Muscle Steatosis and Fibrosis in Older Adults, From the AJR Special Series on Imaging of Fibrosis.

The purpose of this article is to review steatosis and fibrosis of skeletal muscle, focusing on older adults. Although CT, MRI, and ultrasound are commonly used to image skeletal muscle and provide diagnoses for a variety of medical conditions, quantitative assessment of muscle steatosis and fibrosis is uncommon. This review provides radiologists with a broad perspective on muscle steatosis and fibrosis in older adults by considering the public health impact, biologic mechanisms, and evaluation with CT, MRI, and ultrasound. Promising directions in clinical research that entail artificial intelligence algorithms and the imaging assessment of biologic age are also reviewed. The imaging methods presented hold promise for improving the evaluation of common conditions affecting older adults, including sarcopenia, frailty, and cachexia.