Quantification of global myocardial function by cine MRI deformable registration-based analysis: Comparison with MR feature tracking and speckle-tracking echocardiography

Peripartum Cardiomyopathy is Associated With Abnormalities of Myocardial Deformation and Late Gadolinium Enhancement

Purpose: Peripartum cardiomyopathy (PPCM) affects women in late pregnancy and postpartum. Cardiovascular magnetic resonance (CMR) can contribute to PPCM diagnosis and management. We explored CMR findings in PPCM, including myocardial strain and late gadolinium enhancement (LGE) patterns. Materials and Methods: This retrospective single-centre study included patients with PPCM who underwent CMR from 2010 to 2018. Exclusions were other cardiomyopathy causes. CMR parameters, including ventricular function, LGE, and myocardial strain, were compared between the PPCM group and healthy controls. Transthoracic echocardiographic data were reviewed to assess functional improvement in PPCM patients. Results: Thirty-two women with PPCM (mean age 42 ± 6 years) and 26 controls (mean age 43 ± 14 years) were included. PPCM patients had significantly lower left ventricular (LV) ejection fractions (median 37.5% vs 60.5%, P < .001), higher LV end-diastolic volumes (median 108 ml/m² vs 76 ml/m², P < .001), and reduced global LV strain compared to controls. Eighteen PPCM patients (58%) had non-ischaemic pattern LGE, with no LGE in controls besides hingepoint LGE (23%). LGE was most prevalent in the basal and mid anteroseptum. LGE patterns included linear mid-wall, subepicardial, and right ventricular side of the septum. Twenty-four patients (92%) showed improvement in LVEF at follow-up echocardiogram (mean LVEF 28% ± 1.9% at diagnosis and 45% ± 3% at follow-up, P < .001). Conclusion: We identified a non-ischaemic pattern LGE that is nonspecific in isolation but could suggest PPCM in the correct clinical context along with abnormal CMR strain values. Future studies should evaluate the clinical application of these findings to facilitate earlier diagnosis and enhance management.

[Research progress of right ventricular strain imaging evaluation technology in pulmonary arterial hypertension]

Pulmonary arterial hypertension (PAH) has a subtle onset, rapid progression, and high mortality rate. Imaging evaluation is an important diagnostic and follow-up method for PAH patients. Right ventricular (RV) strain evaluation can identify early changes in RV function and predict the prognosis. Currently, various methods such as tissue Doppler imaging, velocity vector imaging, speckle tracking imaging, and cardiac magnetic resonance imaging can be used to evaluate RV strain in PAH patients. This article aims to summarize the research progress of RV strain imaging evaluation technology in PAH patients, in order to provide a basis for clinical diagnosis and follow-up of PAH patients.

Measurement of Abdominal Aortic Aneurysm Strain Using MR Deformable Image Registration: Accuracy and Relationship to Recent Aneurysm Progression

BACKGROUND

Management of asymptomatic abdominal aortic aneurysm (AAA) based on maximum aneurysm diameter and growth rate fails to preempt many ruptures. Assessment of aortic wall biomechanical properties may improve assessment of progression and rupture risk. This study aimed to assess the accuracy of AAA wall strain measured by cine magnetic resonance imaging (MRI) deformable image registration (MR strain) and investigate its relationship with recent AAA progression.

METHODS

The MR strain accuracy was evaluated in silico against ground truth strain in 54 synthetic MRIs generated from a finite element model simulation of an AAA patient's abdomen for different aortic pulse pressures, tissue motions, signal intensity variations, and image noise. Evaluation included bias with 95% confidence interval (CI) and correlation analysis. Association of MR strain with AAA growth rate was assessed in 25 consecutive patients with >6 months of prior surveillance, for whom cine balanced steady-state free-precession imaging was acquired at the level of the AAA as well as the proximal, normal-caliber aorta. Univariate and multivariate regressions were used to associate growth rate with clinical variables, maximum AAA diameter (D max ), and peak circumferential MR strain through the cardiac cycle. The MR strain interoperator variability was assessed using bias with 95% CI, intraclass correlation coefficient, and coefficient of variation.

RESULTS

In silico experiments revealed an MR strain bias of 0.48% ± 0.42% and a slope of correlation to ground truth strain of 0.963. In vivo, AAA MR strain (1.2% ± 0.6%) was highly reproducible (bias ± 95% CI, 0.03% ± 0.31%; intraclass correlation coefficient, 97.8%; coefficient of variation, 7.14%) and was lower than in the nonaneurysmal aorta (2.4% ± 1.7%). D max ( β = 0.087) and MR strain ( β = -1.563) were both associated with AAA growth rate. The MR strain remained an independent factor associated with growth rate ( β = -0.904) after controlling for D max .

CONCLUSIONS

Deformable image registration analysis can accurately measure the circumferential strain of the AAA wall from standard cine MRI and may offer patient-specific insight regarding AAA progression.

A bidirectional registration neural network for cardiac motion tracking using cine MRI images

Using cine magnetic resonance imaging (cine MRI) images to track cardiac motion helps users to analyze the myocardial strain, and is of great importance in clinical applications. At present, most of the automatic deep learning-based motion tracking methods compare two images without considering temporal information between MRI frames, which easily leads to the lack of consistency of the generated motion fields. Even though a small number of works take into account the temporal factor, they are usually computationally intensive or have limitations on image length. To solve this problem, we propose a bidirectional convolution neural network for motion tracking of cardiac cine MRI images. This network leverages convolutional blocks to extract spatial features from three-dimensional (3D) image registration pairs, and models the temporal relations through a bidirectional recurrent neural network to obtain the Lagrange motion field between the reference image and other images. Compared with previous pairwise registration methods, the proposed method can automatically learn spatiotemporal information from multiple images with fewer parameters. We evaluated our model on three public cardiac cine MRI datasets. The experimental results demonstrated that the proposed method can significantly improve the motion tracking accuracy. The average Dice coefficient between estimated segmentation and manual segmentation has reached almost 0.85 on the widely used Automatic Cardiac Diagnostic Challenge (ACDC) dataset.

Comparison between pre- and post-contrast cardiac MRI cine images: the impact on ventricular volume and strain measurement

To explore whether contrast agent administration will affect ventricular volume and strain parameters measured on cardiac magnetic resonance cine images. This prospective study enrolled 88 patients, including 32 patients with cardiac amyloidosis (CA), 32 patients with hypertrophic cardiomyopathy (HCM), and 24 control participants, to perform steady-state free precession (SSFP)-cine imaging twice, respectively before and after contrast agent injection. Indexed left and right ventricular (LV and RV) volume and LV strain parameters (peak radial strain [PRS], peak circumferential strain [PCS], peak longitudinal strain [PLS]) were analyzed and compared between the pre- and post-contrast cine groups. Compared to the group of pre-contrast cine, the end-diastolic volume index (EDVi) and end-systolic volume index (ESVi) significantly increased in the group using post-contrast cine images (all p < 0.05), especially in the right ventricle. After contrast injection, the right ventricular ejection fraction (RVEF) decreased significantly (p < 0.05), while the left ventricular ejection fraction (LVEF) only reduced for patients with HCM (p < 0.05). The PRS (37.1 ± 15.2 vs. 32.0 ± 15.4, p < 0.001) and PCS (- 14.9 ± 4.3 vs. - 14.0 ± 4.1, p < 0.001) derived from post-contrast cine images reduced significantly in all patients and this tendency remained in subgroup analysis except for PCS in the control group. The administration of a contrast agent may influence the measurements of ventricular volume and strain. Acquiring pre-contrast cine images were suggested for patients who required more accurate right ventricle evaluation or precise strain assessment.

Model-Agnostic Temporal Regularizer for Object Localization Using Motion Fields

Video analysis often requires locating and tracking target objects. In some applications, the localization system has access to the full video, which allows fine-grain motion information to be estimated. This paper proposes capturing this information through motion fields and using it to improve the localization results. The learned motion fields act as a model-agnostic temporal regularizer that can be used with any localization system based on keypoints. Unlike optical flow-based strategies, our motion fields are estimated from the model domain, based on the trajectories described by the object keypoints. Therefore, they are not affected by poor imaging conditions. The benefits of the proposed strategy are shown on three applications: 1) segmentation of cardiac magnetic resonance; 2) facial model alignment; and 3) vehicle tracking. In each case, combining popular localization methods with the proposed regularizer leads to improvement in overall accuracies and reduces gross errors.

Evaluation and Comparison of Quantitative Right Ventricular Strain Assessment by Cardiac Magnetic Resonance in Pulmonary Hypertension Using Feature Tracking and Deformable Registration Algorithms

RATIONALE AND OBJECTIVE

Deformable registration algorithms (DRA) has been used to detect left ventricular myocardial changes, however, its clinical utility in right ventricular (RV) function has not been evaluated. In this study, we aim to evaluate and compare quantitative RV strain assessment by cardiac magnetic resonance in pulmonary hypertension (PH) using feature tracking (FT) and DRA.

MATERIALS AND METHODS

Thirty patients were confirmed to have PH using right heart catheterization, and 16 healthy controls were evaluated with cardiac magnetic resonance. Global and segmental RV strain was measured by DRA and FT methods. Intraclass correlation coefficients (ICCs), coefficient of variation, and Bland-Altman analysis were used to assess and compare the interobserver and intraobserver variability of the DRA and FT methods.

RESULTS

DRA was more sensitive than FT in the detection of RV circumferential and septal dysfunction. The global longitudinal strain (GLS) obtained by the two methods was reduced in mild-moderate PH patients (mean pulmonary artery pressure≤45 mm Hg), and the GLS and global circumferential strain (GCS) were reduced in severe PH patients (mean pulmonary artery pressure >45 mm Hg). DRA and FT methods demonstrate similar observer agreement in global strain using ICC (ICC greater than 0.90), but RV strain derived from DRA had lower variability using COV ([8%-14%] for DRA versus [11%-39%] for FT).For segmental longitudinal strain, DRA showed higher ICC and lower COV compared with that of the FT method. Correlations between RVEF and RV global strain parameters were strong (p < 0.01):GLS-DRA, r = -0.696; GLS-FT, r = -0.832; GCS-DRA, r = -0.745; and GCS-FT, r = -0.817. GLS-DRA was weakly correlated with mPAP (r = 0.385, p < 0.05).In multiple linear regression analysis, RVEF and mPAP were independent predictors of GLS-DRA (R² = 0.57, p < 0.01).

CONCLUSIONS

The DRA method is more sensitive and robust for RV myocardial strain measurements than FT method.

The Prognostic Value of Left Ventricular Mechanical Dyssynchrony Derived from Cardiac MRI in Patients with Idiopathic Dilated Cardiomyopathy

Purpose

To investigate the prognostic value of mechanical dyssynchrony evaluated by deformable registration algorithm (DRA) analysis of cardiac MRI (CMR) in patients with idiopathic dilated cardiomyopathy (DCM).

Materials and Methods

This secondary analysis of a prospective study (clinical trial no. ChiCTR1800017058) enrolled 409 patients (mean age, 48 years ± 14:300 men) with idiopathic DCM who underwent CMR between June 2012 and September 2018. Mechanical dyssynchrony was measured as standard deviation of time-to-peak (sdTTP) and uniformity ratio estimate (URE) indexes by DRA strain analysis. The primary endpoint included all-cause mortality and heart transplantation. The secondary endpoint included primary endpoint, aborted sudden cardiac death, and heart failure readmission. Cox regression analyses and Kaplan-Meier survival analysis were performed to identify the association between variables and outcomes.

Results

During a median follow-up of 25.1 months, 57 and 132 patients reached primary and secondary endpoints, respectively. Most URE indexes were significantly lower in patients reaching primary endpoint. In multivariable analysis, circumferential URE (CURE) at apical level was independently associated with primary endpoints (hazard ratio, 0.307 [95% CI: 0.106, 0.883]; P = .03) and secondary endpoints (hazard ratio, 0.452 [95% CI: 0.209, 0.979]; P = .04), whereas most sdTTP measures were not. Furthermore, among patients with left ventricular ejection fraction of less than 35% or presence of late gadolinium enhancement, those with CURE at apical level of less than 0.917 had a significantly higher rate of adverse outcomes.

Conclusion

URE indexes were more predictive of prognostic outcomes compared with sdTTP measurements; the CURE at apical level was an independent predictor of adverse cardiac events in patients with DCM.Keywords: Heart, Outcomes Analysis, MR-ImagingClinical trial registration no. ChiCTR1800017058 Supplemental material is available for this article. See also commentary by Rajiah and François in this issue.© RSNA, 2021.

Pulsed field ablation prevents chronic atrial fibrotic changes and restrictive mechanics after catheter ablation for atrial fibrillation

Aims

Pulsed field ablation (PFA), a non-thermal ablative modality, may show different effects on the myocardial tissue compared to thermal ablation. Thus, this study aimed to compare the left atrial (LA) structural and mechanical characteristics after PFA vs. thermal ablation.

Methods and results

Cardiac magnetic resonance was performed pre-ablation, acutely (<3 h), and 3 months post-ablation in 41 patients with paroxysmal atrial fibrillation (AF) undergoing pulmonary vein (PV) isolation with PFA (n = 18) or thermal ablation (n = 23, 16 radiofrequency ablations, 7 cryoablations). Late gadolinium enhancement (LGE), T2-weighted, and cine images were analysed. In the acute stage, LGE volume was 60% larger after PFA vs. thermal ablation (P < 0.001), and oedema on T2 imaging was 20% smaller (P = 0.002). Tissue changes were more homogeneous after PFA than after thermal ablation, with no sign of microvascular damage or intramural haemorrhage. In the chronic stage, the majority of acute LGE had disappeared after PFA, whereas most LGE persisted after thermal ablation. The maximum strain on PV antra, the LA expansion index, and LA active emptying fraction declined acutely after both PFA and thermal ablation but recovered at the chronic stage only with PFA.

Conclusion

Pulsed field ablation induces large acute LGE without microvascular damage or intramural haemorrhage. Most LGE lesions disappear in the chronic stage, suggesting a specific reparative process involving less chronic fibrosis. This process may contribute to a preserved tissue compliance and LA reservoir and booster pump functions.

Evaluation of strain averaging area and strain estimation errors in a spheroidal left ventricular model using synthetic image data and speckle tracking

BACKGROUND

In majority of studies on speckle tracking echocardiography (STE) the strain estimates are averaged over large areas of the left ventricle. This may impair the diagnostic capability of the STE in the case of e.g. local changes of the cardiac contractility. This work attempts to evaluate, how far one can reduce the averaging area, without sacrificing the estimation accuracy that could be important from the clinical point of view.

METHODS

Synthetic radio frequency (RF) data of a spheroidal left ventricular (LV) model were generated using FIELD II package and meshes obtained from finite element method (FEM) simulation. The apical two chamber (A2C) view and the mid parasternal short axis view (pSAXM) were simulated. The sector encompassed the entire cross-section (full view) of the LV model or its part (partial view). The wall segments obtained according to the American Heart Association (AHA17) were divided into subsegments of area decreasing down to 3 mm2. Longitudinal, circumferential and radial strain estimates, obtained using a hierarchical block-matching method, were averaged over these subsegments. Estimation accuracy was assessed using several error measures, making most use of the prediction of the maximal relative error of the strain estimate obtained using the FEM derived reference. Three limits of this predicted maximal error were studied, namely 16.7%, 33% and 66%. The smallest averaging area resulting in the strain estimation error below one of these limits was considered the smallest allowable averaging area (SAAA) of the strain estimation.

RESULTS

In all AHA17 segments, using the A2C projection, the SAAA ensuring maximal longitudinal strain estimates error below 33% was below 3 mm2, except for the segment no 17 where it was above 278 mm2. The SAAA ensuring maximal circumferential strain estimates error below 33% depended on the AHA17 segment position within the imaging sector and view type and ranged from below 3-287 mm2. The SAAA ensuring maximal radial strain estimates error below 33% obtained in the pSAXM projection was not less than 287 mm2. The SAAA values obtained using other maximal error limits differ from SAAA values observed for the 33% error limit only in limited number of cases. SAAA decreased when using maximal error limit equal to 66% in these cases. The use of the partial view (narrow sector) resulted in a decrease of the SAAA.

CONCLUSIONS

The SAAA varies strongly between strain components. In a vast part of the LV model wall in the A2C view the longitudinal strain could be estimated using SAAA below 3 mm2, which is smaller than the averaging area currently used in clinic, thus with a higher resolution. The SAAA of the circumferential strain estimation strongly depends on the position of the region of interest and the parameters of the acquisition. The SAAA of the radial strain estimation takes the highest values. The use of a narrow sector could increase diagnostic capabilities of 2D STE.

Comprehensive Assessment of Right Ventricular Function by Three-Dimensional Speckle-Tracking Echocardiography: Comparisons with Cardiac Magnetic Resonance Imaging

BACKGROUND

Three-dimensional speckle-tracking echocardiography (3D-STE) has been increasingly used to quantify right ventricular (RV) function. However, direct comparisons of 3D-STE with cardiac magnetic resonance (CMR) imaging for evaluation of RV function are limited. This study aimed to test the feasibility and accuracy of 3D-STE for the quantification of RV volumes, ejection fraction (EF), and longitudinal strain in comparison with CMR imaging and to determine whether 3D-STE for RV strain is superior to two-dimensional (2D) STE in comparison with CMR imaging.

METHODS

A total of 195 consecutive patients referred for both CMR imaging and echocardiography were studied. Right ventricular end-diastolic volume (RVEDV), RV end-systolic volume (RVESV), RVEF, and 3D RV longitudinal strain (3D-RVLS) of the free wall by 3D-STE and 2D-RVLS of the free wall by 2D-STE, were compared with CMR measurements. Pearson correlation and Bland-Altman analyses were used to assess the intertechnique agreement.

RESULTS

Right ventricular 3D-STE was feasible in 174 patients (89%). Right ventricular volumes and EF determined by 3D-STE strongly correlated with CMR values (RVEDV, r = 0.94; RVESV, r = 0.96; RVEF, r = 0.91; all P < .001). Three-dimensional STE slightly underestimated the RV volumes and longitudinal strain and overestimated the RVEF. The 3D-RVLS values correlated better than 2D-RVLS values with CMR values (0.85 vs 0.64, P < .001) with smaller bias and narrower limits of agreement (bias: 2.0 and 2.6; limits of agreement: 8.5 and 12.5, respectively). The bias and limits of agreement for 3D-STE-obtained RVLS were increased in patients with RV dilation, RVEF < 45%, or lower frame rate compared with those with normal RV size, RVEF ≥ 45%, or higher frame rate, respectively. Right ventricular 3D-STE measurements were highly reproducible.

CONCLUSIONS

The 3D-STE measurements of RV volumes, EF, and longitudinal strain are highly feasible and reproducible, and data measured by 3D-STE correlate strongly with those determined using CMR imaging. Thus, 3D-STE may be a valid alternative to CMR imaging for the quantification of RV function in everyday clinical practice.

Cardiac magnetic resonance longitudinal strain analysis in acute ST-segment elevation myocardial infarction: A comparison with speckle-tracking echocardiography

BACKGROUND

Strain analysis with speckle-tracking echocardiography (STE) is considered superior to ejection fraction for ventricular function assessment in different clinical scenarios. Feature tracking (FT) permits cardiac magnetic resonance (CMR) strain analysis in routinely acquired cine images. This study evaluated the feasibility of CMR-FT and its agreement with STE in patients with acute ST-segment elevation myocardial infarction (STEMI).

METHODS

An echocardiogram and CMR were performed in 128 patients who underwent primary percutaneous revascularisation after a STEMI. Adequate strain analysis was obtained by both techniques in 98 patients and peak systolic longitudinal strain (LS) was assessed with STE and CMR-FT.

RESULTS

Of 1568 myocardial segments, 97.2% were correctly tracked with STE and 97.7% with CMR-FT. For global LS, STE showed a mean of -14.8 ± 3.3% and CMR-FT -13.7 ± 3.0%, with good agreement between modalities [intraclass correlation coefficient (ICC) 0.826; bias -1.09%; limits of agreement (LOA) ± 4.2%]. On the other hand, segmental LS agreement was only moderate, with an ICC of 0.678 (bias -1.14%; LOA ± 11.76%) and the ICC ranged from 0.538 at the basal antero-lateral segment to 0.815 at the apical lateral segment. Finally, both STE and CMR-FT showed excellent intra- and inter-observer reproducibility (ICC > 0.9).

CONCLUSIONS

CMR-FT provides LS with similar feasibility to STE and both techniques showed good agreement for global LS, although agreement at segmental level was only moderate. CMR-FT showed excellent reproducibility, strengthening its robustness and potential for both research and clinical applications.

Cardiovascular Magnetic Resonance Imaging: Identifying the Effects of Cancer Therapy

The era of modern oncology incorporates an ever-evolving personalized approach to hematological malignancies and solid tumors. As a result, patient survival rates have, in part, substantially improved, depending on the specific type of underlying malignancy. However, systemic therapies may come along with potential cardiotoxic effects resulting in heart failure with increased morbidity and mortality. Ultimately, patients may survive their malignancy but die as a result of cancer treatment. Cardiovascular magnetic resonance imaging has long been in use for the assessment of function and tissue characteristics in patients with various nonischemic cardiac diseases. Besides an introductory overview on the general definition of cardiotoxicity including potential underlying mechanisms, this review provides insight into the application of various cardiovascular magnetic resonance imaging techniques in the setting of cancer therapy-related cardiac and vascular toxicity. Early identification of cardiotoxic effects may allow for on-time therapy adjustment and/or cardioprotective measures to avoid subsequent long-term heart failure with increased mortality.

Advanced myocardial characterization in hypertrophic cardiomyopathy: feasibility of CMR-based feature tracking strain analysis in a case-control study

OBJECTIVES

This study aimed to evaluate the feasibility and reproducibility of using cardiovascular magnetic resonance feature tracking (CMR-FT) for analysis of bi-ventricular strain and strain rate (SR) in hypertrophic cardiomyopathy (HCM) patients as well as to explore the correlation between right ventricular (RV) and left ventricular (LV) deformation.

METHODS

A total of 60 HCM patients and 48 controls were studied. Global and segmental peak values of bi-ventricular longitudinal, circumferential, radial strain, and systolic SR were analyzed. Pearson analysis was performed to investigate the correlation of RV and LV deformation. Intra-observer and inter-observer reproducibility were also assessed.

RESULTS

LV mass in the HCM group was significantly higher than that in the control group. LV end-systolic and end-diastolic volume and RV end-systolic and end-diastolic volume in the HCM group were all significantly lower than the correlated parameters in the control group (p < 0.001, respectively), whereas no statistical difference was found in ejection fraction (p > 0.05). Global longitudinal strain (GLS), global longitudinal strain rate (GLSR), global circumferential strain (GCS), global circumferential strain rate (GCSR), global radial strain (GRS), and global radial strain rate (GRSR) of the LV and RV were all significantly lower than the control group, and segmental strain and SR were also true (p < 0.001, respectively). Bi-ventricular strain and SR measurements were highly reproducible at both intra- and inter-observer levels. Additionally, Pearson analysis showed RV GCS, GLS, and GRS positively correlated with LV GCS, GLS, and GRS (r = 0.713, p < 0.001; r = 0.728, p < 0.001; r = 0.730, p < 0.001, respectively).

CONCLUSIONS

CMR-FT is a promising approach to analyze impairment of global and segmental myocardium deformation in HCM patients non-invasively and quantitatively.

KEY POINTS

• CMR-FT allows for advanced myocardial characterization with high reproducibility. • As compared with controls, HCM patients have significant differences in CMR-FT strain analysis while ejection fraction was similar. • CMR-FT may serve as an early biomarker of HCM in subjects at risk.

Cardiovascular magnetic resonance-derived myocardial strain in asymptomatic heart transplanted patients and its correlation with late gadolinium enhancement

OBJECTIVES

To investigate whether cardiovascular magnetic resonance (CMR)-derived myocardial strains were abnormal in asymptomatic heart transplant (HT) patients with normal left ventricular ejection fraction (LVEF) and to detect the relationship between CMR-derived myocardial strain parameters and late gadolinium enhancement (LGE) in asymptomatic HT patients.

METHODS

A total of 72 HT patients and 35 healthy volunteers underwent 1.5-T MR scanning. The examination protocol included basic cine imaging and LGE. The deformation registration algorithm (DRA) and feature tracking (FT) software were used for the strain analyses. Myocardial strain measurements included left ventricular global longitudinal strain (LVGLS), LV global circumferential strain (LVGCS), LV global radial strain (LVGRS) and right ventricular longitudinal strain (RVLS).

RESULTS

Compared with healthy volunteers, HT patients had significantly decreased DRA- and FT- derived myocardial strain measurements (all p < 0.05). There was a significant correlation and high reproducibility between the DRA- and FT-derived strain parameters. Both CMR-derived LVGLS and LVGRS were significantly related to the presence of LGE, and multivariate logistic regression analyses showed that the LVGLS measurement obtained from both techniques was independently associated with the presence of LGE. The odds ratios (ORs) for DRA- and FT-LVGLS were 1.340 and 1.342, respectively.

CONCLUSIONS

Asymptomatic HT patients with preserved LVEF exhibited reduced myocardial strain parameters. The CMR-derived LVGLS was independently related to the presence of LGE in HT patients.

KEY POINTS

• Reduced myocardial strain parameters were found in asymptomatic heart transplanted (HT) patients with normal left ventricular ejection fraction (LVEF). • The deformation registration algorithm (DRA) and feature tracking (FT)-derived strains in asymptomatic HT patients had high reproducibility. • DRA- and FT-derived LVGLS had an independent relationship with late gadolinium enhancement (LGE) in asymptomatic HT patients.

Quantitative mechanical dyssynchrony in dilated cardiomyopathy measured by deformable registration algorithm

OBJECTIVES

To investigate the diagnostic value and reproducibility of deformable registration algorithm (DRA)-derived mechanical dyssynchrony parameters in dilated cardiomyopathy (DCM) patients.

METHODS

The present study included 80 DCM patients (40 with normal QRS duration (NQRS-DCM); 40 with left bundle branch block (LBBB-DCM)) and 20 healthy volunteers. The balanced steady-state free-precession (bSSFP) cine images were acquired using a 3.0T scanner. Mechanical dyssynchrony parameters were calculated based on DRA-derived segmental strain, including uniformity ratio estimate (URE) and standard derivation of time-to-peak (T2Psd) parameters in circumferential, radial, and longitudinal orientations.

RESULTS

DCM patients showed significant mechanical dyssynchrony reflected by both URE and T2Psd parameters compared with controls. Among DCM patients, LBBB-DCM showed decreased CURE (0.78 ± 0.21 vs. 0.93 ± 0.05, p < 0.001) and RURE (0.69 ± 0.14 vs. 0.83 ± 0.15, p = 0.001), and increased T2Psd-Ecc (median with interquartile range, 94.1 (54.4-123.2) ms vs. 63.7 (44.9-80.4) ms, p = 0.003) and T2Psd-Err (91.1 (61.1-103.2) ms vs. 62.3 (46.3-104.5) ms, p = 0.041) compared with NQRS-DCM patients. CURE showed a strong correlation with QRS duration (r = - 0.54, p < 0.001), with maximum AUC (0.791) to differentiate LBBB-DCM from NQRS-DCM patients. Improved intra- and inter-observer reproducibility was found using URE indices (coefficient of variation (CoV), 1.20-3.17%) than T2Psd parameters (CoV, 15.28-41.18%).

CONCLUSIONS

The DRA-based CURE showed significant correlation with QRS duration and the highest discriminatory value between LBBB-DCM and NQRS-DCM patients. URE indices showed greater reproducibility compared with T2Psd parameters for assessing myocardial dyssynchrony in DCM patients.

KEY POINTS

• The strain analyses based on DRA suggested that DCM patients have varying degrees of mechanical dyssynchrony and there is a significant difference from normal controls. • CURE showed the strongest correlation with QRS duration and was the best parameter for differentiating DCM patients with normal QRS duration from patients with LBBB, and with normal controls. • URE indices showed improved reproducibility compared with T2Psd parameters in all three orientations (circumferential, radial, and longitudinal).

MRI in cardio-oncology: A review of cardiac complications in oncologic care

From detailed characterization of cardiac abnormalities to the assessment of cancer treatment-related cardiac dysfunction, cardiac MRI is playing a growing role in the evaluation of cardiac pathology in oncology patients. Current guidelines are now incorporating the use of MRI for the comprehensive multidisciplinary approach to cancer management, and innovative applications of MRI in research are expanding its potential to provide a powerful noninvasive tool in the arsenal against cancer. This review focuses on the application of cardiac MRI to diagnose and manage cardiovascular complications related to cancer and its treatment. Following an introduction to current cardiac MRI methods and principles, this review is divided into two sections: functional cardiovascular analysis and anatomical or tissue characterization related to cancer and cancer therapeutics. Level of Evidence: 5 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:1349-1366.

Echocardiography and cardiovascular magnetic resonance based evaluation of myocardial strain and relationship with late gadolinium enhancement

OBJECTIVES

We sought to: (1) determine the agreement in cardiovascular magnetic resonance (CMR) and speckle tracking echocardiography (STE) derived strain measurements, (2) compare their reproducibility, (3) determine which approach is best related to CMR late gadolinium enhancement (LGE).

BACKGROUND

While STE-derived strain is routinely used to assess left ventricular (LV) function, CMR strain measurements are not yet standardized. Strain can be measured using dedicated pulse sequences (strain-encoding, SENC), or post-processing of cine images (feature tracking, FT). It is unclear whether these measurements are interchangeable, and whether strain can be used as an alternative to LGE.

METHODS

Fifty patients underwent 2D echocardiography and 1.5 T CMR. Global longitudinal strain (GLS) was measured by STE (Epsilon), FT (NeoSoft) and SENC (Myocardial Solutions) and circumferential strain (GCS) by FT and SENC.

RESULTS

GLS showed good inter-modality agreement (r-values: 0.71-0.75), small biases (< 1%) but considerable limits of agreement (- 7 to 8%). The agreement between the CMR techniques was better for GLS than GCS (r = 0.81 vs 0.67; smaller bias). Repeated measurements showed low intra- and inter-observer variability for both GLS and GCS (intraclass correlations 0.86-0.99; coefficients of variation 3-13%). LGE was present in 22 (44%) of patients. Both SENC- and FT-derived GLS and GCS were associated with LGE, while STE-GLS was not. Irrespective of CMR technique, this association was stronger for GCS (AUC 0.77-0.78) than GLS (AUC 0.67-0.72) and STE-GLS (AUC = 0.58).

CONCLUSION

There is good inter-technique agreement in strain measurements, which were highly reproducible, irrespective of modality or analysis technique. GCS may better reflect the presence of underlying LGE than GLS.

Implementation and Validation of a Three-dimensional Cardiac Motion Estimation Network

PURPOSE

To describe an unsupervised three-dimensional cardiac motion estimation network (CarMEN) for deformable motion estimation from two-dimensional cine MR images.

MATERIALS AND METHODS

A function was implemented using CarMEN, a convolutional neural network that takes two three-dimensional input volumes and outputs a motion field. A smoothness constraint was imposed on the field by regularizing the Frobenius norm of its Jacobian matrix. CarMEN was trained and tested with data from 150 cardiac patients who underwent MRI examinations and was validated on synthetic (n = 100) and pediatric (n = 33) datasets. CarMEN was compared to five state-of-the-art nonrigid body registration methods by using several performance metrics, including Dice similarity coefficient (DSC) and end-point error.

RESULTS

On the synthetic dataset, CarMEN achieved a median DSC of 0.85, which was higher than all five methods (minimum-maximum median [or MMM], 0.67-0.84; P < .001), and a median end-point error of 1.7, which was lower than (MMM, 2.1-2.7; P < .001) or similar to (MMM, 1.6-1.7; P > .05) all other techniques. On the real datasets, CarMEN achieved a median DSC of 0.73 for Automated Cardiac Diagnosis Challenge data, which was higher than (MMM, 0.33; P < .0001) or similar to (MMM, 0.72-0.75; P > .05) all other methods, and a median DSC of 0.77 for pediatric data, which was higher than (MMM, 0.71-0.76; P < .0001) or similar to (MMM, 0.77-0.78; P > .05) all other methods. All P values were derived from pairwise testing. For all other metrics, CarMEN achieved better accuracy on all datasets than all other techniques except for one, which had the worst motion estimation accuracy.

CONCLUSION

The proposed deep learning-based approach for three-dimensional cardiac motion estimation allowed the derivation of a motion model that balances motion characterization and image registration accuracy and achieved motion estimation accuracy comparable to or better than that of several state-of-the-art image registration algorithms.© RSNA, 2019Supplemental material is available for this article.

Quantitative cardiac MRI

Cardiac MRI has become an indispensable imaging modality in the investigation of patients with suspected heart disease. It has emerged as the gold standard test for cardiac function, volumes, and mass and allows noninvasive tissue characterization and the assessment of myocardial perfusion. Quantitative MRI already has a key role in the development and incorporation of machine learning in clinical imaging, potentially offering major improvements in both workflow efficiency and diagnostic accuracy. As the clinical applications of a wide range of quantitative cardiac MRI techniques are being explored and validated, we are expanding our capabilities for earlier detection, monitoring, and risk stratification of disease, potentially guiding personalized management decisions in various cardiac disease models. In this article we review established and emerging quantitative techniques, their clinical applications, highlight novel advances, and appraise their clinical diagnostic potential. Level of Evidence: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:693-711.

Myocardial volume change during cardiac cycle derived from three orthogonal systolic strains: towards a quality assessment of strains

BACKGROUND

The relative modification of the myocardial volume between end-systole and end-diastole ( Vs/d=Vend-systole/Vend-diastole ) has already been assessed with different methods and falls in a range of 0.9-0.97 (mean value = 0.93).

PURPOSE

To estimate Vs/d from the three longitudinal ( ɛl) , circumferential ( ɛc ), and radial ( ɛr ) strains of the left ventricle using the formula: Vs/d=(1+ɛc)(1+ɛr)(1+ɛl) and to test whether this estimate of Vs/d can be used as a marker of the echocardiography quality.

MATERIAL AND METHODS

Two hundred manuscripts, including a total of 34,690 patients or healthy volunteers, were identified in the Medline database containing values of ɛl , ɛc , and ɛr measured from echocardiography.

RESULTS

The median value of was 0.93, in accordance with the literature, with no significant difference between patients or healthy volunteers ( P = 0.38). The proportion of studies with Vs/d=0.93±0.1 was 79%. When only considering groups of healthy volunteers, the studies failing this test had higher standard deviations for the three individual strains: 0.038 vs. 0.029 ( P = 0.02) for ɛl ; 0.060 vs. 0.034 ( P < 10^-6) for ɛc , and 0.243 vs. 0.101 ( P < 10^-14) for ɛr .

CONCLUSION

The median ratio of the left ventricular myocardial volumes between end-systole and end-diastole in the investigated studies was Vs/d=0.93 . The formula (1+ɛc)(1+ɛr)(1+ɛl)∉[0.83;1.03] could be used to detect studies with inaccurate strain measurements.

Left ventricular MRI wall motion assessment by monogenic signal amplitude image computation

BACKGROUND

Cardiac Magnetic Resonance Imaging (MRI) is the commonly used technique for the assessment of left ventricular (LV) function. Apart manually or semi-automatically contouring LV boundaries for quantification of By visual interpretation of cine images, assessment of regional wall motion is performed by visual interpretation of cine images, thus relying on an experience-dependent and subjective modality.

OBJECTIVE

The aim of this work is to describe a novel algorithm based on the computation of the monogenic amplitude image to be utilized in conjunction with conventional cine-MRI visualization to assess LV motion abnormalities and to validate it against gold standard expert visual interpretation.

METHODS

The proposed method uses a recent image processing tool called "monogenic signal" to decompose the MR images into features, which are relevant for motion estimation. Wall motion abnormalities are quantified locally by measuring the temporal variations of the monogenic signal amplitude. The new method was validated by two non-expert radiologists using a wall motion scoring without and with the computed image, and compared against the expert interpretation. The proposed approach was tested on a population of 40 patients, including 8 subjects with normal ventricular function and 32 pathological cases (20 with myocardial infarction, 9 with myocarditis, and 3 with dilated cardiomyopathy).

RESULTS

The results show that, for both radiologists, sensitivity, specificity and accuracy of cine-MRI alone were similar and around 59%, 77%, and 71%, respectively. Adding the proposed amplitude image while visualizing the cine MRI images significantly increased both sensitivity, specificity and accuracy up to 75%, 89%, and 84%, respectively.

CONCLUSION

Accuracy of wall motion interpretation adding amplitude image to conventional visualization was proven feasible and superior to standard image interpretation on the considered population, in inexperienced observers. Adding the amplitude images as a diagnostic tool in clinical routine is likely to improve the detection of myocardial segments presenting a cardiac dysfunction.

Left Ventricular Myocardial Deformation on Cine MR Images: Relationship to Severity of Disease and Prognosis in Light-Chain Amyloidosis

Purpose To measure left ventricular (LV) myocardial strain with cine magnetic resonance (MR) imaging and a deformable registration algorithm (DRA) and to assess the prognostic value of myocardial strain in patients with light-chain (AL) amyloidosis. Materials and Methods In this prospective study, 78 consecutive patients with AL amyloidosis who underwent contrast material-enhanced cardiac MR imaging were enrolled at West China Hospital. LV myocardial strains and late gadolinium enhancement (LGE) were evaluated. Association between myocardial strain and all-cause mortality was analyzed with the stepwise Cox regression model. Results Global longitudinal strain (GLS) and global circumferential strain (GCS) were significantly lower in the no or nonspecific LGE group compared with the subendocardial LGE and transmural LGE groups (mean GLS, -10% ± 3 [standard deviation] vs -7% ± 3 vs -4% ± 1; P < .001) (mean GCS, -13% ± 3 vs -11% ± 3 vs -7% ± 2; P < .001). GLS and GCS were reduced in patients without clinical cardiac amyloidosis (mean GLS, -13% ± 3 vs -16% ± 2; P = .005) (mean GCS, -16% ± 1 vs -19% ± 2; P = .02). Circumferential and radial strains were impaired in basal segments in accordance with the distribution of LGE. Multivariate Cox analysis revealed that GCS (hazard ratio [HR] = 1.16 per 1% absolute decrease; 95% confidence interval [CI]: 1.03, 1.31; P = .02) and the presence of transmural LGE (HR = 1.75; 95% CI: 1.10, 2.80; P = .02) were independent predictors of all-cause mortality after adjustment for LV ejection fraction, right ventricular ejection fraction, LV mass index, GLS, and global radial strain. Conclusion Strain parameters derived with cine MR imaging-based DRA may be a new noninvasive imaging marker with which to evaluate the extent of cardiac amyloid infiltration and may offer independent prognostic information for all-cause mortality in patients with AL amyloidosis.

LV function validation of computer-assisted interventional system for cardiac resyncronisation therapy

PURPOSE

Cardiac resynchronisation therapy (CRT) is an established treatment for symptomatic patients with heart failure, a prolonged QRS duration, and impaired left ventricular (LV) function; however, non-response rates remain high. Recently proposed computer-assisted interventional platforms for CRT provide new routes to improving outcomes. Interventional systems must process information in an accurate, fast and highly automated way that is easy for the interventional cardiologists to use. In this paper, an interventional CRT platform is validated against two offline diagnostic tools to demonstrate that accurate information processing is possible in the time critical interventional setting.

METHODS

The study consisted of 3 healthy volunteers and 16 patients with heart failure and conventional criteria for CRT. Data analysis included the calculation of end-diastolic volume, end-systolic volume, stroke volume and ejection fraction; computation of global volume over the cardiac cycle as well as time to maximal contraction expressed as a percentage of the total cardiac cycle.

RESULTS

The results showed excellent correlation ([Formula: see text] values of [Formula: see text] and Pearson correlation coefficient of [Formula: see text]) with comparable offline diagnostic tools.

CONCLUSION

Results confirm that our interventional system has good accuracy in everyday clinical practice and can be of clinical utility in identification of CRT responders and LV function assessment.

Improved segmental myocardial strain reproducibility using deformable registration algorithms compared with feature tracking cardiac MRI and speckle tracking echocardiography

BACKGROUND

Segmental myocardial strain using feature tracking (FT) cardiac MRI is not acceptable due to poor reproducibility.

PURPOSE

To assess the reproducibility of left ventricle (LV) segmental myocardial strain measured by deformation registration algorithm (DRA).

STUDY TYPE

Prospective clinical trial.

SUBJECTS

Sixteen healthy volunteers and 28 hypertrophic cardiomyopathy (HCM) patients.

FIELD STRENGTH/SEQUENCE

Retrospective ECG gating cardiac MRI imaging was performed at 3.0T with a steady-state free precession (SSFP) sequence.

ASSESSMENT

LV global and segmental myocardial strains were analyzed by DRA, FT, and speckle tracking echocardiography (STE) by two experienced observers and the reproducibility of global and segmental strains were compared.

STATISTICAL TESTS

Reproducibility was tested by coefficient of variation (COV) and intraclass correlation coefficient (ICC). Receiver operator curves as well as comparison of areas under the curve (AUC) were analyzed.

RESULTS

DRA showed the best observer agreement on segmental strain evaluated by ICC, LS (longitudinal strain): intraobserver variability range (0.98,1.00), interobserver variability range (0.83,0.92), CS (circumferential strain): intraobserver variability range (0.90,0.99), interobserver variability range (0.80,0.97), RS (radial strain): intraobserver variability range (0.84,0.99), interobserver variability range (0.85,0.99). Segmental LS, CS, and RS agreements evaluated by COV for FT and STE were poor. LV global myocardial strain of HCM was significantly lower than controls for all applied techniques, but global CS by DRA had better accuracy compared to FT or STE for distinguishing HCM from healthy subjects: AUC 0.880 (DRA) vs. 0.577 (FT) or 0.736 (STE), P < 0.05.

DATA CONCLUSIONS

DRA is a reliable and robust analysis tool for segmental myocardial strain. Global CS by DRA allows discrimination between HCM and normal controls with better accuracy compared with FT and STE.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2018;48:404-414.

Distribution pattern of left-ventricular myocardial strain analyzed by a cine MRI based deformation registration algorithm in healthy Chinese volunteers

The cine magnetic resonance imaging based technique feature tracking-cardiac magnetic resonance (FT-CMR) is emerging as a novel, simple and robust method to evaluate myocardial strain. We investigated the distribution characteristics of left-ventricular myocardial strain using a novel cine MRI based deformation registration algorithm (DRA) in a cohort of healthy Chinese subjects. A total of 130 healthy Chinese subjects were enrolled. Three components of orthogonal strain (radial, circumferential, longitudinal) of the left ventricle were analyzed using DRA on steady-state free precession cine sequence images. A distinct transmural circumferential strain gradient was observed in the left ventricle that showed universal increment from the epicardial to endocardial myocardial wall (epiwall: -15.4 ± 1.9%; midwall: -18.8 ± 2.0%; endowall: -22.3 ± 2.3%, P < 0.001). Longitudinal strain showed a similar trend from epicardial to endocardial layers (epiwall: -16.0 ± 2.9%; midwall: -15.6 ± 2.7%; endowall: -14.8 ± 2.4%, P < 0.001), but radial strain had a very heterogeneous distribution and variation. In the longitudinal direction from the base to the apex of the left ventricle, there was a trend of decreasing peak systolic longitudinal strain (basal: -23.3 ± 4.6%; mid: -13.7 ± 7.3%; apical: -13.2 ± 5.5%; P < 0.001). In conclusion, there are distinct distribution patterns of circumferential and longitudinal strain within the left ventricle in healthy Chinese subjects. These distribution patterns of strain may provide unique profiles for further study in different types of myocardial disease.