The strain-8 study: a multimodal scan-rescan assessment of myocardial strain repeatability

Area of Science:

• Cardiology
• Medical Imaging
• Biomedical Engineering

Background:

• Myocardial strain is a key non-invasive marker for diagnosing and predicting outcomes in heart disease.
• The clinical utility of myocardial strain is limited by inconsistent repeatability, especially for segmental strain measurements.

Purpose of the Study:

• To evaluate and compare the inter-scan repeatability of myocardial strain measurements across eight different imaging protocols.
• To identify which imaging methods offer the most reliable global and segmental strain quantification.

Main Methods:

• A prospective study involving 20 healthy volunteers scanned twice using eight strain imaging protocols: 1.5T and 3T CMR (cine, tagging, DENSE) and 2D/3D echocardiography (Echo).
• Global and segmental strains were quantified, with repeatability assessed using coefficient of variation (CoV), intraclass correlation coefficient, and Bland-Altman analysis.

Main Results:

• Global strain repeatability varied from excellent to fair (CoV ≤ 20%) depending on the protocol.
• CMR feature tracking at 1.5T indicated significant global longitudinal strain (GLS) changes above 11.2% are not due to variability, compared to 5.5% for 2D Echo.
• Segmental strain values frequently demonstrated poor repeatability (CoV > 20%), particularly for longitudinal and radial strains.

Conclusions:

• Cardiac magnetic resonance (CMR) and echocardiography (Echo) can assess global strain parameters with acceptable repeatability.
• Segmental strain values obtained from current imaging protocols are largely unreliable.
• Future research should focus on enhancing the repeatability of segmental strain measurements, especially longitudinal strain.