Cardiovascular magnetic resonance reference ranges for cardiac function and structure and recommendations for grading severity: the Healthy Hearts Consortium

Introduction

Cardiovascular magnetic resonance (CMR) imaging offers precise quantification of cardiac structure and function. However, its clinical utility is often limited by the absence of robust, standardized reference ranges and severity grading thresholds.

Aims

The aim of this study was to establish age-, sex-, and ethnicity-specific reference ranges and severity grading criteria for CMR-derived ventricular and atrial parameters in healthy adults, accounting for variations between two post-processing software tools.

Methods and results

We analyzed CMR scans from the Healthy Hearts Consortium (HHC), which includes six multi-ethnic international cohorts. Images were automatically segmented using cvi42 (Circle Cardiovascular Imaging) and suiteHEART (Neosoft), with visual and statistical quality control. Ventricular and atrial volumes, myocardial mass, and ejection fractions were derived using short- and long-axis protocols; parameters were indexed to body surface area and height. We defined reference ranges as normal up to the 95% of the prediction interval (PI), and abnormalities as mild up to 99.73%, moderate at 99.73%, and severe at 99.99%, respectively. The final dataset included 4,624 women (51.0%) and 4,435 men (49.0%), with a mean age of 61 ± 13 years (range 18–83), and a multi-ethnic population (81.6% White, 5.6% South Asian, 5.3% Mixed/Other, 3.8% Black, 3.7% Chinese). Minor systematic differences were observed between cvi42 and suiteHEART, particularly in atrial parameters.

Conclusions

Our work provides an evidence-based framework for CMR severity grading, offering age-, sex-, and ethnicity-stratified thresholds for mild, moderate, and severe deviations from the reference. These reference values support improved diagnostic accuracy, better risk stratification, and enhanced comparability of CMR findings worldwide.

Footnote: This graphical abstract summarises the methodology and findings of our study on severity grading using cardiovascular magnetic resonance (CMR). It illustrates the dataset, quality control steps, software tools used and the derivation of population-specific reference ranges and severity grading classification. All reference ranges are available on the Healthy Hearts Consortium website ( www.healthy-hearts.org.uk ). Abbreviations: CMR: cardiovascular magnetic resonance; QC: quality control; EDV: end-diastolic volume; ESV: end-systolic volume; SV: stroke volume; EF: ejection fraction; LV: left ventricle.