MOLLI Sequence Research Articles

Test-retest repeatability of myocardial radiomic features from quantitative cardiac magnetic resonance T1 and T2 mapping

Radiomics of cardiac magnetic resonance (MR) imaging has proved to be potentially useful in the study of various myocardial diseases. Therefore, assessing the repeatability degree in radiomic features measurement is of fundamental importance.The aim of this study was to assess test-retest repeatability of myocardial radiomic features extracted from quantitative T1 and T2 maps.A representative group of 24 subjects (mean age 54 ± 18 years) referred for clinical cardiac MR imaging were enrolled in the study. For each subject, T1 and T2 mapping through MOLLI and T2-prepared TrueFISP acquisition sequences, respectively, were performed at 1.5 T. Then, 98 radiomic features of different classes (shape, first-order, second-order) were extracted from a region of interest encompassing the whole left ventricle myocardium in a short axis slice. The repeatability was assessed performing different and complementary analyses: intraclass correlation coefficient (ICC) and limits of agreement (LOA) (i.e., the interval within which 95% of the percentage differences between two repeated measures are expected to lie).Radiomic features were characterized by a relatively wide range of repeatability degree in terms of both ICC and LOA. Overall, 44.9% and 38.8% of radiomic features showed ICC values > 0.75 for T1 and T2 maps, respectively, while 25.5% and 23.4% of radiomic features showed LOA between ±10%. A subset of radiomic features for T1 (Mean, Median, 10Percentile, 90Percentile, RootMeanSquared, Imc2, RunLengthNonUniformityNormalized, RunPercentage and ShortRunEmphasis) and T2 (MaximumDiameter, RunLengthNonUniformityNormalized, RunPercentage, ShortRunEmphasis) maps presented both ICC > 0.75 and LOA between ±5%.Overall, radiomic features extracted from T1 maps showed better repeatability performance than those extracted from T2 maps, with shape features characterized by better repeatability than first-order and textural features. Moreover, only a limited subset of 9 and 4 radiomic features for T1 and T2 maps, respectively, showed high repeatability degree in terms of both ICC and LOA. These results confirm the importance of assessing test-retest repeatability degree in radiomic feature estimation and might be useful for a more effective/reliable use of myocardial T1 and T2 mapping radiomics in clinical or research studies.

Native myocardial T1 mapping using inversion recovery T1-weighted turbo field echo sequence.

This study proposes the use of the inversion recovery T1-weighted turbo field echo (IR-T1TFE) sequence for myocardial T1 mapping and compares the results obtained with those of the modified Look-Locker inversion recovery (MOLLI) method for accuracy, precision, and reproducibility. A phantom containing seven vials with different T1 values was imaged, thereby comparing the T1 measurements between the inversion recovery spin-echo (IR-SE) technique, MOLLI, and the IR-T1TFE. The accuracy, precision, and reproducibility of the T1-mapping sequences were analyzed in a phantom study. Fifteen healthy subjects were recruited for the in vivo comparison of native myocardial T1 mapping using MOLLI and IR-T1TFE sequences. After myocardium segmentation, the T1 value of the entire myocardium was calculated. In the phantom study, excellent accuracy was achieved using IR-T1TFE for all T1 ranges. MOLLI displayed lower accuracy than IR-T1TFE (p =0.016), substantially underestimating T1 at large T1 values (> 1000ms). In the in vivo study, the first mean myocardial T1 values ± SD using MOLLI and IR-T1TFE were 1306 ± 70ms and 1484 ± 28ms, respectively, and the second were 1297 ± 68ms and 1474 ± 43ms, respectively. The native myocardial T1 obtained with MOLLI was lower than that of IR-T1TFE (p < 0.001). The reproducibility of native myocardial T1 mapping within the same sequence was not statistically significant (p = 0.11). This study demonstrates the utility and validity of myocardial T1 mapping using IR-T1TFE, which is a common sequence. This method was found to have high accuracy and reproducibility.

Repeatability of Open-MOLLI: An open-source inversion recovery myocardial T1 mapping sequence for fast prototyping.

To develop an open-source prototype of myocardial T1 mapping (Open-MOLLI) to improve accessibility to cardiac T1 mapping and evaluate its repeatability. With Open-MOLLI, we aim to enable faster implementation and testing of sequence modifications and to facilitate inter-scanner and cross-vendor reproducibility studies. Open-MOLLI is an inversion-recovery sequence using a balanced SSFP (bSSFP) readout, with inversion and triggering schemes based on the 5(3)3 MOLLI sequence, developed in Pulseq. Open-MOLLI and MOLLI sequences were acquired in the ISMRM/NIST phantom and 21 healthy volunteers. In 18 of those subjects, Open-MOLLI and MOLLI were repeated in the same session (test-retest). Phantom T1 values were comparable between methods, specifically for the vial with reference T1 value most similar to healthy myocardium T1 (T1vial3 = 1027 ms): T1MOLLI = 1011 ± 24 ms versus T1Open-MOLLI = 1009 ± 20 ms. In vivo T1 estimates were similar between Open-MOLLI and MOLLI (T1MOLLI = 1004 ± 33 ms vs. T1Open-MOLLI = 998 ± 52 ms), with a mean difference of -17 ms (p = 0.20), despite noisier Open-MOLLI weighted images and maps. Repeatability measures were slightly higher for Open-MOLLI (RCMOLLI = 3.0% vs. RCOpen-MOLLI = 4.4%). The open-source sequence Open-MOLLI can be used for T1 mapping in vivo with similar mean T1 values to the MOLLI method. Open-MOLLI increases the accessibility to cardiac T1 mapping, providing also a base sequence to which further improvements can easily be added and tested.

Changes in Cardiovascular Magnetic Resonanse T1 and T2 Mapping in Patients Undergoing Autologous Hematopoietic Stem Cell Transplantation

Introduction Despite the significant improvement in survival afforded by hematopoietic stem cell transplantation (HSCT), the therapy is associated with many complications, cardiovascular being one of them. Cardiovascular magnetic resonance (CMR) can depict changes at the tissue level, which could be a reflection of physiology and pathophysiology. In our study we aimed to evaluate the level and progress of diffuse myocardial fibrosis and edema in the heart using T1 and T2 mapping in patients one year after autologous HSCT. Methods Data of 26 patients undergoing autologous HSCT at the Department of Oncology and Hematology in the Hospital of Lithuanian University of Health Sciences Kaunas Clinics between 2021 October and 2022 July was evaluated. Bioethics approvement for prospective study was obtained (No BE-2-96). Cardiac evaluation including cardiovascular magnetic resonance (CMR) was performed before stem cell mobilization and 12 ± 1 months after HSCT. CMR was performed using 3T MRI Siemens Magnetom Skyra, T1 and T2 mapping MOLLI (modified Look-Locker Inversion Recovery) sequences with motion correction (MOCO) were analysed using Syngo.via. Baseline mapping values were compered to values one year after transplantation. SPSS statistics 20 was used for statistical analysis (paired samples T test). Qualitative data is presented as absolute value (N) and percentage (%), quantitative parameters are given as average (m ± standard deviation). Results The mean age of patients was 56,7 ± 13,7 years (ranging from 18 to 74). Out of 26 patients there were 14 men (53,8%) and 12 women (46,2%). Mean T1 mapping value representing diffuse fibrosis significantly increased 12 months after transplantation. Mean T1 mapping value before HSCT was 1215,02 ± 35,2 ms and after 1243,07 ± 46,2 ms (p=0,014). Mean T2 mapping value representing edema did not change significantly. Mean T2 mapping value before HSCT was 38,28 ± 2,1 ms and 39,05 ± 1,8 ms after HSCT. (p=0,059). Conclusions The extent of diffuse fibrosis in the heart represented by elevation of T1 mapping value tend to increase one year after autologous HSCT. This may lead to further remodelling of the heart.

Diabetic atrial cardiomyopathy can be identified by multiparametric mri MRI associating atrio-ventricular groove adipose tissue and left atrial strain profiles

Abstract Background Epicardial adipose tissue (EAT) is tightly associated with neighboring myocardium with free diffusion between the two tissues of fatty acid, peptides and adipokines. In specific circumstances EAT can favors myocardial remodeling and, for instance, contribute to the risk of atrial fibrillation (AF). Thereby, there is a growing interest for EAT as a biomarker of AF however, which is limited by difficulties of delineation of EAT vs. other paracardial adipose tissues. The atrio-ventricular groove adipose tissue (GEAT) has been proven to be pure epicardial adipose tissue. Purpose We tested the feasibility and value of measuring pure EAT of the atrio-ventricular groove (GEAT) using routine cardiovascular magnetic resonance imaging (CMR) in a cohort of patients with distinct metabolic disorders and studied its correlates to determine a CMR cardiometabolic score. Methods One hundred patients from the METACARDIS cohort (EU FP7) who had MRI, all in sinus rhythm and without overt clinical heart disease, were divided into 4 groups based on distinct metabolic profiles: metabolic syndrome (MSD, n=25), severe obesity (SO, BMI ≥ 35 kg/m2, n=18), type-2 diabetes (T2D, n=42) and healthy controls (n=15). Atrioventricular groove EAT volume was measured from cine SSFP MRI images in four-, three-, two-chamber and short-axis views; atrial EAT volume was measured from four- and two-chamber views. Native T1-mapping values of EAT at the anterior atrioventricular groove excluding the coronary vessels were measured from the MOLLI sequence (basal short-axis slice). Results CMR was performed in 100 patients from the MetaCardis cohort. GEAT volume measured from end-diastolic long axis views was obtained in all patients with a high correlation between GEAT and atrial EAT (r=0.95; P&amp;lt;0.0001). GEAT volume was higher in the 3 groups of patients with metabolic disorders and highest in MSD. Together with age, body mass, fat distribution, GEAT volume allowed to distinguish obese, T2D and MSD from controls. T2D patients were uniquely characterized in CMR by decreased GEAT T1 relaxation and decreased peak longitudinal left atrial strain. We developed a CMR score by logistic regression and Random Forest machine-learning algorithm combining GEAT volume, T1 and peak LA strain that identified T2D patients with an AUC of 0.81 (Se:77%, Spe:80%; 95%-CI 0.72–0.91, p &amp;lt;0.0001). Conclusion The epicardial adipose tissue of the AV groove measured by CMR can be used as the proxy of atrial EAT and, in combination with atrial strain and T1 relaxation, allows the early identification of the atrial cardiomyopathy associated with diabetes. There is diagnostic value of a multiparametric CMR approach for the detection of subclinical atrial cardiomyopathy and potentially to identify patients at risk of atrial fibrillation and stroke.

Relationship between cardiac mechanical properties and cardiac magnetic resonance imaging at rest in childhood acute lymphoblastic leukemia survivors.

The characterization of cardiac mechanical properties may contribute to better understanding of doxorubicin-induced cardiotoxicity. Our study aims to investigate the relationship between cardiac mechanical properties, T1 and T2 relaxation times and partition coefficient.Fifty childhood acute lymphoblastic leukemia survivors underwent a cardiac magnetic resonance (CMR) at rest on a 3T MRI system and included a standard ECG-gated 3(3)3(3)5 MOLLI sequence for T1 mapping and an ECG-gated T2-prepared TrueFISP sequence for T2 mapping. Partition coefficient, ejection fraction, end-diastolic volume (EDV) and end-systolic volume (ESV) were calculated. CircAdapt model was used to study cardiac mechanical performance (left ventricle stiffness (LVS), contractility (LVC) and pressure (Pmin and Pmax), cardiac work efficiency (CWE) and ventricular arterial coupling).In the whole cohort, our results showed that LVC (R2 = 69.2%, r = 0.83), Pmin (R2 = 62.9%, r = 0.79) and Pmax can be predicted by significant CMR parameters, while T1 (R2 = 23.2%, r = 0.48) and partition coefficient (R2 = 13.8%, r = 0.37) can be predicted by significant cardiac mechanical properties. In SR group LVS (R2 = 94.8%, r = 0.97), LVC (R2 = 93.7%, r = 0.96) and Pmin (R2 = 90.6%, r = 0.95) can be predicted by significant cardiac mechanical properties, while in HR + DEX group CWE (R2 = 49.8%, r = 0.70) can be predicted by significant cardiac mechanical properties. Partition coefficient (R2 = 72.6%, r = 0.85) can be predicted by significant CMR parameters in SR group.Early characterization of cardiac mechanical properties from CMR parameters has the potential to early detect doxorubicin-induced cardiotoxicity.

DeepFittingNet: A deep neural network-based approach for simplifying cardiac T1 and T2 estimation with improved robustness.

To develop and evaluate a deep neural network (DeepFittingNet) for T1 /T2 estimation of the most commonly used cardiovascular MR mapping sequences to simplify data processing and improve robustness. DeepFittingNet is a 1D neural network composed of a recurrent neural network (RNN) and a fully connected (FCNN) neural network, in which RNN adapts to the different number of input signals from various sequences and FCNN subsequently predicts A, B, and Tx of a three-parameter model. DeepFittingNet was trained using Bloch-equation simulations of MOLLI and saturation-recovery single-shot acquisition (SASHA) T1 mapping sequences, and T2 -prepared balanced SSFP (T2 -prep bSSFP) T2 mapping sequence, with reference values from the curve-fitting method. Several imaging confounders were simulated to improve robustness. The trained DeepFittingNet was tested using phantom and in-vivo signals, and compared to the curve-fitting algorithm. In testing, DeepFittingNet performed T1 /T2 estimation of four sequences with improved robustness in inversion-recovery T1 estimation. The mean bias in phantom T1 and T2 between the curve-fitting and DeepFittingNet was smaller than 30 and 1 ms, respectively. Excellent agreements between both methods was found in the left ventricle and septum T1 /T2 with a mean bias <6 ms. There was no significant difference in the SD of both the left ventricle and septum T1 /T2 between the two methods. DeepFittingNet trained with simulations of MOLLI, SASHA, and T2 -prep bSSFP performed T1 /T2 estimation tasks for all these most used sequences. Compared with the curve-fitting algorithm, DeepFittingNet improved the robustness for inversion-recovery T1 estimation and had comparable performance in terms of accuracy and precision.

A deep learning approach for accurate and robust T1 estimation from cardiac magnetic resonance MOLLI sequences

Abstract Funding Acknowledgements Type of funding sources: None. Background T1 parametric maps of the myocardium are a recent development in cardiac Magnetic Resonance Imaging (MRI). They can be used to characterize the composition of the heart and identify alterations that can be indicative of a pathology. A common method of T1 estimation involves pixel-wise non-linear curve fitting from Modified Look-Locker Inversion Recovery (MOLLI) series [1]. Whilst relatively accurate, this method presents several drawbacks. Firstly, it assumes magnetization recovery to be a purely exponential process dependent on T1, thus neglecting other parameters such as T2 and B1 that can interfere in the process. Secondly, it does not consider that each acquisition during an inversion recovery experiment inverts the magnetization vector by a given angle and thus interferes with the recovery leading to the measurement of a shorter T1* rather than the actual T1 [2]. Additionally, since it considers each pixel individually, neglecting spatial information, it is sensitive to image quality [3]. Finally, since non-linear curve fitting is an iterative algorithm, it is computationally expensive and time-consuming. Methods To address these issues a convolutional neural network, DeepBLESS [4], and two spatially aware variants of it, were trained to predict T1, T2, and B1 with a dataset of MOLLI series simulated from experimental data. The simulation was performed using Bloch simulations and parameters extracted from a dataset composed of 27 single-slice MOLLI series acquired with the 5(3s)3 protocol using a b-SSFP readout at a main magnetic field strength of 3 Tesla. Thus, a dataset could be generated without relying on exponential fitting for ground truth generation. Results The exponential fitting of T1 was shown to consistently underestimate true T1 values by 138 +- 90 ms. In comparison, the spatially naïve DeepBLESS approach showed a mean absolute error of 14 +- 9 ms and the spatially aware DeepBLESS approach (Median-DeepBLESS) showed a mean absolute error of 13 +- 9 ms. As can be seen in Figure 1, Median-DeepBLESS also showed considerably more resilience to noise than exponential fitting and the spatially naïve version of DeepBLESS. Additionally, the deep learning approaches showcased promising results with regards to the estimation of T2 and B1 from MOLLI sequences (See Figure 2). Conclusions It was shown that the Deep Learning approaches eliminated the underestimation bias of exponential fitting with the spatially aware network Median-DeepBLESS being more robust to noise than both exponential fitting and the standard DeepBLESS network for myocardial T1 estimation. Relatively accurate estimation of T2 and B1 from MOLLI sequences was also accomplished through the Deep Learning approach, which may lead to simultaneous T1, T2, and B1 estimation in common clinical practice in the future.

Pilot study to establish the myocardium native T1 mapping reference values in 1.5 Tesla cardiac magnetic resonance of healthy Malaysians

BackgroundCardiac magnetic resonance (CMR) is a powerful and robust imaging modality with the capability for tissue characterisation by quantifying the intrinsic magnetic properties of tissues. The current international consensus recommendation is to determine the local normal T1 mapping value. Recent advancement suggests pooled data or benchmarking of CMR mapping reference values. We present the adult myocardial native T1 mapping value of a common MR acquisition in healthy Malaysians who are predominantly brown skin Asians.MethodsThis is a prospective, cross-sectional study in a single centre. CMR was performed on a 1.5 T MR using 5(3s)3 MOLLI sequence with motion correction, TE = 1.31 ms, TR = 2.78 ms. The analysis of the mid-septal T1 value was done using third-party software (CVi42) and the OsiriX software by two blinded cardiac radiologists.ResultsA total of 51 eligible adults were recruited of which 1 was excluded due to incidental finding of moderate mitral regurgitation. The mean age was 30 years ± 7.0, the majority (64%) was female, the median heart rate was 72 ± 20 bpm and mean the BSA was 1.6 ± 0.1 m2. The ethnicity distribution is Malay 76%, Indian 12%, Chinese 8% and Sabahan 4%. The normal range for mid-septum myocardial T1 using CVi42 was 1012 ± 33 ms and using OsiriX was 1018 ± 37 ms. There is no correlation observed against gender, ethnicity and heart rate. The moderate correlation observed with age is not gender specified. The interobserver reliability was good (coefficient 0.813).ConclusionsFor T1 mapping to be applied clinically, it is imperative to determine the local normal value as recommended by international consensus. The first-ever database on native T1 mapping for 1.5 T CMR reference value for Malaysians who are predominantly brown skin Asians is provided in this pilot study.

Quantitative liver magnetic resonance imaging: correlation between conventional magnetic resonance imaging, laboratory values, and prognostic indices in Budd-Chiari syndrome.

In Budd-Chiari syndrome (BCS), unevenly distributed parenchymal changes and perfusion abnormalities occur due to hepatic venous outflow obstruction. This study aimed to evaluate the changes in the liver parenchyma in BCS using the quantitative magnetic resonance (MR) techniques of MR elastography, T1 and T2 mapping, and diffusion imaging and correlate the quantitative MR parameters through biochemical results and prognostic indices. Fourteen patients with BCS (seven men and seven women) were examined retrospectively. Liver stiffness (kPa), T1 relaxation times (ms) were achieved using the modified Look-Locker inversion recovery (MOLLI) 3(2)3(2)5 sequence and B1-corrected variable flip angle methods, T2 relaxation times (ms), and apparent diffusion coefficient (ADC) values (mm2/s) were measured using regions of interest placed in the same region in all quantitative methods. Measurements were repeated at the precontrast and postcontrast hepatobiliary phases. The reduction rate (RR; %) and adjusted postcontrast T1 (%) were calculated. The values obtained from different liver parenchyma areas (whole liver, caudate lobe, pathological T2 hyperintense tissue, and relatively preserved normal-appearing tissue) were compared using the Wilcoxon signed-rank test. Spearman's correlation coefficient was used to investigate the correlation between quantitative MR parameters and biochemical parameters/ prognostic scores (Child-Pugh score, Clichy score, and Rotterdam index). The parenchymal stiffness and precontrast T1 values of the caudate lobe were significantly lower than those of the remainder of the parenchyma, whereas the adjusted postcontrast T1 percentages (MOLLI) were significantly higher (P ≤ 0.027). The parenchymal stiffness value, T1 and T2 values, percentages of RR (MOLLI), and adjusted postcontrast T1 values for the pathological tissue and relatively normal tissue were significantly different (P < 0.028). No significant difference was found in terms of ADC values between any of the distinct regions of the liver. A strong correlation was detected between the Child-Pugh score, Clichy score, and precontrast T1 values obtained through the MOLLI sequence (r = 0.867, P = 0.012, r = 0.821, P = 0.023, respectively). No correlation was found between the whole liver stiffness values and the laboratory parameters, fibrosis markers, prognostic indices, or MR parameters. A significant correlation was identified between creatinine levels and several T1 parameters and the T2 relaxation time (r ≥ 0.661, P ≤ 0.052). Tissue stiffness and T1 relaxation values are high in the areas identified as fibrosis compared with those in the relatively preserved parenchyma. The T1 relaxation time can offer quantitative information for assessing segmental functional changes and prognosis in BCS.ion for assessing segmental functional changes and prognosis in BCS.

Single breath-hold MR T1 mapping in the heart: Hybrid MOLLI combining saturation and inversion recovery

The native T1 values of the myocardium provide valuable information for tissue characterization and assessment of cardiomyopathies. In this study, we proposed a novel hybrid MOLLI sequence for myocardial T1 mapping. Unlike the two groups of inversion-recovery sampling of the conventional MOLLI5(3 s)3 sequence, the hybrid MOLLI sequence consisted of an inversion-recovery block followed by a saturation-recovery block. Since the second block employed a saturation pulse to spoil the longitudinal magnetization, it did not require a waiting period as MOLLI5(3 s)3 did. As a result, the hybrid MOLLI required less acquisition time leading to a practical application for patients with breath-hold difficulties. Phantom and healthy subject experiments were performed to evaluate the proposed sequence against the MOLLI5(3 s)3 sequence. The phantom study showed that the heart-rate dependency of one variant of the hybrid MOLLI sequences, hbMOLLI4, was comparable to that of MOLLI5(3 s)3. In addition, both hbMOLLI4 and MOLLI53 derived T1 values under 2% variations with simulated heart rates from 50 to 90 beats-per-minute within the range of T1 values for myocardium and blood before contrast administration. Simulation results suggested slightly reduced T1 fitting precision in hbMOLLI4 compared with MOLLI5(3 s)3, but prominently better than saturation recovery. Bland-Altman analysis on accuracy assessment revealed that hbMOLLI4 partially reduced the T1 underestimation of MOLLI5(3 s)3. In the human study, The T1 values of both methods were consistent (hbMOLLI4 vs. MOLLI5(3 s)3, slope = 1.14, R2 > 0.97), with equal reproducibility. The results supported that hybrid MOLLI produced comparable T1 mapping results in terms of accuracy, reproducibility, and heart-rate dependency, at the expense of slightly reduced precision. We concluded that the hybrid MOLLI sequence presents a competitive alternative to the MOLLI5(3 s)3 sequence when a speedy acquisition is required.

The Relationship between Extracellular Volume Compartments and Matrix Metalloproteinases-2 in Left Ventricular Remodeling after Myocardial Infarction.

Matrix metalloproteinases (MMPs) can affect myocardial extracellular volume (ECV) and its compartments, and this can provide more detailed information about the mechanism of adverse left ventricular (LV) remodeling (AR) after acute myocardial infarction (MI). To investigate the role of changes (Δ) in ECV compartments (matrix volume (MVi) and cell volume (CVi)) in the development of AR after MI, and their relationship with MMP-2 expressions. Ninety-two first MI patients who underwent 3 Tesla cardiovascular magnetic resonance imaging performed 2 weeks (baseline) and 6 months post-MI. We measured T1 mapping with MOLLI sequences. ECV was performed post-gadolinium enhancement. ECV and LV mass were used to calculate MVi and CVi. AR was defined as an increase of ≥ 12% in LV end-diastolic volume in 6 months. MMPs were measured using a bead-based multiplex immunoassay system at first day (baseline) and 2 weeks post-MI. P <0.05 was accepted as statistically significant. Mean ECV and mean MVi baseline levels were higher in AR group compared to without AR group (42.9±6.4 vs 39.3±8.2%, p= 0.037; 65.2±13.7 vs 56.7±14.7 mL/m2, p=0.010; respectively). CVi levels was similar between groups. A positive correlation was found between baseline levels of MMP-2 and baseline levels of ECV (r=0.535, p<0.001) and MVi (r=0.549, p<0.001). Increased ΔMVi levels was independently predictor of AR (OR=1.03, p=0.010). ΔMVi had superior diagnostic performance compared to ΔECV in predicting AR (ΔAUC: 0.215±0.07, p<0.001). High MVi levels are associated with AR, and ΔMVi was independently predictor of AR. This may be associated with MMP-2 release due to increased inflammatory response.

Abstract 12664: Comprehensive Histological Analysis of Endomyocardial Biopsy and T1 Mapping for Predicting Left Ventricular Reverse Remodeling in Patients with Recent-Onset Dilated Cardiomyopathy

Background: Cardiomyocyte injury is a key pathological pathway in the progression of heart failure that predicts a poor prognosis; therefore, combined assessment of myocardial fibrosis and cardiomyocyte DNA damage from endomyocardial biopsy (EMB) samples may be of great importance. Meanwhile, cardiovascular magnetic resonance (CMR) native T1 reflects a composite of both intra- and extracellular compartments in the whole myocardium. We sought to assess the performance of native T1 mapping and EMB results to predict left ventricular reverse remodeling (LVRR) in recent-onset dilated cardiomyopathy (DCM). Methods: A total of 29 patients with DCM underwent cine CMR and triple-slice T1 mapping using the MOLLI sequence at 3T, and EMB before receiving guideline-directed medical therapy. Poly ADP-ribose (PAR) nuclear and sirius-red staining were used for quantification of DNA damage and collagen volume fraction (CVF), respectively. LVRR was defined as an increase in LV ejection fraction of ≥10% to the final value of &gt;35%, accompanied by a decrease in LV end-diastolic volume ≥10% at the follow-up CMR. Results: Fifteen patients (52%) achieved LVRR. The mean native T1, histological CVF, and proportion of PAR-positive nuclei were 1376 ± 55 ms, 0.13 ± 0.05, 25 ± 15%, respectively. Native T1 correlated well with CVF (p=0.004) and trended to be higher in DCM patients with increased DNA damage (p=0.17). There was no significant association between CVF and %PAR-positive nuclei. Native T1 &lt;1400 ms provided 86% sensitivity and 67% specificity, with the C-statistic of 0.82 (95% CI 0.67-0.98) for predicting LVRR. By contrast, C-statistic of %PAR nuclei, CVF, and combined assessment of %PAR nuclei and CVF were 0.59, 0.61 and 0.66, respectively. Conclusion: CMR T1 mapping may be a promising strategy for noninvasive biopsy of the whole heart and provide a better prediction of LVRR in recent-onset DCM than comprehensive histological analysis of EMB.

Free-running 3D whole-heart T1 and T2 mapping andcineMRI using low-rank reconstruction withnon-rigid cardiac motion correction.

To introduce non-rigid cardiac motion correction into a novel free-running framework for the simultaneous acquisition of 3D whole-heart myocardial and maps and cine images, enabling a 3-min scan. Data were acquired using a free-running 3D golden-angle radial readout interleaved with inversion recovery and -preparation pulses. After correction for translational respiratory motion, non-rigid cardiac-motion-corrected reconstruction with dictionary-based low-rank compression and patch-based regularization enabled 3D whole-heart and mapping at any given cardiac phase as well as whole-heart cardiac cine imaging. The framework was validated and compared with established methods in 11 healthy subjects. Good quality 3D and maps and cine images were reconstructed for all subjects. Septal values using the proposed approach ( ms) were higher than those from a 2D MOLLI sequence ( ms), which is known to underestimate , while values from the proposed approach ( ms) were in good agreement with those from a 2D GraSE sequence ( ms). The proposed technique provides 3D and maps and cine images with isotropic spatial resolution in a single 3.3-min scan.

Epicardial adipose tissue of atrioventricular grooves is a reliable and early MRI biomarker of the effect of metabolic diseases on atrial myocardium

Abstract Introduction Epicardial adipose tissue (EAT), the visceral adipose tissue surrounding the heart, is implicated in a host of cardiovascular diseases playing a transducer role between systemic metabolic conditions and the myocardium, as illustrated by higher risk of atrial fibrillation in patients with diabetes or obesity. MRI affords comprehensive and non-invasive insights into myocardial structure, function and tissue properties. However, the clinical usefulness of whole atrial EAT is limited by its challenging measurability in clinical routine in several imaging modalities, including MRI. Purpose We hypothesized that atrioventricular groove epicardial adipose tissue (GEAT) which can be measured routinely based on established anatomic landmarks may be: 1) a relevant surrogate of atrial EAT and 2) a relevant imaging biomarker to characterize atrial alterations in patients with varied degrees of metabolic disorders. Methods Ninety-nine patients from the METACARDIS cohort (EU FP7) who had MRI, all in sinus rhythm and without overt clinical heart disease, were divided into 4 groups based on distinct metabolic profiles: metabolic syndrome (MS, n=24), severe obesity (SO, BMI ≥35 kg/m2, n=17), type-2 diabetes (T2D, n=41) and healthy controls (n=17). Atrioventricular groove EAT volume was measured from cine SSFP MRI images in four-, three-, two-chamber and short-axis views; atrial EAT volume was measured from four- and two-chamber views. Native T1-mapping values of EAT at the anterior atrioventricular groove excluding the coronary vessels were measured from the MOLLI sequence (basal short-axis slice). Results We found a high correlation between GEAT and atrial EAT volumes (r=0.96; p&amp;lt;0.0001) indicating that GEAT may reflect global atrial EAT volume. Next, we compared GEAT volume across study groups and found an increased GEAT volume in the 3 groups of patients with metabolic diseases compared to controls, with a significantly higher volume in MS (4.7±1.5 ml), SO (4.1±1.2 ml), and T2D (3.7±1.1 ml) than in Controls (2.6±0.6 ml; p≤0.001, p≤0.01, p≤0.05, respectively). In addition, T2D patients had lower native T1 values within GEAT compared to healthy controls (250±26 ms versus 280±31 ms; p≤0.01). Conclusion Atrioventricular groove EAT can be easily measured from conventional cine SSFP MRI images and could be used as a surrogate of global atrial EAT. Both volume and properties of GEAT are related to the metabolic status of patients. Furthermore, given its pure epicardial origin and pericoronary distribution, GEAT appears as a relevant biomarker of metabolic impacts on atrial myocardium. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Annee-recherche, Agence Regionale de Sante Ile-de-France

Reference values of myocardial native T1 and T2 mapping values in normal Indian population at 1.5 Tesla scanner.

T1 and T2 mapping techniques on cardiovascular magnetic resonance (CMR) provide insights into the myocardial tissue characterisation. We sought to establish the normal reference values of native T1 and T2 mapping in Indian population which can be used subsequently in clinical practice for addressing various cardiac pathologies. This prospective study included consecutive healthy volunteers (18-60years) who underwent CMR on a 1.5 Tesla scanner using standard protocol. T1 mapping sequence was performed using MOLLI sequence with two different flip angles (FA) (35° and 50°). T2 mapping was performed using a hybrid gradient and spin-echo sequence sequence with two different FA (70° and 12°). Images were analysed with ROIs drawn in all the 16 AHA myocardial segments. 50 volunteers (average age-34years, males-72%) were included. All the scans were normal. The mean T1 value at 35-degree FA was 946.86 + 14.16ms and at 50-degree FA was 941.60 + 11.89ms. The mean T2 mapping value at 70-degree FA was 45.67 + 1.39ms and at 12-degree FA was 45.61 + 1.47ms. The mapping values were not statistically different between males and females (all p > 0.2). The T1 and T2 mapping values did not show any significant correlation with LVEF, age, BMI or heart rate (all r < 0.33). The T1 mapping values significantly differ at 35- and 50-degree FAs (p = 0.002). The results establish the normal reference T1 and T2 mapping value for Indian population in institutes using the same protocol and parameters at 1.5 Tesla and may guide future research.

High-resolution systolic T1 mapping with compressed sensing for the evaluation of the right ventricle: a phantom and volunteer study.

To investigate the usefulness of high-resolution systolic T1 mapping using compressed sensing for right ventricular (RV) evaluation. Phantoms and normal volunteers were scanned at 3T by using a high-resolution (HR) modified look-locker inversion recovery (MOLLI) pulse sequence and a conventional MOLLI pulse sequence. The T1 values of the left ventricular (LV) and RV myocardium and blood pool were measured for each sequence. T1 values of HR-MOLLI and MOLLI sequences were compared in the LV myocardium, blood pool, and RV myocardium. The T1 values of HR-MOLLI and MOLLI showed good agreement in both phantoms and the LV myocardium and blood pool of volunteers. However, there was a significant difference between HR-MOLLI and MOLLI in the RV myocardium (1258 ± 52ms vs. 1327 ± 73ms; P = 0.0005). No significant difference was observed between the T1 value of RV and that of LV (1217 ± 32ms) in HR-MOLLI, whereas the T1 value of RV was significantly higher than that of LV in MOLLI (P < 0.0001). The interclass correlation coefficients of intraobserver variabilities from HR-MOLLI and MOLLI were 0.919 and 0.804, respectively, and the interobserver variabilities from HR-MOLLI and MOLLI were 0.838 and 0.848, respectively. Assessment of RV myocardium by using HR systolic T1 mapping was superior to the conventional MOLLI sequence in terms of accuracy and reproducibility.

Preliminary Study on Quantitative Assessment of the Fetal Brain Using MOLLI T1 Mapping Sequence.

Prenatal quantitative evaluation of myelin is important. However, few techniques are suitable for the quantitative evaluation of fetal myelination. To optimize a modified Look-Locker inversion recovery (MOLLI) T1 mapping sequence for fetal brain development study. Prospective observational preliminary cohort study. A total of 71 women with normal fetuses divided into mid-pregnancy (gestational age 24-28 weeks, N=25) and late pregnancy (gestational age > 28 weeks, N=46) groups. A 3 T/MOLLI sequence. T1 values were measured in pedunculus cerebri, basal ganglia, thalamus, posterior limb of the internal capsule, temporal white matter, occipital white matter, frontal white matter, and parietal white matter by two radiologists (11 and 16 years of experience, respectively). The Kruskal-Wallis test was used for reginal comparison. For each region of interest (ROI), differences in T1 values between the mid and late pregnancy groups were assessed by the Mann Whitney U test. Pearson correlation coefficients (r) were used to evaluate the correlations between T1 values and gestational age for each ROI. Intraobserver and interobserver agreement was determined by the intraclass correlation coefficient (ICC). A P value <0.05 was considered statistically significant. Interobserver and intraobserver agreements of T1 were good for all ROIs (all ICCs > 0.700). There were significant differences in T1 values between lobal white matter and deep regions, respectively. Significant T1 values differences were found between middle and late pregnancy groups in pedunculus cerebri, basal ganglion, thalamus, posterior limb of the internal capsule, temporal, and occipital white matter. The T1 values showed significantly negative correlations with gestational weeks in pedunculus cerebri (r=-0.80), basal ganglion (r=-0.60), thalamus (r=-0.68), and posterior limb of the internal capsule (r=-0.77). The T1 values of fetal brain may be assessed using the MOLLI sequence and may reflect the myelination. 3 TECHNICAL EFFICACY: Stage 2.

Liver T1 relaxation time of the 'normal liver' in healthy Asians: measurement with MOLLI and B1-corrected VFA methods at 3T.

Liver T1 is a potential magnetic resonance imaging biomarker for liver diseases. This study aimed to determine the T1 relaxation time of the normal liver (PDFF<5%) in healthy Asian volunteers using modified look-locker inversion recovery (MOLLI) and B1 inhomogeneity-corrected variable flip angle (B1-corrected VFA). 60 healthy Asian volunteers without focal or diffuse liver disease underwent a liver scan at 3T magnetic resonance. Proton density fat fraction (PDFF) and liver stiffness measurements were applied for the quantification of liver fat and fibrosis. T1 mapping was performed with MOLLI and B1-corrected VFA sequences. Bland-Altman, linear regression, Student t-test, and one-way analysis of variance were used for statistical analysis. The mean T1 relaxation times of the whole liver were 901 ± 34 ms by MOLLI, and 948 ± 29 ms by B1-corrected VFA in healthy volunteers. There was a strong correlation (r = 0.86, p < 0.0001) for liver T1 between two T1 mapping methods. There were significant differences between the right and left lobes in liver T1 relaxation times using both methods (p < 0.05). Gender and Asian ethnic disparities had no impact on liver T1 relaxation times. T1 relaxation times of the normal liver (PDFF<5%) in healthy volunteers were established by MOLLI and B1-corrected VFA T1 mapping methods at 3T. It may provide suitable and robust baseline values for the assessment of liver diseases. Gender and Asian ethnic disparities do not impact liver T1 relaxation time measurements.

Improved cardiac T1 mapping accuracy and precision with a new hybrid MOLLI and SASHA technique: MOSHA

PurposeTo develop and validate a new myocardial T1 mapping sequence (MOSHA) which is based on a combination of the modified Look-Locker inversion recovery (MOLLI) and the saturation recovery single-shot acquisition (SASHA) sequences. MethodsPrior studies have shown that myocardial T1 mapping by SASHA is more accurate but less precise than MOLLI. A new myocardial T1 mapping technique (MOSHA) based on single-shot acquisitions is developed by combining the MOLLI and SASHA sequences. Phantom and patient studies on 15 patients (9 males, median age 21 years) were performed to validate and compare MOSHA with the MOLLI and SASHA sequences in terms of accuracy and precision. ResultsIn the phantom study, MOSHA was as accurate as SASHA (P-value = 0.88) and as precise as MOLLI (P-value = 0.59). Similar trends were observed in the patient study. Compared to SASHA, MOSHA accuracy was comparable for blood pre-contrast (P-value≥0.10) and post-contrast (P-value≥0.70), and for myocardium pre-contrast (P-value = 0.70) and post-contrast (P-value = 0.09). Compared to MOLLI, MOSHA precision was lower for blood pre-contrast (P-value<0.01) and higher for blood post-contrast (P-value≤0.01), and comparable for myocardium pre-contrast (P-value = 0.24) and post-contrast (P-value = 0.07). Synthetic Extracellular volume fraction (ECV) calculated by MOSHA was more precise than those of SASHA and MOLLI (P-value≤0.01). ConclusionIn phantom studies and patients, MOSHA has comparable accuracy as SASHA and nearly similar precision as MOLLI for T1 mapping. Precision of MOSHA was better than MOLLI and SASHA in synthetic ECV measurements. Therefore, it may be a superior choice in clinical practice for a precise and accurate calculation of T1 and ECV.