The strain-7 study: multimodal, multivendor, multifield strength, scan:rescan comparison of global longitudinal and circumferential strain in healthy volunteers

Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): National Insitute for Health Research Background There is clinical and prognostic evidence for global longitudinal strain (GLS) and circumferential strain (GCS). A range of techniques exist: 2-dimensional echocardiography (2Decho), 3-dimensional echocardiography (3Decho) and Cardiovascular Magnetic Resonance (CMR). Purpose To investigate inter-study repeatability and inter-method comparison of GLS and GCS techniques. Methods Volunteers underwent same day scan rescan 2Decho, 3Decho, 1.5T Siemens CMR (Cine imaging and Displacement encoding with stimulated echoes [DENSE]), 3T Siemens CMR (Cine Imaging and DENSE) and 3T Philips CMR (Tagging and Fast strain-encoding [fSENC]) imaging. Strain was quantified for 2Decho (EchoPAC), 3Decho (TomTec), Feature tracking (FT) for cine imaging (CircleCVI), CIM (University of Auckland) for DENSE and Tag, and Myostrain (Myocardial solutions) for fSENC. Results 20(6F) volunteers, mean age 33 ± 7 years, mean LVEF 62 ± 4%. All GLS and GCS methods had excellent inter-study agreement (ICC > 0.75) with coefficient of variation (CoV) between 4-8% (Table 1). Median and IQR are presented in Figure 1. Friedman’s test revealed statistically significant inter-method differences for GLS (χ2 = 66.4,p < 0.0001) and GCS (χ2 = 50.9,p < 0.0001). Post hoc analysis using Dunn’s test with Bonferroni correction demonstrated significant differences: -GLS: 2Decho vs DENSE 1.5T (p = 0.001) and Myostrain 3T (p = 0.0116); 3Decho vs FT 3T (p = 0.049) and DENSE 1.5T (p < 0.0001); FT 1.5T vs DENSE 1.5T (p = 0.001) and Myostrain 3T (p = 0.01); FT 3T vs Myostrain 3T (p < 0.0001); DENSE 1.5T vs Tag 3T (p = 0.0008) and Myostrain 3T (p < 0.0001); Tag 3T vs Myostrain (p = 0.02). -GCS: 3Decho vs DENSE 1.5T (P = 0.0005), FT 1.5T (p < 0.001), FT 3T (P < 0.001) and Myostrain (p = 0.003); FT 1.5T vs Tag 3T (p = 0.001), FT 3T vs Myostrain 3T (p = 0.04). Conclusion There is excellent interstudy agreement for GLS and GCS methods. However, there are important inter-method differences in absolute values, that need to be considered for clinical application as a surveillance method and longitudinal studies. Table 1 Acquisiton Post processing GLS CoV(%) GLS ICC GCS CoV(%) GCS ICC 2DEcho EchoPAC 4.88 0.80 - - 3DEcho TomTec 4.77 0.86 3.97 0.85 Siemens 1.5T cine FT CircleCVI 8.30 0.79 6.00 0.85 Siemens 3T cine FT CircleCVI 6.21 0.89 4.76 0.94 Philips 3T Tag CIM 6.15 0.89 5.86 0.88 Siemens 1.5T DENSE CIM 4.36 0.90 4.65 0.89 Philips 3T fSENC Myostrain 8.45 0.81 4.06 0.90 Interstudy agreement for the different GLS and GCS methods. Abstract Figure 1

Comparison of cardiac MR feature tracking and myocardial MR tagging for assessment of regional ventricular function

Background Quantification of regional myocardial function allows risk stratification in heart disease. CMR tagging (TAG) enables the evaluation of segmental cardiac deformation, but it has not reached clinical routine due to the long acquisition and post-processing times. Conversely, CMR feature-tracking (FT) is a post-processing method based on standard cine-MR imaging. Purpose To compare myocardial strain and torsion obtained with CMR-TAG and CMR-FT in healthy volunteers and myocardial infarction (MI). Methods 42 subjects (18 healthy; 24 MI) underwent CMR (1.5T, cine/TAG sequences). Global and segmental (16-segment) circumferential strain (CS), and torsion were measured using FT (CVI42, Canada) and tagging (InTag, France). Inter-method agreement was assessed using 2-way-mixed intraclass correlation coefficient (ICC). Results The agreement for segmental and global CS measurements was good to excellent in both groups (Table). Torsion angle showed excellent (0.763) and good (0.697) agreement for healthy and MI. Conclusion CMR-FT strain and torsion measurements showed high agreement with CMR-tagging. Thus, CMR-FT provides a potential clinical alternative in the assessment of regional ventricular function. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Carlos III Health Institute, Spanish Ministry of Economy and Competiveness; Agencia Valenciana de la Innovaciόn, Generalitat Valenciana

Performance of different myocardial tissue tracking algorithms and acquisition-based strain imaging to characterise myocardial pathology

Background Myocardial deformation imaging is superior in risk-stratification compared to volumetric approaches. Myocardial Feature-Tracking (FT) allows easy post-processing of routinely acquired cine images. Since there is no clear recommendation regarding FT post-processing we sought to compare different FT-strains with reference standard techniques including tagging and strain encoded (SENC) magnetic resonance imaging. Methods CMR-FT software from 4 different vendors (TomTec, Medis, Circle, Neosoft), CMR tagging (Segment) and fastSENC (MyoStrain) were used to determine left ventricular (LV) global longitudinal and circumferential strains (GLS and GCS) in 12 healthy volunteers and 12 heart failure patients. Variability and agreements were assessed using intraclass correlation coefficients, coefficients of variation and Bland Altman plots. Results Compared to tagging, FT-based strain was software independently significantly higher except for GCS using Medis (p=0.178). Compared to fSENC, mean-differences of GLS were smaller within a range of ±1.5%. For GCS this only applied to CVI and Medis (<1.5%) but not TomTec (>7%) or Neosoft (>4%). Absolute agreements comparing FT to tagging were best for CVI (GLS ICC0.70) and Medis (GCS ICC0.85). Compared to fSENC agreement of GLS was generally excellent (ICC>0.77), but only CVI and Medis revealed excellent agreement for GCS (ICC0.88 and 0.85). Consistency and correlation of GLS were software independently high compared with tagging and fSENC (ICC>0.86, r>0.76) while being lower for GCS (ICC>0.68, r>0.72). Conclusion Although agreement differs between deformation assessment approaches, consistency and correlation are high irrespective of the method chosen, thus indicating reliable strain assessment. Further standardisation and introduction of uniform references is warranted for clinical routine implementation. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): DZHK - German Centre for Cardiovascular Research

P1393 Intervendor difference in global and regional 2D speckle tracking strain. comparison against cMR tagging

Funding Acknowledgements Fondation de Recherche Scientifique Belge FRSM PDR 19488731 BACKGROUND 2D-speckle-tracking (ST) echocardiography is currently widely used for estimation of global (G) and regional myocardial deformation. In previous works, we showed good correlation between global longitudinal (LS) and circumferential strain (CS) from one 2DST vendor with cMR-Tagging, however with significant bias between both methods. Also, we found poorer agreement between 2DST and cMR-Tagging on regional basis. However it is unknown how 2DST from other vendors would comparte to cMR tagging. PURPOSE To asssess vendor differences in global and regional strain assessment and compare 1) the agreement of 2 different 2DST softwares for global and regional LS and CS among each other and against cMR-Tagging as reference; and 2) the accuracy of both softwares to detect infarcted segments. METHODS 100 subjects with different cardiac disease (among which 31 with chronic infarct) underwent 2DST and tagging and LGE cMR on the same day. Global and regional CS (16 AHA segments) and LS (18 AHA segments) was computed using 2 different ST vendor softwares and compared to cMR-Tagging with HARP. Accuracy of regional 2D-ST by both vendors to detect infarcted segments (ie >75% transmurality of late gadolinium) was compared using ROC analysis. RESULTS Global LS (ICC = 0.87) and CS 2DST (ICC = 0.83, p < 0.001) agreed well between both vendors, but GCS values of vendor2 were significantly greater than that of vendor 1. Also we fond good correlation between ST of both vendors and cMR-Tagging for GLS (ICC = 0.80 and ICC = 0.69 for vendor 1 and 2 respectively) and GCS (ICC = 0.64 and ICC = 0.50 for vendor 1 and 2 respectively). Bias for GLS (-4.6 ± 2.9% and -6.1 ± 3.8% for vendor 1 and 2 respectively) vs cMR-Tagging was similar, however GCS of vendor 2 had higher bias vs cMR-Tagging (-16.0 ± 8.5%) than vendor 1 (-5.1 ± 5.8%). Agreement for regional strains is shown in the figure below. Overall, regional LS and CS agreed adequately among both vendors. Agreement of regional LS and CS vs cMR-tagging was slightly better for vendor 1, with less bias than for vendor 2, and disagreement was similarly located (ie agreement with cMR-Tagging for LS in inferolateral inferior and inferoseptal basal segments). The predictive accuracy of regional CS and LS for detecting segments with infarct was higher for vendor 2 (AUC 0.76 and 0.68) than for vendor 1 (AUC 0.70 and 0.63) . CONCLUSION GLS agreed well among both vendors and with cMR-Tagging, confirming the universal validity of this measurement. However vendor 2 provided significantly greater GCS values and had higher bias against cMR-Tagging than vendor 1. On regional basis CS and LS agreed moderately well among both vendors, however vendor 2 agreed less with cMR-Tagging than vendor 1, but astoundingly had higher diagnostic accuracy for detecting infarct. Overall this findings call for further efforts in standardization of 2DST CS and regional strain. Abstract P1393 Figure.

Assessment of Global Longitudinal and Circumferential Strain Using Computed Tomography Feature Tracking: Intra-Individual Comparison with CMR Feature Tracking and Myocardial Tagging in Patients with Severe Aortic Stenosis

In this study, we used a single commercially available software solution to assess global longitudinal (GLS) and global circumferential strain (GCS) using cardiac computed tomography (CT) and cardiac magnetic resonance (CMR) feature tracking (FT). We compared agreement and reproducibility between these two methods and the reference standard, CMR tagging (TAG). Twenty-seven patients with severe aortic stenosis underwent CMR and cardiac CT examinations. FT analysis was performed using Medis suite version 3.0 (Leiden, The Netherlands) software. Segment (Medviso) software was used for GCS assessment from tagged images. There was a trend towards the underestimation of GLS by CT-FT when compared to CMR-FT (19.4 ± 5.04 vs. 22.40 ± 5.69, respectively; p = 0.065). GCS values between TAG, CT-FT, and CMR-FT were similar (p = 0.233). CMR-FT and CT-FT correlated closely for GLS (r = 0.686, p < 0.001) and GCS (r = 0.707, p < 0.001), while both of these methods correlated moderately with TAG for GCS (r = 0.479, p < 0.001 for CMR-FT vs. TAG; r = 0.548 for CT-FT vs. TAG). Intraobserver and interobserver agreement was excellent in all techniques. Our findings show that, in elderly patients with severe aortic stenosis (AS), the FT algorithm performs equally well in CMR and cardiac CT datasets for the assessment of GLS and GCS, both in terms of reproducibility and agreement with the gold standard, TAG.