardial damage on DE-CMR had a 9-fold higher rate of adverse events and an 11.5-fold higher rate of cardiac death than patients without damage. CONCLUSIONS: In patients with sarcoidosis, DE-CMR is more than twice as sensitive for cardiac involvement as current consensus criteria. Myocardial damage detected by DE-CMR appears to be associated with future adverse events including cardiac death, but events were few, and this needs confirmation in a larger cohort.

Unrecognized non-Q-wave myocardial infarction: prevalence and prognostic significance in patients with suspected coronary disease.

BACKGROUND: Unrecognized myocardial infarction (UMI) is known to constitute a substantial portion of potentially lethal coronary heart disease. However, the diagnosis of UMI is based on the appearance of incidental Q-waves on 12-lead electrocardiography. Thus, the syndrome of non-Q-wave UMI has not been investigated. Delayed-enhancement cardiovascular magnetic resonance (DE-CMR) can identify MI, even when small, subendocardial, or without associated Q-waves. The aim of this study was to investigate the prevalence and prognosis associated with non-Q-wave UMI identified by DE-CMR. METHODS AND FINDINGS: We conducted a prospective study of 185 patients with suspected coronary disease and without history of clinical myocardial infarction who were scheduled for invasive coronary angiography. Q-wave UMI was determined by electrocardiography (Minnesota Code). Non-Q-wave UMI was identified by DE-CMR in the absence of electrocardiographic Q-waves. Patients were followed to determine the prognostic significance of non-Q-wave UMI. The primary endpoint was all-cause mortality. The prevalence of non-Q-wave UMI was 27% (50/185), compared with 8% (15/185) for Q-wave UMI. Patients with non-Q-wave UMI were older, were more likely to have diabetes, and had higher Framingham risk than those without MI, but were similar to those with Q-wave UMI. Infarct size in non-Q-wave UMI was modest (8%+/-7% of left ventricular mass), and left ventricular ejection fraction (LVEF) by cine-CMR was usually preserved (52%+/-18%). The prevalence of non-Q-wave UMI increased with the extent and severity of coronary disease on angiography (p<0.0001 for both). Over 2.2 y (interquartile range 1.8-2.7), 16 deaths occurred: 13 in non-Q-wave UMI patients (26%), one in Q-wave UMI (7%), and two in patients without MI (2%). Multivariable analysis including New York Heart Association class and LVEF demonstrated that non-Q-wave UMI was an independent predictor of all-cause mortality (hazard ratio [HR] 11.4, 95% confidence interval [CI] 2.5-51.1) and cardiac mortality (HR 17.4, 95% CI 2.2-137.4). CONCLUSIONS: In patients with suspected coronary disease, the prevalence of non-Q-wave UMI is more than 3-fold higher than Q-wave UMI. The presence of non-Q-wave UMI predicts subsequent mortality, and is incremental to LVEF. TRIAL REGISTRATION: Clinicaltrials.gov NCT00493168.

Respiratory motion and cardiac arrhythmia effects on diagnostic accuracy of myocardial delayed-enhanced MR imaging in canines.

PURPOSE: To prospectively compare in canines the diagnostic accuracy for myocardial infarction (MI) of standard delayed-enhancement (DE) magnetic resonance (MR) imaging versus that of subsecond DE MR imaging with and without breath holding and/or cardiac arrhythmia, with histologic findings or absence of surgical creation of MI as the reference standard. MATERIALS AND METHODS: This study was approved by the Institutional Animal Care and Use Committee; 21 canines were imaged with one standard and two subsecond DE MR techniques in four conditions: condition 1, breath holding and steady gating; 2, non-breath holding and steady gating; 3, breath holding and irregular heart rhythm; and 4, non-breath holding and irregular heart rhythm. Images were randomized and scored for diagnostic accuracy, image quality, and observer confidence. Sensitivity, specificity, and diagnostic accuracy for MI detection were calculated for each technique and clinical condition separately. The chi(2), paired t, and McNemar tests were used for comparisons. RESULTS: Fifteen dogs had MIs. Among conditions 2-4, differences were not significant (P > .05); data were pooled and referred to as group B. Condition 1 was group A. Accuracy, image quality, and observer confidence, respectively, for standard DE MR imaging were 96%, 3.7 +/- 0.8, and 2.7 +/- 0.6 in group A but only 74%, 2.4 +/- 0.8, and 1.8 +/- 0.7 in group B (P < or = .004 for each). Corresponding scores for subsecond techniques were unaffected by respiratory motion and/or arrhythmia. Subsecond techniques had higher accuracy (82% and 86% vs 74%), better image quality (3.9 +/- 0.7 and 3.2 +/- 0.8 vs 2.4 +/- 0.8), and greater confidence (2.4 +/- 0.7 and 2.1 +/- 0.7 vs 1.8 +/- 0.7) (P < or = .0002 for each) than standard DE MR imaging. In group A, standard performed better than subsecond DE MR imaging. CONCLUSION: Standard DE MR imaging is appropriate for MI detection with breath holding and regular heart rhythm, while subsecond techniques are appropriate with an irregular heart rhythm and when breath holding is not possible.