T1 Mapping in Characterizing Myocardial Disease: A Comprehensive Review

Simultaneous multi-slice T1 mapping using MOLLI with blipped CAIPIRINHA bSSFP

BACKGROUND

This study evaluates the possibility for replacing conventional 3 slices, 3 breath-holds MOLLI cardiac T1 mapping with single breath-hold 3 simultaneous multi-slice (SMS3) T1 mapping using blipped-CAIPIRINHA SMS-bSSFP MOLLI sequence. As a major drawback, SMS-bSSFP presents unique artefacts arising from side-lobe slice excitations that are explained by imperfect RF modulation rendering and bSSFP low flip angle enhancement. Amplitude-only RF modulation (AM) is proposed to reduce these artefacts in SMS-MOLLI compared to conventional Wong multi-band RF modulation (WM).

MATERIALS AND METHODS

Phantoms and ten healthy volunteers were imaged at 1.5 T using a modified blipped-CAIPIRINHA SMS-bSSFP MOLLI sequence with 3 simultaneous slices. WM-SMS3 and AM-SMS3 were compared to conventional single-slice (SMS1) MOLLI. First, SNR degradation and T1 accuracy were measured in phantoms. Second, artefacts from side-lobe excitations were evaluated in a phantom designed to reproduce fat presence near the heart. Third, the occurrence of these artefacts was observed in volunteers, and their impact on T1 quantification was compared between WM-SMS3 and AM-SMS3 with conventional MOLLI as a reference.

RESULTS

In the phantom, larger slice gaps and slice thicknesses yielded higher SNR. There was no significant difference of T1 values between conventional MOLLI and SMS3-MOLLI (both WM and AM). Positive banding artefacts were identified from fat neighbouring the targeted FOV due to side-lobe excitations from WM and the unique bSSFP signal profile. AM RF pulses reduced these artefacts by 38%. In healthy volunteers, AM-SMS3-MOLLI showed similar artefact reduction compared to WM-SMS3-MOLLI (3 ± 2 vs 5 ± 3 corrupted LV segments out of 16). In-vivo native T1 values obtained from conventional MOLLI and AM-SMS3-MOLLI were equivalent in LV myocardium (SMS1-T1 = 935.5 ± 36.1 ms; AM-SMS3-T1 = 933.8 ± 50.2 ms; P = 0.436) and LV blood pool (SMS1-T1 = 1475.4 ± 35.9 ms; AM-SMS3-T1 = 1452.5 ± 70.3 ms; P = 0.515). Identically, no differences were found between SMS1 and SMS3 postcontrast T1 values in the myocardium (SMS1-T1 = 556.0 ± 19.7 ms; SMS3-T1 = 521.3 ± 28.1 ms; P = 0.626) and the blood (SMS1-T1 = 478 ± 65.1 ms; AM-SMS3-T1 = 447.8 ± 81.5; P = 0.085).

CONCLUSIONS

Compared to WM RF modulation, AM SMS-bSSFP MOLLI was able to reduce side-lobe artefacts considerably, providing promising results to image the three levels of the heart in a single breath hold. However, few artefacts remained even using AM-SMS-bSSFP due to residual RF imperfections. The proposed blipped-CAIPIRINHA MOLLI T1 mapping sequence provides accurate in vivo T1 quantification in line with those obtained with a single slice acquisition.

The prognostic value of multiparametric cardiac magnetic resonance in patients with systemic light chain amyloidosis

Background

Late gadolinium enhancement (LGE) is a classic imaging modality derived from cardiac magnetic resonance (CMR), which is commonly used to describe cardiac tissue characterization. T1 mapping with extracellular volume (ECV) and native T1 are novel quantitative parameters. The prognostic value of multiparametric CMR in patients with light chain (AL) amyloidosis remains to be thoroughly investigated.

Methods

A total of 89 subjects with AL amyloidosis were enrolled from April 2016 to January 2021, and all of them underwent CMR on a 3.0 T scanner. The clinical outcome and therapeutic effect were observed. Cox regression was used to investigate the effect of multiple CMR parameters on outcomes in this population.

Results

LGE extent, native T1 and ECV correlated well with cardiac biomarkers. During a median follow-up of 40 months, 21 patients died. ECV (hazard ratio [HR]: 2.087 for per 10% increase, 95% confidence interval [CI]: 1.379-3.157, P < 0.001) and native T1 (HR: 2.443 for per 100 ms increase, 95% CI: 1.381-4.321, P=0.002) were independently predictive of mortality. A novel prognostic staging system based on median native T1 (1344 ms) and ECV (40%) was similar to Mayo 2004 Stage, and the 5-year estimated overall survival rates in Stage I, II, and III were 95%, 80%, and 53%, respectively. In patients with ECV > 40%, receiving autologous stem cell transplantation had higher cardiac and renal response rates than conventional chemotherapy.

Conclusion

Both native T1 and ECV independently predict mortality in patients with AL amyloidosis. Receiving autologous stem cell transplantation is effective and significantly improves the clinical outcomes in patients with ECV > 40%.

Multimodality imaging in aortic stenosis: new diagnostic and therapeutic frontiers

The advent of transcatheter aortic valve implantation has revolutionized the treatment of calcific aortic valve stenosis. Elderly patients who were previously considered inoperable have currently an efficacious and safe therapy that provides better survival. In addition, current practice guidelines tend to recommend earlier intervention to avoid the irreversible consequences of long-lasting pressure overload caused by the stenotic aortic valve. Appropriate timing of the intervention relies significantly on imaging techniques that provide information on the severity of the aortic stenosis as well as on the hemodynamic consequences and cardiac remodeling. While left ventricular ejection fraction remains one of the main functional parameters for risk stratification in patients with severe aortic stenosis, advances in imaging techniques have provided new structural and functional parameters that allow the identification of patients who will benefit from intervention before the occurrence of symptoms or irreversible cardiac damage. Furthermore, ongoing research aiming to identify the medical therapies that can effectively halt the progression of aortic stenosis relies heavily on imaging endpoints, and new imaging techniques that characterize the metabolic activity of calcific aortic stenosis have been proposed to monitor the effects of these therapies. The present review provides an up-to-date overview of the imaging advances that characterizes the pathophysiology and that have changed the management paradigm of aortic stenosis.

T1 mapping of the myocardium and liver in the single ventricle population

BACKGROUND

Fontan associated liver disease (FALD) is an increasingly recognized complication of the single ventricle circulation characterized by hepatic venous congestion leading to hepatic fibrosis. Within the Fontan myocardium, fibrotic myocardial remodeling may occur and lead to ventricular dysfunction. Magnetic resonance imaging (MRI) T1 mapping can characterize both myocardial and liver properties.

OBJECTIVE

The aim of this study was to compare myocardial and liver T1 between single ventricle patients with and without a Fontan and biventricular controls.

MATERIALS AND METHODS

A retrospective study of 3 groups of patients: 16 single ventricle patients before Fontan (SV_pre 2 newborns, 9 pre-Glenn, 5 pre-Fontan, 31% single right ventricle [SRV]), 16 Fontans (56% SRV) and 10 repaired d-transposition of the great arteries (TGA). Native modified Look-Locker inversion T1 times were measured in the myocardium and liver. Cardiac MRI parameters, myocardial and liver T1 values were compared in the three groups. Correlations were assessed between liver T1 and cardiac parameters.

RESULTS

Myocardial T1 was higher in SV_pre (1,056 ± 48 ms) and Fontans (1,047 ± 41 ms) compared to TGA (1,012 ± 48 ms, P < 0.05). Increased liver T1 was found in both SV_pre (683 ± 82 ms) and Fontan (727 ± 49 ms) patients compared to TGA patients (587 ± 58 ms, P < 0.001). There was no difference between single left ventricle (SLV) versus SRV myocardial or liver T1. Liver T1 showed moderate correlations with myocardial T1 (r = 0.48, confidence interval [CI] 0.26-0.72) and ejection fraction (r = -0.36, CI -0.66-0.95) but not with other volumetric parameters.

CONCLUSION

Increased liver T1 at both pre- and post-Fontan stages suggests there are intrinsic liver abnormalities early in the course of single ventricle palliation. Increased myocardial T1 and its relationship to liver T1 suggest a combination of edema from passive venous congestion and/or myocardial fibrosis occurring in this population. Liver T1 may provide an earlier marker of liver disease warranting further study.

Imaging of heart disease in women: review and case presentation

Cardiovascular diseases (CVD) remain the leading cause of mortality worldwide. Although major diagnostic and therapeutic advances have significantly improved the prognosis of patients with CVD in the past decades, these advances have less benefited women than age-matched men. Noninvasive cardiac imaging plays a key role in the diagnosis of CVD. Despite shared imaging features and strategies between both sexes, there are critical sex disparities that warrant careful consideration, related to the selection of the most suited imaging techniques, to technical limitations, and to specific diseases that are overrepresented in the female population. Taking these sex disparities into consideration holds promise to improve management and alleviate the burden of CVD in women. In this review, we summarize the specific features of cardiac imaging in four of the most common presentations of CVD in the female population including coronary artery disease, heart failure, pregnancy complications, and heart disease in oncology, thereby highlighting contemporary strengths and limitations. We further propose diagnostic algorithms tailored to women that might help in selecting the most appropriate imaging modality.

Cardiac magnetic resonance imaging parameters show association between myocardial abnormalities and severity of chronic kidney disease

BACKGROUND

Chronic kidney disease patients have increased risk of cardiovascular abnormalities. This study investigated the relationship between cardiovascular abnormalities and the severity of chronic kidney disease using cardiac magnetic resonance imaging.

METHODS

We enrolled 84 participants with various stages of chronic kidney disease (group I: stages 1-3, n = 23; group II: stages 4-5, n = 20; group III: hemodialysis patients, n = 41) and 32 healthy subjects. The demographics and biochemical parameters of the study subjects were evaluated. All subjects underwent non-contrast cardiac magnetic resonance scans. Myocardial strain, native T1, and T2 values were calculated from the scanning results. Analysis of covariance was used to compare the imaging parameters between group I-III and the controls.

RESULTS

The left ventricular ejection fraction (49 vs. 56%, p = 0.021), global radial strain (29 vs. 37, p = 0.019) and global circumferential strain (-17.4 vs. -20.6, p < 0.001) were significantly worse in group III patients compared with the controls. Furthermore, the global longitudinal strain had a significant decline in group II and III patients compared with the controls (-13.7 and -12.9 vs. -16.2, p < 0.05). Compared with the controls, the native T1 values were significantly higher in group II and III patients (1,041 ± 7 and 1,053 ± 6 vs. 1,009 ± 6, p < 0.05), and T2 values were obviously higher in group I-III patients (49.9 ± 0.6 and 53.2 ± 0.7 and 50.1 ± 0.5 vs. 46.6 ± 0.5, p < 0.001). The advanced chronic kidney disease stage showed significant positive correlation with global radial strain (r = 0.436, p < 0.001), global circumferential strain (r = 0.386, p < 0.001), native T1 (r = 0.5, p < 0.001) and T2 (r = 0.467, p < 0.001) values. In comparison with the group II patients, hemodialysis patients showed significantly lower T2 values (53.2 ± 0.7 vs. 50.1 ± 0.5, p = 0.002), but no significant difference in T1 values (1,041 ± 7 vs. 1,053 ± 6).

CONCLUSIONS

Our study showed that myocardial strain, native T1, and T2 values progressively got worse with advancing chronic kidney disease stage. The increased T1 values and decreased T2 values of hemodialysis patients might be due to increasing myocardial fibrosis but with reduction in oedema following effective fluid management.

TRIAL REGISTRATION NUMBER

ChiCTR2100053561 (http://www.chictr.org.cn/edit.aspx?pid=139737&htm=4).

Extracellular volume and left ventricular hypertrophy by cardiac magnetic resonance are independent predictors of cardiovascular outcome in obesity

This retrospective cohort study investigated for association between increased extracellular volume (ECV) and left ventricular hypertrophy (LVH) by cardiac magnetic resonance (CMR) and cardiovascular composite outcomes in obesity. Native T1 was measured at the ventricular septum. ECV was calculated from native and post-contrast T1 and hematocrit. Cardiovascular (CV) composite outcomes included acute myocardial infarction, unstable angina requiring hospitalization, myocardial revascularization (excluding early revascularization), heart failure, and CV death. A total of 456 patients with a mean follow-up of 2.1 ± 0.4 years were enrolled. LGE and LVH was detected in 30.5% and 9.2%. 107 patients (23.5%) had the composite outcomes. Multivariable analysis revealed that LGE, LVH, and high ECV as independent predictors for cardiovascular composite outcomes The event rate in the LVH and high ECV, the LVH alone, the high ECV alone, and the no-LVH with lower ECV group was 57.1%, 38.1%, 32.6%, and 17.7%, respectively. Assessment of incremental prognostic value by comparing global chi-square showed that high ECV had additional prognostic value on top of LGE, and LVH. LVH and high ECV are independent predictors of CV composite outcomes in obesity. This is the first study that demonstrate the prognostic value of ECV in obese population.

A Deep Learning Segmentation Pipeline for Cardiac T1 Mapping Using MRI Relaxation-based Synthetic Contrast Augmentation

PURPOSE

To design and evaluate an automated deep learning method for segmentation and analysis of cardiac MRI T1 maps with use of synthetic T1-weighted images for MRI relaxation-based contrast augmentation.

MATERIALS AND METHODS

This retrospective study included MRI scans acquired between 2016 and 2019 from 100 patients (mean age ± SD, 55 years ± 13; 72 men) across various clinical abnormalities with use of a modified Look-Locker inversion recovery, or MOLLI, sequence to quantify native T1 (T1_native), postcontrast T1 (T1_post), and extracellular volume (ECV). Data were divided into training (n = 60) and internal (n = 40) test subsets. "Synthetic" T1-weighted images were generated from the T1 exponential inversion-recovery signal model at a range of optimal inversion times, yielding high blood-myocardium contrast, and were used for contrast-based image augmentation during training and testing of a convolutional neural network for myocardial segmentation. Automated segmentation, T1, and ECV were compared with experts with use of Dice similarity coefficients (DSCs), correlation coefficients, and Bland-Altman analysis. An external test dataset (n = 147) was used to assess model generalization.

RESULTS

Internal testing showed high myocardial DSC relative to experts (0.81 ± 0.08), which was similar to interobserver DSC (0.81 ± 0.08). Automated segmental measurements strongly correlated with experts (T1_native, R = 0.87; T1_post, R = 0.91; ECV, R = 0.92), which were similar to interobserver correlation (T1_native, R = 0.86; T1_post, R = 0.94; ECV, R = 0.95). External testing showed strong DSC (0.80 ± 0.09) and T1_native correlation (R = 0.88) between automatic and expert analysis.

CONCLUSION

This deep learning method leveraging synthetic contrast augmentation may provide accurate automated T1 and ECV analysis for cardiac MRI data acquired across different abnormalities, centers, scanners, and T1 sequences.Keywords: MRI, Cardiac, Tissue Characterization, Segmentation, Convolutional Neural Network, Deep Learning Algorithms, Machine Learning Algorithms, Supervised Learning Supplemental material is available for this article. © RSNA, 2022.

Validation of an electrocardiographic marker of low voltage areas in the right ventricular outflow tract in patients with idiopathic ventricular arrhythmias

BACKGROUND

Previous studies have reported the presence of subtle abnormalities in the right ventricular outflow tract (RVOT) in patients with apparently normal hearts and ventricular arrhythmias (VAs) from the RVOT, including the presence of low voltage areas (LVAs). This LVAs seem to be associated with the presence of ST-segment elevation in V1 or V2 leads at the level of the 2nd intercostal space (ICS).

OBJECTIVE

Our aim was to validate an electrocardiographic marker of LVAs in the RVOT in patients with idiopathic outflow tract VAs.

METHODS

A total of 120 patients were studied, 84 patients referred for ablation of idiopathic VAs with an inferior axis by the same operator, and a control group of 36 patients without VAs. Structural heart disease including arrhythmogenic right ventricular cardiomyopathy was ruled out in all patients. An electrocardiogram was performed with V1-V2 at the 2nd ICS, and ST-segment elevation ≥1 mm and T-wave inversion beyond V1 were assessed. Bipolar voltage map of the RVOT was performed in sinus rhythm (0.5-1.5 mV color display). Areas with electrograms <1.5 mV were considered LVAs, and their presence was assessed. We compared three groups, VAs from the RVOT (n = 66), VAs from the LVOT (n = 18) and Control group (n = 36). ST-elevation, T-wave inversion and left versus right side of the VAs were tested as predictors of LVAs, respective odds ratio (ORs) (95% confidence interval [CI]) and p values, were calculated with univariate logist regression. Variables with a p < .005 were included in the multivariate analysis.

RESULTS

ST-segment elevation, T-wave inversion and LVAs were present in the RVOT group, LVOT group and Control group as follows: (62%, 17%, and 6%, p < .0001), (33%, 29%, and 0%, p = .001) and (62%, 25%, and 14%, p < .0001). The ST-segment elevation, T-wave inversion and right-sided VAs were all predictors of LVAs, respective unadjusted ORs (95% CI), p values were, 32.31 (11.33-92.13), p < .0001, 4.137 (1.615-10.60), p = .003 and 8.200 (3.309-20.32), p < .0001. After adjustment, the only independent predictor of LVAs was the ST-segment elevation, with an adjusted OR (95% CI) of 20.94 (6.787-64.61), p < .0001.

CONCLUSION

LVAs were frequently present in patients with idiopathic VAs. ST-segment elevation was the only independent predictor of their presence.

The Role of Novel Cardiac Imaging for Contemporary Management of Heart Failure

Heart failure is becoming the central problem in cardiology. Its recognition, differential diagnosis, and the monitoring of therapy are intimately coupled with cardiac imaging. Cardiac imaging has witnessed an explosive growth and differentiation, with echocardiography continuing as the first diagnostic step; the echocardiographic exam itself has become considerably more complex than in the last century, with the assessment of diastolic left ventricular function and strain imaging contributing important information, especially in heart failure. Very often, however, echocardiography can only describe the fact of functional impairment and morphologic remodeling, whereas further clarification of the underlying disease, such as cardiomyopathy, myocarditis, storage diseases, sarcoidosis, and others, remains elusive. Here, cardiovascular magnetic resonance and perfusion imaging should be used judiciously to arrive as often as possible at a clear diagnosis which ideally enables specific therapy.

Free-breathing, non-ECG, simultaneous myocardial T1 , T2 , T2 *, and fat-fraction mapping with motion-resolved cardiovascular MR multitasking

PURPOSE

To develop a free-breathing, non-electrocardiogram technique for simultaneous myocardial T1 , T2 , T2 *, and fat-fraction (FF) mapping in a single scan.

METHODS

The MR Multitasking framework is adapted to quantify T1 , T2 , T2 *, and FF simultaneously. A variable TR scheme is developed to preserve temporal resolution and imaging efficiency. The underlying high-dimensional image is modeled as a low-rank tensor, which allows accelerated acquisition and efficient reconstruction. The accuracy and/or repeatability of the technique were evaluated on static and motion phantoms, 12 healthy volunteers, and 3 patients by comparing to the reference techniques.

RESULTS

In static and motion phantoms, T1 /T2 /T2 */FF measurements showed substantial consistency (R > 0.98) and excellent agreement (intraclass correlation coefficient > 0.93) with reference measurements. In human subjects, the proposed technique yielded repeatable T1 , T2 , T2 *, and FF measurements that agreed with those from references.

CONCLUSIONS

The proposed free-breathing, non-electrocardiogram, motion-resolved Multitasking technique allows simultaneous quantification of myocardial T1 , T2 , T2 *, and FF in a single 2.5-min scan.

SAturation-recovery and Variable-flip-Angle-based three-dimensional free-breathing cardiovascular magnetic resonance T1 mapping at 3 T

The purpose of the current study was to develop and validate a three-dimensional (3D) free-breathing cardiac T₁ -mapping sequence using SAturation-recovery and Variable-flip-Angle (SAVA). SAVA sequentially acquires multiple electrocardiogram-triggered volumes using a multishot spoiled gradient-echo sequence. The first volume samples the equilibrium signal of the longitudinal magnetization, where a flip angle of 2° is used to reduce the time for the magnetization to return to equilibrium. The succeeding three volumes are saturation prepared with variable delays, and are acquired using a 15° flip angle to maintain the signal-to-noise ratio. A diaphragmatic navigator is used to compensate the respiratory motion. T₁ is calculated using a saturation-recovery model that accounts for the flip angle. We validated SAVA by simulations, phantom, and human subject experiments at 3 T. SAVA was compared with modified Look-Locker inversion recovery (MOLLI) and saturation-recovery single-shot acquisition (SASHA) in vivo. In phantoms, T₁ by SAVA had good agreement with the reference (R²  = 0.99). In vivo 3D T₁ mapping by SAVA could achieve an imaging resolution of 1.25 × 1.25 × 8 mm³ . Both global and septal T₁ values by SAVA (1347 ± 37 and 1332 ± 42 ms) were in between those by SASHA (1612 ± 63 and 1618 ± 51 ms) and MOLLI (1143 ± 59 and 1188 ± 65 ms). According to the standard deviation (SD) and coefficient of variation (CV), T₁ precision measured by SAVA (SD: 99 ± 14 and 60 ± 8 ms; CV: 7.4% ± 0.9% and 4.5% ± 0.6%) was comparable with MOLLI (SD: 99 ± 25 and 46 ± 12 ms; CV: 8.8% ± 2.5% and 3.9% ± 1.1%) and superior to SASHA (SD: 222 ± 89 and 132 ± 33 ms; CV: 13.8% ± 5.5% and 8.1% ± 2.0%). It was concluded that the proposed free-breathing SAVA sequence enables more efficient 3D whole-heart T₁ estimation with good accuracy and precision.

Myocardial extracellular volume quantified by cardiac magnetic resonance predicts left ventricular aneurysm following acute myocardial infarction

OBJECTIVE

This study aimed to investigate the correlation between increased extracellular matrix estimated by cardiac magnetic resonance (CMR) and left ventricular aneurysm after acute myocardial infarction.

METHODS

A total of 175 patients from 3 centers with an isolated left anterior descending culprit vessel underwent CMR examinations within 1 week and at a 6-month follow-up. Of these, 92 were identified to have left ventricular aneurysms (LVAs): 74 with functional aneurysm and 18 with anatomical aneurysm. The predictive significance of acute extracellular volume (ECV), left gadolinium enhancement (LGE), and other characteristics were analyzed using binary logistic regression analysis.

RESULTS

Patients with LVA were more likely to present with left ventricular adverse remodeling (LVAR) than those without (p = 0.009). With optimal cutoff values of 30.90% for LGE and 33% for ECV to discriminate LVA from non-LVA, the area under the curve (AUC) by receiver operator characteristic curve (ROC) analysis was 0.92 (95% CI: 0.87-0.96; p < 0.001) and 0.93 (95% CI: 0.88-0.96; p < 0.001), respectively. ECV was significantly better than LGE at discriminating between functional and anatomical LVA (p < 0.001). Both acute LGE and ECV were predictors of LVA, with an odds ratio of 1.35 (95% CI: 1.21-1.52, p < 0.001) and 1.23 (95% CI: 1.13-1.33, p < 0.001), respectively, by multivariable logistic regression analysis.

CONCLUSIONS

Acute LGE and ECV of the myocardium provided predictive significance for LVA. The discriminative significance of ECV for functional versus anatomical LVA was better than the discriminative significance of LGE.

KEY POINTS

• Patients with LVA were more likely to present with LVAR. • Acute LGE and ECV of the myocardium provided the strongest predictive significance for LVA. • The discriminative significance of ECV for functional versus anatomical LVA was better than that of LGE.

Improving accuracy of myocardial T1 estimation in MyoMapNet

PURPOSE

To improve the accuracy and robustness of T₁ estimation by MyoMapNet, a deep learning-based approach using 4 inversion-recovery T₁ -weighted images for cardiac T₁ mapping.

METHODS

MyoMapNet is a fully connected neural network for T₁ estimation of an accelerated cardiac T₁ mapping sequence, which collects 4 T₁ -weighted images by a single Look-Locker inversion-recovery experiment (LL4). MyoMapNet was originally trained using in vivo data from the modified Look-Locker inversion recovery sequence, which resulted in significant bias and sensitivity to various confounders. This study sought to train MyoMapNet using signals generated from numerical simulations and phantom MR data under multiple simulated confounders. The trained model was then evaluated by phantom data scanned using new phantom vials that differed from those used for training. The performance of the new model was compared with modified Look-Locker inversion recovery sequence and saturation-recovery single-shot acquisition for measuring native and postcontrast T₁ in 25 subjects.

RESULTS

In the phantom study, T₁ values measured by LL4 with MyoMapNet were highly correlated with reference values from the spin-echo sequence. Furthermore, the estimated T₁ had excellent robustness to changes in flip angle and off-resonance. Native and postcontrast myocardium T₁ at 3 Tesla measured by saturation-recovery single-shot acquisition, modified Look-Locker inversion recovery sequence, and MyoMapNet were 1483 ± 46.6 ms and 791 ± 45.8 ms, 1169 ± 49.0 ms and 612 ± 36.0 ms, and 1443 ± 57.5 ms and 700 ± 57.5 ms, respectively. The corresponding extracellular volumes were 22.90% ± 3.20%, 28.88% ± 3.48%, and 30.65% ± 3.60%, respectively.

CONCLUSION

Training MyoMapNet with numerical simulations and phantom data will improve the estimation of myocardial T₁ values and increase its robustness to confounders while also reducing the overall T₁ mapping estimation time to only 4 heartbeats.

Bowel wall MRI T1 relaxation estimates for assessment of intestinal inflammation in pediatric Crohn's disease

PURPOSE

To compare bowel wall T1 relaxation estimates in young patients with newly diagnosed ileal CD to healthy control participants, characterize their change over time in response to biologic medical therapy, and evaluate their associations with clinical markers of intestinal inflammation.

MATERIALS AND METHODS

Patients with newly diagnosed ileal CD and healthy control participants were prospectively recruited between December 2018 and October 2021. Patients underwent research MRI examinations of the bowel at baseline and at 6-weeks and 6-months into biologic medical treatment; control participants underwent single MRI examinations. MRI examinations included native T1 relaxometry of the terminal ileum using a modified Look-Locker inversion recovery (MOLLI) sequence. T1 estimates were measured on scanner-generated parametric maps. Clinical markers of intestinal inflammation were recorded at each visit. Group differences were assessed using the Mann-Whitney U test; the Friedman test was used to assess longitudinal changes in T1 estimates. Spearman correlation was used to evaluate associations between T1 estimates and inflammatory markers.

RESULTS

Nineteen participants with CD (12 males; median age 14 years) and 15 control participants (7 males; median age 17 years) were included in the study. Bowel wall T1 estimates in CD patients (median 1302 ms) were significantly longer compared to control participants (median 1159 ms) (p < 0.001). In CD patients, T1 estimates changed over time after treatment (p = 0.001), with largest reductions between baseline and 6-weeks (p < 0.001). T1 estimates correlated with inflammatory markers, including erythrocyte sedimentation rate (ρ = 0.35; p = 0.01), c-reactive protein level (ρ = 0.34; p = 0.02), and weighted Pediatric Crohn's Disease Activity Index (ρ = 0.39; p = 0.005). T1 estimates did not correlate with serum albumin (ρ = - 0.28; p = 0.051) and fecal calprotectin (ρ = 0.07; p = 0.63).

CONCLUSION

Bowel wall T1 estimates are abnormally increased in newly diagnosed ileal CD patients and decrease in response to medical therapy.

Efficient phase-cycling strategy for high-resolution 3D gradient-echo quantitative parameter mapping

Magnetization-prepared (MP) gradient-echo (GRE) sequences suffer from signal contaminations from T₁ recovery during the readout train, which can be eliminated by paired RF phase cycling (PC) at the cost of doubling the scan time. The objective of this study was to develop and validate a novel unpaired PC strategy to eliminate the time penalty for high-resolution quantitative parameter mapping in 3D MP-GRE sequences. Based on the observation that the contaminating T₁ recovery signal along the GRE readout train is independent of magnetization preparation, its impact can be eliminated using a novel curve-fitting approach with complex-valued data without needing paired PC acquisitions. Four new unpaired PC schemes were compared with two traditional paired PC schemes in both phantom and in vivo human knee studies at 3 T using a MP angle-modulated partitioned k-space spoiled gradient-echo snapshots (MAPSS) T_1ρ mapping sequence. In the phantom study, all methods resulted in consistent T_1ρ measurements (∆T_1ρ  < 0.5%) at the center slice when B₀ /B₁ values were uniform. Results were not consistent when off-center slices with nonideal B₀ /B₁ were included. Two unpaired PC schemes had comparable or significantly improved quantitative accuracy and scan-rescan reproducibility compared with the paired PC schemes. There was no significant T_1ρ quantitative variability increase or spatial fidelity loss using the new unpaired PC schemes. Unpaired PC schemes also had different T_1ρ spectral responses at different B₀ frequency offsets, which can potentially be exploited to reduce sensitivity to B₀ field inhomogeneities. The human knee study results were consistent with the phantom study findings. In conclusion, an unpaired PC strategy potentially allows more accurate quantitative parameter mapping with halved scan time compared with the paired PC approach to eliminate signal contaminations from T₁ recovery. It therefore offers additional flexibility in SNR optimization, spatial resolution improvement, and choice of imaging sampling points to obtain more accurate quantitative parameter mapping.

Cardiovascular magnetic resonance native T1 mapping in Anderson-Fabry disease: a systematic review and meta-analysis

BACKGROUND

T1 mapping is an established cardiovascular magnetic resonance (CMR) technique that can characterize myocardial tissue. We aimed to determine the weighted mean native T1 values of Anderson-Fabry disease (AFD) patients and the standardized mean differences (SMD) as compared to healthy control subjects.

METHODS

A comprehensive literature search of the PubMed, Scopus and Web of Science databases was conducted according to the PRISMA statement to retrieve original studies reporting myocardial native T1 values in AFD patients and healthy controls. A random effects model was used to calculate SMD, and meta-regression analysis was conducted to explore heterogeneity sources. Subgroup analysis was also performed according to scanner field strength and sequence type.

RESULTS

From a total of 151 items, 14 articles were included in the final analysis accounting for a total population of 982 subjects. Overall, the weighted mean native T1 values was 984 ± 47 ms in AFD patients and 1016 ± 26 ms in controls (P < 0.0001) with a pooled SMD of - 2.38. In AFD patients there was an inverse correlation between native T1 values and male gender (P = 0.002) and left ventricular hypertrophy (LVH) (P < 0.001). Subgroup analyses confirmed lower T1 values in AFD patients compared to controls with a pooled SMD of -  2.54,  -  2.28, -   2.46 for studies performed on 1.5T with modified Look-Locker inversion recovery (MOLLI), shortened MOLLI and saturation-recovery single-shot acquisition, respectively and of -  2.41 for studies conducted on 3T.

CONCLUSIONS

Our findings confirm a reduction of native T1 values in AFD patients compared to healthy controls and point out that the degree of T1 shortening in AFD is influenced by gender and LVH. Although T1 mapping is useful in proving cardiac involvement in AFD patients, there is need to standardize shreshold values according to imaging equipment and protocols.

Magnetic Resonance Elastography-derived Stiffness Predicts Renal Function Loss and Is Associated With Microvascular Inflammation in Kidney Transplant Recipients

Background.

Organ stiffening can be caused by inflammation and fibrosis, processes that are common causes of transplant kidney dysfunction. Magnetic resonance elastography (MRE) is a contrast-free, noninvasive imaging modality that measures kidney stiffness. The objective of this study was to assess the ability of MRE to serve as a prognostic factor for renal outcomes.

Methods.

Patients were recruited from the St Michael’s Hospital Kidney Transplant Clinic. Relevant baseline demographic, clinical, and Banff histologic information, along with follow-up estimated glomerular filtration rate (eGFR) data, were recorded. Two-dimensional gradient-echo MRE imaging was performed to obtain kidney “stiffness” maps. Binary logistic regression analyses were performed to examine for relationships between stiffness and microvascular inflammation score. Linear mixed-effects modeling was used to assess the relationship between stiffness and eGFR change over time controlling for other baseline variables. A G²-likelihood ratio Chi-squared test was performed to compare between the baseline models with and without “stiffness.”

Results.

Sixty-eight transplant kidneys were scanned in 66 patients (mean age 56 ± 12 y, 24 females), with 38 allografts undergoing a contemporaneous biopsy. Mean transplant vintage was 7.0 ± 6.8 y. In biopsied allografts, MRE-derived allograft stiffness was associated only with microvascular inflammation (Banff g + ptc score, Spearman ρ = 0.43, P = 0.01), but no other histologic parameters. Stiffness was negatively associated with eGFR change over time (Stiffness × Time interaction β = –0.80, P < 0.0001), a finding that remained significant even when adjusted for biopsy status and baseline variables (Stiffness × Time interaction β = –0.46, P = 0.04). Conversely, the clinical models including “stiffness” showed significantly better fit (P = 0.04) compared with the baseline clinical models without “stiffness.”

Conclusions.

MRE-derived renal stiffness provides important prognostic information regarding renal function loss for patients with allograft dysfunction, over and above what is provided by current clinical variables.

Noncontrast T1ρ dispersion imaging is sensitive to diffuse fibrosis: A cardiovascular magnetic resonance study at 3T in hypertrophic cardiomyopathy

PURPOSE

To determine the sensitivity of a noncontrast T1 dispersion cardiovascular magnetic resonance technique for detecting diffuse fibrosis in hypertrophic cardiomyopathy (HCM).

METHODS

Thirty-two adult HCM patients and ten age- and gender-matched healthy volunteers were prospectively included in this study. Patients and controls underwent cine, T1ρ-mapping, and pre- and post-contrast T1-mapping imaging using a 3-T magnetic resonance system. Myocardial extracellular volume fraction (ECV) maps were obtained using pre- and post-contrast T1 maps to determine reference values for diffuse fibrosis. Myocardial T1ρ and T1ρ dispersion maps called myocardial fibrosis index (mFI) maps provided 570 myocardial segments for Pearson or Spearman correlation analysis. The left ventricle myocardia of the HCM patients were divided into 16 segments that were further classified as either normal-thickness myocardium (<15 mm) (HCM-N) or hypertrophic myocardium (≥15 mm) (HCM-H).

RESULTS

ECV and mFI values increased progressively on a per-segment basis from healthy controls to the HCM-N group and then to the HCM-H group (ECV: 27.4 ± 2.8% vs. 31.1 ± 4.2% vs. 37.6 ± 6.9%, respectively [P < 0.0001]; mFI: 6.1 ± 0.9 ms vs. 8 ± 1.9 ms vs. 11 ± 3.3 ms, respectively [P < 0.0001]). There was a strong positive correlation between the segmented ECV and the mFI (r = 0.878). The mFI was equally or significantly better than the ECV for differentiating fibrosis content in HCM-N and HCM-H according to their receiver operating characteristic curves.

CONCLUSION

A T1ρ dispersion imaging mFI can sensitively detect diffuse myocardial fibrosis in HCM, even in HCM-N.

Repeatability and robustness of MP-GRASP T1 mapping

PURPOSE

To demonstrate the repeatability of fast 3D T1 mapping using Magnetization-Prepared Golden-angle RAdial Sparse Parallel (MP-GRASP) MRI and its robustness to variation of imaging parameters including flip angle and spatial resolution in phantoms and the brain.

THEORY AND METHODS

Multiple imaging experiments were performed to (1) assess the robustness of MP-GRASP T1 mapping to B1 inhomogeneity using a single tube phantom filled with uniform MnCl2 liquid; (2) compare the repeatability of T1 mapping between MP-GRASP and inversion recovery-based spin-echo (IR-SE; over 12 scans), using a commercial T1MES phantom; (3) evaluate the longitudinal variation of T1 estimation using MP-GRASP with varying imaging parameters, including spatial resolution, flip angle, TR/TE, and acceleration rate, using the T1MES phantom (106 scans performed over a period of 12 months); and (4) evaluate the variation of T1 estimation using MP-GRASP with varying imaging parameters in the brain (24 scans in a single visit). In addition, the accuracy of MP-GRASP T1 mapping was also validated against IR-SE by performing linear correlation and calculating the Lin's concordance correlation coefficient (CCC).

RESULTS

MP-GRASP demonstrates good robustness to B1 inhomogeneity, with intra-slice variability below 1% in the single tube phantom experiment. The longitudinal variability is good both in the phantom (below 2.5%) and in the brain (below 2%) with varying imaging parameters. The T1 values estimated from MP-GRASP are accurate compared to that from the IR-SE imaging (R2 = 0.997, Lin's CCC = 0.996).

CONCLUSION

MP-GRASP shows excellent repeatability of T1 estimation over time, and it is also robust to variation of different imaging parameters evaluated in this study.

Case Report: Transient Increase of CMR T1 Mapping Indices in a Patient With COVID-19 mRNA Vaccine Induced Acute Myocarditis

Background

Acute myocarditis is commonly associated with viral infections, including severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Myocarditis following mRNA COVID-19 vaccination has also been reported, however this is rare and usually resolves within days or weeks. We present a case of acute myocarditis reported after vaccination with mRNA-1273 COVID-19 vaccine (Moderna) diagnosed using cardiac magnetic resonance imaging (CMR). This report describes the utility of CMR in the diagnosis and follow-up of such patients using parameters which could suggest the clinical course of myocarditis.

Case Summary

A 23-year-old male presented in the emergency department with complaints of chest pain radiating to the left arm following vaccination with the second dose of COVID-19 mRNA-1273 vaccine (Moderna). Patient's history revealed an incidence of myocarditis in the past. CMR showed a mid-range left ventricular ejection fraction (38%) and subepicardial late gadolinium enhancement (LGE) in the inferolateral and apical myocardial segments with diffuse elevation of native T1 mapping relaxation times in all myocardial segments. The patient was admitted briefly in the intensive care unit and after a favorable clinical course was discharged from the hospital in stable condition. A follow-up CMR after 3 months revealed normalization of LVEF (57%) and native T1- times in most segments. Scarred myocardium reflecting chronic myocarditis continued to show elevated T1 times.

Conclusions

Our patient presenting with acute myocarditis after recent COVID-19 mRNA vaccination reported a favorable clinical course. CMR revealed increased T1 mapping relaxation times diffusely spread across the myocardium and an impairment of the left ventricular function (LVEF) during the acute phase. However, the LVEF as well as the T1 times normalized at follow-up in all segments except for myocardium affected by chronic myocarditis.

Cardiac Magnetic Resonance Imaging in Immune Check-Point Inhibitor Myocarditis: A Systematic Review

Immune checkpoint inhibitors (ICIs) are a family of anticancer drugs in which the immune response elicited against the tumor may involve other organs, including the heart. Cardiac magnetic resonance (CMR) imaging is increasingly used in the diagnostic work-up of myocardial inflammation; recently, several studies investigated the use of CMR in patients with ICI-myocarditis (ICI-M). The aim of the present systematic review is to summarize the available evidence on CMR findings in ICI-M. We searched electronic databases for relevant publications; after screening, six studies were selected, including 166 patients from five cohorts, and further 86 patients from a sub-analysis that were targeted for a tissue mapping assessment. CMR revealed mostly preserved left ventricular ejection fraction; edema prevalence ranged from 9% to 60%; late gadolinium enhancement (LGE) prevalence ranged from 23% to 83%. T1 and T2 mapping assessment were performed in 108 and 104 patients, respectively. When available, the comparison of CMR with endomyocardial biopsy revealed partial agreement between techniques and was higher for native T1 mapping amongst imaging biomarkers. The prognostic assessment was inconsistently assessed; CMR variables independently associated with the outcome included decreasing LVEF and increasing native T1. In conclusion, CMR findings in ICI-M include myocardial dysfunction, edema and fibrosis, though less evident than in more classic forms of myocarditis; native T1 mapping retained the higher concordance with EMB and significant prognostic value.

Monitoring Rotator Cuff Muscle Fatty Infiltration Progression by Magnetic Resonance Imaging T1 Mapping: Correlation With Direct Evaluation Findings in Rats

BACKGROUND

Monitoring the fatty infiltration (FI) process in rotator cuff muscles is of value in establishing a treatment plan and predicting the postoperative prognosis. Quantitative T1 mapping shows promise for evaluating muscle degeneration, while its validity in monitoring rotator cuff muscle FI progression needs further investigation.

PURPOSE

To determine the validity of T1 mapping in monitoring FI progression of rotator cuff muscles.

STUDY DESIGN

Controlled laboratory study.

METHODS

Sprague-Dawley rats (N = 108) underwent left supraspinatus (SS) and infraspinatus (IS) tenotomy only (TT), suprascapular nerve transection only (NT), or SS and IS tenotomy plus suprascapular nerve transection (TT+NT). Sham surgery on the right shoulder served as the control. The magnetic resonance imaging examination included T1 mapping performed at 12, 16, and 20 weeks postoperation. SS and IS muscles were harvested to quantitatively evaluate FI via direct evaluation (triglyceride quantification assay and histological analysis) at the same predetermined intervals. The correlation of the imaging data with direct evaluation of rotator cuff muscles was analyzed.

RESULTS

T1 values were significantly lower in left SS and IS muscles at 12, 16, and 20 weeks postoperation as compared with those on the right side. T1 values of the left SS and IS muscles were continuously decreased in all groups. The TT+NT group had a greater decrease in T1 value than did the TT and NT groups. Triglyceride quantification assay and histological analysis demonstrated significant and progressive FI of the left SS and IS muscles in the 3 groups. The most serious FI changes were observed in the TT+NT group. T1 values were also well correlated with triglyceride contents and area fractions of fat.

CONCLUSION

T1 mapping can be an effective imaging modality for sensitive and quantitative monitoring of FI progression in rotator cuff muscles.

CLINICAL RELEVANCE

The findings of this study provide a tool for researchers to noninvasively and quantitatively monitor the process of muscle degeneration, contributing to the evaluation of surgical indication and postoperative prognosis.

T1 and T2 Mapping in Uremic Cardiomyopathy: An Update

Uremic cardiomyopathy (UC) is the cardiac remodelling that occurs in patients with chronic kidney disease (CKD). It is characterised by a left ventricular (LV) hypertrophy phenotype, diastolic dysfunction and generally preserved LV ejection fraction. UC has a major role mediating the increased rate of cardiovascular events, especially heart failure related, observed in patients with CKD. Recently, the use of T1 and T2 mapping techniques on cardiac MRI has expanded the ability to characterise cardiac involvement in CKD. Native T1 mapping effectively tracks the progression of interstitial fibrosis in UC, whereas T2 mapping analysis suggests the contribution of myocardial oedema, at least in a subgroup of patients. Both T1 and T2 increased values were related to worsening clinical status, myocardial injury and B-type natriuretic peptide release. Studies investigating the prognostic relevance and histology validation of mapping techniques in CKD are awaited.

Case Report: Cytomegalovirus Reactivation and Pericarditis Following ChAdOx1 nCoV-19 Vaccination Against SARS-CoV-2

As the coronavirus disease 2019 (COVID-19) pandemic is ongoing and new variants of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) are emerging, there is an urgent need for vaccines to protect individuals at high risk for complications and to potentially control disease outbreaks by herd immunity. Surveillance of rare safety issues related to these vaccines is progressing, since more granular data emerge about adverse events of SARS-CoV-2 vaccines during post-marketing surveillance. Varicella zoster virus (VZV), Epstein-Barr virus (EBV) and cytomegalovirus (CMV) reactivation has already been reported in COVID-19 patients. In addition, adverse events after SARS-CoV-2 mRNA vaccination have also been in the context of varicella zoster virus (VZV) reactivation and directly associated with the mRNA vaccine. We present the first case of CMV reactivation and pericarditis in temporal association with SARS-CoV-2 vaccination, particularly adenovirus-based DNA vector vaccine ChAdOx1 nCoV-19 against SARS-CoV-2. After initiation of antiviral therapy with oral valganciclovir, CMV viremia disappeared and clinical symptoms rapidly improved. Since huge vaccination programs are ongoing worldwide, post-marketing surveillance systems must be in place to assess vaccine safety that is important for the detection of any events. In the context of the hundreds of millions of individuals to be vaccinated against SARS-CoV-2, a potential causal association with CMV reactivation may result in a considerable number of cases with potentially severe complications.

Atrial function and geometry differences in transthyretin versus immunoglobulin light chain amyloidosis: a cardiac magnetic resonance study

To determine the differences in left atrial (LA) function and geometry assessed by cardiac magnetic resonance (CMR) between transthyretin (ATTR) and immunoglobulin light chain (AL) cardiac amyloidosis (CA). We performed a retrospective analysis of 54 consecutive patients (68.5% male, mean age 67 ± 11 years) with confirmed CA (24 ATTR, 30 AL) who underwent comprehensive CMR examinations. LA structural and functional assessment including LA volume, LA sphericity index, and LA strain parameters were compared between both subtypes. In addition, 15 age-matched controls were compared to all groups. Patients with ATTR-CA were older (73 ± 9 vs. 62 ± 10 years, p < 0.001) and more likely to be male (83.3% vs. 56.7%, p = 0.036) when compared to AL-CA. No significant difference existed in LA maximum volume and LA sphericity index between ATTR-CA and AL-CA. LA minimum volumes were larger in ATTR-CA when compared with AL-CA. There was a significant difference in LA function with worse strain values in ATTR vs AL: left atrial reservoir [7.4 (6.3–12.8) in ATTR vs. 13.8 (6.90–24.8) in AL, p = 0.017] and booster strains [3.6 (2.6–5.5) in ATTR vs. 5.2 (3.6–12.1) in AL, p = 0.039]. After adjusting for age, LA reservoir remained significantly lower in ATTR-CA compared to AL-CA (p = 0.03), but not LA booster (p = 0.16). We demonstrate novel differences in LA function between ATTR-CA and AL-CA despite similar LA geometry. Our findings of more impaired LA function in ATTR may offer insight into higher AF burden in these patients.

Myocardial fibrosis in congenital heart disease

Myocardial fibrosis resulting from the excessive deposition of collagen fibers through the myocardium is a common histopathologic finding in a wide range of cardiovascular diseases, including congenital anomalies. Interstitial fibrosis has been identified as a major cause of myocardial dysfunction since it distorts the normal architecture of the myocardium and impairs the biological function and properties of the interstitium. This review summarizes current knowledge on the mechanisms and detrimental consequences of myocardial fibrosis in heart failure and arrhythmias, discusses the usefulness of available imaging techniques and circulating biomarkers to assess this entity and reviews the current body of evidence regarding myocardial fibrosis in the different subsets of congenital heart diseases with implications in research and treatment.

Feasibility of cardiac-synchronized quantitative T1 and T2 mapping on a hybrid 1.5 Tesla magnetic resonance imaging and linear accelerator system

Background and Purpose

Materials and methods

Results

Conclusions

The value of cardiac magnetic resonance imaging in endocardial fibroelastosis

INTRODUCTION

Endocardial fibroelastosis (EFE), an uncommon congenital heart disorder often occurring in infants, has a poor prognosis. It is of great significance to perform early diagnosis and accurately analyze cardiac function to enable further clinical treatment and prognosis decisions. This study aimed to explore the findings of cardiac magnetic resonance (CMR) in patients with EFE, including morphological changes and cardiac function analyses. Additionally, we compared the difference in the evaluation of the cardiac function between CMR and echocardiography (Echo).

METHODS

Eleven patients with EFE (nine females and two males, aged between 0.3 and 1.9 years), treated in our hospital, were analyzed retrospectively. Left ventricular posterior wall thickness (LVPW), anterior wall thickness (LVAW), fractional shortening (FS), ejection fraction (EF), end-systolic diameter (ESD), end-diastolic diameter (EDD), end-systolic volume (ESV), and end-diastolic volume (EDV) were assessed using both Echo and CMR. The Original Ross classification and the New York Heart Association functional classification were used to grade the patients' cardiac function. The correlations between clinical cardiac function classification and MRI- and Echo-derived imaging data were determined.

RESULTS

All patients showed a thickened endocardium and left ventricle globular dilatation on CMR. We observed significant systolic dysfunction and whole or segmental abnormal ventricular movement. Compared with those measured by Echo, the EF, FS, and EDV values were significantly lower when measured using CMR. Compared with Echo measurements, the ESV, ESD, LVAW, and LVPW values were significantly higher when measured using CMR. CMR-measured EF and FS correlated better with the clinical cardiac functional score than those derived from Echo (EF, r = 0.646 > 0.224; FS, r = 0.627 > 0.245, respectively).

CONCLUSION

In patients with EFE, the characteristic morphological changes of the heart could be displayed accurately using CMR. The parameters measured by CMR were more accurate than those of Echo and correlated well with clinical cardiac function scores, mainly because it does not make invalid geometrical assumptions.

A guide for assessment of myocardial stiffness in health and disease

Myocardial stiffness is an intrinsic property of the myocardium that influences both diastolic and systolic cardiac function. Myocardial stiffness represents the resistance of this tissue to being deformed and depends on intracellular components of the cardiomyocyte, particularly the cytoskeleton, and on extracellular components, such as collagen fibers. Myocardial disease is associated with changes in myocardial stiffness, and its assessment is a key diagnostic marker of acute or chronic pathological myocardial disease with the potential to guide therapeutic decision-making. In this Review, we appraise the different techniques that can be used to estimate myocardial stiffness, evaluate their advantages and disadvantages, and discuss potential clinical applications.

Myocardial Extracellular Volume Fraction and T1 Mapping by Cardiac Magnetic Resonance Compared Between Patients With and Without Type 2 Diabetes, and the Effect of ECV and T2D on Cardiovascular Outcomes

Background: To investigate the difference in myocardial extracellular volume fraction (ECV) by cardiac magnetic resonance (CMR) T1 mapping between patients with and without type 2 diabetes (T2D), and the effect of ECV and T2D on cardiovascular (CV) outcomes. Methods: All patients aged > 18 years with known or suspected coronary artery disease who underwent CMR for assessment of myocardial ischemia or myocardial viability at the Department of Cardiology of the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand from September 2017 to December 2018 were screened for inclusion eligibility. Left ventricular ejection fraction (LVEF), late gadolinium enhancement, and T1 mapping were performed. ECV values were derived from myocardial native T1 and contrast-enhanced T1 values that were obtained using modified Look-Locker inversion recovery at the septum of the mid-cavity short-axis map. Demographic data, clinical characteristics, and CV outcomes were collected by retrospective chart review. Composite CV outcomes included CV death, acute coronary syndrome, heart failure hospitalization, or ventricular tachycardia (VT)/ventricular fibrillation. Results: A total of 739 subjects (mean age: 69.5 ± 14.0 years, 49.3% men) were included. Of those, 188 subjects had T2D (25.4%). ECV was significantly higher in T2D than in non-T2D (30.0 ± 5.9% vs. 28.8 ± 4.7%, p = 0.004). During the mean follow-up duration of 26.2 ± 8.5 months, 43 patients (5.8%) had a clinical composite outcome, as follows: three CV death (0.4%), seven acute coronary syndrome (0.9%), 33 heart failure hospitalization (4.5%), and one VT (0.1%). T2D, low LVEF, and high ECV were all identified as independent predictors of CV events. Patients with T2D and high ECV had the highest risk of CV events. Conclusion: Among patients with known or suspected coronary artery disease, patients with T2D had a higher ECV. T2D and high ECV were both found to be independent risk factors for adverse CV outcomes.

Dual flip-angle IR-FLASH with spin history mapping for B1+ corrected T1 mapping: Application to T1 cardiovascular magnetic resonance multitasking

PURPOSE

To develop a single-scan method for B 1 + -corrected T1 mapping and apply it for free-breathing (FB) cardiac MR multitasking without electrocardiogram (ECG) triggering.

METHODS

One dual flip-angle (2FA) inversion recovery (IR)-FLASH scan provides two observations of T 1 ∗ (apparent T1 ) corresponding to two distinct combinations of the nominal FA α and B 1 + . Spatiotemporally coregistered T1 and B 1 + spin history maps are obtained by fitting the 2FA signal model. T1 estimate accuracy and repeatability for single flip-angle (1FA) and 2FA IR-FLASH sequence MR multitasking were evaluated at 3T. A T1 phantom was first imaged on the scanner table, then on two human subjects' thoraxes in both breath-hold (BH) and FB conditions. IR-turbo spin echo (IR-TSE) static phantom T1 measurements served as reference. In 10 healthy subjects, myocardial T1 was evaluated with ECG-free, FB multitasking sequences alongside ECG-triggered BH MOLLI.

RESULTS

For phantom-on-table T1 estimates, 2FA agreed better with IR-TSE (intraclass correlation coefficient [ICC] = 0.996, mean error ± SD = -1.6% ± 1.9%) than did 1FA (ICC = 0.922; mean error ± SD = -4.3% ± 12%). For phantom-on-thorax, 2FA was more repeatable and robust to respiration than 1FA (coefficient of variation [CoV] = 1.2% 2FA, = 11.3% 1FA). In vivo, in intrasession T1 repeatability, 2FA (septal CoV = 2.4%, six-segment CoV = 4.4%) outperformed 1FA (septal CoV = 3.1%, six-segment CoV = 5.5%). In six-segment T1 homogeneity, 2FA (CoV = 7.9%) also outperformed 1FA (CoV = 11.1%).

CONCLUSION

The 2FA IR-FLASH improves T1 estimate accuracy and repeatability over 1FA IR-FLASH, and enables single-scan B 1 + -corrected T1 mapping without BHs or ECG when used with MR multitasking.

Cardiac Pathology in Myotonic Dystrophy Type 1

Myotonic dystrophy type 1 (DM1), the most common muscular dystrophy affecting adults and children, is a multi-systemic disorder affecting skeletal, cardiac, and smooth muscles as well as neurologic, endocrine and other systems. This review is on the cardiac pathology associated with DM1. The heart is one of the primary organs affected in DM1. Cardiac conduction defects are seen in up to 75% of adult DM1 cases and sudden death due to cardiac arrhythmias is one of the most common causes of death in DM1. Unfortunately, the pathogenesis of cardiac manifestations in DM1 is ill defined. In this review, we provide an overview of the history of cardiac studies in DM1, clinical manifestations, and pathology of the heart in DM1. This is followed by a discussion of emerging data about the utility of cardiac magnetic resonance imaging (CMR) as a biomarker for cardiac disease in DM1, and ends with a discussion on models of cardiac RNA toxicity in DM1 and recent clinical guidelines for cardiologic management of individuals with DM1.

Global, segmental and layer specific analysis of myocardial involvement in Duchenne muscular dystrophy by cardiovascular magnetic resonance native T1 mapping

BACKGROUND

Progressive cardiomyopathy accounts for almost all mortality among Duchenne muscular dystrophy (DMD) patients.‍ Thus, our aim was to comprehensively characterize myocardial involvement by investigating the heterogeneity of native T1 mapping in DMD patients using global and regional (including segmental and layer-specific) analysis across a large cohort.

METHODS

We prospectively enrolled 99 DMD patients (8.8 ± 2.5 years) and 25 matched male healthy controls (9.5 ± 2.5 years). All subjects underwent cardiovascular magnetic resonance (CMR) with cine, T1 mapping and late gadolinium enhancement (LGE) sequences. Native T1 values based on the global and regional myocardium were measured, and LGE was defined.

RESULTS

LGE was present in 49 (49%) DMD patients. Global native T1 values were significantly longer in LGE-positive (LGE +) patients than in healthy controls, both in basal slices (1304 ± 55 vs. 1246 ± 27 ms, p < 0.001) and in mid-level slices (1305 ± 57 vs. 1245 ± 37 ms, p < 0.001). No significant difference in global native T1 was found between healthy controls and LGE-negative (LGE-) patients. In segmental analysis, LGE + patients had significantly increased native T1 in all analyzed segments compared to the healthy control group. Meanwhile, the comparison between LGE- patients and healthy controls showed significantly elevated values only in the basal anterolateral segment (1273 ± 62 vs. 1234 ± 40 ms, p = 0.034). Interestingly, the epicardial layer had a significantly higher native T1 in LGE- patients than in healthy controls (p < 0.05), whereas no such pattern was noticed in the global myocardium. Epicardial layer native T1 resulted in the highest diagnostic performance for distinguishing between healthy controls and DMD patients in receiver operating curve analyses (area under the curve [AUC] 0.84 for basal level and 0.85 for middle level) when compared to global native T1 and endocardial layer native T1.

CONCLUSIONS

Myocardial regional native T1, particularly epicardial native T1, seems to have potential as a novel robust marker of very early cardiac involvement in DMD patients.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ( http://www.chictr.org.cn/index.aspx ) ChiCTR1800018340, 09/12/2018, Retrospectively registered.

Cardiac Magnetic Resonance Reveals Incipient Cardiomyopathy Traits in Adult Patients With Phenylketonuria

Background Phenylketonuria is the most common inborn error of amino acid metabolism, where oxidative stress and collateral metabolic abnormalities are likely to cause cardiac structural and functional modifications. We aim herein to characterize the cardiac phenotype of adult subjects with phenylketonuria using advanced cardiac imaging. Methods and Results Thirty-nine adult patients with phenylketonuria (age, 30.5±8.7 years; 10-year mean phenylalanine concentration, 924±330 µmol/L) and 39 age- and sex-matched healthy controls were investigated. Participants underwent a comprehensive cardiac magnetic resonance and echocardiography examination. Ten-year mean plasma levels of phenylalanine and tyrosine were used to quantify disease activity and adherence to treatment. Patients with phenylketonuria had thinner left ventricular walls (septal end-diastolic thickness, 7.0±17 versus 8.8±1.7 mm [P<0.001]; lateral thickness, 6.1±1.4 versus 6.8±1.2 mm [P=0.004]), more dilated left ventricular cavity (end-diastolic volume, 87±14 versus 80±14 mL/m² [P=0.0178]; end-systolic volume, 36±9 versus 29±8 mL/m² [P<0.001]), lower ejection fraction (59±6% versus 64±6% [P<0.001]), reduced systolic deformation (global circumferential strain, -29.9±4.2 % versus -32.2±5.0 % [P=0.027]), and lower left ventricular mass (38.2±7.9 versus 47.8±11.0 g/m² [P<0.001]). T1 native values were decreased (936±53 versus 996±26 ms [P<0.001]), with particular low values in patients with phenylalanine >1200 µmol/L (909±48 ms). Both mean phenylalanine (P=0.013) and tyrosine (P=0.035) levels were independently correlated with T1; and in a multiple regression model, higher phenylalanine levels and higher left ventricular mass associate with lower T1. Conclusions Cardiac phenotype of adult patients with phenylketonuria reveals some traits of an early-stage cardiomyopathy. Regular cardiology follow-up, tighter therapeutic control, and prophylaxis of cardiovascular risk factors, in particular dyslipidemia, are recommended.

Free-breathing simultaneous T1 , T2 , and T2∗ quantification in the myocardium

PURPOSE

To implement a free-breathing sequence for simultaneous quantification of T 1 , T 2 , and T 2 ∗ for comprehensive tissue characterization of the myocardium in a single scan using a multi-gradient-echo readout with saturation and T 2 preparation pulses.

METHODS

In the proposed Saturation And T 2 -prepared Relaxometry with Navigator-gating (SATURN) technique, a series of multi-gradient-echo (GRE) images with different magnetization preparations was acquired during free breathing. A total of 35 images were acquired in 26.5 ± 14.9 seconds using multiple saturation times and T 2 preparation durations and with imaging at 5 echo times. Bloch simulations and phantom experiments were used to validate a 5-parameter fit model for accurate relaxometry. Free-breathing simultaneous T 1 , T 2 , and T 2 ∗ measurements were performed in 10 healthy volunteers and 2 patients using SATURN at 3T and quantitatively compared to conventional single-parameter methods such as SASHA for T 1 , T 2 -prepared bSSFP, and multi-GRE for T 2 ∗ .

RESULTS

Simulations confirmed accurate fitting with the 5-parameter model. Phantom measurements showed good agreement with the reference methods in the relevant range for in vivo measurements. Compared to single-parameter methods comparable accuracy was achieved. SATURN produced in vivo parameter maps that were visually comparable to single-parameter methods. No significant difference between T 1 , T 2 , and T 2 ∗ times acquired with SATURN and single-parameter methods was shown in quantitative measurements (SATURN T 1 = 1573 ± 86 ms , T 2 = 33.2 ± 3.6 ms , T 2 ∗ = 25.3 ± 6.1 ms ; conventional methods: T 1 = 1544 ± 107 ms , T 2 = 33.2 ± 3.6 ms , T 2 ∗ = 23.8 ± 5.5 ms ; P > . 2 ) CONCLUSION: SATURN enables simultaneous quantification of T 1 , T 2 , and T 2 ∗ in the myocardium for comprehensive tissue characterization with co-registered maps, in a single scan with good agreement to single-parameter methods.

Multimodality imaging of myocardial viability: an expert consensus document from the European Association of Cardiovascular Imaging (EACVI)

In clinical decision making, myocardial viability is defined as myocardium in acute or chronic coronary artery disease and other conditions with contractile dysfunction but maintained metabolic and electrical function, having the potential to improve dysfunction upon revascularization or other therapy. Several pathophysiological conditions may coexist to explain this phenomenon. Cardiac imaging may allow identification of myocardial viability through different principles, with the purpose of prediction of therapeutic response and selection for treatment. This expert consensus document reviews current insight into the underlying pathophysiology and available methods for assessing viability. In particular the document reviews contemporary viability imaging techniques, including stress echocardiography, single photon emission computed tomography, positron emission tomography, cardiovascular magnetic resonance, and computed tomography and provides clinical recommendations for how to standardize these methods in terms of acquisition and interpretation. Finally, it presents clinical scenarios where viability assessment is clinically useful.

Multi-parametric assessment of left ventricular hypertrophy using late gadolinium enhancement, T1 mapping and strain-encoded cardiovascular magnetic resonance

AIM

To evaluate the ability of single heartbeat fast-strain encoded (SENC) cardiovascular magnetic resonance (CMR) derived myocardial strain to discriminate between different forms of left ventricular (LV) hypertrophy (LVH).

METHODS

314 patients (228 with hypertensive heart disease (HHD), 45 with hypertrophic cardiomyopathy (HCM), 41 with amyloidosis, 22 competitive athletes, and 33 healthy controls) were systematically analysed. LV ejection fraction (LVEF), LV mass index and interventricular septal (IVS) thickness, T1 mapping and atypical late gadolinium enhancement (LGE) were assessed. In addition, the percentage of LV myocardial segments with strain ≤ - 17% (%normal myocardium) was determined.

RESULTS

Patients with amyloidosis and HCM exhibited the highest IVS thickness (17.4 ± 3.3 mm and 17.4 ± 6 mm, respectively, p < 0.05 vs. all other groups), whereas patients with amyloidosis showed the highest LV mass index (95.1 ± 20.1 g/m2, p < 0.05 vs all others) and lower LVEF compared to controls (50.5 ± 9.8% vs 59.2 ± 5.5%, p < 0.05). Analysing subjects with mild to moderate hypertrophy (IVS 11-15 mm), %normal myocardium exhibited excellent and high precision, respectively for the differentiation between athletes vs. HCM (sensitivity and specificity = 100%, Area under the curve; AUC%normalmyocardium = 1.0, 95%CI = 0.85-1.0) and athletes vs. HHD (sensitivity = 83%, specificity = 75%, AUC%normalmyocardium = 0.85, 95%CI = 0.78-0.90). Combining %normal myocardial strain with atypical LGE provided high accuracy also for the differentiation of HHD vs. HCM (sensitivity = 82%, specificity = 100%, AUCcombination = 0.92, 95%CI = 0.88-0.95) and HCM vs. amyloidosis (sensitivity = 83%, specificity = 100%, AUCcombination = 0.83, 95%CI = 0.60-0.96).

CONCLUSION

Fast-SENC derived myocardial strain is a valuable tool for differentiating between athletes vs. HCM and athletes vs. HHD. Combining strain and LGE data is useful for differentiating between HHD vs. HCM and HCM vs. cardiac amyloidosis.

Prolonged Right Ventricular Outflow Tract Endocardial Activation Duration and Presence of Deceleration Zones in Patients With Idiopathic Premature Ventricular Contractions. Association With Low Voltage Areas

BACKGROUND AND AIMS

The wavefront propagation velocity in the myocardium with fibrosis is characterized by the presence of deceleration zones and late activated zones, that are absent in the normal myocardium. Our aim was to study the right ventricular outflow tract (RVOT) endocardial activation duration in sinus rhythm, and assess the presence of deceleration zones, in patients with premature ventricular contractions (PVCs) and in controls.

METHODS

We studied 29 patients with idiopathic PVCs from the outflow tract, subjected to catheter ablation that had an activation and voltage map of the RVOT in sinus rhythm. A control group of 15 patients without PVCs that underwent ablation of supraventricular arrhythmias was also studied. RVOT endocardial activation duration and number of 10 ms isochrones across the RVOT were assessed. Propagation speed was calculated at the zone with the higher number of isochrones per cm radius. Deceleration zones were defined as zones with >3 isochrones within 1 cm radius. Low voltage areas were defined as areas with local electrogram with amplitude <1.5 mV.

RESULTS

The two groups did not differ in relation to age, gender or number of points in the map. RVOT endocardial activation duration and number of 10 ms isochrones were higher in the PVC group; 56 (41-66) ms vs. 39 (35-41) ms, p = 0.001 and 5 (4-8) vs. 4 (4-5), p = 0.001. Presence of deceleration zones and low voltage areas were more frequent in the PVC group; 20 (69%) vs. 0 (0%), p < 0.0001 and 21 (72%) vs. 0 (0%), p < 0.0001. The wavefront propagation speed was significantly lower in patients with PVCs than in the control group, 0.35 (0.27-0.40) vs. 0.63 (0.56-0.66) m/s, p < 0.0001. Patients with low voltage areas had longer activation duration 60 (52-67) vs. 36 (32-40) ms, p < 0.0001, more deceleration zones, 20 (95%) vs. 0 (0%), p < 0.0001, and lower wavefront propagation speed, 0.30 (0.26-0.36) vs. 0.54 (0.36-0.66) m/s, p = 0.002, than patients without low voltage areas.

CONCLUSION

Right ventricular outflow tract endocardial activation duration was longer, propagation speed was lower and deceleration zones were more frequent in patients with PVCs than in controls and were associated with the presence of low voltage areas.

Cardiovascular magnetic resonance demonstrates structural cardiac changes following transjugular intrahepatic portosystemic shunt

Transjugular intrahepatic portosystemic shunt (TIPS) reduces portal hypertension in patients with liver cirrhosis. The exact cardiac consequences of subsequent increase of central blood volume are unknown. Cardiovascular magnetic resonance (CMR) imaging is the method of choice for quantifying cardiac volumes and ventricular function. The aim of this study was to investigate effects of TIPS on the heart using CMR, laboratory, and imaging cardiac biomarkers. 34 consecutive patients with liver cirrhosis were evaluated for TIPS. Comprehensive CMR with native T1 mapping, transthoracic echocardiography, and laboratory biomarkers were assessed before and after TIPS insertion. Follow-up (FU) CMR was obtained in 16 patients (47%) 207 (170–245) days after TIPS. From baseline (BL) to FU, a significant increase of all indexed cardiac chamber volumes was observed (all P < 0.05). Left ventricular (LV) end-diastolic mass index increased significantly from 45 (38–51) to 65 (51–73) g/m² (P =  < 0.01). Biventricular systolic function, NT-proBNP, high-sensitive troponin T, and native T1 time did not differ significantly from BL to FU. No patient experienced cardiac decompensation following TIPS. In conclusion, in patients without clinically significant prior heart disease, increased cardiac preload after TIPS resulted in increased volumes of all cardiac chambers and eccentric LV hypertrophy, without leading to cardiac impairment during follow-up in this selected patient population.

Native T1 mapping and extracellular volume fraction for differentiation of myocardial diseases from normal CMR controls in routine clinical practice

Background

This study aimed to determine native T1 and extracellular volume fraction (ECV) in distinct types of myocardial disease, including amyloidosis, dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), myocarditis and coronary artery disease (CAD), compared to controls.

Methods

We retrospectively enrolled patients with distinct types of myocardial disease, CAD patients, and control group (no known heart disease and negative CMR study) who underwent 3.0 Tesla CMR with routine T1 mapping. The region of interest (ROI) was drawn in the myocardium of the mid left ventricular (LV) short axis slice and at the interventricular septum of mid LV slice. ECV was calculated by actual hematocrit (Hct) and synthetic Hct. T1 mapping and ECV was compared between myocardial disease and controls, and between CAD and controls. Diagnostic yield and cut-off values were assessed.

Results

A total of 1188 patients were enrolled. The average T1 values in the control group were 1304 ± 42 ms at septum, and 1294 ± 37 ms at mid LV slice. The average T1 values in patients with myocardial disease and CAD were significantly higher than in controls (1441 ± 72, 1349 ± 59, 1345 ± 59, 1355 ± 56, and 1328 ± 54 ms for septum of amyloidosis, DCM, HCM, myocarditis, and CAD). Native T1 of the mid LV level and ECV at septum and mid LV with actual and synthetic Hct of patients with myocardial disease or CAD were significantly higher than in controls.

Conclusions

Although native T1 and ECV of patients with cardiomyopathy and CAD were significantly higher than controls, the values overlapped. The greatest clinical utilization was found for the amyloidosis group.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02086-3.

Multiparametric Early Detection and Prediction of Cardiotoxicity Using Myocardial Strain, T1 and T2 Mapping, and Biochemical Markers: A Longitudinal Cardiac Resonance Imaging Study During 2 Years of Follow-Up

BACKGROUND

Our goal was to evaluate the ability of cardiovascular magnetic resonance for detecting and predicting cardiac dysfunction in patients receiving cancer therapy. Left ventricular ejection fraction, global and regional strain utilizing fast-strain-encoded, T1 and T2 mapping, and cardiac biomarkers (troponin and BNP [brain natriuretic peptide]) were analyzed.

METHODS

Sixty-one patients (47 with breast cancer, 11 with non-Hodgkin lymphoma, and 3 with Hodgkin lymphoma) underwent cardiovascular magnetic resonance scans at baseline and at regular intervals during 2 years of follow-up. The percentage of all left ventricular myocardial segments with strain ≤-17% (normal myocardium [%]) was analyzed. Clinical cardiotoxicity (CTX) and sub-CTX were defined according to standard measures.

RESULTS

Nine (15%) patients developed CTX, 26 (43%) had sub-CTX. Of the 35 patients with CTX or sub-CTX, 24 (69%) were treated with cardioprotective medications and showed recovery of cardiac function. The amount of normal myocardium (%) exhibited markedly higher accuracy for the detection of CTX and sub-CTX compared with left ventricular ejection fraction, T1, and T2 mapping as well as troponin I (Δareas under the curve=0.20, 0.24, and 0.46 for normal myocardium (%) versus left ventricular ejection fraction, troponin I, and T1 mapping, P<0.001 for all). In addition, normal myocardium (%) at baseline accurately identified patients with subsequent CTX (P<0.001), which was not achieved by any other markers.

CONCLUSIONS

Normal myocardium (%) derived by fast-strain-encoded cardiovascular magnetic resonance, is an accurate and sensitive tool that can establish cardiac safety in patients with cancer undergoing cardiotoxic chemotherapy not only for the early detection but also for the prediction of those at risk of developing CTX. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03543228.

Multimodality Imaging Assessment of Myocardial Fibrosis

Myocardial fibrosis, seen in ischemic and nonischemic cardiomyopathies, is associated with adverse cardiac outcomes. Noninvasive imaging plays a key role in early identification and quantification of myocardial fibrosis with the use of an expanding array of techniques including cardiac magnetic resonance, computed tomography, and nuclear imaging. This review discusses currently available noninvasive imaging techniques, provides insights into their strengths and limitations, and examines novel developments that will affect the future of noninvasive imaging of myocardial fibrosis.