Left atrial volume affects the correlation of voltage map with magnetic resonance imaging

BACKGROUND

The low-voltage area detected by electroanatomic mapping (EAM) is a surrogate marker of left atrial fibrosis. However, the correlation between the EAM and late gadolinium enhancement magnetic resonance imaging (LGE-MRI) has been inconsistent among studies. This study aimed to investigate how LA size affects the correlation between EAM and LGE-MRI.

METHODS

High-density EAMs of the LA during sinus rhythm were collected in 22 patients undergoing AF ablation. The EAMs were co-registered with pre-ablation LGE-MRI models. Voltages in the areas with and without LGE were recorded. Left atrial volume index (LAVI) was calculated from MRI, and LAVI > 62 ml/m2 was defined as significant LA enlargement (LAE).

RESULTS

Atrial bipolar voltage negatively correlates with the left atrial volume index. The median voltages in areas without LGE were 1.1 mV vs 2.0 mV in patients with vs without significant LAE (p = 0.002). In areas of LGE, median voltages were 0.4 mV vs 0.8 mV in patients with vs without significant LAE (p = 0.02). A voltage threshold of 1.7 mV predicted atrial LGE in patients with normal or mildly enlarged LA (sensitivity and specificity of 74% and 59%, respectively). In contrast, areas of voltage less than 0.75 mV correlated with LGE in patients with significant LA enlargement (sensitivity 68% and specificity 66%).

CONCLUSIONS

LAVI affects left atrial bipolar voltage, and the correlation between low-voltage areas and LGE-MRI. Distinct voltage thresholds according to the LAVI value might be considered to identify atrial scar by EAM.

Prognostic Role of Early Cardiac Magnetic Resonance in Myocardial Infarction With Nonobstructive Coronary Arteries

BACKGROUND

Cardiac magnetic resonance (CMR) plays a pivotal diagnostic role in myocardial infarction with nonobstructive coronary arteries (MINOCA). To date, a prognostic stratification of these patients is still lacking.

OBJECTIVES

This study aims to assess the prognostic role of CMR in MINOCA.

METHODS

The authors assessed 437 MINOCA from January 2017 to October 2021. They excluded acute myocarditis, takotsubo syndromes, cardiomyopathies, and other nonischemic etiologies. Patients were classified into 3 subgroups according to the CMR phenotype: 1) presence of late gadolinium enhancement (LGE) and abnormal mapping (M) values (LGE+/M+); 2) regional ischemic injury with abnormal mapping and no LGE (LGE-/M+); and 3) nonpathological CMRs (LGE-/M-). The primary outcome was the presence of major adverse cardiovascular events (MACE). The mean follow-up was 33.7 ± 12.0 months and CMR was performed on average at 4.8 ± 1.5 days from the acute presentation.

RESULTS

The final cohort included 198 MINOCA; 116 (58.6%) comprised the LGE+/M+ group. During follow-up, MACE occurred significantly more frequently in MINOCA LGE+/M+ than in the LGE+/M- and normal-CMR (LGE-/M-) subgroups (20.7% vs 6.7% and 2.7%; P = 0.006). The extension of myocardial damage at CMR was significantly greater in patients who developed MACE. In multivariable Cox regression, %LGE was an independent predictor of MACE (HR: 1.123 [95% CI: 1.064-1.185]; P < 0.001) together with T2 mapping values (HR: 1.190 [95% CI: 1.145-1.237]; P = 0.001).

CONCLUSIONS

In MINOCA with early CMR execution, the %LGE and abnormal T2 mapping values were identified as independent predictors of adverse cardiac events at ∼3.0 years of follow-up. These parameters can be considered as high-risk markers in MINOCA.

Cardiac Fibrosis Automated Diagnosis Based on FibrosisNet Network Using CMR Ischemic Cardiomyopathy

Ischemic heart condition is one of the most prevalent causes of death that can be treated more effectively and lead to fewer fatalities if identified early. Heart muscle fibrosis affects the diastolic and systolic function of the heart and is linked to unfavorable cardiovascular outcomes. Cardiac magnetic resonance (CMR) scarring, a risk factor for ischemic heart disease, may be accurately identified by magnetic resonance imaging (MRI) to recognize fibrosis. In the past few decades, numerous methods based on MRI have been employed to identify and categorize cardiac fibrosis. Because they increase the therapeutic advantages and the likelihood that patients will survive, developing these approaches is essential and has significant medical benefits. A brand-new method that uses MRI has been suggested to help with diagnosing. Advances in deep learning (DL) networks contribute to the early and accurate diagnosis of heart muscle fibrosis. This study introduces a new deep network known as FibrosisNet, which detects and classifies fibrosis if it is present. It includes some of 17 various series layers to achieve the fibrosis detection target. The introduced classification system is trained and evaluated for the best performance results. In addition, deep transfer-learning models are applied to the different famous convolution neural networks to find fibrosis detection architectures. The FibrosisNet architecture achieves an accuracy of 96.05%, a sensitivity of 97.56%, and an F1-Score of 96.54%. The experimental results show that FibrosisNet has numerous benefits and produces higher results than current state-of-the-art methods and other advanced CNN approaches.

Sex-based differences in late gadolinium enhancement among patients with acute myocarditis

OBJECTIVE

The aims of our study were to investigate the sex differences in late gadolinium enhancement (LGE) using cardiovascular magnetic resonance (CMR) in a single-centre cohort of consecutive patients with acute myocarditis (AM).

METHOD

This retrospective study performed CMR scans in 135 consecutive patients with AM that met the Lake Louise criteria. On CMR, LV ventricular strain functions were performed on conventional cine SSFP sequences. Besides myocardial strain measurements, myocardial scar location, extension, and size were assigned and quantified by LGE imaging.

RESULTS

There was no difference in age (age 42.51 ± 19.64 years vs 40.92 ± 19.94 years; p = 0.74) and cardiovascular risk profile between women and men. Despite similar comorbidities, women were more like to present with dyspnea (p = 0.001). Women demonstrated higher prevalence of septal LGE (p = 0.004) and increased global circumferential strain parameters (p = 0.008) in comparison with men. In multivariate analysis, female sex remained an independent determinant of septal LGE (β coefficient = -0.520, p = 0.001).

CONCLUSION

This is the first study reporting sex differences in LGE localization in AM. Women have more septal LGE involvement independent of age, cardiovascular risk factors, and CMR parameters. These findings further emphasize the sex-based differences in cardiovascular diseases.

Modeling of factors affecting late gadolinium enhancement kinetics in MRI of cardiac amyloid

BACKGROUND

Late gadolinium enhancement (LGE) is a valuable part of cardiac magnetic resonance imaging (CMR). In particular, inversion-recovery imaging of LGE, with nulling of the signal from reference areas of myocardium, can have a distinctive pattern in some patients with cardiac amyloid, including both diffuse (relatively faint) subendocardial LGE and a relatively dark appearance of the blood. However, the underlying reasons for this distinctive appearance have not previously been well investigated. Pharmacokinetic modeling of myocardial contrast enhancement kinetics can potentially provide insight into the mechanisms of the distinctive LGE appearance that can be seen in cardiac amyloid, as well as why it may be unreliable in some patients.

METHODS

An interactive three-compartment pharmacokinetic model of the dynamics of myocardial contrast enhancement in CMR was implemented, and used to simulate LGE dynamics in normal, scar, and cardiac amyloid myocardium; the results were compared with previously published values.

RESULTS

The three-compartment model is able to capture the qualitative features of LGE, in patients with cardiac amyloid. In particular, the characteristic "dark blood" appearance of PSIR images of LGE in cardiac amyloid is seen to likely primarily reflect expansion of the extravascular extracellular space (EES) by amyloid in the "reference" myocardium; the cardiac amyloid contrast enhancement dynamics also reflect expansion of the body EES.

CONCLUSION

The distinctive appearance of LGE in cardiac amyloid is likely due to a combination of diffuse expansion by amyloid of the EES of the reference myocardium and of the body EES.

How many clues make an evidence? An unusual case of aborted cardiac arrest due to mitral valve prolapse

There is an increasing awareness on the association between mitral valve prolapse (MVP) and sudden cardiac death. Mitral annular disjunction (MAD) is a phenotypic risk feature that can help in risk stratification. We present a case of a 58-year-old woman who experienced an out-of-hospital cardiac arrest caused by ventricular fibrillation interrupted by a direct current-shock. No coronary lesions were documented. Echocardiogram showed myxomatous MVP. Nonsustained ventricular tachycardia have been registered during hospital stay. Interestingly, cardiac magnetic resonance revealed MAD and a late gadolinium enhancement area in inferior wall. Finally, a defibrillator has been implanted. For arrhythmic risk stratification of MVP with MAD, multimodality imaging is the diagnostic tool to find out the disease behind many cardiac arrests of unknown cause.

Dark-Blood Late Gadolinium Enhancement MRI Is Noninferior to Bright-Blood LGE in Non-Ischemic Cardiomyopathies

(1) Background and Objectives: Dark-blood late gadolinium enhancement has been shown to be a reliable cardiac magnetic resonance (CMR) method for assessing viability and depicting myocardial scarring in ischemic cardiomyopathy. The aim of this study was to evaluate dark-blood LGE imaging compared with conventional bright-blood LGE for the detection of myocardial scarring in non-ischemic cardiomyopathies. (2) Materials and Methods: Patients with suspected non-ischemic cardiomyopathy were prospectively enrolled in this single-centre study from January 2020 to March 2023. All patients underwent 1.5 T CMR with both dark-blood and conventional bright-blood LGE imaging. Corresponding short-axis stacks of both techniques were analysed for the presence, distribution, pattern, and localisation of LGE, as well as the quantitative scar size (%). (3) Results: 343 patients (age 44 ± 17 years; 124 women) with suspected non-ischemic cardiomyopathy were examined. LGE was detected in 123 of 343 cases (36%) with excellent inter-reader agreement (κ 0.97-0.99) for both LGE techniques. Dark-blood LGE showed a sensitivity of 99% (CI 98-100), specificity of 99% (CI 98-100), and an accuracy of 99% (CI 99-100) for the detection of non-ischemic scarring. No significant difference in total scar size (%) was observed. Dark-blood imaging with mean 5.35 ± 4.32% enhanced volume of total myocardial volume, bright-blood with 5.24 ± 4.28%, p = 0.84. (4) Conclusions: Dark-blood LGE imaging is non-inferior to conventional bright-blood LGE imaging in detecting non-ischemic scarring. Therefore, dark-blood LGE imaging may become an equivalent method for the detection of both ischemic and non-ischemic scars.

Diagnostic accuracy of left atrial function and strain for differentiating between acute and chronic myocardial infarction

BACKGROUND

The cardiac magnetic resonance tissue tracking (CMR-TT) technique was used to obtain left atrial strain and strain rate in patients with myocardial infarction (MI) and to evaluate the utility of this technique in the quantitative assessment of myocardial infarction for distinguishing acute from chronic myocardial infarction.

METHODS

We retrospectively analyzed 36 consecutive patients with acute myocardial infarction (AMI) and 29 patients with chronic myocardial infarction (CMI) who underwent CMR and 30 controls. Left atrial (LA) and ventricular functions were quantified by volumetric, and CMR-TT derived strain analysis from long and short left ventricular view cines. Receiver Operating Characteristics (ROC) analysis was used to determine the diagnostic accuracy of CMR-TT strain parameters for discriminating between acute and chronic myocardial infarction.

RESULTS

AMI and CMI participants had impaired LA reservoir function, conduit function and LA booster pump dysfunction compared to the controls. LA strain was more sensitive than LV global strain for the assessment of the MI stage. Peak late-negative SR yielded the best areas under the ROC curve (AUC) of 0.879, showing differentiation between acute and chronic myocardial infarction of all the LA strain parameters obtained. The highest significant differences between chronic myocardial infarction and normal myocardium were also found in the LV strain (p < 0.001) and LA functional parameters (p < 0.001), but there was no difference between AMI and normals.

CONCLUSIONS

CMR-TT-derived LA strain is a potential and robust tool in demonstrating impaired LA mechanics and quantifying LA dynamics, which have high sensitivity and specificity in the differential diagnosis of acute versus chronic myocardial infarction. Their use is thus worth popularizing in clinical application.

A distinct septal pattern of late gadolinium enhancement specific for COVID-induced myocarditis: A multicenter cardiovascular magnetic resonance study

BACKGROUND

Coronavirus disease-19 (COVID-19) is a great medical challenge provoking acute respiratory distress, pulmonary manifestations, and cardiovascular (CV) consequences.

AIMS

This study compares cardiac injury in COVID-19 myocarditis patients with non-COVID myocarditis patients.

METHODS

Patients who recovered from COVID-19 were scheduled for cardiovascular magnetic resonance (CMR) owing to clinical myocarditis suspicion. The retrospective non-COVID-19 myocarditis (2018-2019) group was enrolled (n=221 patients). All patients underwent a contrast-enhanced CMR, conventional myocarditis protocol, and late gadolinium enhancement (LGE). The COVID study group included 552 patients with a mean (standard deviation [SD]) age 45.9 (12.6) years old.

RESULTS

CMR assessment confirmed a myocarditis-like LGE in 46% of the cases (68.5% of the segments with LGE <25% transmural extent), left ventricular (LV) dilatation in 10%, and systolic dysfunction in 16%. The COVID-myocarditis group showed a smaller median (interquartile range [IQR]) LV LGE (4.4% [2.9%-8.1%] vs. 5.9% [4.4%-11.8%]; P <0.001), lower LVEDV (144.6 [125.5-178] ml vs. 162.8 [136.6-194] ml; P <0.001), limited functional consequence (LVEF, 59% [54.1%-65%] vs. 58% [52%-63%]; P = 0.01), and a higher rate of pericarditis (13.6% vs. 6%; P = 0.03) compared to non-COVID myocarditis. The COVID-induced injury was more frequent in septal segments (2, 3, 14), and non-COVID myocarditis showed higher affinity to lateral wall segments (P <0.01). Neither obesity nor age was associated with LV injury or remodeling in subjects with COVID-myocarditis.

CONCLUSIONS

COVID-19-induced myocarditis is associated with minor LV injury with a significantly more frequent septal pattern and a higher pericarditis rate than non-COVID-19 myocarditis.

Building a comprehensive cardiovascular magnetic resonance exam on a commercial 0.55 T system: A pictorial essay on potential applications

Background

Contemporary advances in low-field magnetic resonance imaging systems can potentially widen access to cardiovascular magnetic resonance (CMR) imaging. We present our initial experience in building a comprehensive CMR protocol on a commercial 0.55 T system with a gradient performance of 26 mT/m amplitude and 45 T/m/s slew rate. To achieve sufficient image quality, we adapted standard imaging techniques when possible, and implemented compressed-sensing (CS) based techniques when needed in an effort to compensate for the inherently low signal-to-noise ratio at lower field strength.

Methods

A prototype CMR exam was built on an 80 cm, ultra-wide bore commercial 0.55 T MR system. Implementation of all components aimed to overcome the inherently lower signal of low-field and the relatively longer echo and repetition times owing to the slower gradients. CS-based breath-held and real-time cine imaging was built utilizing high acceleration rates to meet nominal spatial and temporal resolution recommendations. Similarly, CS 2D phase-contrast cine was implemented for flow. Dark-blood turbo spin echo sequences with deep learning based denoising were implemented for morphology assessment. Magnetization-prepared single-shot myocardial mapping techniques incorporated additional source images. CS-based dynamic contrast-enhanced imaging was implemented for myocardial perfusion and 3D MR angiography. Non-contrast 3D MR angiography was built with electrocardiogram-triggered, navigator-gated magnetization-prepared methods. Late gadolinium enhanced (LGE) tissue characterization methods included breath-held segmented and free-breathing single-shot imaging with motion correction and averaging using an increased number of source images. Proof-of-concept was demonstrated through porcine infarct model, healthy volunteer, and patient scans.

Results

Reasonable image quality was demonstrated for cardiovascular structure, function, flow, and LGE assessment. Low-field afforded utilization of higher flip angles for cine and MR angiography. CS-based techniques were able to overcome gradient speed limitations and meet spatial and temporal resolution recommendations with imaging times comparable to higher performance scanners. Tissue mapping and perfusion imaging require further development.

Conclusion

We implemented cardiac applications demonstrating the potential for comprehensive CMR on a novel commercial 0.55 T system. Further development and validation studies are needed before this technology can be applied clinically.

Cardiovascular Magnetic Resonance Demonstrates Myocardial Inflammation of Differing Etiologies and Acuities in Patients with Genetic and Inflammatory Myopathies

INTRODUCTION

Myopathies are heterogeneous neuromuscular diseases of genetic and/or inflammatory etiology that affect both cardiac and skeletal muscle. We investigated the prevalence of cardiac inflammation in patients with myopathies, cardiovascular symptoms, and normal echocardiography using cardiovascular magnetic resonance (CMR).

METHODS

We prospectively evaluated 51 patients with various genetic (n = 23) and inflammatory (n = 28) myopathies (median age, IQR: 12 (11-15) years, 22% girls; 61 (55-65) years, 46% women, respectively) and compared their CMR findings to corresponding age- and sex-matched controls (n = 21 and 20, respectively) and to each other.

RESULTS

Patients with genetic myopathy had similar biventricular morphology and function to healthy controls but showed higher late gadolinium enhancement (LGE), native T1 mapping, extracellular volume fraction (ECV), and T2 mapping values. Collectively, 22 (95.7%) patients with genetic myopathy had a positive T1-criterion and 3 (13.0%) had a positive T2-criterion according to the updated Lake Louise criteria. Compared with healthy controls, patients with inflammatory myopathy showed preserved left ventricular (LV) function and reduced LV mass, while all CMR-derived tissue characterization indices were significantly higher (p < 0.001 for all). All patients had a positive T1-criterion, and 27 (96.4%) had a positive T2-criterion. A positive T2-criterion or T2-mapping > 50 ms could discriminate between patients with genetic and inflammatory myopathies with a sensitivity of 96.4% and a specificity of 91.3% (AUC = 0.9557).

CONCLUSIONS

The vast majority of symptomatic patients with inflammatory myopathies and normal echocardiography show evidence of acute myocardial inflammation. In contrast, acute inflammation is rare in patients with genetic myopathies, who show evidence of chronic low-grade inflammation.

Myocardial late gadolinium enhancement using delayed 3D IR-FLASH in the pediatric population: feasibility and diagnostic performance compared to single-shot PSIR-bSSFP

BACKGROUND

This study compares three-dimensional (3D) high-resolution (HR) late gadolinium enhancement (LGE; 3D HR-LGE) imaging using a respiratory navigated, electrocardiographically-gated inversion recovery gradient echo sequence with conventional LGE imaging using a single-shot phase-sensitive inversion recovery (PSIR) balanced steady-state free precession (bSSFP; PSIR-bSSFP) sequence for routine clinical use in the pediatric population.

METHODS

Pediatric patients (0-18 years) who underwent clinical cardiovascular magnetic resonance (CMR) with both 3D HR-LGE and single-shot PSIR-bSSFP LGE between January 2018 and June 2020 were included. Image quality (0-4) and detection of LGE in the left ventricle (LV) (per 17 segments), in the right ventricle (RV) (per 3 segments), as endocardial fibroelastosis (EFE), at the hinge points, and at the papillary muscles was analyzed by two blinded readers for each sequence. Ratios of the mean signal intensity of LGE to normal myocardium (LGE:Myo) and to LV blood pool (LGE:Blood) were recorded. Data is presented as median (1st-3rd quartiles). Wilcoxon signed rank test and chi-square analyses were used as appropriate. Inter-rater agreement was analyzed using weighted κ-statistics.

RESULTS

102 patients were included with median age at CMR of 8 (1-13) years-old and 44% of exams performed under general anesthesia. LGE was detected in 55% of cases. 3D HR LGE compared to single-shot PSIR-bSSFP had longer scan time [4:30 (3:35-5:34) vs 1:11 (0:47-1:32) minutes, p < 0.001], higher image quality ratings [3 (3-4) vs 2 (2-3), p < 0.001], higher LGE:Myo [23.7 (16.9-31.2) vs 5.0 (2.9-9.0), p < 0.001], detected more segments of LGE in both the LV [4 (2-8) vs 3 (1-7), p = 0.045] and RV [1 (1-1) vs 1 (0-1), p < 0.001], and also detected more cases of LGE with 13/56 (23%) of patients with LGE only detectable by 3D HR LGE (p < 0.001). 3D HR LGE specifically detected a greater proportion of RV LGE (27/27 vs 17/27, p < 0.001), EFE (11/11 vs 5/11, p = 0.004), and papillary muscle LGE (14/15 vs 4/15, p < 0.001). Inter-rater agreement for the recorded variables ranged from 0.42 to 1.00.

CONCLUSIONS

3D HR LGE achieves greater image quality and detects more LGE than conventional single-shot PSIR-bSSFP LGE imaging, and should be considered an alternative to conventional LGE sequences for routine clinical use in the pediatric population.

Prediction of Recurrence of Atrial Fibrillation Post-ablation Based on Atrial Fibrosis Seen on Late Gadolinium Enhancement MRI: A Metaanalysis

OBJECTIVES

This meta-analysis aims to investigate the recurrence of atrial fibrillation (AF) post-ablation based on the various stages of fibrosis seen in the late gadolinium enhancement magnetic resonance imaging (LGE-MRI).

METHODS

Electronic databases were searched using specific terms and identified nine studies that met the inclusion criteria. A total of 1,787 patients underwent LGE-MRI to assess atrial fibrosis before catheter ablation for AF. We performed three analyses: first, we compared stage IV versus stage I (reference group). The second set examined the combined stages III and IV versus stages I and II (reference group). The third set compared stage IV versus combined stages I, II, and III. The metanalysis relied on a random-effects model to pool the odds ratios (OR) and 95% confidence intervals (CI) using the DerSimonian and Laird method. The data was analyzed using StatsDirect software in England.

RESULTS

The study showed a higher rate of AF recurrence after ablation in stage IV atrial fibrosis than in stage I (OR, 9.54; 95% CI, 3.81 to 28.89; P<00001). Also, in patients with combined stages III & IV of atrial fibrosis, AF recurrence was significantly higher after ablation than in stages I & II groups (OR, 2.37; 95% CI, 1.61 to 3.50; P<00001). Similarly, compared to combined stages I, II, and III, patients with stage IV have higher odds of recurrence post-ablation (OR, 4.24; 95% CI, 2.39- 7.52, P < 0.001).

CONCLUSION

This metanalysis demonstrates the strong association between left atrial fibrosis in LGE-MRI and AF post-ablation recurrence. The finding of this study will further assist clinicians in predicting the recurrence rate of AF based on the amount of fibrosis and tailor therapeutic decisions for further management.

Comprehensive Cardiac Magnetic Resonance to Detect Subacute Myocarditis

(1) Background: Compared to acute myocarditis in the initial phase, detection of subacute myocarditis with cardiac magnetic resonance (CMR) parameters can be challenging due to a lower degree of myocardial inflammation compared to the acute phase. (2) Objectives: To systematically evaluate non-invasive CMR imaging parameters in acute and subacute myocarditis. (3) Methods: 48 patients (age 37 (IQR 28−55) years; 52% female) with clinically suspected myocarditis were consecutively included. Patients with onset of symptoms ≤2 weeks prior to 1.5T CMR were assigned to the acute group (n = 25, 52%), patients with symptom duration >2 to 6 weeks were assigned to the subacute group (n = 23, 48%). CMR protocol comprised morphology, function, 3D-strain, late gadolinium enhancement (LGE) imaging and mapping (T1, ECV, T2). (4) Results: Highest diagnostic performance in the detection of subacute myocarditis was achieved by ECV evaluation either as single parameter or in combination with T1 mapping (applying a segmental or global increase of native T1 > 1015 ms and ECV > 28%), sensitivity 96% and accuracy 91%. Compared to subacute myocarditis, acute myocarditis demonstrated higher prevalence and extent of LGE (AUC 0.76) and increased T2 (AUC 0.66). (5) Conclusions: A comprehensive CMR approach allows reliable diagnosis of clinically suspected subacute myocarditis. Thereby, ECV alone or in combination with native T1 mapping indicated the best performance for diagnosing subacute myocarditis. Acute vs. subacute myocarditis is difficult to discriminate by CMR alone, due to chronological connection and overlap of pathologic findings.

Using Multiparametric Cardiac Magnetic Resonance to Phenotype and Differentiate Biopsy-Proven Chronic from Healed Myocarditis and Dilated Cardiomyopathy

(1) Objectives: To discriminate biopsy-proven myocarditis (chronic vs. healed myocarditis) and to differentiate from dilated cardiomyopathy (DCM) using cardiac magnetic resonance (CMR). (2) Methods: A total of 259 consecutive patients (age 51 ± 15 years; 28% female) who underwent both endomyocardial biopsy (EMB) and CMR in the years 2008−2021 were evaluated. According to right-ventricular EMB results, patients were divided into either chronic (n = 130, 50%) or healed lymphocytic myocarditis (n = 60, 23%) or DCM (n = 69, 27%). The CMR protocol included functional, strain, and late gadolinium enhancement (LGE) imaging, T2w imaging, and T2 mapping. (3) Results: Left-ventricular ejection fraction (LV-EF) was higher, and the indexed end-diastolic volume (EDV) was lower in myocarditis patients (chronic: 42%, median 96 mL/m²; healed: 49%, 86 mL/m²) compared to the DCM patients (31%, 120 mL/m²), p < 0.0001. Strain analysis demonstrated lower contractility in DCM patients vs. myocarditis patients, p < 0.0001. Myocarditis patients demonstrated a higher LGE prevalence (68% chronic; 59% healed) than the DCM patients (45%), p = 0.01. Chronic myocarditis patients showed a higher myocardial edema prevalence and ratio (59%, median 1.3) than healed myocarditis (23%, 1.3) and DCM patients (13%, 1.0), p < 0.0001. T2 mapping revealed elevated values more frequently in chronic (90%) than in healed (21%) myocarditis and DCM (23%), p < 0.0001. T2 mapping yielded an AUC of 0.89 (sensitivity 90%, specificity 76%) in the discrimination of chronic from healed myocarditis and an AUC of 0.92 (sensitivity 86%, specificity 91%) in the discrimination of chronic myocarditis from DCM, both p < 0.0001. (4) Conclusions: Multiparametric CMR imaging, including functional parameters, LGE and T2 mapping, may allow differentiation of chronic from healed myocarditis and DCM and therefore help to optimize patient management in this clinical setting.

Association of NT-proBNP and hs-cTnT with Imaging Markers of Diastolic Dysfunction and Focal Myocardial Fibrosis in Hypertrophic Cardiomyopathy

Serum biomarkers such as N-terminal prohormone of the brain natriuretic peptide (NT-proBNP) and cardiac troponins are elevated in patients with hypertrophic cardiomyopathy (HCM). At present, it is not clear if these markers are associated with distinct clinical alterations in HCM, such as left ventricular hypertrophy, outflow tract obstruction, myocardial fibrosis and/or diastolic dysfunction (DD), which are associated with adverse cardiovascular outcome. Here we evaluate the association of NT-proBNP and high sensitivity cardiac troponin T (hs-cTnT) to a variety of cardiac imaging parameters in HCM patients in a multivariable regression analysis. This retrospective cross-sectional study included 366 HCM patients who underwent transthoracic echocardiography (TTE), 218 of whom also obtained cardiovascular magnetic resonance (CMR) to assess focal myocardial fibrosis by LGE. Multivariable regression analyses revealed the strongest association of the DD parameters E/E′ mean and E/E′ septal with NT-proBNP (b = 0.06, 95%-CI [0.05−0.07], p < 0.001, R2 = 0.28; b = 0.08, 95%-CI [0.06−0.1], p < 0.001, R2 = 0.25) and LGE size showed the strongest association with hs-cTnT (b = 0.20, 95%-CI [0.15−0.24], p < 0.001, R2 = 0.28). This study indicates that NT-proBNP and hs-cTnT are associated with structural and functional alterations in HCM. NT-proBNP is a stronger predictor for DD, while hs-cTnT is associated with the extent of focal myocardial fibrosis. Both biomarkers might be useful in the diagnostic procedure in addition to imaging parameters.

Cardiovascular magnetic resonance for suspected cardiac amyloidosis: where are we now?

Cardiac amyloidosis (CA) is an underdiagnosed form of restrictive cardiomyopathy leading to a rapid progression into heart failure. Evaluation of CA requires a multimodality approach making use of echocardiography, cardiac magnetic imaging (CMR), and nuclear imaging. With superior tissue characterization, high-resolution imaging, and precise cardiac assessment, CMR has emerged as a versatile tool in the workup of cardiac amyloidosis with a wide array of parameters both visual and quantitative. This includes late gadolinium enhancement patterns, T1/T2 mapping, and extracellular volume (ECV) measurement providing robust diagnostic accuracies, patient stratification, and prognostication. Recent advancements have introduced new measures able to identify early disease, track disease progression, and response to therapy positioning CMR as an instrumental imaging modality in the era of rising interest in CA screening and emerging effective therapies.

Acute-Phase Inflammatory Reaction Predicts CMR Myocardial Scar Pattern and 2-Year Mortality in STEMI Patients Undergoing Primary PCI

(1) Background: The inflammatory response following MI plays an important role in the healing, scar formation, and left ventricle (LV) remodeling. Cardiac magnetic resonance (CMR) imaging can accurately quantify the extent of myocardial scarring. The study aimed to investigate: (a) the relationship between acute inflammatory response and the CMR parameters of the scarring extent, and (b) the predictive power of inflammatory biomarkers and myocardial scarring for 2-year mortality. (2) Methods: The study included 202 STEMI patients, who underwent pPCI. Serum hs-CRP, IL-6, P-selectin, E-selectin, I-CAM, and V-CAM levels were determined at admission, and hs-CRP on the fifth day. Patients underwent LGE-CMR after 1 month, for LV volumes, ejection fraction (EF), infarct size (IS), and transmurality. Subjects were divided into tertiles according to the IS, and 2-year all-cause mortality was determined. (3) Results: IL-6 was associated with IS (r = 0.324, p = 0.01), increased transmurality index (r = 0.3, p = 0.01), and lower LVEF (r = −0.3, p = 0.02). Admission hs-CRP levels were not associated with IS, transmurality, or mortality, while hs-CRP at day 5 was a significant predictor for IS (AUC = 0.635, p = 0.05) as well as IL-6 levels (AUC = 0.685, p < 0.001). Mortality was significantly higher in the upper IS tertiles (6% vs. 8.7% vs. 24.52%, p = 0.005). IS was a significant predictor of 2-year mortality (AUC = 0.673, p = 0.002), with a cut-off value of 28.81 g, as well as high transmurality (AUC = 0.641, p = 0.013), with a cut off value of 18.38 g. (4) Conclusions: The serum levels of IL-6 and day-5 hs-CRP predict IS and transmurality, and day-5 hs-CRP levels are independent predictors of 2-year mortality in STEMI patients treated with pPCI. The CMR pattern of myocardial scarring after 1 month, as expressed by the magnitude of IS and transmurality, is a significant predictor for 2-year mortality after revascularized STEMI.

Dlx1/2-dependent expression of Meis2 promotes neuronal fate determination in the mammalian striatum

The striatum is a central regulator of behavior and motor function through the actions of D1 and D2 medium-sized spiny neurons (MSNs), which arise from a common lateral ganglionic eminence (LGE) progenitor. The molecular mechanisms of cell fate specification of these two neuronal subtypes are incompletely understood. Here, we found that deletion of murine Meis2, which is highly expressed in the LGE and derivatives, led to a large reduction in striatal MSNs due to a block in their differentiation. Meis2 directly binds to the Zfp503 and Six3 promoters and is required for their expression and specification of D1 and D2 MSNs, respectively. Finally, Meis2 expression is regulated by Dlx1/2 at least partially through the enhancer hs599 in the LGE subventricular zone. Overall, our findings define a pathway in the LGE whereby Dlx1/2 drives expression of Meis2, which subsequently promotes the fate determination of striatal D1 and D2 MSNs via Zfp503 and Six3.

Cardiovascular Magnetic Resonance-Guided Radiofrequency Ablation: Where Are We Now?

The possibilities of cardiovascular magnetic resonance (CMR) imaging for myocardial tissue characterization and catheter ablation guidance are accompanied by some fictional concepts. In this review, we present the available facts about CMR-guided catheter ablation procedures as well as promising, however unproven, theoretical concepts. CMR promises to visualize the respective arrhythmogenic substrate and may thereby make it more localizable for electrophysiology (EP)-based ablation. Robust CMR imaging is challenged by motion of the heart resulting from cardiac and respiratory cycles. In contrast to conventional "passive" tracking of the catheter tip by real-time CMR, novel approaches based on "active" tracking are performed by integrating microcoils into the catheter tip that send a receiver signal. Several experimental and clinical studies were already performed based on real-time CMR for catheter ablation of atrial and ventricular arrhythmias. Importantly, successful ablation of the cavotricuspid isthmus was already performed in patients with typical atrial flutter. However, a complete EP procedure with real-time CMR-guided transseptal puncture and subsequent pulmonary vein isolation has not been shown so far in patients with atrial fibrillation. Moreover, real-time CMR-guided EP for ventricular tachycardia ablation was only performed in animal models using a transseptal, retrograde, or epicardial access-but not in humans. Essential improvements within the next few years regarding basic technical requirements, such as higher spatial and temporal resolution of real-time CMR imaging as well as clinically approved cardiac magnetic resonance-conditional defibrillators, are ultimately required-but can also be expected-and will move this field forward.

The Role of Cardiovascular Magnetic Resonance Imaging in the Assessment of Myocardial Fibrosis in Young and Veteran Athletes: Insights From a Meta-Analysis

Background: Cardiac magnetic resonance (CMR) combined with late gadolinium enhancement (LGE) has revealed a non-negligible increased incidence of myocardial fibrosis (MF) in athletes compared to healthy sedentary controls.

Objective: The aim of this systematic research and meta-analysis is to investigate and present our perspective regarding CMR indices in athletes compared to sedentary controls, including T1 values, myocardial extracellular volume (ECV) and positive LGE indicative of non-specific fibrosis, also to discuss the differences between young and veteran athletes.

Methods: The protocol included searching, up to October 2021, of MEDLINE, EMBASE, SPORTDiscus, Web of Science and Cochrane databases for original studies assessing fibrosis via CMR in athletes. A mean age of 40 years differentiated studies' athletic populations to veteran and young.

Results: The research yielded 14 studies including in total 1,312 individuals. There was a statistically significant difference in LGE fibrosis between the 118/759 athletes and 16/553 controls (Z = 5.2, P < 0.001, I² = 0%, P_I = 0.45). Notably, LGE fibrosis differed significantly between 546 (14.6%) veteran and 140 (25.7%) young athletes (P = 0.002). At 1.5T, T1 values differed between 117 athletes and 48 controls (P < 0.0001). A statistically significant difference was also shown at 3T (110 athletes vs. 41 controls, P = 0.0004), as well as when pooling both 1.5T and 3T populations (P < 0.00001). Mean ECV showed no statistically significant difference between these groups.

Conclusions: Based on currently available data, we reported that overall LGE based non-specific fibrosis and T1 values differ between athletes and sedentary controls, in contrast to ECV values. Age of athletes seems to have impact on the incidence of MF. Future prospective studies should focus on the investigation of the underlying pathophysiological mechanisms.

Multiparametric Cardiovascular Magnetic Resonance Approach in Diagnosing, Monitoring, and Prognostication of Myocarditis

Myocarditis represents the entity of an inflamed myocardium and is a diagnostic challenge caused by its heterogeneous presentation. Contemporary noninvasive evaluation of patients with clinically suspected myocarditis using cardiac magnetic resonance (CMR) includes dimensions and function of the heart chambers, conventional T2-weighted imaging, late gadolinium enhancement, novel T1 and T2 mapping, and extracellular volume fraction calculation. CMR feature-tracking, texture analysis, and artificial intelligence emerge as potential modern techniques to further improve diagnosis and prognostication in this clinical setting. This review will describe the evidence surrounding different CMR methods and image postprocessing methods and highlight their values for clinical decision making, monitoring, and risk stratification across stages of this condition.

Dark-blood late gadolinium enhancement CMR improves detection of papillary muscle fibrosis in patients with mitral valve prolapse

PURPOSE

Papillary muscle fibrosis may act as an arrhythmogenic substrate in patients with mitral valve prolapse (MVP). Previous studies used conventional bright-blood late gadolinium enhancement cardiovascular magnetic resonance (LGE CMR) imaging to assess papillary muscle fibrosis, although this technique suffers from poor scar-to-blood contrast which may limit its sensitivity, in contrast to dark-blood LGE. This study sought to compare bright-blood and dark-blood LGE for the detection of papillary muscle fibrosis in patients with MVP.

METHOD

60 patients with known isolated MVP referred for CMR were prospectively recruited. A routine CMR protocol was used to obtain cine imaging, dark-blood LGE and bright-blood LGE in three long-axis views and a stack of short-axis views. Flow mapping of the proximal aorta was performed to calculate mitral regurgitant volume. Images were analysed for cardiac volumes, ejection fraction, mitral regurgitation severity, MVP characteristics (mitral annular disjunction, prolapse volume) and presence of LGE at the papillary muscles and myocardium.

RESULTS

Dark-blood LGE detected significantly more subjects with LGE at the papillary muscles than bright-blood LGE (35% vs 15%, p = 0.002). There was no difference between LGE techniques regarding myocardial (non-papillary muscle) fibrosis (present in 25% each). No statistical differences were observed between patients with or without LGE at the papillary muscles regarding demographics, clinical data (including ventricular arrhythmia) and MVP characteristics. Furthermore, no association was found between LGE at the papillary muscles and at the myocardium.

CONCLUSIONS

Compared to bright-blood LGE, dark-blood LGE CMR improves the detection of LGE at the papillary muscles in patients with MVP.

Genome silencer therapy leading to 'regression' of cardiac amyloid load on cardiovascular magnetic resonance: a case report

BACKGROUND

Hereditary or variant transthyretin amyloidosis (ATTRv) is a progressive disease manifesting with neuropathy and/or cardiomyopathy. An early and accurate diagnosis of cardiac amyloidosis is a pre-requisite for timely and appropriate patient management, including anti-amyloid therapies, as it is associated with heart failure, conduction disease, and arrhythmias, leading to reduced quality of life and early death.

CASE SUMMARY

We present the case of an ATTRv male patient presenting with a mixed amyloidosis phenotype (neuropathy and cardiomyopathy). Cardiac disease manifestation comprised tachyarrhythmias (atrial fibrillation) and conduction abnormalities (atrio-ventricular block) in addition to segmental left ventricular (LV) hypertrophy (septal wall) due to regionally pronounced amyloid deposits in the basal LV myocardium. Interestingly, by means of serial cardiovascular magnetic resonance (CMR) studies, we were able to demonstrate an impressive and unexpected improvement of cardiomyopathy findings within a relatively short period-of-time after the implementation of genome-silencer therapies.

DISCUSSION

This is our second case report that showed ATTRv cardiomyopathy reversal under anti-amyloid therapy-documented by multi-parametric CMR. Our findings support the hypothesis that amyloid infiltration leading to cardiomyopathy is not an irreversible pathological process-but rather a dynamic one, that cannot only be stopped but even reversed (to a certain degree) by currently emerging anti-amyloid therapies. Moreover, the role of serial multi-parametric CMR imaging for surveillance of cardiomyopathy dynamics under these therapies is nicely illustrated.

Endogenous T1ρ cardiovascular magnetic resonance in hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is characterized by increased left ventricular wall thickness, cardiomyocyte hypertrophy, and fibrosis. Adverse cardiac risk characterization has been performed using late gadolinium enhancement (LGE), native T1, and extracellular volume (ECV). Relaxation time constants are affected by background field inhomogeneity. T1ρ utilizes a spin-lock pulse to decrease the effect of unwanted relaxation. The objective of this study was to study T1ρ as compared to T1, ECV, and LGE in HCM patients.

METHODS

HCM patients were recruited as part of the Novel Markers of Prognosis in Hypertrophic Cardiomyopathy study, and healthy controls were matched for comparison. In addition to cardiac functional imaging, subjects underwent T1 and T1ρ cardiovascular magnetic resonance imaging at short-axis positions at 1.5T. Subjects received gadolinium and underwent LGE imaging 15-20 min after injection covering the entire heart. Corresponding basal and mid short axis LGE slices were selected for comparison with T1 and T1ρ. Full-width half-maximum thresholding was used to determine the percent enhancement area in each LGE-positive slice by LGE, T1, and T1ρ. Two clinicians independently reviewed LGE images for presence or absence of enhancement. If in agreement, the image was labeled positive (LGE + +) or negative (LGE --); otherwise, the image was labeled equivocal (LGE + -).

RESULTS

In 40 HCM patients and 10 controls, T1 percent enhancement area (Spearman's rho = 0.61, p < 1e-5) and T1ρ percent enhancement area (Spearman's rho = 0.48, p < 0.001e-3) correlated with LGE percent enhancement area. T1 and T1ρ percent enhancement areas were also correlated (Spearman's rho = 0.28, p = 0.047). For both T1 and T1ρ, HCM patients demonstrated significantly longer relaxation times compared to controls in each LGE category (p < 0.001 for all). HCM patients also showed significantly higher ECV compared to controls in each LGE category (p < 0.01 for all), and LGE -- slices had lower ECV than LGE + + (p = 0.01).

CONCLUSIONS

Hyperenhancement areas as measured by T1ρ and LGE are moderately correlated. T1, T1ρ, and ECV were elevated in HCM patients compared to controls, irrespective of the presence of LGE. These findings warrant additional studies to investigate the prognostic utility of T1ρ imaging in the evaluation of HCM patients.

Clinical impact of myocardial fibrosis in severe aortic stenosis

The pressure overload due to the progressive narrowing of the valve area determines the development of the left ventricular hypertrophy which characterizes aortic stenosis (AS). The onset of myocardial fibrosis marks the inexorable decline of an initially compensatory response towards heart failure. However, myocardial fibrosis does not yet represent a key element in the prognostic and therapeutic framework of AS. In this context, cardiac magnetic resonance imaging plays a major role by highlighting both the focal irreversible fibrotic replacement, using the late gadolinium enhancement (LGE) technique, and the earlier diffuse reversible interstitial fibrosis, using the T1 mapping techniques. For this reason, the presence of myocardial fibrosis would be useful to identify a subgroup of patients at greater risk of events among the subjects with severe AS. Actually, more and more evidences seem to identify the presence of LGE as a powerful prognostic factor to be used to optimize the timing of prosthetic valve replacement. Randomized clinical trials, such as the EVoLVeD trial currently underway, will be needed to better define the importance of myocardial fibrosis assessment in the management of patients with AS.

The Association between the Extent of Late Gadolinium Enhancement and Diastolic Dysfunction in Hypertrophic Cardiomyopathy

Background Diastolic dysfunction in hypertrophic cardiomyopathy (HCM) patients is a frequent, yet poorly understood phenomenon.

Purpose The purpose of this study is to assess the relationship between the myocardial fibrosis and diastolic dysfunction in patients with HCM.

Materials and Methods We retrospectively investigated the impact of the myocardial fibrosis, as assessed by the extent of late gadolinium enhancement (LGE-%) on cardiac magnetic resonance imaging (CMRI), on diastolic dysfunction in 110 patients with HCM. The diastolic dysfunction was evaluated by the left atrial (LA) volume index measured on CMRI and lateral septal E/E′ ratio calculated on echocardiography.

Results : There was a moderate correlation between the LGE-% and LA volume ( r = 0.59, p < 0.0001). The logistic regression model of LGE-%, mitral regurgitation, and total left ventricular mass that investigated the independent predictors of LA volume identified LGE-% as the only independent parameter associated with the LA volume index ( β = 0.30, p = 0.003). No correlation was observed between the LGE-% and E/E′( r = 0.24, p = 0.009).

Conclusions Myocardial fibrosis in HCM patients is associated with a chronic diastolic burden as represented by increased LA volume. However, the fibrosis does not influence the E/E′ ratio, which is a well-known parameter of ventricular relaxation, restoring forces, and filling pressure.

Cardiovascular magnetic resonance imaging of functional and microstructural changes of the heart in a longitudinal pig model of acute to chronic myocardial infarction

BACKGROUND

We examined the dynamic response of the myocardium to infarction in a longitudinal porcine study using relaxometry, functional as well as diffusion cardiovascular magnetic resonance (CMR). We sought to compare non contrast CMR methods like relaxometry and in-vivo diffusion to contrast enhanced imaging and investigate the link of microstructural and functional changes in the acute and chronically infarcted heart.

METHODS

CMR was performed on five myocardial infarction pigs and four healthy controls. In the infarction group, measurements were obtained 2 weeks before 90 min occlusion of the left circumflex artery, 6 days after ischemia and at 5 as well as 9 weeks as chronic follow-up. The timing of measurements was replicated in the control cohort. Imaging consisted of functional cine imaging, 3D tagging, T2 mapping, native as well as gadolinium enhanced T1 mapping, cardiac diffusion tensor imaging, and late gadolinium enhancement imaging.

RESULTS

Native T1, extracellular volume (ECV) and mean diffusivity (MD) were significantly elevated in the infarcted region while fractional anisotropy (FA) was significantly reduced. During the transition from acute to chronic stages, native T1 presented minor changes (< 3%). ECV as well as MD increased from acute to the chronic stages compared to baseline: ECV: 125 ± 24% (day 6) 157 ± 24% (week 5) 146 ± 60% (week 9), MD: 17 ± 7% (day 6) 33 ± 14% (week 5) 29 ± 15% (week 9) and FA was further reduced: - 31 ± 10% (day 6) - 38 ± 8% (week 5) - 36 ± 14% (week 9). T2 as marker for myocardial edema was significantly increased in the ischemic area only during the acute stage (83 ± 3 ms infarction vs. 58 ± 2 ms control p < 0.001 and 61 ± 2 ms in the remote area p < 0.001). The analysis of functional imaging revealed reduced left ventricular ejection fraction, global longitudinal strain and torsion in the infarct group. At the same time the transmural helix angle (HA) gradient was steeper in the chronic follow-up and a correlation between longitudinal strain and transmural HA gradient was detected (r = 0.59 with p < 0.05). Comparing non-gadolinium enhanced data T2 mapping showed the largest relative change between infarct and remote during the acute stage (+ 33 ± 4% day 6, with p = 0.013 T2 vs. MD, p = 0.009 T2 vs. FA and p = 0.01 T2 vs. T1) while FA exhibited the largest relative change between infarct and remote during the chronic follow-up (+ 31 ± 2% week 5, with p = N.S. FA vs. MD, p = 0.03 FA vs. T2 and p = 0.003 FA vs. T1). Overall, diffusion parameters provided a higher contrast (> 23% for MD and > 27% for FA) during follow-up compared to relaxometry (T1 17-18%/T2 10-20%).

CONCLUSION

During chronic follow-up after myocardial infarction, cardiac diffusion tensor imaging provides a higher sensitivity for mapping microstructural alterations when compared to non-contrast enhanced relaxometry with the added benefit of providing directional tensor information to assess remodelling of myocyte aggregate orientations, which cannot be otherwise assessed.

Long-term risk of sudden cardiac death in hypertrophic cardiomyopathy: a cardiac magnetic resonance outcome study

AIMS

Sudden cardiac death (SCD) is an appalling complication of hypertrophic cardiomyopathy (HCM). There is an ongoing discussion about the optimal SCD risk stratification strategy since established SCD risk models have suboptimal discriminative power. The aim of this study was to evaluate the prognostic value of late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) for SCD risk stratification compared to the European Society of Cardiology (ESC) SCD risk score and traditional risk factors in an >10-year follow-up.

METHODS AND RESULTS

Two hundred and twenty consecutive patients with HCM and LGE-CMR were enrolled. Follow-up data were available in 203 patients (median age 58 years, 61% male) after a median follow-up period of 10.4 years. LGE was present in 70% of patients with a median LGE amount of 1.6%, the median ESC 5-year SCD risk score was 1.84. In the overall cohort, SCD rates were 2.3% at 5 years, 4.8% at 10 years, and 15.7% at 15 years, independent from established risk models. An LGE amount of >5% left ventricular (LV) mass portends the highest risk for SCD with SCD prevalences of 5.5% at 5 years, 13.0% at 10 years, and 33.3% at 15 years. Conversely, patients with no or ≤5% LGE of LV mass have favourable prognosis.

CONCLUSIONS

LGE-CMR in HCM patients allows effective 10-year SCD risk stratification beyond established risk factors. LGE amount might be added to established risk models to improve its discriminatory power. Specifically, patients with >5% LGE should be carefully monitored and might be adequate candidates for primary prevention implantable cardioverter-defibrillator during the clinical long-term course.

Homeobox Gene Six3 is Required for the Differentiation of D2-Type Medium Spiny Neurons

Medium spiny neurons (MSNs) in the striatum, which can be divided into D1 and D2 MSNs, originate from the lateral ganglionic eminence (LGE). Previously, we reported that Six3 is a downstream target of Sp8/Sp9 in the transcriptional regulatory cascade of D2 MSN development and that conditionally knocking out Six3 leads to a severe loss of D2 MSNs. Here, we showed that Six3 mainly functions in D2 MSN precursor cells and gradually loses its function as D2 MSNs mature. Conditional deletion of Six3 had little effect on cell proliferation but blocked the differentiation of D2 MSN precursor cells. In addition, conditional overexpression of Six3 promoted the differentiation of precursor cells in the LGE. We measured an increase of apoptosis in the postnatal striatum of conditional Six3-knockout mice. This suggests that, in the absence of Six3, abnormally differentiated D2 MSNs are eliminated by programmed cell death. These results further identify Six3 as an important regulatory element during D2 MSN differentiation.

Cine and late gadolinium enhancement MRI registration and automated myocardial infarct heterogeneity quantification

PURPOSE

To develop an approach for automated quantification of myocardial infarct heterogeneity in late gadolinium enhancement (LGE) cardiac MRI.

METHODS

We acquired 2D short-axis cine and 3D LGE in 10 pigs with myocardial infarct. The 2D cine myocardium was segmented and registered to the LGE images. LGE image signal intensities within the warped cine myocardium masks were analyzed to determine the thresholds of infarct core (IC) and gray zone (GZ) for the standard-deviation (SD) and full-width-at-halfmaximum (FWHM) methods. The initial IC, GZ, and IC + GZ segmentations were postprocessed using a normalized cut approach. Cine segmentation and cine-LGE registration accuracies were evaluated using dice similarity coefficient and average symmetric surface distance. Automated IC, GZ, and IC + GZ volumes were compared with manual results using Pearson correlation coefficient (r), Bland-Altman analyses, and intraclass correlation coefficient.

RESULTS

For n = 87 slices containing scar, we achieved cine segmentation dice similarity coefficient = 0.87 ± 0.12, average symmetric surface distance = 0.94 ± 0.74 mm (epicardium), and 1.03 ± 0.82 mm (endocardium) in the scar region. For cine-LGE registration, dice similarity coefficient was 0.90 ± 0.06 and average symmetric surface distance was 0.72 ± 0.39 mm (epicardium) and 0.86 ± 0.53 mm (endocardium) in the scar region. For both SD and FWHM methods, automated IC, GZ, and IC + GZ volumes were strongly (r > 0.70) correlated with manual measurements, and the correlations were not significantly different from interobserver correlations (P > .05). The agreement between automated and manual scar volumes (intraclass correlation coefficient = 0.85-0.96) was similar to that between two observers (intraclass correlation coefficient = 0.81-0.99); automated scar segmentation errors were not significantly different from interobserver segmentation differences (P > .05).

CONCLUSIONS

Our approach provides fully automated cine-LGE MRI registration and LGE myocardial infarct heterogeneity quantification in preclinical studies.

Ventricular Tachycardia: A Rare Case of Myocardial Silicosis

Chronic exposure to silica is a recognized health hazard. Manifestations of pulmonary and extrapulmonary silicosis are well described. Secondary pulmonary arterial hypertension and pericardial involvement are described, but myocardial involvement has not been reported. In this case of newly diagnosed pulmonary silicosis, ventricular tachycardia results are shown from pathological involvement of ventricular myocardium. (Level of Difficulty: Beginner.).

Cardiac magnetic resonance imaging for the detection of myocardial involvement in granulomatosis with polyangiitis

The prevalence of undiagnosed cardiac involvement in granulomatosis with polyangiitis (GPA) is unknown. In this prospective study we investigated the utility of cardiovascular magnetic resonance (CMR) to identify myocardial abnormalities in GPA and their correlation with disease phenotype. Twenty-six patients with GPA and no cardiovascular disease or diabetes mellitus underwent contrast-enhanced CMR, including late gadolinium-enhancement (LGE), T1-mapping for native T1 and extra-cellular volume (ECV) quantification for assessment of myocardial fibrosis, cine imaging and tissue tagging for assessment of left ventricular (LV) function. Twenty-five healthy volunteers (HV) with comparable age, sex, BMI and arterial blood pressure served as controls. Patients with GPA had similar cardiovascular risk profile to HV. A focal, non-ischaemic LGE pattern of fibrosis was detected in 24% of patients and no controls (p = 0.010). Patients with myocardial LGE were less frequently PR3 ANCA (7% vs 93%, p = 0.007), and had involvement of the lower respiratory tract and skin. LGE scar mass was higher in patients presenting with renal involvement. Native T1 and ECV were higher in patients with GPA than HV; ECV was higher in those with relapsing disease, and native T1 was inversely associated with PR3 ANCA (β = - 0.664, p = 0.001). Peak systolic strain was slightly reduced in GPA compared to controls; LV ejection function was inversely correlated with disease duration (β = - 0.454, p = 0.026). Patients with GPA have significant myocardial abnormalities on CMR. ANCA, systemic involvement and disease severity were associated with myocardial fibrosis. CMR could be a useful tool for risk stratification of myocardial involvement in GPA.

Association of scar distribution with epicardial electrograms and surface ventricular tachycardia QRS duration in nonischemic cardiomyopathy

INTRODUCTION

The association of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) with epicardial and surface ventricular tachycardia (VT) electrogram features, in nonischemic cardiomyopathy (NICM), is unknown. We sought to define the association of LGE and viable wall thickness with epicardial electrogram features and exit site paced QRS duration in patients with NICM.

METHODS

A total of 19 patients (age 53.5 ± 11.5 years) with NICM (ejection fraction 40.2 ± 13.2%) underwent CMR before VT ablation. LGE transmurality was quantified on CMR and coregistered with 2294 endocardial and 2724 epicardial map points.

RESULTS

Both bipolar and unipolar voltage were associated with transmural signal intensity on CMR. Longer electrogram duration and fractionated potentials were associated with increased LGE transmurality, but late potentials or local abnormal ventricular activity were more prevalent in nontransmural versus transmural LGE regions (p < .05). Of all critical VT sites, 19% were located adjacent to regions with LGE but normal bipolar and unipolar voltage. Exit site QRS duration was affected by LGE transmurality and intramural scar location, but not by wall thickness, at the impulse origin.

CONCLUSIONS

In patients with NICM and VT, LGE is associated with epicardial electrogram features and may predict critical VT sites. Additionally, exit site QRS duration is affected by LGE transmurality and intramural location at the impulse origin or exit.

Late gadolinium enhancement on CMRI in patients with LV noncompaction: An overestimated phenomenon?

BACKGROUND AND PURPOSE

Subendocardial fibrosis is recognized finding in left ventricular noncompaction (LVNC); however, the evidence regarding the patterns and the frequency of late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMRI) is controversial. The present study sought to assess the frequency and patterns of LGE in LVNC.

MATERIALS AND METHODS

Patients with a diagnosis of LVNC based on the echocardiographic CMRI criteria were enrolled in this retrospective study. The myocardial noncompacted-to-compacted ratio (NC/C) was perpendicularly measured on short-axis cine images. Two observers jointly assessed the presence of LGE on short-axis LGE images. The long-axis four-chamber and long-axis two-chamber images were used to confirm the presence of LGE if needed.

RESULTS

A total of 42 patients, 20 females (47.7%) and 22 were males (52.3%), were included in the study. The median age of the patients was 32.4 years (range 18-63). LGE was identified in 2 out of 42 patients (4.7%) with LVNC. LGE was identified in the interventricular septum involving the subendocardial layer and noncompacted lateral myocardial wall involving the trabeculae at mid-ventricular and basal levels.

CONCLUSION

LGE is uncommon in patients with LVNC. We highlight that the diagnosis of LVNC in patients with atypical LGE patterns, such as epicardial or transmural enhancement, should be reappraised and the other cardiac diseases should be discarded before establishing the final diagnosis.

Dmrt factors determine the positional information of cerebral cortical progenitors via differential suppression of homeobox genes

The spatiotemporal identity of neural progenitors and the regional control of neurogenesis are essential for the development of cerebral cortical architecture. Here, we report that mammalian DM domain factors (Dmrt) determine the identity of cerebral cortical progenitors. Among the Dmrt family genes expressed in the developing dorsal telencephalon, Dmrt3 and Dmrta2 show a medial^high/lateral^low expression gradient. Their simultaneous loss confers a ventral identity to dorsal progenitors, resulting in the ectopic expression of Gsx2 and massive production of GABAergic olfactory bulb interneurons in the dorsal telencephalon. Furthermore, double-mutant progenitors in the medial region exhibit upregulated Pax6 and more lateral characteristics. These ventral and lateral shifts in progenitor identity depend on Dmrt gene dosage. We also found that Dmrt factors bind to Gsx2 and Pax6 enhancers to suppress their expression. Our findings thus reveal that the graded expression of Dmrt factors provide positional information for progenitors by differentially repressing downstream genes in the developing cerebral cortex.

Clinical value of dark-blood late gadolinium enhancement cardiovascular magnetic resonance without additional magnetization preparation

BACKGROUND

For two decades, bright-blood late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) has been considered the reference standard for the non-invasive assessment of myocardial viability. While bright-blood LGE can clearly distinguish areas of myocardial infarction from viable myocardium, it often suffers from poor scar-to-blood contrast, making subendocardial scar difficult to detect. Recently, we proposed a novel dark-blood LGE approach that increases scar-to-blood contrast and thereby improves subendocardial scar conspicuity. In the present study we sought to assess the clinical value of this novel approach in a large patient cohort with various non-congenital ischemic and non-ischemic cardiomyopathies on both 1.5 T and 3 T CMR scanners of different vendors.

METHODS

Three hundred consecutive patients referred for clinical CMR were randomly assigned to a 1.5 T or 3 T scanner. An entire short-axis stack and multiple long-axis views were acquired using conventional phase sensitive inversion recovery (PSIR) LGE with TI set to null myocardium (bright-blood) and proposed PSIR LGE with TI set to null blood (dark-blood), in a randomized order. The bright-blood LGE and dark-blood LGE images were separated, anonymized, and interpreted in a random order at different time points by one of five independent observers. Each case was analyzed for the type of scar, per-segment transmurality, papillary muscle enhancement, overall image quality, observer confidence, and presence of right ventricular scar and intraventricular thrombus.

RESULTS

Dark-blood LGE detected significantly more cases with ischemic scar compared to conventional bright-blood LGE (97 vs 89, p = 0.008), on both 1.5 T and 3 T, and led to a significantly increased total scar burden (3.3 ± 2.4 vs 3.0 ± 2.3 standard AHA segments, p = 0.015). Overall image quality significantly improved using dark-blood LGE compared to bright-blood LGE (81.3% vs 74.0% of all segments were of highest diagnostic quality, p = 0.006). Furthermore, dark-blood LGE led to significantly higher observer confidence (confident in 84.2% vs 78.4%, p = 0.033).

CONCLUSIONS

The improved detection of ischemic scar makes the proposed dark-blood LGE method a valuable diagnostic tool in the non-invasive assessment of myocardial scar. The applicability in routine clinical practice is further strengthened, as the present approach, in contrast to other recently proposed dark- and black-blood LGE techniques, is readily available without the need for scanner adjustments, extensive optimizations, or additional training.

Retention Mechanism of Proteins in Hydroxyapatite Chromatography - Multimodal Interaction Based Protein Separations: A Model Study

BACKGROUND

Retention mechanism of proteins in hydroxyapatite chromatography (HAC) was investigated by linear gradient elution experiments (LGE).

MATERIALS AND METHODS

Several mobile phase (buffer) solution strategies and solutes were evaluated in order to probe the relative contributions of two adsorption sites of hydroxyapatite (HA) particles, C-site due to Ca (metal affinity) and P-site due to PO4 (cation-exchange). When P-site was blocked, two basic proteins, lysozyme (Lys) and ribonuclease A(RNase), were not retained whereas cytochrome C(Cyt C) and lactoferrin (LF) were retained and also retention of acidic proteins became stronger as the repulsion due to P-site was eliminated. The number of the binding site B values determined from LGE also increased, which also showed reduction of repulsion forces.

CONCLUSION

The selectivity (retention) of four basic proteins (RNase, Lys, Cyt C, LF) in HAC was different from that in ion-exchange chromatography. Moreover, it was possible to tune the selectivity by using NaCl gradient.

SP8 and SP9 coordinately promote D2-type medium spiny neuron production by activating Six3 expression

Dopamine receptor DRD1-expressing medium spiny neurons (D1 MSNs) and dopamine receptor DRD2-expressing medium spiny neurons (D2 MSNs) are the principal projection neurons in the striatum, which is divided into dorsal striatum (caudate nucleus and putamen) and ventral striatum (nucleus accumbens and olfactory tubercle). Progenitors of these neurons arise in the lateral ganglionic eminence (LGE). Using conditional deletion, we show that mice lacking the transcription factor genes Sp8 and Sp9 lose virtually all D2 MSNs as a result of reduced neurogenesis in the LGE, whereas D1 MSNs are largely unaffected. SP8 and SP9 together drive expression of the transcription factor Six3 in a spatially restricted domain of the LGE subventricular zone. Conditional deletion of Six3 also prevents the formation of most D2 MSNs, phenocopying the Sp8/9 mutants. Finally, ChIP-Seq reveals that SP9 directly binds to the promoter and a putative enhancer of Six3 Thus, this study defines components of a transcription pathway in a regionally restricted LGE progenitor domain that selectively drives the generation of D2 MSNs.

Defining myocardial fibrosis in haemodialysis patients with non-contrast cardiac magnetic resonance

Background

Extent of myocardial fibrosis (MF) determined using late gadolinium enhanced (LGE) predicts outcomes, but gadolinium is contraindicated in advanced renal disease. We assessed the ability of native T1-mapping to identify and quantify MF in aortic stenosis patients (AS) as a model for use in haemodialysis patients.

Methods

We compared the ability to identify areas of replacement-MF using native T1-mapping to LGE in 25 AS patients at 3 T. We assessed agreement between extent of MF defined by LGE full-width-half-maximum (FWHM) and the LGE 3-standard-deviations (3SD) in AS patients and nine T1 thresholding-techniques, with thresholds set 2-to-9 standard-deviations above normal-range (1083 ± 33 ms). A further technique was tested that set an individual T1-threshold for each patient (T11SD). The technique that agreed most strongly with FWHM or 3SD in AS patients was used to compare extent of MF between AS (n = 25) and haemodialysis patients (n = 25).

Results

Twenty-six areas of enhancement were identified on LGE images, with 25 corresponding areas of discretely increased native T1 signal identified on T1 maps. Global T1 was higher in haemodialysis than AS patients (1279 ms ± 5.8 vs 1143 ms ± 12.49, P < 0.01). No signal-threshold technique derived from standard-deviations above normal-range associated with FWHM or 3SD. T11SD correlated with FWHM in AS patients (r = 0.55) with moderate agreement (ICC = 0.64), (but not with 3SD). Extent of MF defined by T11SD was higher in haemodialysis vs AS patients (21.92% ± 1 vs 18.24% ± 1.4, P = 0.038), as was T1 in regions-of-interest defined as scar (1390 ± 8.7 vs 1276 ms ± 20.5, P < 0.01). There was no difference in the relative difference between remote myocardium and regions defined as scar, between groups (111.4 ms ± 7.6 vs 133.2 ms ± 17.5, P = 0.26).

Conclusions

Areas of MF are identifiable on native T1 maps, but absolute thresholds to define extent of MF could not be determined. Histological studies are needed to assess the ability of native-T1 signal-thresholding techniques to define extent of MF in haemodialysis patients.

Data is taken from the PRIMID-AS (NCT01658345) and CYCLE-HD studies (ISRCTN11299707).

Quantification of myocardial infarct area based on TRAFFn relaxation time maps - comparison with cardiovascular magnetic resonance late gadolinium enhancement, T1ρ and T2 in vivo

BACKGROUND

Two days after myocardial infarction (MI), the infarct consists mostly on necrotic tissue, and the myocardium is transformed through granulation tissue to scar in two weeks after the onset of ischemia in mice. In the current work, we determined and optimized cardiovascular magnetic resonance (CMR) methods for the detection of MI size during the scar formation without contrast agents in mice.

METHODS

We characterized MI and remote areas with rotating frame relaxation time mapping including relaxation along fictitious field in nth rotating frame (RAFFn), T1ρ and T2 relaxation time mappings at 1, 3, 7, and 21 days after MI. These results were compared to late gadolinium enhancement (LGE) and Sirius Red-stained histology sections, which were obtained at day 21 after MI.

RESULTS

All relaxation time maps showed significant differences in relaxation time between the MI and remote area. Areas of increased signal intensities after gadolinium injection and areas with increased TRAFF2 relaxation time were highly correlated with the MI area determined from Sirius Red-stained histology sections (LGE: R2 = 0.92, P < 0.01, TRAFF2: R2 = 0.95, P < 0.001). Infarct area determined based on T1ρ relaxation time correlated highly with Sirius Red histology sections (R2 = 0.97, P < 0.01). The smallest overestimation of the LGE-defined MI area was obtained for TRAFF2 (5.6 ± 4.2%) while for T1ρ overestimation percentage was > 9% depending on T1ρ pulse power.

CONCLUSION

T1ρ and TRAFF2 relaxation time maps can be used to determine accurately MI area at various time points in the mouse heart. Determination of MI size based on TRAFF2 relaxation time maps could be performed without contrast agents, unlike LGE, and with lower specific absorption rate compared to on-resonance T1ρ relaxation time mapping.

Myocardial fibrosis evaluated by diffusion-weighted imaging and its relationship to 3D contractile function in patients with hypertrophic cardiomyopathy

BACKGROUND

Previous studies have shown that diffusion-weighted imaging (DWI) is sensitive to myocardial fibrosis in ischemic and nonischemic cardiomyopathy.

PURPOSE

To explore the prognostic value of apparent diffusion coefficient (ADC) for detecting myocardial fibrosis and its relationship to the contractile function in hypertrophic cardiomyopathy (HCM).

STUDY TYPE

Prospective.

POPULATION

A total of 45 HCM patients and 20 controls.

FIELD STRENGTH/SEQUENCE

3.0T cardiac MRI. The cardiac MR sequences included cine, T₁ mapping, and DWI.

ASSESSMENT

According to the presence of late gadolinium enhancement (LGE) and the extracellular volume (ECV) values (+2 SD of control subjects), respectively, reader W and reader J assessed the value of ADC of each segment for detecting myocardial fibrosis and its relationship to impaired contractile function in HCM patients.

STATISTICAL TESTS

Independent sample t-test, Pearson analysis, and intraclass correlation (ICC).

RESULTS

The value of ECV was 23.6 ± 3.0% for control. ECV ≥ 29.6% and ECV < 29.6% groups were classified. ADC values in the ECV ≥ 29.6% group were significantly increased compared to the ECV < 29.6% group, (2.41 ± 0.23 μm² /ms vs. 2.03 ± 0.16 μm² /ms, P < 0.005). Compared to the LGE - group, ECV (32.1 ± 2.3% vs. 29.0 ± 2.8%, P < 0.005) and ADC (2.60 ± 0.18 μm² /ms vs. 2.10 ± 0.07 μm² /ms, P < 0.005) values were significantly increased in the LGE + group. ADC values were linearly associated with ECV values (R²  = 0.65) in HCM patients. ADC values were linearly associated with circumferential and longitudinal strain (R²  = 0.60, R²  = 0.46), as well as circumferential, longitudinal, and radial strain rate (R²  = 0.13, R²  = 0.25, R²  = 0.17, respectively).

DATA CONCLUSION

Contractile dysfunction in HCM is predominantly associated with ADC, which is a feasible alternative to ECV and LGE for detecting myocardial fibrosis.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1139-1146.

MGE-derived nNOS+ interneurons promote fear acquisition in nNOS-/- mice

Neuronal nitric oxide synthase (nNOS) ¹, mainly responsible for NO release in central nervous system (CNS) ², plays a significant role in multiple physiological functions. However, the function of nNOS⁺ interneurons in fear learning has not been much explored. Here we focused on the medial ganglionic eminences (MGE) ³-derived nNOS⁺ interneurons in fear learning. To determine the origin of nNOS⁺ interneurons, we cultured neurons in vitro from MGE, cortex, lateral ganglionic eminence (LGE) ⁴, caudal ganglionic eminences (CGE) ⁵ and preoptic area (POA) ⁶. The results showed that MGE contained the most abundant precursors of nNOS⁺ interneurons. Moreover, donor cells from E12.5 embryos demonstrated the highest positive rate of nNOS⁺ interneurons compared with other embryonic periods (E11.5, E12, E13, E13.5 and E14). Additionally, these cells from E12.5 embryos showed long axonal and abundant dendritic arbors after 10 days culture, indicating the capability to disperse and integrate in host neural circuits after transplantation. To investigate the role of MGE-derived nNOS⁺ interneurons in fear learning, donor MGE cells were transplanted into dentate gyrus (DG) ⁷ of nNOS knock-out (nNOS^-/-) or wild-type mice. Results showed that the transplantation of MGE cells promoted the acquisition of nNOS^-/- but not the wild-type mice, suggesting the importance of nNOS⁺ neurons in fear acquisition. Moreover, we transplanted MGE cells from nNOS^-/- mice or wild-type mice into DG of the nNOS^-/- mice and found that only MGE cells from wild-type mice but not the nNOS^-/- mice rescued the deficit in acquisition of the nNOS^-/- mice, further confirming the positive role of nNOS⁺ neurons in fear learning.

Characterization of Glcci1 expression in a subpopulation of lateral ganglionic eminence progenitors in the mouse telencephalon

BACKGROUND

The lateral ganglionic eminence (LGE) in the ventral telencephalon is a diverse progenitor domain subdivided by distinct gene expression into a dorsal region (dLGE) that gives rise to olfactory bulb and amygdalar interneurons and a ventral region (vLGE) that gives rise to striatal projection neurons. The homeobox gene, Gsx2, is an enriched marker of the LGE and is expressed in a high dorsal to low ventral gradient in the ventricular zone (VZ) as development proceeds. Aside from Gsx2, markers restricted to the VZ in the dLGE and/or vLGE remain largely unknown.

RESULTS

Here, we show that the gene and protein expression of Glucocorticoid-induced transcript 1 (Glcci1) has a similar dorsal to ventral gradient of expression in the VZ as Gsx2. We found that Glcci1 gene and protein expression are reduced in Gsx2 mutants, and are increased in the cortex after early and late Gsx2 misexpression. Moreover, Glcci1 expressing cells are restricted to a subpopulation of Gsx2 positive cells on the basal side of the VZ and co-express Ascl1, but not the subventricular zone dLGE marker, Sp8.

CONCLUSIONS

These findings suggest that Glcci1 is a new marker of a subpopulation of LGE VZ progenitor cells in the Gsx2 lineage. Developmental Dynamics 247:222-228, 2018. © 2017 Wiley Periodicals, Inc.

T1 and T2 mapping for evaluation of myocardial involvement in patients with ANCA-associated vasculitides

BACKGROUND

Myocardial involvement in AAV patients might be silent, presenting with no or nonspecific symptoms, normal ECG, and preserved left-ventricular ejection fraction (LV-EF). Since up to 50% of deaths in these patients may be due to myocardial involvement, a reliable diagnostic tool is warranted. In contrast to LGE-CMR, which has its strengths in detecting focal inflammatory or fibrotic processes, recent mapping techniques are able to detect even subtle, diffuse inflammatory or fibrotic processes. Our study sought to investigate ANCA (antineutrophil cytoplasmic antibody) associated vasculitides (AAV) patients for myocardial involvement by a cardiovascular magnetic resonance (CMR) protocol, including late gadolinium enhancement (LGE) and mapping sequences.

METHODS

Thirty seven AAV patients were prospectively enrolled and underwent CMR imaging. Twenty healthy volunteers served as controls.

RESULTS

Mean LV-EF was 64%; LGE prevalence of the AAV patients was 43%. AAV patients had higher median native T1 (988 vs. 952 ms, p < 0.001), lower post-contrast T1 (488 vs. 524 ms, p = 0.03), expanded extracellular volume (ECV) (27.5 vs. 24.5%, p < 0.001), and higher T2 (53 vs. 49 ms, p < 0.001) compared to controls, with most parameters independent of the LGE status. Native T1 and T2 in AAV patients showed the highest prevalence of abnormally increased values beyond the 95% percentile of controls.

CONCLUSION

AAV patients demonstrated increased T1, ECV, and T2 values, with native T1 and T2 showing the highest prevalence of values beyond the 95% percentile of normal. Since these findings seem to be independent of LGE, mapping techniques may provide complementary information to LGE-CMR in the assessment of myocardial involvement in patients with AAV.