About MyoStrain® Accuracy

What is Strain?

“Strain” in everyday language can mean “stretching” and it is used to describe “deformation” (D’Hooge 2000). The MyoStrain report will show the amount of strain (deformation) for 37 segments of the left ventricle and 11 segments of the right ventricle. The value of each segment is calculated by taking the average of “peak strain” of each of the pixels within that segment.

In a heathy heart, the wall will deform well as it goes through cardiac cycle; however, in an unhealthy heart, the heart wall might be stiffer and not move or “deform” as much. Or even worse, the muscle can be so weak that the wall bulges out instead of compressing as the heart goes into systolic phase. The strain numbers are negative because we are measuring compression of the myocardium. A lower strain number indicates more compression of the given region of the myocardium.

MyoStrain Strain Scale

More information regarding the strain legend used in the MyoStrain program can be found from the following papers:

Neizel M, et al. “Strain-encoded MRI for evaluation of left ventricular function and transmurality in acute myocardial infarction.” Circ Cardiovasc Imaging. 2009;2(2):116-122 View Publication >>

Wong DT, et al. “Magnetic resonance-derived circumferential strain provides a superior and incremental assessment of improvement in contractile function in patients early after ST-segment elevation myocardial infarction.” European Radiology. 2014;24:1219-1228. View Publication >>

Oyama-Manabe N, et al. “Identification and further differentiation of subendocardial and transmural myocardial infarction by fast strain-encoded (SENC) magnetic resonance imaging at 3.0 Tesla” European Radiology. 2011;21(11):2362-2368. View Publication >>

Neizel M, et al. “Impact of Systolic and Diastolic Deformation Indexes Assessed by Strain-Encoded Imaging to Predict Persistent Severe Myocardial Dysfunction in Patients After Acute Myocardial Infarction at Follow-Up.” Journal of the American College of Cardiology. 2010;56:1056-1062. View Publication >>

Choi E-Y, et al. “Prognostic value of myocardial circumferential strain for incident heart failure and cardiovascular events in asymptomatic individuals: the Multi-Ethnic Study of Atherosclerosis.” European Heart Journal. 2013;34:2354-2361. View Publication >>

Koos R, et al. “Layer-specific strain-encoded MRI for the evaluation of left ventricular function and infarct transmurality in patients with chronic coronary artery disease.” Int J Cardiol. 2013;166:85-89. View Publication >>

Steen H, et al. Left and right ventricular strain using fast strain-encoded cardiac magnetic resonance for the diagnostic classification of patients with chronic nonischemic heart failure due to dilated or hypertrophic cardiomyopathies and cardiac amyloidosis. JCMR. 2021;23:45. doi:10.1186/s12968-021-00711-w. View Publication >>

Korosoglou, G., et al . Systematic review and meta-analysis for the value of cardiac magnetic resonance strain to predict cardiac outcomes. Sci Rep 14, 1094 (2024). https://doi.org/10.1038/s41598-023-50835-5 View Publication >>

Korosoglou, G et al. 2019 Strain-encoded magnetic re sonance: a method for the assessment of myocardial deformation ESC Heart Fail. 2019 Aug; 6(4): 584–602.doi: 10.1002/ehf2.12442 View Publication >>

Pezel T, et al. Regional strain score as prognostic marker of cardiovascular events from the multi-ethnic study of atherosclerosis (MESA). Front Cardiovasc. Med. 2022;9:870942 View Publication >>

Steen H, et al. Multi-parametric non-contrast cardiac magnetic resonance for the differentiation between cardiac amyloidosis and hypertrophic cardiomyopathy. Clinical Research in Cardiology. 2023. doi:10.1007/s00392-023-02348-4. View Publication >>

American Heart Association (AHA) Model

The AHA models used in MyoStrain are derived from the following publication:

Cerqueira et al., “Standardize Myocardial Segmentation and Nomenclature for Tomographic Imaging of the Heart,” Circulation, 2002;105:539-542 View Publication >>

Traditional Global Measurements

Normal Ranges of MyoStrain Measurements

The output of the SENC images post-processing is a report that shows various measurements.  One set of measurements is the traditional global measurements (ejection fraction, chamber volumes and masses).

These measurements are presented with the normal ranges published by Zhan et al.¹ The other set is the strain measurements (circumferential and longitudinal) presented with the normal ranges of strains as published by Neizel et al.²

Traditional Global measurements (LVEF and indexed LVEDV, LVESV, LVSV and LV Mass):

1. Y. Zhan et al., “Derivation of consolidated normal reference values for right and left ventricular quantification by cardiac magnetic resonance using a novel meta-analytic approach,” Journal of Cardiovascular Magnetic Resonance, vol. 18, no. 1, p. O75, 2016/01/27 2016 View Publication >>

Strain (circumferential and longitudinal):

2. M Neizel  et al. “Strain-encoded MRI for evaluation of left ventricular function and transmurality in acute myocardial infarction.” Circ Cardiovasc Imaging. 2009;2(2):116-122. View Publication >>

Accuracy of MyoStrain 3D Traditional Global Measurements

The accuracy of Myo3D measurements will be determined by the Limit of Agreement (LOA) with measurement from CMR measurements. LOA is the difference (disagreement between the measurements of the two devices) range within which fall 95% of all the measurements from the two devices. LOA depends on many factors, including images quality and inter-operator and inter-observer variabilities. Based on the Bland-Altman analysis of previously published LOA of traditional measurements using different imaging modalities versus cardiac MRI (Wood PW et al, 2014 & Crean AM et al, 2011), we use the following bounds for the 95% LOA between Myo3D and CMR data from the Prefect study.

  • LVEF: (-20%,+20%)
  • LVMass: (-35g, +35g)
  • LVEDV: (-45mL,+45mL)
  • LVESV: (-25mL,+25mL)
  • LVSV: (-40mL,+40mL)
  • RV EF: (-20%,+20%)
  • RVEDV: (-100mL,+100mL)
  • RVESV: (-50mL,+50mL)

Based on a sample size N=175 analyzed exams, MyoStrain demonstrated the following acceptable LOA:

  • LVEF: (-11%,+13%)
  • LVMass: (-26g, +29g)
  • LVEDV: (-26mL,+19mL)
  • LVESV: (-21mL,+15mL)
  • LVSV: (-24mL,+29mL)
  • RVEF: (-6%, +16%)
  • RVEDV: (-34mL, +37mL)
  • RVESV: (-26mL, +14mL)

The Bland-Altman Graphs of these calculations can be seen below:

Accuracy of MyoStrain 2D Traditional Global Measurements

The accuracy of MyoStrain measurements will be determined by the LOA with measurement from CMR measurements. LOA is the difference (disagreement between the measurements of the two devices) range within which fall 95% of all the measurements from the two devices. The LOA depends on many factors, including images quality and inter-operator and inter-observer variabilities. Based on the Bland-Altman analysis of previously published LOAs of traditional measurements from different imaging modalities versus cardiac MRI (Wood PW et al, 2014 & Crean AM et al, 2011), we use the following bounds for the 95% LOA between MyoStrain and CMR data from the Prefect study.

  • LVEF: (-20%,+20%)
  • LVEDV: (-45mL,+45mL)
  • LVESV: (-25mL,+25mL)
  • LVSV: (-40mL, +40mL)

Based on a sample size N=175 analyzed exams, MyoStrain demonstrated the following acceptable LOA :

  • LVEF: (-14%,+16%)
  • LVEDV: (-32mL,+36mL)
  • LVESV: (-22mL,+19mL)
  • LVSV: (-30mL,+35mL)

The Bland-Altman Graphs of these calculations can be seen below:

Timing Metrics

References to Timing Metrics can be found in the publications below:

Toro-Salazar O, et al. Identification of subclinical myocardial dysfunction by fastSENC cardiac magnetic resonance imaging in cardio-oncology patients. SCMR. 2023 January 26;1349140.

Dodeja A, et al. Novel tem poral strain parameters to assess dyssynchrony using fSENC in congenital heart disease. SCMR. 2023 January 27;1348910