Left ventricular shape variation in asymptomatic populations: the multi-ethnic study of atherosclerosis |
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| Authors: | Pau Medrano-Gracia Brett R Cowan Bharath Ambale-Venkatesh David A Bluemke John Eng John Paul Finn Carissa G Fonseca Joao AC Lima Avan Suinesiaputra Alistair A Young |
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| Affiliation: | 1.Department of Anatomy with Radiology, University of Auckland, Auckland, New Zealand;2.The Donald W. Reynolds Cardiovascular Clinical Research Center, The Johns Hopkins University, Baltimore, USA;3.National Institute of Biomedical Imaging and Bioengineering, Bethesda, Maryland, USA;4.Department of Radiology, University of California, Los Angeles (UCLA), Los Angeles, USA |
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| Abstract: | BackgroundAlthough left ventricular cardiac geometric indices such as size and sphericity characterize adverse remodeling and have prognostic value in symptomatic patients, little is known of shape distributions in subclinical populations. We sought to quantify shape variation across a large number of asymptomatic volunteers, and examine differences among sub-cohorts.MethodsAn atlas was constructed comprising 1,991 cardiovascular magnetic resonance (CMR) cases contributed from the Multi-Ethnic Study of Atherosclerosis baseline examination. A mathematical model describing regional wall motion and shape was used to establish a coordinate map registered to the cardiac anatomy. The model was automatically customized to left ventricular contours and anatomical landmarks, corrected for breath-hold mis-registration between image slices. Mathematical techniques were used to characterize global shape distributions, after removal of translations, rotations, and scale due to height. Differences were quantified among ethnicity, sex, smoking, hypertension and diabetes sub-cohorts.ResultsThe atlas construction process yielded accurate representations of global shape (errors between manual and automatic surface points in 244 validation cases were less than the image pixel size). After correction for height, the dominant shape component was associated with heart size, explaining 32% of the total shape variance at end-diastole and 29% at end-systole. After size, the second dominant shape component was sphericity at end-diastole (13%), and concentricity at end-systole (10%). The resulting shape components distinguished differences due to ethnicity and risk factors with greater statistical power than traditional mass and volume indices.ConclusionsWe have quantified the dominant components of global shape variation in the adult asymptomatic population. The data and results are available at cardiacatlas.org. Shape distributions were principally explained by size, sphericity and concentricity, which are known correlates of adverse outcomes. Atlas-based global shape analysis provides a powerful method for quantifying left ventricular shape differences in asymptomatic populations.Trial registrationClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00005487","term_id":"NCT00005487"}}NCT00005487 |
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| Keywords: | Cardiovascular magnetic resonance Atlas Principal component analysis |
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