Assessment of Myocardial Stiffness in Healthy Adults by Magnetic Resonance Elastography: Effects of Slice Location and Demographic Factors

Abstract

Purpose

To establish normal myocardial stiffness values in healthy adults using cardiac MR elastography (MRE) and assess the impact of slice location and demographic factors.

Methods

125 healthy volunteers underwent cardiac MRE using a 140-Hz vibration frequency, with data acquired during early systole (approximately 100 ms after the R-wave). Stiffness was measured in basal, mid, and apical short-axis views. Statistics included repeated-measures ANOVA (slice locations), t-tests (sex), Spearman correlation (age), and multivariable linear regression (controlling for age, sex, body mass index, and body surface area).

Results

Global myocardial stiffness was 8.1 ± 1.1 kPa. A significant apical-to-basal gradient existed (apex: 8.7 ± 1.1, mid: 8.3 ± 1.2, base: 7.4 ± 1.3 kPa; all P < 0.05). Males had non-significantly higher global stiffness than females (8.3 ± 1.0 vs. 8.0 ± 1.1 kPa, P = 0.068). Stiffness correlated with age in both sexes (r = 0.48 in male, r = 0.42 in female, both P < 0.05). Multivariable regression confirmed age as an independent predictor (β = 0.037 kPa/year, P < 0.001) with no age-sex interaction (P = 0.929). Intra-/inter-observer and scan-rescan reproducibility were excellent (ICCs ≥ 0.97).

Conclusion

This study establishes that myocardial stiffness in healthy adults follows an apical-to-basal gradient and is independently influenced by age, providing location-specific baseline stiffness values for the clinical interpretation of cardiac MR elastography.

delete this paragraph--Advances in knowledge

This study establishes comprehensive, location-specific normal ranges for myocardial stiffness across the entire left ventricle (apex, mid, base) in healthy adults, addressing a key gap in the existing CMRE literature which has been largely confined to mid-ventricular data. It demonstrates the significant impact of slice location on stiffness values, revealing an apical-to-basal gradient. These findings underscore the necessity of specifying and standardizing slice location in future CMRE protocols for accurate interpretation and comparison, both in research and potential clinical applications. The study also provides a robust, confounder-adjusted analysis confirming the independent effect of age on myocardial stiffness.