Differential Aging Signals in Abdominal CT Scans

Rationale and Objectives: Changes in the composition of body tissues are major aging phenotypes but they have been difficult to study in depth. Here we describe age-related change in abdominal tissues observable in Computed Tomography (CT) scans. We used pattern recognition and machine learning to detect and quantify these changes in a model-agnostic fashion. Materials and Methods: CT scans of abdominal L4 sections were obtained from Baltimore Longitudinal Study of Aging (BLSA) participants. Age-related change in the constituent tissues were determined by training machine classifiers to differentiate age groups within male and female strata ('Younger' at 50-70 y.o., vs. 'Older' at 80-99 y.o.). The accuracy achieved by the classifiers in differentiating the age cohorts was used as a surrogate measure of the aging signal in the different tissues. Results: The highest accuracy for discriminating age differences was 0.76 and 0.72 for males and females, respectively. The classification accuracy was 0.79 and 0.71 for adipose tissue, 0.70 and 0.68 for soft tissue, and 0.65 and 0.64 for bone. Conclusions: Using image data from a large sample of well characterized pool of participants dispersed over a wide age-range we explored age-related differences in gross morphology and texture of abdominal tissues. This technology is advantageous for tracking effects of biological aging and predicting adverse outcomes when compared to the traditional use of specific molecular biomarkers. Application of pattern recognition and machine learning as a tool for analyzing medical images may provide much needed insight into tissue changes occurring with aging, and further, connect these changes with their metabolic and functional consequences.