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Cortical and trabecular volumetric bone mineral density (vBMD), cortical thickness and surface BMD (sBMD, density-to-thickness ratio) were analyzed in the proximal femur of elite female football players and artistic swimmers using three-dimensional dual-energy X-ray absorptiometry (3D-DXA) software and compared to sedentary controls. Football players had significantly higher (p

Summary In postmenopausal osteoporotic women in ACTIVE, abaloparatide reduced fracture risk and increased areal bone mineral density (BMD) more than teriparatide at the hip and wrist. DXA-based 3D modeling showed significantly greater increases in hip cortical volumetric BMD with abaloparatide versus teriparatide. This may explain differences reported in aBMD by DXA. Introduction In ACTIVE, abaloparatide (ABL) increased bone mineral density (BMD) shown by dual-energy X-ray absorptiometry (DXA) while reducing fracture incidence in postmenopausal osteoporotic women. Changes in DXA BMD with ABL, 80 μg, were significantly greater than with open-label teriparatide (TPTD), 20 μg, at cortical sites including total hip, femoral neck, and 1/3 distal radius. The purpose of this study was to better understand the relative effects of ABL and TPTD on cortical and cancellous compartments in the proximal femur. Methods Hip DXA images from a subset of randomly selected patients in the ACTIVE trial (n = 250/arm) were retrospectively analyzed using three-dimensional modeling methods (3D-SHAPER software) to evaluate changes from baseline at months 6 and 18. Results Similar significant increases in trabecular volumetric BMD (vBMD, + 9%) and cortical thickness (+ 1.5%) were observed with ABL and TPTD by 3D-DXA at 18 months. In contrast, only ABL significantly increased cortical vBMD versus baseline (+ 1.3%), and changes in both cortical vBMD and cortical surface BMD were significantly greater with ABL versus TPTD. In the TPTD group, changes in cortical vBMD were inversely correlated with changes in serum CTX (carboxy-terminal telopeptide of type I collagen) and PINP (procollagen type I N-terminal propeptide), suggesting that higher bone turnover may have attenuated cortical gains. Conclusion These results suggest previously reported differences in areal BMD increases between ABL and TPTD may be due to differential effects on cortical vBMD. Further studies are warranted to investigate how these differences affect therapeutic impact on hip strength in postmenopausal women with osteoporosis.

The feasibility and efficacy of home-based, impact exercise are unclear. This pilot impact exercise intervention was feasible and safe, and improved bone health and physical function in postmenopausal women with low bone density. Appropriately designed randomised controlled trials are now required to determine whether such interventions can reduce fracture risk. The feasibility and efficacy of impact exercise in postmenopausal women with low bone mineral density (BMD) are unclear. We aimed to determine adherence, safety and changes in BMD, bone microarchitecture and physical function following a pilot home-based, impact exercise intervention in postmenopausal women with low BMD. Fifty community-dwelling postmenopausal women with BMD T-scores < − 1.0 participated in 16 weeks of home-based impact exercise progressively increasing to 50 multi-directional unilateral hops on each leg daily. Bone density and structure were assessed by lumbar spine and hip dual-energy X-ray absorptiometry (DXA), 3D modelling (3D-SHAPER) of hip DXA scans and distal tibial high-resolution peripheral quantitative computed tomography scans. Physical performance was assessed by repeated chair stand time and stair climb time. Forty-four women (mean ± SD age 64.5 ± 7.5 years) completed the intervention, with adherence of 85.3 ± 17.3%. Reasons for withdrawal were related soreness (n = 2), unrelated injury (n = 1) and loss of interest (n = 3). Femoral neck areal BMD increased by 1.13 ± 3.76% (p = 0.048). Trabecular volumetric BMD (vBMD) increased at the total hip (2.27 ± 7.03%; p = 0.038) and femoral neck increased (3.20 ± 5.39%; p < 0.001). Distal tibia total vBMD increased by 0.32 ± 0.88% (p = 0.032) and cortical cross-sectional area increased by 0.55 ± 1.54% (p = 0.034). Chair stand and stair climb time improved by 2.34 ± 1.88 s (p < 0.001) and 0.27 ± 0.49 s (p < 0.001), respectively. A 16-week home-based, impact exercise was feasible and may be effective in improving femoral neck areal BMD, total hip and distal tibial vBMD and physical function in postmenopausal women. Appropriately designed randomised controlled trials are now required to determine whether such interventions can reduce fracture risk in older populations.

Previous subgroup analyses from the ACTIVE trial in women with postmenopausal osteoporosis (NCT01343004) using three-dimensional (3D)-processing of dual X-ray absorptiometry (DXA) scans indicated greater increases in total hip cortical volumetric bone mineral density (Ct.vBMD) and estimated indices of hip strength following 18 months of abaloparatide (ABL) versus placebo or teriparatide. The current post hoc analyses describe hip 3D-DXA data for ACTIVExtend (NCT01657162), in which 18 months of ABL followed by 24 months of alendronate (ABL/ALN) increased hip and spine areal BMD (aBMD) and reduced fracture risk versus placebo (PBO) followed by ALN (PBO/ALN). In an ACTIVExtend subgroup (ABL/ALN

Introduction: In ACTIVE, abaloparatide increased areal BMD (aBMD) of the hip and femoral neck versus teriparatide and placebo in women with osteoporosis. Previously, 3D-processing of dual X-ray absorptiometry (DXA) scans of a subgroup of ACTIVE subjects showed similar increases in trabecular volumetric BMD (Tb.vBMD) and greater increases in cortical vBMD (Ct.vBMD) of the total hip with abaloparatide versus teriparatide. The current analyses from this subgroup describe 2D- and 3D-DXA data for hip subregions. Methods: Randomly-selected subjects from ACTIVE (n=250/treatment group) who received 18 months of placebo, abaloparatide 80 µg, or open-label teriparatide 20 µg by daily subcutaneous injection underwent hip DXA at baseline, and months 6 and 18 of treatment. Areal BMD of the femoral neck, trochanter, and femoral shaft was determined using standard 2D-DXA and 3D-SHAPER software to retrospectively evaluate changes from baseline in volumetric parameters of these three hip subregions, including trabecular and cortical segmentation. Changes in biomechanical parameters cross-sectional moment of inertia (CSMI), section modulus (Z), and buckling ratio were also evaluated. Results: Femoral neck, trochanter, and shaft aBMD increased in the abaloparatide and teriparatide groups at months 6 and 18 versus placebo, with greater increases for abaloparatide versus teriparatide at the femoral neck at month 6 and the shaft at months 6 and 18. All three subregions showed similar significant increases in Tb.vBMD with abaloparatide and teriparatide versus placebo, whereas Ct.vBMD of all three subregions showed greater increases after 18 months of abaloparatide versus teriparatide. Biomechanical parameters improved in all subregions with abaloparatide and teriparatide versus placebo, with greater improvements in CSMI and Z of the femoral neck and lower shaft after 6 and 18 months of abaloparatide versus teriparatide. Conclusion: Differential femoral neck and shaft Ct.vBMD responses may explain the greater increases in CSMI and Z of those subregions with abaloparatide versus teriparatide.

Women have lower areal BMD (g/cm2) than men; however, the women have smaller-size bones. Our study showed that women ≤ 59 years have a hip volumetric BMD by DXA 3D similar to that of men of the same age. This makes us think about the importance of taking into account bone size at the time of analyzing the sex-related differences in bone mass. Women have lower areal BMD (g/cm2) than men; however, these studies do not take into account that women have smaller-size bones. Recently, three-dimensional (3D) modeling methods were proposed to analyze volumetric BMD (vBMD). We want to determine the values of vBMD at the hip by DXA-based 3D modeling in a cohort of people in order to know the age- and sex-related differences. A total of 2647 people of both sexes (65% women) were recruited from a large cohort (Camargo cohort, Santander, Spain). 3D-SHAPER® software (version 2.8, Galgo Medical, Barcelona, Spain) was used to derive 3D analysis from the hip DXA scans at baseline The differences were less pronounced for vBMD (cortical sBMD 9.3%, trabecular vBMD 6.4%, integral vBMD 2.2%) compared to aBMD (FN aBMD 11.4% and TH aBMD 13.3%). After stratifying by age (≤ 59 years, 60–69 years, 70–79 years, and ≥ 80 years), we observed in ≤ 59 years that aBMD was lower in women compared to men, at FN (0.758 [0.114] g/cm2 vs. 0.833 [0.117] g/cm2; p = 1.4 × 10−20) and TH (0.878 [0.117] g/cm2 vs. 0.990 [0.119] g/cm2; p = 4.1 × 10−40). Nevertheless, no statistically significant difference was observed for integral vBMD (331 [58] mg/cm3 in women and 326 [51] mg/cm3 in men; p = 0.19) and trabecular vBMD (190 [41] mg/cm3 in women and 195 [39] mg/cm3 in men; p = 0.20). Our results make us think about the importance of taking into account bone size at the time of analyzing the sex-related differences in bone mass.

Osteoporotic bone fractures reduce quality of life and drastically increase mortality. Minimally irradiating imaging techniques such as dual-energy X-ray absorptiometry (DXA) allow assessment of bone loss through the use of bone mineral density (BMD) as descriptor. Yet, the accuracy of fracture risk predictions remains limited. Recently, DXA-based 3D modelling algorithms were proposed to analyse the geometry and BMD spatial distribution of the proximal femur. This study hypothesizes that such approaches can benefit from finite element (FE)-based biomechanical analyses to improve fracture risk prediction. One hundred and eleven subjects were included in this study and stratified in two groups: (a) 62 fracture cases, and (b) 49 non-fracture controls. Side fall was simulated using a static peak load that depended on patient mass and height. Local mechanical fields were calculated based on relationships between tissue stiffness and BMD. The area under the curve (AUC) of the receiver operating characteristic method evaluated the ability of calculated biomechanical descriptors to discriminate fracture and control cases. The results showed that the major principal stress was better discriminator (AUC > 0.80) than the volumetric BMD (AUC ≤ 0.70). High discrimination capacity was achieved when the analysis was performed by bone type, zone of fracture and gender/sex (AUC of 0.91 for women, trabecular bone and trochanter area), and outcomes suggested that the trabecular bone is critical for fracture discrimination. In conclusion, 3D FE models derived from DXA scans might significantly improve the prediction of hip fracture risk; providing a new insight for clinicians to use FE simulations in clinical practice for osteoporosis management.

The osteoanabolic agent abaloparatide (ABL) has been shown to significantly increase total hip BMD over an 18-month period in postmenopausal women with osteoporosis. However, it remains unknown if these gains predominantly occur in the cortical or trabecular compartments of the proximal femur, and how they may differ from the effects of teriparatide (TPTD). Therefore, a 3D modeling approach was applied to DXA images from patients in the ACTIVE trial to estimate cortical and trabecular changes in the proximal femur over 18 months of treatment with placebo (PBO), ABL, or TPTD. A subset of 750 patients, 250 from each of the treatment groups in ACTIVE (PBO, ABL, TPTD) with non-missing BMD data were randomly selected with data stratified by study site and patient race/ethnicity. Hip DXA scans at baseline and months 6 and 18 were subjected to DXA-based 3D modeling to evaluate volumetric BMD (vBMD) in the cortical and trabecular compartments, as well as cortical thickness and cortical surface BMD (sBMD) (3D-SHAPER v2.10.1, Galgo Medical, Spain). Pairwise group comparisons were made for percentage change from baseline data using P-values derived from contrast tests based on an MMRM model adjusting for BMI, age, value at baseline, and DXA scanner. At 18 months, total hip areal BMD was significantly increased in both the ABL and TPTD groups (P

A case-control study assessing the association of DXA-derived 3D measurements at lumbar spine with osteoporotic hip fractures was performed. Stronger association was found between transcervical hip fractures and integral (AUC = 0.726), and cortical (AUC = 0.696) measurements at the lumbar spine compared with measurements at the trabecular bone (AUC = 0.617); although femur areal bone mineral density (aBMD) remains the referent measurement for hip fracture risk evaluation (AUC = 0.838). The aim of the present study was to evaluate the association between DXA-derived 3D measurements at lumbar spine and osteoporotic hip fractures. We analyzed a case-control database composed by 61 women with transcervical hip fractures and 61 age-matched women without any type of fracture. DXA scans at lumbar spine were acquired, and areal bone mineral density (aBMD) was measured. Integral, trabecular and cortical volumetric BMD (vBMD), cortical thickness, and cortical surface BMD (sBMD) at different regions of interest were assessed using a DXA-based 3D modeling software. Descriptive statistics, tests of difference, odds ratio (OR), and area under the receiver operating curve (AUC) were used to compare hip fracture and control groups. Integral vBMD, cortical vBMD, cortical sBMD, and cortical thickness were the DXA-derived 3D measurements at lumbar spine that showed the stronger association with transcervical hip fractures, with AUCs in the range of 0.685–0.726, against 0.670 for aBMD. The highest AUC (0.726) and OR (2.610) at the lumbar spine were found for integral vBMD at the posterior vertebral elements. Significantly, lower AUC (0.617) and OR (1.607) were found for trabecular vBMD at the vertebral body. Overall, total femur aBMD remains the DXA-derived measurement showing the highest AUC (0.838) and OR (6.240). This study showed the association of DXA-derived measurements at lumbar spine with transcervical hip fractures. A strong association between vBMD at the posterior vertebral elements and transcervical hip fractures was observed, probably because of global deterioration of the cortical bone. Further studies should be carried out to investigate on the relative risk of transcervical fracture in patients with long-term cortical structural deterioration.

Objetivo: Valorar la asociación de las mediciónes tridimensionales (3D) derivadas de la absorciometría de rayos X de energía dual (DXA) lumbar con las fracturas osteoporóticas en las vértebras dorsales. Material y métodos: Analizamos retrospectivamente 32 mujeres postmenopáusicas: 16 con fracturas incidentes en las vértebras dorsales y 16 controles sin ningún tipo de fractura. Las DXA lumbares se adquirieron en la visita inicial (es decir, antes del evento de fractura) y se midió la densidad mineral ósea de área (DMOa) en las vértebras L1 a L4. Las mediciónes 3D derivadas de la DXA se evaluaron utilizando un software de modelado 3D (3DSHAPER). La densidad mineral ósea volumétrica (DMOv) se calculó en el hueso trabecular, cortical e integral. También se midió el grosor cortical y la DMO superficial (DMOs) cortical. Las diferencias en las mediciónes derivadas de la DXA entre los grupos de fracturados y controles se evaluaron utilizando una prueba t de Student no pareada. También se calculó la razón de probabilidades (OR) y el área bajo la curva característica operativa del receptor (AUC). Resultados: En el presente estudio casocontrol ajustado por edad no se encontraron diferencias significativas entre los grupos de fracturados y controles en términos de peso (ρ=0,44), altura (ρ=0,25) y DMOa (ρ=0,11). Sin embargo, sí se encontraron diferencias significativas (ρ

Objetivo: El diagnóstico de osteoporosis se ha fundamentado en la medición de la densidad mineral ósea, si bien esta variable tiene una capacidad limitada en la discriminación de pacientes con o sin fracturas. La aplicación del análisis de elementos finitos (FE) sobre imágenes volumétricas de tomografía computarizada ha mejorado la clasificación de sujetos hasta 90%, aunque la dosis de radiación, complejidad y coste no aconsejan su práctica regular. Nuestro objetivo es aplicar el análisis FE a modelos tridimensionales con absorciometría radiológica dual (3DDXA), para clasificar pacientes con fractura osteoporótica de fémur proximal y sin fractura. Material y métodos: Se selecciónó una cohorte de 111 pacientes con osteoporosis densitométrica: 62 con fractura y 49 sin ella. Se utilizaron modelos FE sujetoespecíficos para el impacto, como la simulación estática de la caída lateral. Las simulaciónes de impacto permiten identificar la región crítica en el 95% de los casos, y la respuesta mecánica a una fuerza lateral máxima. Se realizó un análisis mediante un clasificador discriminativo (Support Vector Machine) por tipo de fractura, tejido y género, utilizando las mediciónes DXA y parámetros biomecánicos. Resultados: Los resultados mostraron una sensibilidad de clasificación del 100%, y una tasa de falsos negativos de 0% para los casos de fractura de cuello para el hueso trabecular en las mujeres. Se identifica la variable tensión principal mayor (MPS) como el mejor parámetro para la clasificación. Conclusión: Los resultados sugieren que el uso de modelos 3DDXA podría ayudar a discriminar mejor a los pacientes con elevado riesgo de fracturarse. Objetive: The diagnosis of osteoporosis has been based on the measurement of bone mineral density, although this variable has a limited capacity in discriminating patients with or without fractures. The application of finite element analysis (FE) on computed tomography volumetric images has improved the classification of subjects by up to 90%, although the radiation dose, complexity, and cost do not favor their regular practice. Our objective is to apply FE analysis to threedimensional models with dualenergy xray absorptiometry (3DDXA), to classify patients who present osteoporotic fracture of the proximal femur and those without fracture. Material and methods: A cohort of 111 patients with densitometric osteoporosis was selected: 62 with fracture and 49 without it. Subjectspecific FE models for impact were used, such as static simulation of lateral fall. Impact simulations allow identifying the critical region in 95% of cases, and the mechanical response to maximum lateral force. An analysis was performed using a discriminative classifier (Support Vector Machine) by fracture type, tissue and gender, using DXA measurements and biomechanical parameters. Results: The results showed a classification sensitivity of 100%, and a false negative rate of 0% for cases of neck fracture for trabecular bone in women. The variable major main stress (MPS) is identified as the best parameter for the classification. Conclusion: The results suggest that using 3DDXA models help in order to better discriminate patients with raised fracture risk. Este estudio ha sido posible gracias al soporte a la investigación que ha supuesto la beca FEIOMM y ayuda financiera del MINECO (RYC-2015-18888).

Structural parameters of the proximal femur evaluate the strength of the bone and its susceptibility to fracture. These parameters are computed from dual-energy X-ray absorptiometry (DXA) or from quantitative computed tomography (QCT). The 3-dimensional (3D)-DXA software solution provides 3D models of the proximal femur shape and bone density from anteroposterior DXA scans. In this paper, we present and evaluate a new approach to compute structural parameters using 3D-DXA software. A cohort of 60 study subjects (60.9 ± 14.7 yr) with DXA and QCT examinations was collected. 3D femoral models obtained by QCT and 3D-DXA software were aligned using rigid registration techniques for comparison purposes. Geometric, cross-sectional, and volumetric structural parameters were computed at the narrow neck, intertrochanteric, and lower shaft regions for both QCT and 3D-DXA models. The accuracy of 3D-DXA structural parameters was evaluated in comparison with QCT. Correlation coefficients (r) between geometric parameters computed by QCT and 3D-DXA software were 0.86 for the femoral neck axis length and 0.71 for the femoral neck shaft angle. Correlation coefficients ranged from 0.86 to 0.96 for the cross-sectional parameters and from 0.84 to 0.97 for the volumetric structural parameters. Our study demonstrated that accurate estimates of structural parameters for the femur can be obtained from 3D-DXA models. This provides clinicians with 3D indexes related to the femoral strength from routine anteroposterior DXA scans, which could potentially improve osteoporosis management and fracture prevention.

Background Most obese women with low-trauma fractures present normal areal bone mineral density (aBMD), suggesting that other bone parameters are more determinant for fracture risk in these patients. Objectives (i) Determine the effects of obesity in young women on areal bone mineral density (aBMD), bone geometry, strength, and volumetric BMD determined by advanced DXA-based methods; (ii) model the profiles of bone parameters for each population with age; and (iii) determine the factors related to body composition (i.e. lean tissue mass and fat mass) potentially implicated in the “bone adaptation” in the femoral region. Subjects and methods Two hundred and twenty adolescent and young women from 18 to 35 years old were enrolled in this study: 128 patients with obesity and 92 age-matched (±6 months) normal-weight controls. aBMD was determined with DXA, whereas hip geometry and strength parameters were assessed by hip structural analysis (HSA) and volumetric BMD by 3D-SHAPER® software. Results Compared with controls, subjects with obesity presented significantly higher aBMD at all bone sites, but the difference was greater at hip compared with lumbar spine or radius. Bone size estimates (i.e. cortical thickness), as well as strength estimates (i.e. cross-sectional area) were higher at all femoral subregions including femoral neck, intertrochanteric region and femoral shaft in young women with obesity. In whole proximal femur and all femoral compartments, vBMD was also higher in subjects with obesity, but the difference between groups was greater for cortical vBMD compared with trabecular vBMD. When hip bone parameters were modelled for each group from individual values, maximal values were reached between 20 and 26 years in both groups but, whatever the age, subjects with obesity presented higher values than controls. In both groups, lean body mass (LBM) was the parameter most positively associated with the greatest number of bone parameters studied. Conclusion Our study confirmed that young women with obesity presented higher aBMD, better hip geometry and greater strength compared with normal-weight controls. Additionally, cortical and trabecular compartments measured by 3D-SHAPER® were favourably and concomitantly modified. However, it remains to be demonstrated whether the evaluation of these new parameters would provide better prediction of fracture risk in this population than aBMD.

We thank the Editor for the opportunity to respond to the Letter to the Editor: “Concerns regarding the use of 3D-DXA” in relation to our recent publication, Harding et al., Bone, 136, 2020, 115,362. The Letter author writes “It is my understanding that it is not possible to measure the cortical parameters from a two-dimensional dual-energy X-ray absorptiometry (DXA) image.” This is correct. Technically, all so-called ‘measures’ from indirect densitometry are estimates, but more to the writer's point, it is typically not possible to parse out cortical from trabecular bone from a standard areal BMD exam. The 3D-DXA modelling software was built from a database of Quantitative Computed Tomographic scans of the proximal femur, to develop a statistical shape and density model; technical details of the modelling algorithm have been published previously.

The 3D distribution of the cortical and trabecular bone mass in the proximal femur is a critical component in determining fracture resistance that is not taken into account in clinical routine Dual-energy X-ray Absorptiometry (DXA) examination. In this paper, a statistical shape and appearance model together with a 3D-2D registration approach are used to model the femoral shape and bone density distribution in 3D from an anteroposterior DXA projection. A model-based algorithm is subsequently used to segment the cortex and build a 3D map of the cortical thickness and density. Measurements characterising the geometry and density distribution were computed for various regions of interest in both cortical and trabecular compartments. Models and measurements provided by the "3D-DXA" software algorithm were evaluated using a database of 157 study subjects, by comparing 3D-DXA analyses (using DXA scanners from three manufacturers) with measurements performed by Quantitative Computed Tomography (QCT). The mean point-to-surface distance between 3D-DXA and QCT femoral shapes was 0.93 mm. The mean absolute error between cortical thickness and density estimates measured by 3D-DXA and QCT was 0.33 mm and 72mg/cm(3). Correlation coefficients (R) between the 3D-DXA and QCT measurements were 0.86, 0.93, and 0.95 for the volumetric bone mineral density at the trabecular, cortical, and integral compartments respectively, and 0.91 for the mean cortical thickness. 3D-DXA provides a detailed analysis of the proximal femur, including a separate assessment of the cortical layer and trabecular macrostructure, which could potentially improve osteoporosis management while maintaining DXA as the standard routine modality.

Health-related quality of life (HRQoL) and physical function deteriorate with age and may adversely impact bone health in older adults. We determined associations of objective measures of physical function and HRQoL with bone health in postmenopausal women with low areal bone mineral density (aBMD). Fifty postmenopausal women (64.4 7.7 years old, mean standard deviation) with low spine, hip or femoral neck aBMD (T- or Z-score &lt, &minus, 1.0) on dual-energy X-ray absorptiometry (DXA) participated. Femoral surface BMD, trabecular, integral and cortical volumetric BMD (vBMD) measurements were obtained using 3D-SHAPER software on DXA. Distal tibial vBMD and microarchitecture were assessed using high-resolution peripheral quantitative computed tomography (HRpQCT). Participants completed self-administered EuroQol-5D (EQ-5D) and modified falls efficacy scale (MFES) questionnaires, and physical function assessments. Stair climb power was positively associated with bone parameters at the hip, femoral neck, and distal tibia (all p &lt, 0.05) in multivariable linear regression. EQ-5D demonstrated no significant associations with bone parameters and MFES was positively associated only with distal tibial cortical vBMD and cortical von Mises stress (both p &lt, 0.05). Objective measures of physical function, particularly muscle power, are more consistently associated with bone parameters compared with self-administered HRQoL questionnaires.

We analyzed volumetric bone mineral density, by 3D analysis, in 76 people with Down syndrome and 76 controls. People with Down syndrome, particularly men, have a lower hip volumetric bone mineral density than the general population. Besides, volumetric bone mineral density declines more rapidly in Down syndrome. People with Down syndrome (DS) have a lower areal bone mineral density (aBMD) estimated by dual-energy X-ray absorptiometry (DXA). However, they have smaller-sized bones, which could influence the measurements. Therefore, our objective was to determine volumetric BMD in these patients. We included 76 outpatients with DS and 76 control healthy volunteers matched for age and sex distribution. Clinical data were obtained with a standardized interview and physical exam, including age, sex, height, weight, and body mass index (BMI). aBMD was measured by dual-energy X-ray at the femoral neck (FN) and total hip (TH). The 3D-SHAPER® software (version 2.8, Galgo Medical, Barcelona, Spain) was used to derive 3D analysis from participants’ hip DXA scans. DS femurs had a similar 3D geometry, compared with the femurs of controls. However, 3D analysis showed that participants with DS had smaller cortical thickness (1.84 mm ± 0.17 vs. 2.02 ± 0.20 mm; p

Associations of current and previous physical activity (PA) with bone health are unclear. In postmenopausal women with low bone mineral density (BMD), current PA was positively associated with femoral neck BMD and microarchitecture. Past PA was positively associated with tibial microarchitecture. PA appears beneficial for bone health throughout the lifespan. To compare associations of current and past self-reported bone-specific physical activity, and current accelerometer-determined physical activity (PA), with bone structure (bone mineral density [BMD] and microarchitecture) in postmenopausal women with osteopenia or osteoporosis. Fifty community-dwelling postmenopausal women (mean age 64.4 ± 7.7) with hip or spine BMD T-score < − 1.0 SD were recruited for an exercise intervention. At baseline, current, past and total Bone-specific Physical Questionnaire (BPAQ) scores were self-reported, and percentages of sedentary, light and moderate to vigorous PA (MVPA) were objectively determined by accelerometer measurements. Bone structure was assessed by lumbar spine and hip dual-energy X-ray absorptiometry (DXA), 3D modelling algorithms (3D-SHAPER) of hip DXA scans and distal tibial high-resolution peripheral quantitative computed tomography (HR-pQCT) scans. Current BPAQ scores and MVPA were significantly positively associated with femoral neck areal BMD (β = 0.315, p = 0.031 and β = 0.311, p = 0.042, respectively) following multivariable adjustments. MVPA was also positively associated with femoral cortical surface BMD (β = 0.333, p = 0.028) and mean cortical thickness (β = 0.374, p = 0.013). Past and total BPAQ scores demonstrated positive associations with tibial trabecular number (β = 0.391, p = 0.008 and β = 0.381, p = 0.010, respectively), and negative associations with trabecular separation (β = − 0.396, p = 0.006 and β = − 0.380, p = 0.009, respectively) and distribution (β = − 0.411, p = 0.004 and β = − 0.396, p = 0.006, respectively). Current BPAQ score was positively associated with tibial cortical periosteal perimeter (β = 0.278, p = 0.014). BPAQ scores were most consistently associated with tibial bone parameters in older women, with past PA having lasting benefits for trabecular microarchitecture, and current PA positively associated with cortical bone.

Background Scarce evidence exists on the assessment of bone mineral density (BMD) in adult Hypophosphatasia (HPP). Recent studies suggest that dual-energy X-ray absorptiometry (DXA) could not appropriately predict their fracture risk and note the importance on further explore bone microstructure. Objectives To evaluate BMD at the lumbar spine (LS) and proximal femur (PF) assessed by DXA, the trabecular bone score (TBS) at the LS and the fracture risk assessment (FRAX and adjusted by TBS, T-FRAX) in patients with persistent low alkaline phosphatase levels (ALP) and HPP genetically confirmed (HPP TG +) compared with a group of subjects with the same biochemical abnormality and a negative HPP genetic test (HPP TG-). As a secondary objective, to assess the cortical and trabecular bone at the PF using DXA-based 3D modeling. Methods Seventy-three subjects with persistent low ALP levels - at least two values 45 IU/L - and a genetic test for HPP performed were included. Individuals were distributed into 2 groups according to their genetic status. BMD was measured using GE-LUNAR iDXA and TBS. The 3D-SHAPER software was employed in a subgroup of 52 subjects matched by age, gender and body mass index. A clinical questionnaire and a battery of lab measures to assess risk factors for Osteoporosis were also performed. Results Demographic, densitometric, TBS and 3D-DXA parameters are shown in table 1. Of the 73 subjects included, 38 (52%) had pathogenic mutations in ALPL. Between postmenopausal women and men above 50 years, 9 subjects (29%) with ALPL mutations had osteopenia and 4 (13%), osteoporosis whereas 4 (13%) and 2 (6,5%) were detected in the HPP-GT group, respectively (p>0,05). Between premenopausal women and men under age 50, only 2 (5%) showed low BMD (Z-score Conclusion HPP + GT group showed less BMD at femoral neck and wards area and this trend was also observed at the diaphysis. At the femur, vBMD was also lower in this group. No differences in BMD at the lumbar spine and in TBS were found. These findings and its value for predicting the risk of fractures, specially in atypical femoral fractures, must be elucidated. Disclosure of Interests: Carolina Tornero: None declared, Monica Coronado: None declared, Ludovic Humbert: None declared, Sara Garcia-Carazo: None declared, Carmen Lancha: None declared, Domenico Monachello: None declared, Luis Dominguez-Gadea: None declared, Alejandro Balsa Grant/research support from: Abbvie, Pfizer, Novartis, BMS, Nordic, Sanofi, Consultant for: Abbvie, Pfizer, Novartis, BMS, Nordic, Sanofi, Sandoz, Lilly, Paid instructor for: Pfizer, Speakers bureau: Pfizer, Novartis, UCB, Nordic, Sanofi, Sandoz, Lilly, Pilar Aguado: None declared

Purpose: Cortical thickness and density are critical components in determining the strength of bony structures. Computed tomography(CT) is one possible modality for analyzing the cortex in 3D. In this paper, a model-based approach for measuring the cortical bone thickness and density from clinical CTimages is proposed. Methods: Density variations across the cortex were modeled as a function of the cortical thickness and density, location of the cortex, density of surrounding tissues, and imaging blur. High resolution micro-CT data of cadaver proximal femurs were analyzed to determine a relationship between cortical thickness and density. This thickness-density relationship was used as prior information to be incorporated in the model to obtain accurate measurements of cortical thickness and density from clinical CT volumes. The method was validated using micro-CT scans of 23 cadaver proximal femurs. Simulated clinical CTimages with different voxel sizes were generated from the micro-CT data. Cortical thickness and density were estimated from the simulated images using the proposed method and compared with measurements obtained using the micro-CT images to evaluate the effect of voxel size on the accuracy of the method. Then, 19 of the 23 specimens were imaged using a clinical CT scanner. Cortical thickness and density were estimated from the clinical CTimages using the proposed method and compared with the micro-CT measurements. Finally, a case-control study including 20 patients with osteoporosis and 20 age-matched controls with normal bone density was performed to evaluate the proposed method in a clinical context. Results: Cortical thickness (density) estimation errors were 0.07 ± 0.19 mm (−18 ± 92 mg/cm3) using the simulated clinical CT volumes with the smallest voxel size (0.33 × 0.33 × 0.5 mm3), and 0.10 ± 0.24 mm (−10 ± 115 mg/cm3) using the volumes with the largest voxel size (1.0 × 1.0 × 3.0 mm3). A trend for the cortical thickness and density estimation errors to increase with voxel size was observed and was more pronounced for thin cortices. Using clinical CT data for 19 of the 23 samples, mean errors of 0.18 ± 0.24 mm for the cortical thickness and 15 ± 106 mg/cm3 for the density were found. The case-control study showed that osteoporotic patients had a thinner cortex and a lower cortical density, with average differences of −0.8 mm and −58.6 mg/cm3 at the proximal femur in comparison with age-matched controls (p-value < 0.001). Conclusions: This method might be a promising approach for the quantification of cortical bone thickness and density using clinical routine imaging techniques. Future work will concentrate on investigating how this approach can improve the estimation of mechanical strength of bony structures, the prevention of fracture, and the management of osteoporosis.

Methods using statistical shape and appearance models have been proposed to analyze bone mineral density (BMD) in 3D from dual energy X-ray absorptiometry (DXA) scans. This paper presents a retrospective case-control study assessing the association of DXA-derived 3D measurements with osteoporotic hip fracture in postmenopausal women. Patients who experienced a hip fracture between 1 and 6 years from baseline and age-matched controls were included in this study. The 3D-SHAPER software (version 2.7, Galgo Medical, Barcelona, Spain) was used to derive 3D analysis from hip DXA scans at baseline. DXA and 3D measurements were compared between groups. Total hip areal BMD of hip fracture group as measured by DXA was 10.7% lower compared to control group. Differences in volumetric BMD (total hip) as measured by 3D-SHAPER were more pronounced in the trabecular compartment (-23.3%) than in the cortex (-8.2%). The area under the receiver operating curve was 0.742 for trabecular volumetric BMD, 0.706 for cortical volumetric BMD, and 0.712 for total hip areal BMD. Differences in the cortex were locally more pronounced at the medial aspect of the shaft, the lateral aspect of the greater trochanter, and the superolateral aspect of the neck. Marked differences in volumetric BMD were observed in the greater trochanter. This case-control study showed the association of DXA-derived 3D measurements with hip fracture. Analysis of large cohorts will be performed in future work to determine if DXA-derived 3D measurements could improve fracture risk prediction in clinical practice.

A retrospective case-control study assessing the association of DXA-derived 3D measurements with osteoporosis-related vertebral fractures was performed. Trabecular volumetric bone mineral density was the measurement that best discriminates between fracture and control groups. The aim of the present study was to evaluate the association of DXA-derived 3D measurements at the lumbar spine with osteoporosis-related vertebral fractures. We retrospectively analyzed a database of 74 postmenopausal women: 37 subjects with incident vertebral fractures and 37 age-matched controls without any type of fracture. DXA scans at the lumbar spine were acquired at baseline (i.e., before the fracture event for subjects in the fracture group), and areal bone mineral density (aBMD) was measured. DXA-derived 3D measurements, such as volumetric BMD (vBMD), were assessed using a DXA-based 3D modeling software (3D-SHAPER). vBMD was computed at the trabecular, cortical, and integral bone. Cortical thickness and cortical surface BMD were also measured. Differences in DXA-derived measurements between fracture and control groups were evaluated using unpaired t test. Odds ratio (OR) and area under the receiver operating curve (AUC) were also computed. Subgroup analyses according to fractured vertebra were performed. aBMD of fracture group was 9.3% lower compared with control group (p

The medical image analysis field has traditionally been focused on the development of organ-, and disease-specific methods. Recently, the interest in the development of more 20 comprehensive computational anatomical models has grown, leading to the creation of multi-organ models. Multi-organ approaches, unlike traditional organ-specific strategies, incorporate inter-organ relations into the model, thus leading to a more accurate representation of the complex human anatomy. Inter-organ relations are not only spatial, but also functional and physiological. Over the years, the strategies 25 proposed to efficiently model multi-organ structures have evolved from the simple global modeling, to more sophisticated approaches such as sequential, hierarchical, or machine learning-based models. In this paper, we present a review of the state of the art on multi-organ analysis and associated computation anatomy methodology. The manuscript follows a methodology-based classification of the different techniques 30 available for the analysis of multi-organs and multi-anatomical structures, from techniques using point distribution models to the most recent deep learning-based approaches. With more than 300 papers included in this review, we reflect on the trends and challenges of the field of computational anatomy, the particularities of each anatomical region, and the potential of multi-organ analysis to increase the impact of 35 medical imaging applications on the future of healthcare., Paper under review

Dual Energy X-ray Absorptiometry (DXA) is the standard exam for osteoporosis diagnosis and fracture risk evaluation at the spine. However, numerous patients with bone fragility are not diagnosed as such. In fact, standard analysis of DXA images does not differentiate between trabecular and cortical bone; neither specifically assess of the bone density in the vertebral body, which is where most of the osteoporotic fractures occur. Quantitative computed tomography (QCT) is an alternative technique that overcomes limitations of DXA-based diagnosis. However, due to the high cost and radiation dose, QCT is not used for osteoporosis management. We propose a method that provides a 3-D subject-specific shape and density estimation of the lumbar spine from a single anteroposterior (AP) DXA image. A 3-D statistical shape and density model is built, using a training set of QCT scans, and registered onto the AP DXA image so that its projection matches it. Cortical and trabecular bone compartments are segmented using a model-based algorithm. Clinical measurements are performed at different bone compartments. Accuracy was evaluated by comparing DXA-derived to QCT-derived 3-D measurements for a validation set of 180 subjects. The shape accuracy was 1.51 mm at the total vertebra and 0.66 mm at the vertebral body. Correlation coefficients between DXA and QCT-derived measurements ranged from 0.81 to 0.97. The method proposed offers an insightful 3-D analysis of the lumbar spine, which could potentially improve osteoporosis and fracture risk assessment in patients who had an AP DXA scan of the lumbar spine without any additional examination.

Given the lack of relevant data, the aim of this study was to examine femur cortical and trabecular bone in female and male professional ballet dancers. 40 professional ballet dancers and 40 sex- and age-matched non-exercising controls volunteered. Femoral bone density was scanned by dual-energy X-ray absorptiometry (DXA) scan. A 3D-DXA software was used to analyse trabecular and cortical bone. Anthropometry, maturation (Tanner staging), menstrual parameters (age at menarche and primary amenorrhea), energy availability and nutritional analysis (3-day record) were also assessed.Compared to non-exercising participants, dancers exhibited significantly higher volumetric density for integral, cortical and trabecular bone, and thicker cortex at the femur. Ballet dancers demonstrated lower body weight compared to controls (p 0.01). Female dancers had their menarche later than controls, and the prevalence of primary amenorrhea were significantly higher in dancers than controls (p 0.01). Dancer's energy availability was below the normal range (30 kcal/kgFFM/day). Despite the presence of certain osteoporosis risk factors such as low energy availability, primary amenorrhoea and lower body weight, professional ballet dancers revealed higher bone density for both cortical and trabecular bone compartments compared to controls.

The 3D distribution of the cortical and trabecular bone mass is a critical component in determining the resistance of a bone to fracture that is not assessed in standard dual-energy X-ray absorptiometry (DXA) exams. In this work, we assessed in vivo short-term precision of measurements provided by 3D modeling techniques from DXA scans and trend assessment intervals (TAIs) in postmenopausal women. Subjects included to study precision errors were scanned twice, with repositioning for duplicate hip scans, using either a Lunar iDXA scanner (GE Healthcare, Madison, WI) or a Discovery W scanner (Hologic, Inc., Waltham, MA). Postmenopausal women having baseline and 18-mo follow-up visit were scanned using a Lunar iDXA device to assess TAIs. TAIs indicate what time intervals are required to allow accurate assessment of response to treatment or progression of disease. The 3D-SHAPER software (Galgo Medical, Barcelona, Spain) was used to derive 3D measurements from hip DXA scans. Least significant changes were 10.39 and 8.72 mg/cm3 for integral volumetric bone mineral density (BMD), 9.64 and 9.59 mg/cm3 for trabecular volumetric BMD, and 6.25 and 5.99 mg/cm2 for cortical surface BMD, using the Lunar iDXA and Discovery W scanners, respectively. TAIs in postmenopausal women were 2.9 yr (integral volumetric BMD), 2.6 yr (trabecular volumetric BMD), and 3.5 yr (cortical surface BMD), using the Lunar iDXA scanner. As a comparison, TAIs for areal BMD were 2.8 yr at neck and 2.7 yr at total femur. Least significant changes of measurements provided by 3D modeling techniques from DXA were assessed. TAIs in postmenopausal women were similar to those measured for areal BMD measurements. DXA-derived 3D measurements could potentially provide additional indicators to improve patient monitoring in clinical practices.

Effects of osteoporosis drugs on proximal femur cortical and trabecular bone were studied using dual-energy x-ray absorptiometry (DXA)-based 3D modeling method. Changes observed in this head-to-head study were consistent with those obtained using computed tomography in the literature. The aim of the present study was to assess the effects of osteoporosis drugs on cortical and trabecular bone at the proximal femur using DXA-based 3D modeling. We retrospectively analyzed 155 patients stratified by treatments: naive of treatment (NAIVE), alendronate (AL), denosumab (DMAB), and teriparatide (TPTD). DXA scans were performed at baseline and after treatment, and areal bone mineral density at spine and femur were measured. A software algorithm (3D-SHAPER) was used to derive 3D models from hip DXA scans and compute: trabecular and cortical volumetric BMD (vBMD), cortical thickness (Cth), and cortical surface BMD (cortical sBMD). Changes from baseline were normalized at 24 months and evaluated in terms or percentage. After 24 months, a non-significant decrease was observed for trabecular vBMD, Cortical sBMD, Cth, and cortical vBMD (− 2.3, − 0.8, − 0.3, and − 0.5%) in the NAIVE group. Under AL and DMAB, significant increases were observed in trabecular vBMD (3.8 and 7.3%), cortical vBMD (1.4 and 2.0%), and cortical sBMD (1.5 and 3.6%). An increase in Cth was observed in patients under DMAB (1.8%). Under TPTD, a significant increase in Trabecular vBMD was observed (5.9%) associated with a non-significant increase of Cth (+ 1%) concomitant with a decrease in cortical vBMD (− 1.1%). Results obtained in this head-to-head study are consistent with those obtained using computed tomography in the literature. DXA-based modeling techniques could complement standard DXA examination to monitor treatment effects on trabecular and cortical compartments.

Background Spinal cord injury (SCI) is associated with a marked increase in bone loss and risk of osteoporosis development short-term after injury. 3D-DXA is a new imaging analysis providing volumetric measurements of the cortical and trabecular bone from DXA scans. Objectives The aim of this study was to assess the evolution of 3D femoral shape, trabecular macrostructure and cortical bone from DXA scans in patients with recent SCI followed over 12 months. Methods 16 males with recent SCI ( Results vBMD measured by 3D-DXA significantly decreased at integral, trabecular and cortical compartments at 6 months (-31.1 mg/cm3, -8.8%, p Conclusions 3D-DXA shows the differentiation of the marked bone loss that occurs at both proximal femoral compartments (cortical and trabecular) short-term after SCI. The present data suggest that 3D-DXA could be a useful complementary assessment tool in SCI patients. Disclosure of Interest None declared

High bone mass (HBM), a rare phenotype, can be detected by dual-energy X-ray absorptiometry (DXA) scanning. Measurements with peripheral quantitative computed tomography at the tibia have found increased trabecular bone mineral density and changes in cortical bone density and structure, all of which lead to increased bone strength. However, no studies on cortical and trabecular bone have been performed at the femur. The recently developed 3-dimensional (3D)-DXA software algorithm quantifies the trabecular and cortical volumetric bone mineral density (vBMD) and the anatomical distribution of cortical thickness using routine hip DXA scans. We analyzed the femurs of 15 women with HBM and 15 controls from the Barcelona Osteoporosis (BARCOS) cohort using the 3D-DXA technique. The mean vBMD of proximal femur was 29.7% higher in HBM cases than in controls for the integral bone, 41.3% higher for the trabecular bone, and 7.3% higher for the cortical bone (p < 0.001). No differences in bone size were detected between cases and controls. Patients with HBM had a thicker cortex and higher trabecular and cortical vBMDs, as measured by 3D-DXA at the femur and compared to controls; bone size was similar in both groups. To the best of our knowledge, this is the first description of trabecular and cortical characteristics of the hip in patients with HBM.

Marked trabecular and cortical bone loss was observed at the proximal femur short-term after spinal cord injury (SCI). 3D-DXA provided measurement of vBMD evolution at both femoral compartments and cortical thinning, thereby suggesting that this technique could be useful for bone analysis in these patients. SCI is associated with a marked increase in bone loss and risk of osteoporosis development short-term after injury. 3D-DXA is a new imaging analysis technique providing 3D analysis of the cortical and trabecular bone from DXA scans. The aim of this study was to assess the evolution of trabecular macrostructure and cortical bone using 3D-DXA in patients with recent SCI followed over 12 months. Sixteen males with recent SCI (< 3 months since injury) and without antiosteoporotic treatment were included. Clinical assessment, bone mineral density (BMD) measurements by DXA, and 3D-DXA evaluation at proximal femur (analyzing the integral, trabecular and cortical volumetric BMD [vBMD] and cortical thickness) were performed at baseline and at 6 and 12 months of follow-up. vBMD significantly decreased at integral, trabecular, and cortical compartments at 6 months (- 8.8, - 11.6, and - 2.4%), with a further decrease at 12 months, resulting in an overall decrease of - 16.6, - 21.9, and - 5.0%, respectively. Cortical thickness also decreased at 6 and 12 months (- 8.0 and - 11.4%), with the maximal decrease being observed during the first 6 months. The mean BMD losses by DXA at femoral neck and total femur were - 17.7 and - 21.1%, at 12 months, respectively. Marked trabecular and cortical bone loss was observed at the proximal femur short-term after SCI. 3D-DXA measured vBMD evolution at both femoral compartments and cortical thinning, providing better knowledge of their differential contributory role to bone strength and probably of the effect of therapy in these patients.

Cortical thickness and density are critical components in determining the strength of bony structures. Computed tomography (CT) is one possible modality for analyzing the cortex in 3D. In this paper, a model-based approach for measuring the cortical bone thickness and density from clinical CT images is proposed.Density variations across the cortex were modeled as a function of the cortical thickness and density, location of the cortex, density of surrounding tissues, and imaging blur. High resolution micro-CT data of cadaver proximal femurs were analyzed to determine a relationship between cortical thickness and density. This thickness-density relationship was used as prior information to be incorporated in the model to obtain accurate measurements of cortical thickness and density from clinical CT volumes. The method was validated using micro-CT scans of 23 cadaver proximal femurs. Simulated clinical CT images with different voxel sizes were generated from the micro-CT data. Cortical thickness and density were estimated from the simulated images using the proposed method and compared with measurements obtained using the micro-CT images to evaluate the effect of voxel size on the accuracy of the method. Then, 19 of the 23 specimens were imaged using a clinical CT scanner. Cortical thickness and density were estimated from the clinical CT images using the proposed method and compared with the micro-CT measurements. Finally, a case-control study including 20 patients with osteoporosis and 20 age-matched controls with normal bone density was performed to evaluate the proposed method in a clinical context.Cortical thickness (density) estimation errors were 0.07 ± 0.19 mm (-18 ± 92 mg/cm(3)) using the simulated clinical CT volumes with the smallest voxel size (0.33 × 0.33 × 0.5 mm(3)), and 0.10 ± 0.24 mm (-10 ± 115 mg/cm(3)) using the volumes with the largest voxel size (1.0 × 1.0 × 3.0 mm(3)). A trend for the cortical thickness and density estimation errors to increase with voxel size was observed and was more pronounced for thin cortices. Using clinical CT data for 19 of the 23 samples, mean errors of 0.18 ± 0.24 mm for the cortical thickness and 15 ± 106 mg/cm(3) for the density were found. The case-control study showed that osteoporotic patients had a thinner cortex and a lower cortical density, with average differences of -0.8 mm and -58.6 mg/cm(3) at the proximal femur in comparison with age-matched controls (p-value0.001).This method might be a promising approach for the quantification of cortical bone thickness and density using clinical routine imaging techniques. Future work will concentrate on investigating how this approach can improve the estimation of mechanical strength of bony structures, the prevention of fracture, and the management of osteoporosis.

Although the areal Bone Mineral Density (BMD) measurements from dual-energy X-ray absorptiometry (DXA) are able to discriminate between hip fracture cases and controls, the femoral strength is largely determined by the 3D bone structure. In a previous work a statistical model was presented which parameterizes the 3D shape and BMD distribution of the proximal femur. In this study the parameter values resulting from the registration of the model onto DXA images are evaluated for their hip fracture discrimination ability with respect to regular DXA derived areal BMD measurements. The statistical model was constructed from a large database of QCT scans of females with an average age of 67.8 ± 17.0 years. This model was subsequently registered onto the DXA images of a fracture and control group. The fracture group consisted of 175 female patients with an average age of 66.4 ± 9.9 years who suffered a fracture on the contra lateral femur. The control group consisted of 175 female subjects with an average age of 65.3 ± 10.0 years and no fracture history. The discrimination ability of the resulting model parameter values, as well as the areal BMD measurements extracted from the DXA images were evaluated using a logistic regression analysis. The area under the receiver operating curve (AUC) of the combined model parameters and areal BMD values was 0.840 (95% CI 0.799-0.881), whilst using only the areal BMD values resulted in an AUC of 0.802 (95% CI 0.757-0.848). These results indicate that the discrimination ability of the areal BMD values is improved by supplementing them with the model parameter values, which give a more complete representation of the subject specific shape and internal bone distribution. Thus, the presented method potentially allows for an improved hip fracture risk estimation whilst maintaining DXA as the current standard modality.

Purpose: Dual-energy x-ray absorptiometry (DXA) is used in clinical routine to provide a two-dimensional (2D) analysis of the bone mineral density (BMD). 3D reconstruction methods from 2D DXA images could improve the BMD analysis. To find the optimal configuration that should be used in clinical routine, this paper relies on a 3D reconstruction method from DXA images to compare the accuracy that can be obtained from one single-view and from multiview DXA images (two to four projections). Methods: The 3D reconstruction method uses a statistical model and a nonrigid registration technique to recover in 3D the shape and the BMD distribution of the proximal femur. The accuracy was evaluatedin vivo by comparing 3D reconstructions obtained from simulated DXA images of 30 patients (using between one and four DXA views) with quantitative computed tomographyreconstructions. Results: This comparison showed that the use of one single DXA provides accurate 3D reconstructions (mean shape accuracy of 1.0 mm and BMD distribution errors of 7.0%). Among the multiview configurations, the use of two views (0° and 45°) was the best compromise, increasing the accuracy of pose (mean accuracy of 0.7°/1.2°/0.9° against 1.0°/3.5°/3.3° for the single view), reducing slightly the BMD errors (5.7%) while maintaining the same shape accuracy. Conclusions: The use of two views constitutes an interesting configuration when multiview DXA devices are available in clinical routine. However, the use of only one single view remains an accurate solution to recover the shape and the BMD distribution in 3D, with the advantage of a higher potential for clinical translation.

Study design A three-dimensional analysis of spino-pelvic alignment in 60 asymptomatic young adult males and females. Objectives To analyze the differences in sagittal spino-pelvic alignment in a group of asymptomatic young adult males and females and describe gender specific reference values. Summary of background data Several spinal disorders like idiopathic scoliosis and Scheuermann's disease have a well-known sex-related prevalence ratio. As spino-pelvic alignment plays an important role in spinal biomechanics, it is imperative to analyze possible differences between the male and female spino-pelvic alignment. Furthermore, in spinal fusion surgery, normal sagittal balance should be recreated as closely as possible. Methods An innovative biplanar ultra low-dose radiographic technique was used to obtain three-dimensional reconstructions of the spine (T1-L5), sacrum, and pelvis in a freestanding position of 30 asymptomatic young male and 30 young female adults. Values were calculated for thoracic kyphosis (T4-T12), lumbar lordosis (L1-S1), total and regional lumbopelvic lordosis (PRT12, PRL2, PRL4, and PRL5), sagittal plumb line of T1, T4, and T9 (HAT1, HAT4, and HAT9), T1-L5 sagittal spinal inclination, T9 sagittal offset, and pelvic parameters (pelvic tilt, sacral slope, and pelvic incidence). In addition, vertebral inclination in the sagittal plane of each vertebra was measured. Differences in spino-pelvic alignment between the sexes were analyzed. Results The female spine was more dorsally inclined (11 degrees vs. 8 degrees ; P = 0.003). High thoracic and thoracolumbar vertebrae were more dorsally inclined in women than in men. Thoracic kyphosis, lumbar lordosis, regional lumbopelvic lordosis, sagittal plumb lines, T9 sagittal offset, and pelvic parameters were not statistically different between the sexes. Conclusion These results indicate that the female spine is definitely different from the male spine. The spine as whole and individual vertebrae in certain regions of the normal spine is more backwardly inclined in females than in males. Based on our previous research this signifies that these spinal regions are subjected to different biomechanical loading conditions. These vertebral segments are possibly less rotationally stable in females than in males.

Reconstruction methods from biplanar X-rays provide 3D analysis of spinal deformities for patients in standing position with a low radiation dose. However, such methods require an important reconstruction time and there is a clinical need for fast and accurate techniques. This study proposes and evaluates a novel reconstruction method of the spine from biplanar X-rays. The approach uses parametric models based on longitudinal and transversal inferences. A first reconstruction level, dedicated to routine clinical use, allows to get a fast estimate (reconstruction time: 2 min 30 s) of the 3D reconstruction and accurate clinical measurements. The clinical measurements precision (evaluated on asymptomatic subjects, moderate and severe scolioses) was between 1.2 degrees and 5.6 degrees. For a more accurate 3D reconstruction (complex pathologies or research purposes), a second reconstruction level can be obtained within a reduced reconstruction time (10 min) with a fine adjustment of the 3D models. The mean shape accuracy in comparison with CT-scan was 1.0 mm. The 3D reconstruction method precision was 1.8mm for the vertebrae position and between 2.3 degrees and 3.9 degrees for the orientation. With a reduced reconstruction time, an improved accuracy and precision and a method proposing two reconstruction levels, this approach is efficient for both clinical routine uses and research purposes.

Introduction. The advantages of a patient-specific 3D-model of the Spine for congenital scoliosis have been lately attested by some clinical researches (Peng et al. 2006. Chin J Radiol. 40(3):297–300). Method. This preliminary study was conducted on a patient affected by congenital scoliosis. She benefited from an EOS biplanar X-ray exam. Results. The full spine could be reconstructed including the hemivertebra. The precision of the reconstruction was qualitatively compared to a CT reconstruction and various parameters could be quantified. Conclusions. Providing a clinical validation, the presented method could extend the actual possibilities of today's algorithm to reconstruct congenital 3D-deformations.

Background Polio is a devastating infectious disease that causes paralysis and severe muscular atrophy. When any of the legs is affected, a low aBMD at the corresponding hip is a common finding in DXA measurement. Objectives to study the influence of polio consequences on volumetric bone density and cortical thickness using the 3D-DXA technology. Methods 22 patients of both sexes suffering post-polio syndromes (mean age 57±uffering pos were scanned using a GE iDXA system and both proximal femurs were reconstructed using the 3D-DXA technology. 3D-DXA is based on the registration of a 3D statistical model of the femoral shape and density onto the 2D DXA image and provides measurements of volumetric BMD (vBMD) and BMCof the trabecular and cortical bone as well as a quantification of the cortical thickness. The measurements at the leg affected by polio were compared by t-test with those at the non-affected leg. Results Trabecular BMC was 22% lower (-1.8 g, p 3 , p 3 , p 3 , p Conclusions A long period of decreased of mechanical charges, low muscle strength, postural imbalance has dramatic consequences on bone development. The analyses performed using the 3D-DXA technology indicates an overall impairment of cortical and trabecular BMD and a significant decrease of the cortical thickness. Disclosure of Interest None declared

Dual-energy x-ray absorptiometry (DXA) is used in clinical routine to provide a two-dimensional (2D) analysis of the bone mineral density (BMD). 3D reconstruction methods from 2D DXA images could improve the BMD analysis. To find the optimal configuration that should be used in clinical routine, this paper relies on a 3D reconstruction method from DXA images to compare the accuracy that can be obtained from one single-view and from multiview DXA images (two to four projections).The 3D reconstruction method uses a statistical model and a nonrigid registration technique to recover in 3D the shape and the BMD distribution of the proximal femur. The accuracy was evaluated in vivo by comparing 3D reconstructions obtained from simulated DXA images of 30 patients (using between one and four DXA views) with quantitative computed tomography reconstructions.This comparison showed that the use of one single DXA provides accurate 3D reconstructions (mean shape accuracy of 1.0 mm and BMD distribution errors of 7.0%). Among the multiview configurations, the use of two views (0° and 45°) was the best compromise, increasing the accuracy of pose (mean accuracy of 0.7°/1.2°/0.9° against 1.0°/3.5°/3.3° for the single view), reducing slightly the BMD errors (5.7%) while maintaining the same shape accuracy.The use of two views constitutes an interesting configuration when multiview DXA devices are available in clinical routine. However, the use of only one single view remains an accurate solution to recover the shape and the BMD distribution in 3D, with the advantage of a higher potential for clinical translation.