Regional cardiac 31P-MRSI at 7T: detection of spatially heterogeneous patterns of myocardial energetic impairment
- 1Wolfson Brain Imaging Center
Abstract
BackgroundThe phosphocreatine-to-ATP ratio (PCr/ATP), measurable by 3{superscript 1}P magnetic resonance spectroscopic imaging (3{superscript 1}P-MRSI), is a sensitive marker of myocardial energetic reserve. Regional energetic-mechanical coupling, evaluable only per-segment to avoid confounding from spatially heterogeneous disease, represents an important target for cardiac metabolic trials. We extend our previously validated 7T regional 3{superscript 1}P-MRSI approach to patients with cardiovascular disease.
MethodsTwenty-one participants underwent same-day 7T 3{superscript 1}P-MRSI and 3T CMR: 9 healthy volunteers, 4 with type 2 diabetes, 5 with heart failure, and 3 with ischaemic cardiomyopathy. PCr/ATP was mapped across six mid-ventricular AHA segments. Ejection fraction, global longitudinal strain, peak filling rate, and regional circumferential and radial strain were derived from 3T CMR. Group differences were assessed by Kruskal-Wallis test with Bonferroni-corrected pairwise comparisons; segment-level associations by per-segment Spearman correlation and linear mixed effects models.
ResultsPCr/ATP differed significantly across groups (p = 0.005, {superscript 2} = 0.58), ranging from 1.78 {+/-} 0.21 in healthy volunteers to 1.10 {+/-} 0.28 in heart failure. Mean PCr/ATP correlated with ejection fraction (rs = 0.65, p = 0.002), global longitudinal strain (rs = -0.63, p < 0.001), and peak filling rate (rs = 0.52, p = 0.023). Segment-level energetic-mechanical coupling was significant in the anteroseptal and inferoseptal segments (circumferential strain rs = -0.49 to -0.56; radial strain rs = 0.43 to 0.57, all p < 0.05), with no significant associations in other segments, consistent with a displacement-related measurement quality gradient. In ischaemic patients, PCr/ATP was significantly lower in infarct segments (0.79 {+/-} 0.20) than remote myocardium (1.33 {+/-} 0.22, p = 0.008, r = 0.62). All three ischaemic patients demonstrated remote PCr/ATP below the healthy volunteer median, with two below the 5th percentile (rank-sum p = 0.018; Fisher p = 0.045).
ConclusionsRegional 7T 3{superscript 1}P-MRSI detects segment-level energetic differences across cardiovascular disease states and reveals spatially specific energetic-mechanical coupling confined to the septal segments in the current ungated acquisition. Energetic impairment in ischaemic cardiomyopathy extends into structurally preserved remote myocardium. These findings support larger studies using regional 3{superscript 1}P-MRSI to investigate regional energetic-mechanical coupling as a target for metabolic cardiac therapies.
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BibTeX
@misc{karkouri2026regional,
title = {{Regional cardiac 31P-MRSI at 7T: detection of spatially heterogeneous patterns of myocardial energetic impairment}},
author = {J. Karkouri and W. Watson and T. Horn and M. Hill and D. Klomp and M. Mallouppas and C. Bhagra and S. Hoole and C. Rodgers},
howpublished = {medRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.04.26362251},
url = {https://www.medrxiv.org/content/10.64898/2026.09.04.26362251v1},
note = {CC BY-ND},
}
RIS
TY - UNPB
TI - Regional cardiac 31P-MRSI at 7T: detection of spatially heterogeneous patterns of myocardial energetic impairment
AU - J. Karkouri
AU - W. Watson
AU - T. Horn
AU - M. Hill
AU - D. Klomp
AU - M. Mallouppas
AU - C. Bhagra
AU - S. Hoole
AU - C. Rodgers
PY - 2026
DA - 2026/09/04
PB - medRxiv
DO - 10.64898/2026.09.04.26362251
UR - https://www.medrxiv.org/content/10.64898/2026.09.04.26362251v1
AB - BackgroundThe phosphocreatine-to-ATP ratio (PCr/ATP), measurable by 3{superscript 1}P magnetic resonance spectroscopic imaging (3{superscript 1}P-MRSI), is a sensitive marker of myocardial energetic reserve. Regional energetic-mechanical coupling, evaluable only per-segment to avoid confounding from spatially heterogeneous disease, represents an important target for cardiac metabolic trials. We extend our previously validated 7T regional 3{superscript 1}P-MRSI approach to patients with cardiovascular disease. MethodsTwenty-one participants underwent same-day 7T 3{superscript 1}P-MRSI and 3T CMR: 9 healthy volunteers, 4 with type 2 diabetes, 5 with heart failure, and 3 with ischaemic cardiomyopathy. PCr/ATP was mapped across six mid-ventricular AHA segments. Ejection fraction, global longitudinal strain, peak filling rate, and regional circumferential and radial strain were derived from 3T CMR. Group differences were assessed by Kruskal-Wallis test with Bonferroni-corrected pairwise comparisons; segment-level associations by per-segment Spearman correlation and linear mixed effects models. ResultsPCr/ATP differed significantly across groups (p = 0.005, {superscript 2} = 0.58), ranging from 1.78 {+/-} 0.21 in healthy volunteers to 1.10 {+/-} 0.28 in heart failure. Mean PCr/ATP correlated with ejection fraction (rs = 0.65, p = 0.002), global longitudinal strain (rs = -0.63, p < 0.001), and peak filling rate (rs = 0.52, p = 0.023). Segment-level energetic-mechanical coupling was significant in the anteroseptal and inferoseptal segments (circumferential strain rs = -0.49 to -0.56; radial strain rs = 0.43 to 0.57, all p < 0.05), with no significant associations in other segments, consistent with a displacement-related measurement quality gradient. In ischaemic patients, PCr/ATP was significantly lower in infarct segments (0.79 {+/-} 0.20) than remote myocardium (1.33 {+/-} 0.22, p = 0.008, r = 0.62). All three ischaemic patients demonstrated remote PCr/ATP below the healthy volunteer median, with two below the 5th percentile (rank-sum p = 0.018; Fisher p = 0.045). ConclusionsRegional 7T 3{superscript 1}P-MRSI detects segment-level energetic differences across cardiovascular disease states and reveals spatially specific energetic-mechanical coupling confined to the septal segments in the current ungated acquisition. Energetic impairment in ischaemic cardiomyopathy extends into structurally preserved remote myocardium. These findings support larger studies using regional 3{superscript 1}P-MRSI to investigate regional energetic-mechanical coupling as a target for metabolic cardiac therapies.
ER -