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Updated: Mar 27, 2026
Quantification of Mouse Heart Left Ventricular Function, Myocardial Strain, and Hemodynamic Forces by Cardiovascular Magnetic Resonance Imaging
Published on: May 24, 2021
Automatic Measurement of the Myocardial Interstitium: Synthetic Extracellular Volume Quantification Without
Thomas A Treibel1, Marianna Fontana1, Viviana Maestrini2
1Barts Heart Centre, St Bartholomew's Hospital, London, United Kingdom; Institute of Cardiovascular Science, University College London, London, United Kingdom.
Objectives:
The authors sought to generate a synthetic extracellular volume fraction (ECV) from the relationship between hematocrit and longitudinal relaxation rate of blood.
Background:
ECV quantification by cardiac magnetic resonance (CMR) measures diagnostically and prognostically relevant changes in the extracellular space. Current methodologies require blood hematocrit (Hct) measurement-a complication to easy clinical application. We hypothesized that the relationship between Hct and longitudinal relaxation rate of blood (R1 = 1/T1blood) could be calibrated and used to generate a synthetic ECV without Hct that was valid, user-friendly, and prognostic.
Methods:
Proof-of-concept: 427 subjects with a wide range of health and disease were divided into derivation (n = 214) and validation (n = 213) cohorts. Histology cohort: 18 patients with severe aortic stenosis with histology obtained during valve replacement. Outcome cohort: For comparison with external outcome data, we applied synthetic ECV to 1,172 consecutive patients (median follow-up 1.7 years; 74 deaths). All underwent CMR scanning at 1.5-T with ECV calculation from pre- and post-contrast T1 (blood and myocardium) and venous Hct.
Results:
Proof-of-concept: In the derivation cohort, native R1blood and Hct showed a linear relationship (R(2) = 0.51; p < 0.001), which was used to create synthetic Hct and ECV. Synthetic ECV correlated well with conventional ECV (R(2) = 0.97; p < 0.001) without bias. These results were maintained in the validation cohort. Histology cohort: Synthetic and conventional ECV both correlated well with collagen volume fraction measured from histology (R(2) = 0.61 and 0.69, both p < 0.001) with no statistical difference (p = 0.70). Outcome cohort: Synthetic ECV related to all-cause mortality (hazard ratio 1.90; 95% confidence interval 1.55 to 2.31; for every 5% increase in ECV). Finally, we engineered a synthetic ECV tool, generating automatic ECV maps during image acquisition.
Conclusions:
Synthetic ECV provides validated noninvasive quantification of the myocardial extracellular space without blood sampling and is associated with cardiovascular outcomes.
