Dual-energy X-ray Absorptiometry Scans Research Articles

Utility of fat-free adipose tissue correction formula for tracking body composition changes with dual-energy X-ray absorptiometry.

Fat loss is often the target of weight loss interventions; however, preservation of lean soft tissue (LST) may be more important for health and weight maintenance. Though some LST loss may be inevitable when tracking body composition changes using dual-energy X-ray absorptiometry (DXA), correcting for the fat-free component of adipose tissue (FFAT) in DXA-derived LST (DXALST) has been proposed. This analysis sought to evaluate differences between DXALST and FFAT-corrected LST (FFATLST) amongst varied populations and interventions to understand application of the correction formula on LST outcomes. 226 subjects were analyzed across five prior studies. Three studies evaluated combined nutrition and exercise (high-intensity interval training [HIIT] or high-intensity resistance training [HIRT]) interventions, including HIIT + HIRT with pre- and post-nutrient timing (HIITRT), HIIT + essential amino acids (HIITAA), and HIRT + protein (HIRTPRO). Remaining studies evaluated HIIT (HIITOW) and protein following bariatric surgery (BARPRO). Pre and post total body DXA scans were used to measure DXALST, body mass, and fat mass (FM). The correction formula was applied to calculate FFATLST. Paired sample t-tests were used to evaluate differences between DXALST and FFATLST change scores (Δ) across all subjects, within each study and intervention. Significant differences between ΔDXALST and ΔFFATLST were observed for BARPRO (mean difference [MD; ΔDXALST-ΔFFATLST] ± standard error [SE]: -3.5 ± 1.2 kg, p < 0.001), as well as HIRTPRO (-0.1 ± 0.2 kg, p = 0.004). When evaluating LST, the FFAT correction may be specifically applicable to cases of significant weight loss (>10% of original weight) or body recomposition (≥2% FM loss and ≥2% LST gain).

Abstract 4136678: Detecting Myosteatosis-Related Low Physical Function in Heart Failure Patients Using Abdominal Computed Tomography and Plasma Amino Acid Profile

Background: Evaluation of sarcopenia requires quantifying appendicular skeletal muscle mass and functional capacity, but resource constraints often limit feasibility. Alterations in muscle quality, especially intramuscular lipid infiltration (i.e., myosteatosis), and systemic metabolic derangements are associated with disability. Hypothesis: Opportunistic CT imaging and plasma amino acid profiling could identify low physical function in patients with heart failure (HF). Methods: We retrospectively examined 220 HF patients (74 ± 13 years old; 59% male) who underwent plasma amino acid profiling, abdominal CT imaging, and dual-energy X-ray absorptiometry (DXA) scan within two months. Myosteatosis was evaluated using single-slice CT imaging at the L3/4 level and quantified as mean muscle attenuation (MMA). Physical function was assessed by the short physical performance battery (SPPB), with low physical function defined as SPPB ≤9. Results: CT-derived single-slice areas of skeletal muscle and adipose tissue were highly correlated with DXA-derived appendicular skeletal muscle mass and total fat mass. Logistic regression analyses revealed that higher age and lower MMA, but not skeletal muscle area, were significantly associated with low physical function independently of NT-proBNP. Subjects with MMA below the median value (32.0 HU for males and 23.7 HU for females) had higher odds of low physical function (adjusted OR 2.04, 95% CI 1.04-3.96). Ten amino acids and the Fischer ratio were significantly correlated with MMA levels. Multivariate regression analyses, adjusted for potential confounders including age, gender, and body mass index, demonstrated that serum albumin and Fischer ratio were independent determinants of MMA levels. When serum albumin and Fischer ratio were dichotomized by their median values (3.6 mg/dL and 3.23, respectively), the prevalence of low physical function was significantly higher in subjects with low albumin and low Fischer ratio, but not in those with low levels of only either parameter, compared to those with high albumin and high Fischer ratio (adjusted OR 2.36, 95% CI 1.02-5.49). Conclusions: Myosteatosis assessed by single-slice abdominal CT imaging is an independent determinant of low physical function in HF patients. Combined with an assessment of serum albumin and Fischer ratio, these simple biomarkers could facilitate the early detection of patients at risk for developing frailty.

Accreditation of in-abattoir Dual Energy X-ray Absorptiometry scanning apparatus to predict lamb carcass composition in Australia

Dual Energy X-ray Absorptiometry (DXA) scanners operating at abattoir processing speeds are currently installed in six sheep meat abattoirs around Australia, predicting carcass composition as estimates of computed tomography (CT) determined fat %, lean %, and bone %. This study tested an updated bone-detection algorithm for these DXA scanners. This algorithm improved the precision of prediction for carcass fat% and lean%, but most notably for bone % (R2 = 0.92, RMSE = 0.61 %), compared to the previous algorithm (R2 = 0.51, RMSE = 1.57 %). This was due to improved allocation of bone-containing pixels, resulting from the inclusion of tissue thickness in the bone-detection equation. In a second experiment, the predictions from this new algorithm, along with an automated phantom calibration technique, were assessed relative to their ability to meet the AUS-MEAT accreditation accuracy standards required for predicting CT determined carcass fat%, lean%, and bone%. The DXA met these standards for predicting fat % (range 10.9 % - 37.1 %), lean % (range 49.0 % - 66.2 %), and bone % (range 11.6 % - 25.0 %), across three weight bands of light carcasses (<22 kg), mid-weight carcasses (22-28 kg), and heavy carcasses (>28 kg). This work allowed for the accreditation of DXA, enabling its predictions of carcass composition to be used for trading sheep carcasses in Australia. The accuracy of these predictions far exceed those provided by the historical industry measure of GR tissue depth, and hot carcass weight.

Fat Distribution and Urolithiasis Risk Parameters in Uric Acid Stone Formers and Patients with Type 2 Diabetes Mellitus.

Key Points Under a controlled diet, uric acid stone formers (UASFs) and diabetic patients have higher endogenous net acid production.Under a controlled diet, UASFs have lower ammonium-to-net acid excretion ratio.Body fat inversely correlates with urine buffer capacity in normal individuals, but this relationship is lost in diabetic patients and UASFs. Background Uric acid (UA) nephrolithiasis affects approximately 10% of kidney stones, with a greater preponderance among patients with obesity and diabetes mellitus (DM). UA lithogenicity is driven by abnormally acidic urine pH. Distinguishing the contribution of intrinsic (e.g., body adiposity) versus external (e.g., dietary) factors to UA stone propensity is challenging because of uncontrolled diets in outpatients in previously published studies. Methods This compilation of metabolic studies with body composition examined by dual-energy x-ray absorptiometry scan and blood and urine biochemistry collected under a controlled metabolic diet was conducted across three distinct populations: 74 UA stone formers (UASF group), 13 patients with type 2 DM without kidney stones (DM group), and 51 healthy volunteers (HV group). Results Compared with HVs, both UASFs and patients with DM exhibited higher levels of net acid excretion (NAE) and significantly lower urine pH and lower proportion of NAE excreted as ammonium (NH4 +/NAE), all under controlled diets. UASFs exhibited significantly lower NH4 +/NAE compared with patients with DM. UASFs also showed higher total body and truncal fat compared with HVs. Among the HVs, lower NH4 +/NAE ratio correlated with higher truncal and total fat. However, this association was abolished in the UASF and DM groups who exhibit a fixed low NH4 +/NAE ratio across a range of body and truncal fat. Conclusions The findings suggest a dual defect of diet-independent increase in acid production and impaired kidney NH4 + excretion as major contributors to the risk of UA stone formation. There is an inverse physiologic association between body fat content and NH4 +/NAE in HVs, whereas NH4 +/NAE is persistently low in UASFs and patients with DM, regardless of body fat, representing pathophysiology.

Restricted Feeding Of Weight Control Diets Induces Weight Loss And Affects Body Composition, Voluntary Physical Activity, Blood Metabolites, Hormones, And Oxidative Stress Markers, And Fecal Metabolites And Microbiota Of Obese Cats.

Feline obesity puts many cats at risk for comorbidities such as hepatic lipidosis, diabetes mellitus, urinary tract diseases, and others. Restricted feeding of specially formulated diets may improve feline health and safely support weight loss while maintaining lean mass. The objective of this study was to determine the effects of restricted intake of weight control diets on weight loss, body composition, voluntary physical activity, serum metabolic and inflammatory markers, and fecal metabolites and microbiota of obese cats. Twenty-four obese adult domestic shorthair cats [body weight (BW) = 5.51 ± 0.92kg; body condition score (BCS) = 8.44 ± 0.53] were used. A leading grocery brand diet was fed during a 4-wk baseline to identify intake needed to maintain BW. After baseline (wk 0), cats were allotted to one of two weight control diets (DRY or CAN) and fed to lose 1.5% BW per wk for 18wk. At baseline and 6, 12, 18wk after weight loss, dual-energy x-ray absorptiometry scans were performed, blood and fecal samples were collected, and voluntary physical activity was measured. Change from baseline data were analyzed statistically using the Mixed Models procedure of SAS, with P<0.05 being significant and P<0.10 being trends. BW was reduced by 1.54 ± 0.51% per wk. Restricted feeding of both diets led to BW (P<0.01) and fat mass loss (P<0.01), reduced BCS (P<0.01), reduced leptin (P<0.01) and insulin (P<0.01) concentrations, and increased superoxide dismutase (P<0.01) and active ghrelin (P<0.01) concentrations. Change from baseline fecal scores were reduced (P<0.01) with restricted feeding and weight loss, while total short-chain fatty acid, acetate, and propionate concentration reductions were greater (P<0.05) in cats fed CAN than those fed DRY. Fecal bacterial alpha diversity measures increased (P<0.01) with restricted feeding and weight loss. Fecal bacterial beta diversity was altered by time in all cats, with wk 0 being different (P<0.05) than wk 6, 12, and 18. Change from baseline relative abundances of 3 fecal bacterial phyla and over 30 fecal bacterial genera were impacted (P<0.05) or tended to be impacted (P<0.10) by dietary treatment. Our data demonstrate that restricted feeding of both weight control diets was an effective means for weight loss in obese adult domestic cats. Some changes were also impacted by diet, highlighting the importance of diet formulation and format, and nutrient composition in weight control diets.

Evaluating the Importance of Practice-Level Factors on Adherence to Prostate Cancer Treatment Guidelines in Urology

ObjectiveTo evaluate adherence to treatment guideline recommendations across the continuum of prostate cancer care by US community urologists using several prostate cancer (PCa) specific performance indicators (PIs). Additionally, to determine which practice-related factors, such as having a designated PCa patient champion, active patient management in a patient portal, and in-office dispensing of medications, were associated with improved PI performance. MethodsElectronic medical record data was collected retrospectively from the PPS Analytics Patient Population Health Management Platform. The cohort consisted of adult patients with a PCa-related service visit during the period 7/1/2019 to 6/30/2022. Five PIs were reviewed: dual-energy x-ray absorptiometry (DEXA) scanning with androgen deprivation therapy (ADT), systemic therapy in metastatic PCa, external beam radiation therapy (EBRT) concurrent with ADT, image monitoring, and regular testosterone testing and monitoring. ResultsA total of 101,186 patients were identified from 95 urology practices. PI adherence rates ranged from a low of 13.6% for a DEXA scan within 6-months of ADT initiation to a high of 72.3% for EBRT concurrent with ADT in intermediate/high risk localized PCa. The results also demonstrated that several practice-related features were associated with better PI adherence. ConclusionsThe findings suggest there exists a wide range in PI adherence rates for urologists in the delivery of community urology care in the Unites States compared to clinical guideline recommendations. Future research should examine the factors associated with PI nonadherence and promote implementation of interventions that enhance guideline concordant care.

In-utero exposure to tenofovir-containing pre-exposure prophylaxis and bone mineral content in HIV-unexposed infants in South Africa.

Tenofovir disoproxil fumarate (TDF) is a common drug of choice for pre-exposure prophylaxis (PrEP) or as a combination HIV treatment for pregnant women. In-utero exposure to TDF was found to be associated with lower bone mineral content (BMC) in HIV-exposed uninfected neonates. Data for infants born to women taking TDF-PrEP are lacking. The CAP016 randomized control trial was conducted in South Africa between September 2017 and August 2021 and pregnant women either initiated TDF/FTC PrEP in pregnancy (Immediate PrEP arm-IP) or at cessation of breastfeeding (Deferred PrEP arm-DP). In a secondary data analysis, we evaluated BMC in HIV-unexposed infants in the CAP016 trial in the first 18 months of life in association with maternal TDF-PrEP use during pregnancy. Infants born to women randomized to the IP arm or DP arm in the CAP016 clinical trial had BMC measurements of the whole body with head (WBH) and lumbar spine (LS) by dual energy X-ray absorptiometry (DXA) at 6, 26, 50 and 74 weeks. Of 481 infants born to women enrolled in the CAP016 clinical trial, 335 (69.6%) infants had a minimum of one DXA scan of the WBH and LS between 6 and 74 weeks of age (168 IP and 167 DP). Women in the IP arm received TDF-FTC PreP for a median of 19 weeks between initiation in pregnancy and delivery. Using a mixed linear regression model and adjusted for gestational age, sex and ever-breastfed, the mean difference (95% CI) for BMC of the WBH between IP and DP arms were -0.74 (-8.69 to 7.20), -1.26 (-10.75 to 8.23), -9.17 (-20.02 to 1.69) and 5.02 (-6.74 to 16.78) g at 6, 26, 50 and 74 weeks (p = 0.283). Mean differences in BMC of the LS were 0.07 (-0.10 to 0.23), 0.02 (-0.18 to 0.22), -0.14 (-0.36 to 0.09) and 0.14 (-0.11 to 0.38) g at 6, 26, 50 and 74 weeks, respectively (p = 0.329). In a randomized controlled trial, there were no differences in BMC of the WBH and LS between infants exposed to in-utero TDF-FTC PrEP and unexposed infants in the first 18 months of life.

Optimized surveillance frequency for low bone mineral density (BMD) screening using dual energy X-ray absorptiometry (DXA) in patients after lung transplant

BackgroundApproximately 2700 lung transplants are performed annually in the United States. These patients are at increased risk of developing low bone mineral density (osteopenia/osteoporosis) and subsequent osteoporosis-related fractures. Dual energy x-ray absorptiometry (DXA) is the most common method used for screening for low BMD, however, the optimal surveillance frequency for low BMD using DXA is unknown. MethodsWe evaluated the change in femoral neck, total femur, L1, L2, L3 and L4 BMD after lung transplant in a retrospective cohort of 259 patients (69.9% male) who were followed with serial DXA scans for a median of 725 (interquartile range (IQR) (361-1116)) days after transplant. Generalized linear mixed effects models allowing for random intercepts and random slopes adjusting for sex, time, time-squared, baseline osteopenia/osteoporosis, active rejection, and their interaction terms were used to model the rate of change of BMD at each site. The final multivariable models for the femoral neck, L1, and L4 BMD measurements had random slopes and intercepts, and the models for the total hip, L2, and L3 measurements had random slopes. Results65% of the patients undergoing lung transplants had osteopenia or osteoporosis before transplant. Men exhibited higher baseline BMD levels compared to women at all sites (P<0.001 for all). After transplant, the greatest rate of BMD decrease was at the femoral neck. Although patients with low BMD (osteopenia/osteoporosis) had significantly lower baseline BMDs (P<0.001 for all), they experienced a slower rate of BMD decrease at all sites compared to patients with normal BMD at baseline (P<0.001 for all). All patients received corticosteroids. 25% of patients had a history of active rejection. Patients with low BMD at baseline had significantly higher odds of receiving bisphosphonate therapy (odds ratio (OR) = 3.95, 95% CI (1.44, 13.51), P=0.003). We estimated that a significant change in the femoral neck BMD would be expected to occur within 409 days (95% CI (131, 708)) and again at 867 days (95% CI (551, 1216)) after lung transplant. ConclusionsOn average, patients undergoing lung transplant should be screened annually with DXA for the first two years after transplant, consistent with the current International Society for Heart and Lung Transplantation (ISHLT) guidelines.

Biometric Changes Up to 2 Years After Hip Arthroscopy in National Collegiate Athletic Association Division I Athletes.

Patients who undergo hip arthroscopy for femoroacetabular impingement (FAI) require lower extremity immobilization for an extended period of time. Periods of immobilization combined with surgery have been associated with decreased muscle mass and bone mineral density (BMD). The purpose of this study was to characterize postoperative body composition and BMD changes after arthroscopy for FAI. It was hypothesized that both lean mass and BMD would decrease postoperatively and then normalize over time. Case series; Level of evidence, 4. This was a retrospective review of 23 National Collegiate Athletic Association Division I athletes who underwent hip arthroscopy between 2017 and 2019 and had a dual-energy x-ray absorptiometry scan preoperatively and at 3, 6, 12, or 24 months postoperatively. Linear mixed-effects models were used to compare pre- with postoperative lean and fat mass values for the total body and total leg (both operative and nonoperative sides) as well as trunk, pelvic, and spinal BMD. For total-leg, femur, and femoral BMD, linear mixed-effects models were used to evaluate the influence of time, side (operative vs nonoperative), and their interaction on each outcome measure. Regarding pelvic BMD, compared with baseline (mean, 1.41 g/cm2 [95% CI, 1.33-1.49]), significant decreases were seen at postoperative 3 months (mean, 1.36 g/cm2 [95% CI, 1.28-1.45 g/cm2]; P < .001) and 6 months (mean, 1.39 g/cm2 [95% CI, 1.27-1.52 g/cm2]; P < .01) but not at 12 months (mean, 1.42 g/cm2 [95% CI, 1.33-1.51 g/cm2]; P = .319). Total-leg BMD for the operative side increased significantly from baseline (mean, 1.52 g/cm2 [95% CI, 1.43-1.61 g/cm2]) to ≥2 years postoperatively (mean, 1.56 g/cm2 [95% CI, 1.47-1.65 g/cm2]) (P = .005). Combined leg fat mass was increased from baseline (mean, 6427 g [95% CI, 4855-7999 g]) to ≥2 years (mean, 11645 g [95% CI, 7845-15,446 g]) (P < .01). There were no significant differences in total-body fat or lean mass or combined-leg lean mass. In this patient population, a postoperative decrease in pelvic BMD that resolved by 12 months and an increase in total-leg BMD on the operative side at ≥2 years were observed. While hip arthroscopy for FAI may have significant benefits for long-term body composition and bone mass, clinicians should be aware of the potential implications of decreased bone mass for up to 12 months postoperatively.

Bone Mineral Density Screening in People With Epilepsy and Intellectual Disability.

Vitamin D measurements and dual energy x-ray absorptiometry (DXA) scans are recommended in people with intellectual disability and/or epilepsy in order to prevent bone-linked harm. The prevalence of vitamin D supplementation and bone mineral density screening were evaluated in 68 people with epilepsy and intellectual disability (EID) and 68 matched controls with epilepsy without intellectual disability. DXA scans were not performed in any of the people with EID but were performed in 11.8% of the people in the control group. People with EID had a higher vitamin D supplementation rate and were treated with more antiepileptic drugs (AEDs) and more AED combinations, including first generation AEDs. Increased awareness of bone health screening in people with epilepsy and especially EID is warranted.

Identification of gut microbiome features associated with host metabolic health in a large population-based cohort

The complex relationship between the gut microbiome and host metabolic health has been an emerging research area. Several recent studies have highlighted the potential effects of the microbiome’s diversity, composition and metabolic production capabilities on Body Mass Index (BMI), liver health, glucose homeostasis and Type-2 Diabetes (T2D). The majority of these studies were constrained by relatively small cohorts, mostly focusing on individuals with metabolic disorders, limiting a comprehensive understanding of the microbiome’s role in metabolic health. Leveraging a large-scale, comprehensive cohort of nearly 9000 individuals, measured using Continuous Glucose Monitoring (CGM), Dual-energy X-ray absorptiometry (DXA) scan and liver Ultrasound (US) we examined the functional profile of the gut microbiome, and its relation to 38 metabolic health measures. We identified 145 unique bacterial pathways significantly correlated with metabolic health measures, with 86.9% of these showing significant associations with more than one metabolic health measure. Furthermore, 87,678 unique bacterial gene families were found to be significantly associated with at least one metabolic health measure. Notably, “key” bacterial pathways such as purine ribonucleosides degradation and anaerobic energy metabolism demonstrated multiple robust associations across various metabolic health measures, highlighting their potential roles in regulating metabolic processes. Our results remained largely unchanged after adjustments for nutritional habits and for BMI they were replicated in a geographically independent cohort. These insights pave the way for future research and potentially the development of microbiome-targeted interventions to enhance metabolic health.

Musculoskeletal Tissue Asymmetries Following Anterior Cruciate Ligament Reconstruction

OBJECTIVE: To compare musculoskeletal tissue asymmetries between those who had undergone ACLR and non-surgical controls, and to evaluate the influence of sex on asymmetries and perceptions of knee function in ACLR patients. DESIGN: Cross-sectional cohort analysis. METHODS: Individuals (female n=11, male n=11) with a history of ACLR and matched controls (female n=10, male n=9) completed Dual-energy X-ray Absorptiometry (DXA) scans to measure lower-body bone mineral content (BMC), Fat%, and lean mass (LM). Perceptions of knee function were captured via the International Knee Documentation Committee (IKDC) instrument and inter-limb asymmetry indices (AI%) were calculated for each DXA outcome. Surgical groups and sexes were compared using independent t-tests ( p&lt;0.05) and Cohen’s effect sizes ( d). Additionally, Pearson’s Correlation Coefficients evaluated the association between AI% and IKDC scores. RESULTS: The ACLR group showed greater lower-body asymmetries, specifically less BMC and LM and greater Fat% in the ACLR limb ( p≤0.044; d=0.63–0.87). ACLR group sex comparisons found that females had lower IKDC scores, greater asymmetries for BMC and LM ( p≤0.027, d=0.40–0.74), and these asymmetries were negatively correlated with IKDC scores (all r≥0.755; p≤0.007) while males demonstrated no such correlations. CONCLUSIONS: Individuals with a history of ACLR had persistent musculoskeletal tissue asymmetries that favored the non-surgical leg. The asymmetries were greater in female versus male patients and were associated with lower perceptions of knee function. Thus, musculoskeletal imaging may provide complementary information to the current standard of care during ACLR rehabilitation.

Examining the Influence of Season Phase, Age, and Anthropometrics on Body Composition Trends in National Basketball Association Athletes.

Russell, JL, Baker, BS, Mercer, RA, and McLean, BD. Examining the influence of season phase, age, and anthropometrics on body composition trends in NBA athletes. J Strength Cond Res XX(X): 000-000, 2024-This study aimed to describe seasonal body composition changes in NBA athletes using Dual-energy X-ray Absorptiometry (DXA) and to explore the relationship between these changes and factors such as age and anthropometrics. A retrospective analysis was conducted using 402 DXA scans from 62 professional male basketball players, obtained from one NBA team between 2012 and 2023. Seasonal phases were defined as preseason, pre all-star, post all-star, and offseason. A custom region of interest (ROI) method was used to ensure consistent scan areas for taller athletes who exceeded the DXA bed length. Linear mixed models analyzed the influence of seasonal phases, age, and height on lean mass (LM), fat mass (FM), and bone mineral content (BMC). In-season phases (pre all-star and post all-star) showed small increases in LM and decreases in FM compared with the preseason, with no significant BMC changes. Chronological age was associated with increases in LM but not FM. Taller athletes exhibited increases in LM, FM, and BMC. Significant random variance across players and seasons indicated that additional unmeasured factors might influence body composition. NBA athletes generally gain LM and lose FM during the season, with older players showing increased LM gain. The study's novel ROI method provide reliable data for athletes exceeding standard DXA limits, highlighting the importance of tailored body composition assessments in professional basketball. These findings can inform strength and conditioning, nutrition, and player development strategies across different seasonal phases and ages.

A 5-year natural history study in LAMA2-related muscular dystrophy and SELENON-related myopathy: the Extended LAST STRONG study

BackgroundSELENON-related myopathy (SELENON-RM) is a rare congenital myopathy characterized by slowly progressive axial muscle weakness, rigidity of the spine, scoliosis, and respiratory insufficiency. Laminin-a2-related muscular dystrophy (LAMA2-MD) has a similar clinical phenotype, which ranges from severe, early-onset congenital muscular dystrophy type 1A (MDC1A) to milder forms presenting as childhood- or adult-onset limb-girdle type muscular dystrophy. The first 1.5-year natural history follow-up showed that 90% of the patients had low bone quality, respiratory impairments were found in all SELENON-RM and most of the LAMA2-MD patients, and many had cardiac risk factors. However, further extensive knowledge on long-term natural history data, and clinical and functional outcome measures is needed to reach trial readiness. Therefore, we extended the natural history study with 3- and 5-year follow-up visits (Extended LAST STRONG).MethodsThe Extended LAST STRONG is a long-term natural history study in Dutch-speaking patients of all ages diagnosed with genetically confirmed SELENON-RM or LAMA2-MD, starting in September 2023. Patients visit our hospital twice over a period of 2 years to complete a 5-year follow up from the initial LAST-STRONG study. At both visits, they undergo standardized neurological examination, hand-held dynamometry (age ≥ 5 years), functional measurements, muscle ultrasound, respiratory assessments (spirometry, maximal inspiratory and expiratory pressure, sniff nasal inspiratory pressure; age ≥ 5 years), Dual-energy X-ray absorptiometry (DEXA-)scan (age ≥ 2 years), X-ray of the left hand (age ≤ 17 years), lower extremity MRI (age ≥ 10 years), accelerometry for 8 days (age ≥ 2 years), and questionnaires (patient report and/or parent proxy; age ≥ 2 years). All examinations are adapted to the patient’s age and functional abilities. Disease progression between all subsequent visits and relationships between outcome measures will be assessed.DiscussionThis study will provide valuable insights into the 5-year natural history of patients with SELENON-RM and LAMA2-MD and contribute to further selecting relevant and sensitive to change clinical and functional outcome measures. Furthermore, this data will help optimize natural history data collection in clinical care and help develop clinical care guidelines.Trial registrationThis study protocol including the patient information and consent forms has been approved by medical ethical reviewing committee (‘METC Oost-Nederland’; https://www.ccmo.nl/metcs/erkende-metcs/metc-oost-nederland, file number: 2023–16401). It is registered at ClinicalTrials.gov (NCT06132750; study registration date: 2023-10-05; study first passed date: 2023-11-15).

AI-Powered Identification of Osteoporosis in Dental Panoramic Radiographs: Addressing Methodological Flaws in Current Research.

Background: Osteoporosis, a systemic skeletal disorder, is expected to affect 60% of women over 50. While dual-energy X-ray absorptiometry (DXA) scans are the current gold standard for diagnosis, they are typically used only after fractures occur, highlighting the need for early detection tools. Initial studies have shown panoramic radiographs (PRs) to be a potential medium, but these have methodological flaws. This study aims to address these shortcomings by developing a robust AI application for accurate osteoporosis identification in PRs. Methods: A total of 348 PRs were used for development, 58 PRs for validation, and 51 PRs for hold-out testing. Initially, the YOLOv8 object detection model was employed to predict the regions of interest. Subsequently, the predicted regions of interest were extracted from the PRs and processed by the EfficientNet classification model. Results: The model for osteoporosis detection on a PR achieved an overall sensitivity of 0.83 and an F1-score of 0.53. The area under the curve (AUC) was 0.76. The lowest detection sensitivity was for the cropped angulus region (0.66), while the highest sensitivity was for the cropped mental foramen region (0.80). Conclusion: This research presents a proof-of-concept algorithm showing the potential of deep learning to identify osteoporosis in dental radiographs. Furthermore, our thorough evaluation of existing algorithms revealed that many optimistic outcomes lack credibility when subjected to rigorous methodological scrutiny.

Can Trabecular Bone Score Enhance Fracture Risk Assessment in Long-Distance Runners With Bone Stress Injuries?

Objective: To evaluate the trabecular bone score (TBS) Z scores in long-distance runners with bone stress injuries (BSIs) in whom the bone mineral density (BMD) Z score is more than −1.0 (Aim 1) and whether the number of runners with abnormal TBS Z scores would be higher in those with BSI in trabecular-rich sites as compared with cortical-rich sites (Aim 2). Design: Retrospective cohort study. Setting: Institutional sports medicine center. Patients: We analyzed Z scores derived from the TBS and BMD in 44 long-distance runners aged 18 to 40 years who had sustained BSIs between 2017 and 2023 and undergone a dual-energy x-ray absorptiometry scan with reported TBS measurements within 1 year before or 2 years after their injuries. Independent Variables: Bone mineral density and TBS Z scores. Main Outcome Measures: Evaluation of BMD and TBS Z scores in long-distance runners with BSIs, further stratified according to cortical-rich and trabecular-rich BSIs. Results: Bone mineral density assessments revealed an average Z score of −0.96 ± 0.99. In this cohort of 44 runners, 55% (n = 24) of runners were reported to have BMD Z score more than −1.0. Within this subgroup, 54% (n = 13) displayed abnormal TBS. Stratifying BSIs by trabecular- (n = 23) and cortical-rich (n = 19) sites, we found no significant difference in sex, mean BMD, or the number of runners with abnormal TBS between the 2 groups. Conclusions: Trabecular bone score Z scores in sports medicine may provide complementary information to BMD in long-distance runners with BSI, particularly when the BMD Z scores are more than −1.0. However, further research is needed to validate the usefulness of TBS Z scores in this context. Study Design: Cohort study. Level of Evidence: Retrospective Case Series, IV.

The impact of minimal sunlight exposure on bone health: insights from a cohort study in erythropoietic protoporphyria.

Erythropoietic protoporphyria (EPP) is a rare inherited metabolic disease, causing lifelong painful phototoxic reactions, minimal sunlight exposure, and vitamin D deficiency. Previous studies reported a high osteoporosis prevalence in EPP patients. The objective is to identify those at risk for low bone mineral density (BMD) and assess which factors, including treatment with cholecalciferol and afamelanotide, improve BMD in EPP. A longitudinal ambispective single centre cohort study. Data from patient files and two-time questionnaires from adult patients with EPP who underwent at least one dual-energy X-ray absorptiometry (DEXA) scan between 2012 and 2023 were used. BMD is low in EPP patients, with 82.7% of the139 patients having a Z-score below 0 standard deviation (SD) at baseline. Low BMD classified as osteopenia was found in 39.5%, and osteoporosis in 15.3%. There were 50 osteoporosis-related fractures in 34.2% of patients. Aging (OR 1.08; CI: 1.03-1.12), persistent vitamin D deficiency (OR 1.11; 95% CI: 1.00-1.23) and a low body-mass index(OR 0.91; 95% CI: 0.82-0.99) increased the odds of low BMD. Patients with a vitamin D deficiency (OR 5.51; 95% CI: 1.69-17.92) and no cholecalciferol at baseline (OR 0.22; 95% CI: 0.04-1.34) had the highest odds of improving their BMD. Afamelanotide did not improve BMD. 25-hydroxyvitamin D (25(OH)D) status plays a crucial role in both preventing low BMD and improving BMD. EPP is a natural model for lack of sunlight exposure and vitamin D deficiency, underlining the importance of lifelong adequate vitamin D status for bone health in the general population.

Retrospective analysis of dual-energy x-ray absorptiometry data demonstrates body composition changes with age in dogs and cats.

Use 18 years of dual-energy x-ray absorptiometry (DEXA) scan data to characterize how body composition changes with age in dogs and cats. This was a retrospective observational study using data obtained from DEXA scans performed between 2006 and 2023. A total of 6,973 observations from 1,273 colony-housed dogs ≤ 1 to 16.1 years old and 6,593 observations from 1,096 colony-housed cats ≤ 1 to 16.9 years old were obtained. Animal ages were rounded to the nearest 1/10-year intervals. Means for each interval were calculated and quadratic, cubic, and quartic polynomial models were fit to assess trends over age. Age had an effect on all DEXA measurements. In dogs, lean mass increased early in life before slowing to a peak at age 6.3 and then declined gradually. Fat mass also increased until slowing to a peak at age 9.3 and then decreased. In cats, lean mass increased before slowing to a peak at age 4.5, decreased gradually until age 12.5, and then sharply declined. Fat mass increased until slowing to a peak at age 7.5 and then decreased gradually. This retrospective study provides a baseline for how body composition changes with age. Results suggest that lean mass loss may begin earlier than previously reported in dogs and cats. Sarcopenia and obesity are common conditions in aging pets. Results can be used to improve body composition assessment of patients and investigate the efficacy of nutritional interventions.

8740 Visceral Adipose Tissue Assessment in Patients With Mild Autonomous Cortisol Secretion Using Dual-Energy X-Ray Absorptiometry: A Cross-Sectional Study

Abstract Disclosure: J. Saini: None. C.D. Zhang: None. V. Fell: None. E. Atkinson: None. S. Achenbach: None. I. Bancos: None. Background: Several studies employing computed tomography (CT) scans for body composition measurements have reported lower muscle mass and a higher proportion of visceral fat in patients with mild autonomous cortisol secretion (MACS) compared to referent subjects. While a CT scan assesses visceral adipose tissue (VAT) at a single slice level (L3), no studies have evaluated the overall VAT in patients with MACS using Dual-Energy X-ray absorptiometry (DXA). Objective: To determine the impact of MACS on VAT using DXA scan as compared to referent subjects. Methods: We conducted a single-center cross-sectional study of adults with 75 MACS and 75 referent subjects. MACS was defined as serum cortisol&amp;gt;1.8 mcg/dL after 1 mg dexamethasone suppression test in patients with adrenal adenomas and no features of overt hypercortisolism. Referent subjects were included if they had abdominal imaging and had no adrenal disorders. All the participants underwent a full body DXA scan between 04/2019 and 07/2022. We applied the CoreScan software to estimate the (1) total lean and fat mass (2) visceral fat mass and volume (3) lean android, fat android, and android mass, and compared measurements of patients and referent subjects using linear regression models adjusted for sex and BMI. Results: A total of 75 patients with MACS (median age 57.0 years, IQR 47.8-65.6, 67% women) and 75 referent subjects (median age 57.6 years, IQR 49.1-65.8, 67% women) were included. Patients had a higher BMI compared to referent subjects (median 31.7 kg/m2, IQR 27.4-37.9 vs 28.7, IQR, 25.4-33.8, P=0.004). The median post-DST cortisol in patients was 3.1 mcg/dL (IQR, 2.2-5.2). When compared to referent subjects, and after adjustment for sex and BMI, patients had a similar total body fat (estimate=846, p-value=0.28) and lean mass (estimate=-201, p-value=0.83), similar android fat mass (estimate=59, p-value=0.64) but lower gynoid fat mass (estimate=400, 0.007). Notably, sex and BMI-adjusted analysis also showed that patients had a higher VAT fat mass (estimate= -225, p-value=0.084) and a higher VAT fat mass/total mass ratio (estimate= -0.007, p-value=0.026). Conclusions: When adjusted for BMI and sex, patients with MACS do not demonstrate differences in overall fat and lean mass. However, we showed that MACS is associated with increased visceral adiposity, a known cardiovascular risk factor. Body composition assessment by DXA could be a safer and less expensive alternative in the evaluation and follow-up of patients with MACS. Presentation: 6/2/2024

12460 Bilateral Parietal Thinning: A Rare Condition Of Unclear Etiology

Abstract Disclosure: T.L. Madsen-Barbosa: None. M. Cheikh: None. I. Marcano: None. Background: Bilateral parietal bone thinning (BPT) is an infrequent and often underdiagnosed condition characterized by the external thinning of the skull's parietal bone. The pathophysiology is unclear, but some studies suggest a link to osteoporosis. We present a case of osteoporosis diagnosed on evaluation of BPT. Case Description: A 77-year-old woman with a history of chronic kidney disease (CKD stage IV) and type 2 diabetes was referred to the Bone Health Clinic for evaluation of low bone density. She initially presented to Neurosurgery clinic for evaluation of head indentations. A dual energy x-ray absorptiometry (DEXA) scan showed values in osteopenia range (left total hip bone mineral density (BMD) 0.678 and T-score of -2.2, left femoral neck BMD 0.272 and T-score of -1.6, and left 33% radius BMD 0.577 and T-score of -2.0), leading to the referral. The patient reported painless indentations in the parietal bones that had been progressing for four years, with no history of head trauma, inflammatory disease, or prolonged steroid use. A head computed tomography (CT) scan showed symmetric thinning of the skull’s parietal bones, with an average thickness of 2.34 mm (compared to 5.1 mm four years earlier). Review of prior images also revealed a T11 compression fracture on spine X-ray from 2019. Laboratory tests showed elevated parathyroid hormone (PTH) 155 pg/mL (reference range 15-65 pg/mL), low vitamin D 25-OH 10.6 ng/mL (reference range 30-100 ng/mL), elevated alkaline phosphatase 142 units/L (reference range 46-116 units/L), and high creatinine level 2.7 mg/dL (reference range 0.5-0.8 mg/dL), other laboratory tests were normal. After discussion with the patient and Nephrology, Denosumab therapy along with Calcium and Vitamin D supplementation were started in November 2023. The patient continues the treatment with antiresorptive medication every 6 months and head CT scan to monitor the skull thinning changes. Discussion: BPT is rare, with only approximately 150 cases reported. Crucial aspects such as its etiology, pathophysiology, treatment, and prognosis remain unknown. It can result from various conditions like trauma, systemic mastocytosis, diabetes mellitus, hereditary diseases, or idiopathic causes and mainly affects women of advanced age. Osteoporosis is suggested as a possible cause based on histological findings on prior studies that propose BPT may result from osteoporosis-induced decreased bone formation rather than increased bone destruction. The reason for excessive bone resorption in the skull of osteoporotic patients remains unclear. Our case highlights progressive and symmetric BPT possibly related to systemic conditions like osteoporosis, with a focus on treatment options. Conclusion: This case sheds light on the clinical presentation, imaging findings, pathogenesis, and treatment options for the rare condition of bilateral parietal bone thinning. Presentation: 6/3/2024