A team led by scientists at Queen Mary University of London reports that certain risk factors for heart disease are linked to common changes in the structure and appearance of the heart.
Risk factors for heart disease, including male sex, diabetes, high blood pressure, high cholesterol, and smoking, were linked to a darker appearance of the heart muscle, as well as a change in its texture.
For the study (“Cardiac Magnetic Resonance Radiomics Reveal Differential Impact of Sex, Age, and Vascular Risk Factors on Cardiac Structure and Myocardial Tissue”), which is published in Frontiers in Cardiovascular Medicine, researchers analyzed images from heart magnetic resonance imaging (MRI) scans using a new toolkit called radiomics. It was developed in collaboration with the University of Barcelona to get highly detailed information on the shape and texture of the heart.
“Cardiovascular magnetic resonance (CMR) radiomics analysis provides multiple quantifiers of ventricular shape and myocardial texture, which may be used for detailed cardiovascular phenotyping,” write the investigators.
“We studied variation in CMR radiomics phenotypes by age and sex in healthy UK Biobank participants. Then, we examined independent associations of classical vascular risk factors (VRFs: smoking, diabetes, hypertension, high cholesterol) with CMR radiomics features, considering potential sex and age differential relationships.
“Image acquisition was with 1.5 Tesla scanners (MAGNETOM Aera, Siemens). Three regions of interest were segmented from short axis stack images using an automated pipeline: right ventricle, left ventricle, myocardium. We extracted 237 radiomics features from each study using Pyradiomics. In a healthy subset of participants (n = 14,902) without cardiovascular disease or VRFs, we estimated independent associations of age and sex with each radiomics feature using linear regression models adjusted for body size.
“We then created a sample comprising individuals with at least one VRF matched to an equal number of healthy participants (n = 27,400). We linearly modelled each radiomics feature against age, sex, body size, and all the VRFs. Bonferroni adjustment for multiple testing was applied to all p-values. To aid interpretation, we organized the results into six feature clusters.
“Amongst the healthy subset, men had larger ventricles with dimmer and less texturally complex myocardium than women. Increasing age was associated with smaller ventricles and greater variation in myocardial intensities. Broadly, all the VRFs were associated with dimmer, less varied signal intensities, greater uniformity of local intensity levels, and greater relative presence of low signal intensity areas within the myocardium.
“Diabetes and high cholesterol were also associated with smaller ventricular size; this association was of greater magnitude in men than women. The pattern of alteration of radiomics features with the VRFs was broadly consistent in men and women. However, the associations between intensity based radiomics features with both diabetes and hypertension were more prominent in women than men.
“We demonstrate novel independent associations of sex, age, and major VRFs with CMR radiomics phenotypes. Further studies into the nature and clinical significance of these phenotypes are needed.”
Using their novel approach, the researchers studied heart MRI scans from almost 30,000 people from the U.K. Biobank to look at the overall shape and structure of the heart in detail. They found that for all the key risk factors studied the heart muscle was darker in appearance and had a smoother, less complex texture.
Men were found to have larger hearts with the heart muscle appearing smoother and less texturally complex in comparison to women. The heart muscle in healthy women was brighter than male hearts with a more complex appearance of the muscle architecture, according to researchers.
Current methods used to image the heart in hospitals are not able to fully reflect complexity of the heart’s structure, says the team. By applying their new imaging toolkit to MRI scans the researchers were able to look at the structure and texture of the heart much greater detail than is possible using existing standard techniques.
“Our findings provide new insights into the impact of risk factors on the heart and identify differences in the size, structure, and appearance of hearts between healthy men and women,” explained Zahra Raisi-Estabragh, MD, NIHR clinical lecturer in cardiology at Queen Mary and lead author.
“The study forms part of our wider research program aimed at developing the radiomics imaging toolkit to transform patient care. Our novel approach has the potential to provide faster, more accurate diagnosis of heart disease, improve our estimations of future risk of heart conditions, and better understand the processes underlying cardiovascular disease.”
The researchers are now exploring whether the observed changes in heart muscle translate to higher risk of having significant heart problems, such as heart attacks.
“As we’ve shown that these changes are associated with known major risk factors for heart disease, it’s very likely that they represent unhealthy changes to the heart muscle. However more research is needed to confirm this,” added Raisi-Estabragh.