Abdominal MRI

Developed an abdominal MRI-based machine-learning regression model (gradient-boosted regression on raw MRI signal intensities) to accurately estimate liver fat from UK Biobank abdominal MRI scans (correlation 0.97-0.99 with ground truth). Trained on 4,511 participants with gold-standard MRI biomarker measurements and applied to 32,192 additional individuals. GWAS identified 8 associated variants (5 novel: MTARC1, ADH1B, TRIB1, GPAM, MAST3) and a polygenic score strongly associated with future chronic liver disease risk (HR>1.32 per SD, p<9e-17).

MRI signal regression, liver fat quantification, abdominal MRI, hepatic steatosis, gradient boosting, UK Biobank

Excess liver fat, called hepatic steatosis, is a leading risk factor for end-stage liver disease and cardiometabolic diseases but often remains undiagnosed in clinical practice because of the need for direct imaging assessments. We developed an abdominal MRI-based machine-learning algorithm to accurately estimate liver fat from a truth dataset of 4,511 middle-aged UK Biobank participants, enabling quantification in 32,192 additional individuals. A genome-wide association study of common genetic variants and liver fat replicated three known associations and identified five newly associated variants.

Applied a U-Net-based CNN segmentation pipeline to over 38,000 abdominal MRI scans from UK Biobank. The deep learning model automatically segmented 7 organs/tissues (liver, pancreas, kidneys, spleen, lungs, visceral adipose tissue, subcutaneous adipose tissue) and quantified their volume, fat content (via signal intensity), and iron content (via T2* mapping). GWAS on these 11 DL-derived traits identified 93 independent genome-wide significant associations (heritability 8-44%), including 4 novel liver trait associations.

deep learning, abdominal MRI segmentation, U-Net, organ volume quantification, liver fat, pancreas iron, UK Biobank

Cardiometabolic diseases are an increasing global health burden. While socioeconomic, environmental, behavioural, and genetic risk factors have been identified, a better understanding of the underlying mechanisms is required to develop more effective interventions. Magnetic resonance imaging (MRI) has been used to assess organ health, but biobank-scale studies are still in their infancy. Using over 38,000 abdominal MRI scans in the UK Biobank, we used deep learning to quantify volume, fat, and iron in seven organs and tissues, and demonstrate that imaging-derived phenotypes reflect health status. We identify 93 independent genome-wide significant associations.