Ashley A. Weaver

Automotive trauma in motor vehicle crash (MVC) occupants and pedestrians is a leading cause of injuries and death amongst children and adults in the United States (NHTSA 2024, 2025). Many of these ...

Long‐duration spaceflight poses several challenges to human health, including muscle loss and fat deposition. To mitigate these effects, exercise countermeasures are prescribed. This study aimed to measure neck muscle size and composition changes with long‐duration spaceflight using quantitative magnetic resonance imaging (MRI) and examine associations with in‐flight exercise modality and volume. Nine astronauts (mission duration: 7.1 ± 1.8 months) underwent pre‐ and post‐flight 3T Dixon MRI of the cervical spine. Cross‐sectional area (CSA) and muscle fat fraction (MFF) were measured bilaterally in 11 neck muscles. Mixed‐effects models assessed monthly percentage changes and associations with resistance (ARED), cycle ergometer and treadmill training volumes. The CSA and MFF of most neck muscles did not change across long‐duration missions. CSA increased for the sternocleidomastoid (+1.21%/month, P = 0.004) and the rhomboid minor (+1.71%/month, P = 0.057). Semispinalis capitis MFF increased (+1.10%/month, P = 0.051). More ARED repetitions of different exercises were associated with CSA increases in four muscles ( P < 0.001–0.097) and MFF reductions in three muscles ( P = 0.040–0.093). More cycle ergometer time was associated with a CSA increase in the sternocleidomastoid ( P = 0.053) and an MFF increase in the scalenus medius ( P = 0.019), while treadmill time was linked to CSA decreases in the trapezius ( P = 0.095) and rhomboid minor ( P = 0.047). Neck muscle size and composition were generally preserved during modern long‐duration missions in which structured exercise countermeasures were performed. Because all crewmembers completed in‐flight exercises, these findings should not be interpreted as evidence that exercise countermeasures prevented neck muscle changes.

DXA and HR-pQCT are used for bone assessment but also image adjacent soft tissue. This pilot study examined association between HR-pQCT-measured leg muscle cross-sectional area (CSA) and density vs DXA-derived lean mass, and explored associations with muscle strength, power, and physical performance in adults with obesity. Patients eligible for bariatric surgery (BMI ≥ 30 kg/m2; ages ≥30) received baseline HR-pQCT (XtremeCT II) and DXA (Hologic) scans. HR-pQCT scans of the non-dominant leg were acquired at 30% of tibial length and processed using a custom Python script for muscle segmentation, followed by manual editing. Whole-body DXA scans were analyzed to extract lean mass for the total leg and subregions analogous to the HR-pQCT. Functional measures included gait speed (400-m walk), muscle power (12-step stair climb), and knee extensor strength (isokinetic dynamometer). Pearson correlations assessed relationships between imaging modalities and functional measures. Among 28 adults (ages: 47.7 ± 8.6; BMI: 43.8 ± 4.6 kg/m2), HR-pQCT muscle CSA and density averaged 36.0 ± 4.8 cm2 and 60.1 ± 8.1 HU, respectively. DXA lean mass was 2.23 ± 0.40 kg for the total leg and 0.107 ± 0.019 kg for the 30% site. HR-pQCT muscle CSA correlated moderately with DXA lean mass (r = 0.57-0.69, p = .0017-<.0001), whereas HR-pQCT muscle density showed negligible correlations with DXA lean mass (r = −0.01-0.04, p = .84-0.96). Significant positive correlations were observed for DXA total leg lean mass with absolute muscle power (r = 0.40) and HR-pQCT muscle CSA with knee strength (r = 0.41; both p < .05). In adults with obesity, HR-pQCT and DXA may provide complementary measures of leg muscle quantity, with moderate association for CSA and lean mass, but limited associations with muscle density. Body weight and whole-body lean mass showed stronger correlations with stair climb power (r = 0.42-0.70) than localized leg muscle measures (r = 0.17-0.40). Muscle density and muscle quantity may capture different aspects of musculoskeletal health, warranting further investigation in larger samples.

Low BMD and impaired bone strength are established risk factors for fractures in older adults. Decreased muscle size also contributes to fracture risk; however, the relationship between muscle size and bone density, microarchitecture, and strength using state-of-the-art assessment methods is not clear. In The Study of Muscle, Mobility and Aging, muscle size was assessed using whole-body muscle mass (kg, deuterated creatine [D3Cr] dilution method) and thigh muscle volume (L, by MRI). We investigated cross-sectional associations between baseline D3Cr muscle mass and MRI thigh muscle volume with bone volumetric density, microarchitecture, and strength from HR-pQCT at the distal tibia (DT) and radius (DR), and hip areal BMD from DXA at the first annual follow-up visit (year 1). Muscle and bone parameters were standardized within sex and analyses were stratified by sex. Linear regression models were adjusted for age, race, weight, ≥1 alcoholic drink/wk, ever cigarette smoker, total activity from wrist-worn accelerometry, multimorbidity count (0-11), arthritis, and tibia or ulna length. In 181 women (age 76.2 ± 4.7 yr, 86% White) and 118 men (age 76.1 ± 4.3 yr, 93% White), higher thigh muscle volume (per SD: 1.1 L women; 1.5 L men) was associated with higher DT and DR failure load (p < .05). Greater thigh muscle volume was associated with higher DXA total hip BMD in men but not in women. Greater D3Cr muscle mass (per SD: 4.4 kg women; 5.5 kg men) was associated with higher DT and DR failure load (p < .05) in women only. Associations of muscle size with microarchitecture were variable and differed by sex. Given that failure load is a strong predictor of fracture risk, future studies should investigate whether interventions that target muscle size may impact fracture risk in older adults.

Background: Skeletal muscle health is a key determinant of aging, independence, and disease outcomes. Traditional computed tomography (CT)-derived measures of muscle cross-sectional area (CSA) and density reflect muscle quantity and quality but may not capture structural heterogeneity relevant to functional decline. Radiomics, a CT image analysis approach, enables extraction of high-dimensional texture features, offering additional insight into muscle quality. While muscle radiomics have been associated with strength and mobility in older adults, longitudinal applications remain understudied. We examined whether 5-year changes in thigh muscle radiomic features were associated with changes in muscle strength and performance in the Health, Aging, and Body Composition Study. Methods: Thigh CT scans from 1321 older adults were analyzed using automated muscle segmentation to quantify CSA, density, and extract radiomic features. Strength measures included grip strength and maximal isokinetic knee extension; performance measures included 20-m walking speed, 5-time chair stands, and a modified performance score. Factor analysis reduced radiomic features to seven latent factors. Nested linear mixed-effects models tested associations of muscle CSA and density with outcomes, with and without radiomic factors. Results: Factors 2 and 5 were consistently associated with 5-year changes across muscle outcomes. Factor 2 (high pixel gray-level intensity and uniformity) was positively associated, whereas Factor 5 (pixel clustering asymmetry and heterogeneity) was inversely associated. Adding radiomic factors modestly improved model fit (p < 0.05), explaining 1–2% additional variation in performance. Conclusion: Longitudinal changes in thigh muscle radiomics capture subtle compositional characteristics beyond muscle CSA or density, enhancing understanding of functional decline with aging.

Motor vehicle collisions (MVCs) are a leading cause of fracture-related morbidity and healthcare cost in the United States (Peterson et al. 2021; Yuan et al. 2023). However, fracture risk following...

As HR-pQCT increases in popularity for studying bone dynamics, it becomes increasingly important to quantify the factors that impact rigor and reproducibility in research, particularly for longitudinal studies. Previously reported data for HR-pQCT precision primarily use first-generation HR-pQCT, and focus on single operators, with narrow study populations that reflect the population of a larger research question. This study at a single academic imaging center with standardized, single-analyst post-processing was designed to investigate how operator characteristics in scan acquisition and participant demographics influence measurement precision. In total, 45 adults (58% female; 22-82 yr; BMI 18.4-44.8 kg/m2) underwent same-day repeat HR-pQCT scanning of the distal tibia and radius, with 3 imaging technologists each acquiring 15 participant scan pairs, and registration was applied in post-processing to accurately depict the standard workflow at the center. The root-mean-square coefficient of variation was ≤1.3% for BMD measures and <2% for area measures in both the radius and tibia. Trabecular microarchitecture ranged from 1.22% to 2.24% in the radius and from 1.14% to 2.82% in the tibia, while cortical thickness precision was calculated as 1.99% in the radius and 1.57% in the tibia. Cortical porosity was much higher, at 24.66% in the radius and 20.90% in the tibia. Significant differences were not found when analyzed by technologists, or in statistical modeling of participant demographics as potential covariates. While final image quality scores varied among technologists, it did not influence precision outcomes. These results offer reference values for the least significant change and demonstrate that standardized technologist training can yield consistent scan-rescan precision across operators.

Pectus excavatum is the most common congenital chest wall deformity, characterized by a depression of the anterior chest wall which may compromise cardiac function and cause symptoms like exercise intolerance, chest pain, and shortness of breath. While diagnosis is often based on appearance, imaging-based metrics provide objective severity assessment. This study evaluated associations between pectus excavatum severity indices and cardiac rotation angle in 37 adolescents generated two sex-specific anatomical models of severe cases for future diagnostic and treatment planning. Chest computed tomography (CT) scans of 30 male and 7 female pectus excavatum patients aged 12-16 years were analyzed to measure the Haller index, Correction index, and cardiac rotation angle. Severity by Haller index was classified as mild (2.0-3.2cm, n=15), moderate (3.2-3.5cm, n=7), or severe (>3.5cm, n=15). Cardiac rotation angle increased with severity (p=0.001): mild (37.6±13.1°), moderate (44.8±13.6°), and severe (51±13.2°). Cardiac rotation angle was positively associated with the Haller index (R²=0.24, p=0.002), but not the Correction index (R²=0.01, p=0.55). CT scans of a representative male and female were segmented to generate 3D models of thoracic and abdominal structures. These measurements and models may inform diagnostic criteria, treatment planning, and personalized device development for adolescents with pectus excavatum.

Age-related changes to BMD, morphometry, and microarchitecture do not occur uniformly across the population and the common skeletal phenotypes beyond BMD are not well defined. Additionally, the associations between bone and muscle are critical to understanding fall and fracture risk. We hypothesized that unsupervised clustering of HR-pQCT measures at the distal tibia (DT) and radius (DR), separately, would reveal unique skeletal phenotypes; and certain phenotypes would be associated with worse muscle function. In the Study of Muscle, Mobility and Aging (SOMMA; first annual follow-up visit), a cohort of community-dwelling older women and men (61% women; 87% White), HR-pQCT parameters acquired at the DT (N = 321; 76.3 ± 4.6 yr) and DR (N = 295; 76.1 ± 4.5 yr) were standardized within-sex then combined to form clusters. This resulted in 3 phenotypic clusters, (C1) high total BMD (Tt.BMD) and cortical area (Ct.Ar); (C2) medium Tt.BMD, Ct.Ar, and low trabecular BMD (Tb.BMD); and (C3) low Tt.BMD, and Ct.Ar. DT C2 and C3 exhibited lower micro-finite element analysis failure loads, with the cortical load fraction higher in C2 and lower in C3. C2 and C3 both had a similar proportion of osteoporotic and osteopenic/low bone density individuals, highlighting the novel granularity of HR-pQCT clusters vs aBMD clinical cutoffs. In linear regression models for women, DT C3 was associated with lower leg power (p < .05). For men, DT C3 was associated with lower stair climb and leg power (p < .05). No significant difference was found in grip strength between DT clusters. For DR, no significant difference or association was found between muscle function and clusters for women and men. These findings suggest the concept of bone phenotypic-specific associations with lower but not upper extremity muscle function and have possible implications for the interaction between skeletal phenotypes and muscle function as potential contributory factors to fracture risk.

Musculoskeletal pain and mobility disability are common in older adults, but relationships among pain parameters and physical performance are poorly understood. We quantified the impact of different pain measures—recalled and movement-evoked pain—on walk and stair climb time in older adults from the Study of Muscle, Mobility and Aging (SOMMA). In SOMMA (N = 879, age = 76.3 ± 5.0 years, 59% women, 84% non-Hispanic White), participants completed usual pace 400-m walk (avg = 6.6 ± 1.2 min) and stair climb tests (avg = 26.6 ± 7.2 s.). Assessments of recalled pain included the Brief Pain Inventory, total lower body pain, and Neuropathy Total Symptom Score. Movement-evoked pain was assessed separately for the 400-m walk and stair climb tasks. Multivariable linear regression modeled the associations of pain with time to complete the tasks, reported as β [95%CI] expressed per SD increment of pain measure or per pain categories, adjusted for age, sex, race/ethnicity, BMI, prescription medications, and depressive symptoms. A greater degree of any pain measure was associated with longer (worse) physical performance time. For each SD increment in lower body pain (back, hips, knees, feet/ankles), participants had longer walk (+ 10.5 s [6.1, 14.8]) and stair climb time (+ 0.6 s [0.1, 1.1]). Compared to participants with no pain, walk time was longer in those with resting pain (+ 22.8 s [4.9,40.6]) and movement-evoked pain (+ 19.1 s [8.9, 29.2]) but not movement-evoked hypoalgesia (+ 12.6 s [−4.4, 29.7]); stair climb showed similar patterns. Different pain assessments captured heterogeneous pain contextual factors (e.g., type, state, temporality) among these older adults. However, all pain measures were similarly associated with physical performance, suggesting that multiple assessments may provide a more comprehensive characterization of pain and physical function outcomes.