RSNA 2025 Imaging the Individual

Take a look at the latest discoveries in medical imaging research, education and technology that will be presented at RSNA 2025.

More Muscle, Less Belly Fat Slows Brain Aging

A specific body profile—higher muscle mass combined with a lower visceral fat to muscle ratio—tracks with a younger brain age. Examining 1,164 healthy participants with whole-body MRI, researchers at Washington University’s Mallinckrodt Institute of Radiology quantified total normalized muscle volume, visceral fat (hidden belly fat), subcutaneous fat (fat under the skin) and brain age—the computational estimate of chronological age from a structural MRI scan of the brain.

They found that participants with more muscle tended to have “younger”-looking brains, while those with more hidden belly fat relative to their muscle had “older”-looking brains. Subcutaneous fat, however, had no association with brain age.

Building muscle and reducing visceral fat are actionable goals, and whole-body MRI and brain-age estimates can help provide achievable targets for muscle-building and fat-reducing programs and therapies.

AI Detects First Imaging Biomarker of Chronic Stress

Using a deep learning AI model, researchers at Johns Hopkins identified the first-of-its-kind biomarker of chronic stress detectable through routine chest CT. The researchers obtained data on 2,842 participants from the Multi-Ethnic Study of Atherosclerosis, a comprehensive study combining chest CT scans, validated stress questionnaires, cortisol measures and markers of allostatic load—the cumulative physiological and psychological effects of chronic stress on the body.

The researchers retrospectively applied their deep learning model to the CT scans to segment and calculate the volume of the adrenal glands. Unlike single cortisol measurements, which provide a momentary snapshot of stress levels, adrenal volume reflects cumulative exposure to stress.

Chronic stress can contribute to the development of heart disease, depression and obesity, and increases in adrenal volume index were linked to greater risk of heart failure and mortality. This research introduces an entirely new, practical way to quantify chronic stress with a common routine imaging exam.

Shape of Your Behind May Signal Diabetes

The shape of the gluteus maximus muscle in the buttocks changes in different ways with aging, lifestyle, frailty, osteoporosis and type 2 diabetes, and these changes differ between women and men. Using data from 61,290 MRI exams, researchers at the University of Westminster in the UK used MRI 3D mapping to create detailed 3D anatomical models of participants’ gluteus maximus muscles.

The researchers then compared these models with 86 different variables—including physical measurements, demographics, disease biomarkers, medical history and answers to lifestyle questionnaires—to demonstrate how they relate to changes in muscle shape over time.

They found that people with higher fitness had a greater gluteus maximus shape, while aging, frailty and long sitting times were linked to muscle thinning. Men with diabetes showed muscle shrinkage, while women with diabetes showed enlarged muscle, likely due to infiltration of fat.

These findings revealed distinct, sex-specific patterns in the gluteus maximus that were associated with type 2 diabetes, suggesting that the shape—not the size—of the muscle may reflect underlying metabolic differences that determine patients’ risk.

AI Tops Density in Predicting Breast Cancer Risk

Harvard researchers found that an image-only AI model for predicting the five-year risk of breast cancer provided stronger and more precise risk stratification than breast density assessment. The model was applied to a study group of 236,422 bilateral 2D screening mammograms from five U.S. sites and 8,810 from one European site that were obtained between 2011 and 2017.

Accounting for breast density, women in the high-risk AI group had more than a fourfold higher cancer incidence than women in the average-risk group (5.9% vs. 1.3%). By contrast, breast density alone showed only modest separation (3.2% for dense vs. 2.7% for non-dense).

While breast density legislation enacted in 32 states requires health care providers to inform women undergoing a screening mammogram of their breast density, the researchers say adding an AI image-based risk score can provide a more personalized prediction of risk.

Pro Fighters Risk Damage to the Brain’s ‘Garbage Disposal’

The brain’s waste-clearing system significantly declines in function with repeated head impacts, according to a new study of cognitively impaired professional boxers and mixed martial arts fighters.

Researchers from the University of Alabama at Birmingham and Cleveland Clinic Nevada used diffusion tensor imaging along the perivascular space (DTI-ALPS) to measure changes in the participants’ glymphatic system—a network of fluid-filled channels that plays a crucial role in clearing waste products from the brain—and how they compared with the history of knockouts in fighters with signs of cognitive impairment versus those that didn’t.

Contrary to their hypothesis, the investigators observed a significantly higher glymphatic index among impaired fighters that deteriorated over time with the total number of knockouts. In athletes with continued trauma, glymphatic function significantly declined. The researchers suggest that the brain initially responds to repeated head injuries by ramping up its cleaning mechanism, but it eventually becomes overwhelmed.