Impact of Multi-parametric Analyses on Normal Left Atrial Strain by Cardiovascular Magnetic Resonance Feature Tracking

Left-atrial (LA) strain is the result of complex hemodynamics, increasingly assessed by feature-tracking cardiovascular magnetic resonance (CMR). We investigate the value of multi-parametric regression (MPR) analyses and the influence of the heart rate on LA-strain. As LA-strain data remains limited, CMR-quantified sex- and age-dependent normal values were derived. After following a health assessment questionnaire, 183 healthy volunteers (11-70 years, 97 females, median 32.9±28.3 years) were recruited for LA-strain assessment. LA volumetric data, left ventricular strain, transmitral and pulmonary venous blood flow parameters were utilized to create clusters for MPR analyses for all subjects and heart rate-specific subgroups (range: 60–75 beats-per-minute, N=106). In comparison to the total cohort, subgroups showed no gender differences (p>0.05) for LA reservoir, conduit and booster strains (all: 47.3±12.7%; 29.0±15.5%; 17.6±5.4%) and strain rates (all: 2.1±1.0 s−1; -2.9 ± 1.5 s−1; -2.3 ± 1.0 s−1). MPR analyses identified parameter clusters with large effect size (|R²|≥0.26) for reservoir-, conduit- and booster strain and corresponding active and passive cardiac functional parameters. Increased correlations for the subgroup were found. In contrast to previous studies, heart rate selected subgroups showed no gender differences in LA-strain. MPR analyses improve characterization of LA-strain at selected heart rates.

Reproducibility and its confounders of CMR feature tracking myocardial strain analysis in patients with suspected myocarditis

Objectives Cardiovascular magnetic resonance feature tracking (CMR-FT) is an emerging technique for assessing myocardial strain with valuable diagnostic and prognostic potential. However, the reproducibility of biventricular CMR-FT analysis in a large cardiovascular population has not been assessed. Also, evidence of confounders impacting reader reproducibility for CMR-FT in patients is unknown and currently limits the clinical implementation of this technique. Methods From a dual-center database of patients referred to CMR for suspected myocarditis, 125 patients were randomly selected to undergo biventricular CMR-FT analysis for 2-dimensional systolic and diastolic measures, with additional 3-dimensional analysis for the left ventricle. All image analysis was replicated by a single reader and by a second reader for intra- and inter-reader analysis (Circle Cardiovascular Imaging). Reliability was tested with intraclass correlation (ICC) tests, and the impact of imaging confounders on agreement was assessed through multivariable analysis. Results Left and right ventricular ejection fractions were reduced in 34% and 37% of the patients, respectively. Good to excellent reliability was shown for 2D (all ICC > 0.85) and 3D (all ICC > 0.70) peak strain and early diastolic strain rate for both ventricles in longitudinal orientation as well as circumferential orientations for the left ventricle. An increased slice number improved agreement while the presence of pericardial effusion compromised diastolic strain rate agreement, and arrhythmia compromised right ventricular agreement. Conclusion In a large clinical cohort, we could show CMR-FT yields excellent inter-reader and intra-reader reproducibility. Multi-parametric CMR-FT of the right and left ventricles appears to be a robust tool in cardiovascular patients referred to CMR. Clinical trial registration. ClinicalTrials.gov Identifier: NCT03470571, NCT04774549. Key Points • Cardiovascular magnetic resonance feature tracking (CMR-FT) is an emerging technique to measure myocardial strain in cardiovascular patients referred for CMR; however, the evaluation of its reproducibility in a large cohort has not yet been performed. • In a large clinical cohort, CMR-FT yields excellent inter-reader and intra-reader reproducibility for both left and right ventricular systolic and diastolic parameters. • Arrhythmia and pericardial effusion compromise agreement of select FT parameters, but poor ejection fraction does not.

Acute impact of an endurance race on biventricular and biatrial myocardial strain in competitive male and female triathletes evaluated by feature-tracking CMR

Objectives Cardiac adaptation in endurance athletes is a well-known phenomenon, but the acute impact of strenuous exercise is rarely reported on. The aim of this study was to analyze the alterations in biventricular and biatrial function in triathletes after an endurance race using novel feature-tracking cardiac magnetic resonance (FT-CMR). Methods Fifty consecutive triathletes (45 ± 10 years; 80% men) and twenty-eight controls were prospectively recruited, and underwent 1.5-T CMR. Biventricular and biatrial volumes, left ventricular ejection fraction (LVEF), FT-CMR analysis, and late gadolinium imaging (LGE) were performed. Global systolic longitudinal (GLS), circumferential (GCS), and radial strain (GRS) were assessed. CMR was performed at baseline and following an endurance race. High-sensitive troponin T and NT-proBNP were determined. The time interval between race completion and CMR was 2.3 ± 1.1 h (range 1–5 h). Results Post-race troponin T (p < 0.0001) and NT-proBNP (p < 0.0001) were elevated. LVEF remained constant (62 ± 6 vs. 63 ± 7%, p = 0.607). Post-race LV GLS decreased by tendency (− 18 ± 2 vs. − 17 ± 2%, p = 0.054), whereas GCS (− 16 ± 4 vs. − 18 ± 4%, p < 0.05) and GRS increased (39 ± 11 vs. 44 ± 11%, p < 0.01). Post-race right ventricular GLS (− 19 ± 3 vs. − 19 ± 3%, p = 0.668) remained constant and GCS increased (− 7 ± 2 vs. − 8 ± 3%, p < 0.001). Post-race left atrial GLS (30 ± 8 vs. 24 ± 6%, p < 0.0001) decreased while right atrial GLS remained constant (25 ± 6 vs. 24 ± 6%, p = 0.519). Conclusions The different alterations of post-race biventricular and biatrial strain might constitute an intrinsic compensatory mechanism following an acute bout of endurance exercise. The combined use of strain parameters may allow a better characterization of ventricular and atrial function in endurance athletes. Key Points • Triathletes demonstrate a decrease of LV global longitudinal strain by tendency and constant RV global longitudinal strain following an endurance race. • Post-race LV and RV global circumferential and radial strains increase, possibly indicating a compensatory mechanism after an acute endurance exercise bout. • Subgroup analyses of male triathletes with focal myocardial fibrosis did not demonstrate alterations in biventricular and biatrial strain after an endurance race.

Myocardial Deformation Parameters Assessed By CMR Feature Tracking In Chronic Heart Failure: The Influence of An Optimal Medical Therapy On Myocardial Remodeling

Background: Myocardial deformation parameters have been shown to yield early detection of pathological changes in chronic heart failure (CHF). Aim of our study was to evaluate myocardial deformation changes under optimal medical therapy (OMT) in CHF patients.Methods: CHF patients were examined longitudinally with two cardiac magnetic resonance imaging (CMR) examinations at a median time interval of 140 days. Left and right ventricular volumes were quantified, and deformation analysis was performed using feature tracking, respectively.Results: 57 patients were included into the study. There was a high rate of OMT with a prescription of beta blockers in 98.2% and ACE-inhibitors/Angiotensin receptor blockers in 93.0%. In the total cohort, there were indications of positive remodeling with a significant improvement in left ventricular (LV) ejection fraction (38.9% ± 11.6 vs. 43.0% ± 12.7, p=0.009), LV enddiastolic volume indexed (92.1ml/m2 ± 23.5 vs. 87.2ml/m2 ± 21.2, p=0.007), LV mass (140.3g ± 35.7 vs. 128.0g ± 34.4, p=0.001) and right ventricular global longitudinal strain (RV GLS) (-18.1% ± 5.1 vs. -20.3% ± 4.5, p<0.001) during follow-up. Discussion: Patients with CHF and OMT show positive reverse remodeling with improvement of LV volumes and function and RV GLS. This has a potential impact on the surveillance of this patient group, which should be further investigated in larger prospective studies.

415 Correlation between tissue abnormalities and myocardial deformation indices in arrhythmogenic cardiomyopathy: a pilot study

Aims To evaluate the correlation between cardiac magnetic resonance (CMR) tissue abnormalities and impairment of myocardial deformation indices in patients with definite diagnosis of arrhythmogenic cardiomyopathy (AC). Methods and results 41 AC Patients with available CMR study were enrolled. Myocardial deformation indices (i.e. global longitudinal strain -GLS-; global circumferential strain -GCS-; global radial strain -GRS-) for both ventricles were calculated using feature tracking analysis. Quantification of tissue abnormalities (i.e. late gadolinium enhancement -LGE- extension expressed as percentage of total ventricular mass) was performed. Spearman’s rho correlation was evaluated. Mean age was 44 ± 13 years and 26 (63%) patients were male. Mean left ventricular (LV) ejection fraction (EF) was 54 ± 10% and mean right ventricular (RV) EF was 49 ± 12%. Median LV LGE extension was 8.9% (1.05–21) and median RV LGE extension was 0 (0–6.92). All myocardial deformation indices were moderately associated with LGE extension (for LV 3D GLS Spearman’s Rho 0.423, P 0.016; 2D GCS Spearman’s Rho 0.388, P 0.028; 3D GCS 0.362, P 0.042; 2D GRS Spearman’s Rho −0.417, P 0.018; 3D GRS −0.396, P 0.025; for RV 2D GLS Spearman’s Rho 0.385, P 0.030; RV GCS Spearman’s Rho 0.450, P 0.010; RV GRS Spearman’s Rho −0.459, P 0.008). Conclusions All myocardial deformation indices showed a moderate association with LGE extension in a cohort of patients with definite AC. Further studies are needed to validate this observation and understand its implications.

Ανίχνευση υποκειμένου οργανικού υποστρώματος σε ασθενείς με κοιλιακές αρρυθμίες

Οι συνήθεις απεικονιστικές μεθόδοι αδυνατούν να αναγνώρισουν δομικές ανωμαλίες σε ένα σημαντικό ποσοστό ασθενών με ιδιοπαθείς κοιλιακές αρρυθμίες. Η μυοκαρδιακή παραμόρφωση έχει αναδειχθεί ως ανώτερος δείκτης της συστολικής απόδοσης σε σχέση με το κλάσμα εξώθησης. Σκοπός της παρούσας διατριβής ήταν η εκτίμηση της διαγνωστικής αξίας της Μαγνητικής Τομογραφίας Καρδιάς (ΜΤΚ), συμπεριλαμβανομένης της μυοκαρδιακής παραμόρφωσης με την τεχνική feature-tracking σε ασθενείς με συχνές κοιλιακές αρρυθμίες και φυσιολογικές δομικά καρδιές. Στη μελέτη συμπεριλήφθηκαν 72 ασθενείς (μέση ηλικία 46 ± 16 έτη, 53% γυναίκες) με συχνά πρώιμα κοιλιακά συμπλέγματα (ΠΚΣ ≥ 500/24ωρο) και/ή μη εμμένουσα κοιλιακή ταχυκαρδία, φυσιολογικό υπερηχοκαρδιογράφημα και αρνητική μελέτη για στεφανιαία νόσο, καθώς και 72 υγιείς εθελοντές. Η ΜΤΚ παρείχε επιπλέον διαγνωστική αξία στο 54,2% των ασθενών. Η συχνότερη διάγνωση ήταν η προηγούμενη μυοκαρδίτιδα (23,6%), ακολουθούμενη από μυοκαρδιοπάθεια προκαλούμενη από ΠΚΣ (20,8%), μη ισχαιμική μυοκαρδιοπάθεια (8,3%), και ισχαιμική καρδιακή νόσος (1,4%). Το αρσενικό φύλο, η μεγαλύτερη ηλικία και η προέλευση της κοιλιακής αρρυθμίας εκτός των χώρων εξόδου των κοιλιών ή αρρυθμίες με πολλαπλές μορφολογίες, αποτελούσαν ανεξάρτητους προγνωστικούς παράγοντες παθολογικών ευρημάτων στη ΜΤΚ. Σε σχέση με τους υγιείς εθελοντές, οι ασθενείς με κοιλιακές αρρυθμίες είχαν επηρεασμένη μέγιστη συνολική ακτινική παραμόρφωση (GRS) (28,88% [IQR: 25,87% έως 33,97%] έναντι 36,65% [IQR: 33,19% έως 40.,2%], p < 0,001) και μέγιστη συνολική κυκλοτερή παραμόρφωση (GCS) της αριστερής κοιλίας (-17,73% [IQR: -19,8% έως -16,33%] έναντι -20,66% [IQR: -21,72% έως -19,6%], p < 0,001). Οι ασθενείς με χαμηλότερο GRS (<29,91%) είχαν 5 φορές μεγαλύτερη πιθανότητα να πάσχουν από κοιλιακές αρρυθμίες. Συμπεραίνουμε ότι η ΜΤΚ αποκαλύπτει υποκείμενο οργανικό υπόστρωμα και επηρεασμένη μυοκαρδιακή παραμόρφωση σε έναν σημαντικό αριθμό ασθενών με ιδιοπαθείς κοιλιακές αρρυθμίες. Το αρσενικό φύλο, η μεγαλύτερη ηλικία και η προέλευση της κοιλιακής αρρυθμίας εκτός των χώρων εξόδου των κοιλιών, μπορεί να αποτελέσουν κλινικά κριτήρια για παραπομπή για ΜΤΚ.

Image Processing Methods for Gesture-Based Robot Control

In this paper we discuss some image processing methods that can be used for motion recognition of human body parts such as hands or arms in order to interact with robots. This interaction is usually associated to gesture-based control. The considered image processing methods have been experienced for feature recognition in applications involving human robot interaction. They are namely: Sequential Similarity Detection Algorithm (SSDA), an appearance-based approach that uses image databases to model objects, and Kanade-Lucas-Tomasi (KLT) algorithm which is usually used for feature tracking. We illustrate the gesture-based interaction by using KLT algorithm. We discuss the adaptation of each of these methods to the context of gesture-based robot interaction and some of their related issues.