Soft Tissue Composition Research Articles

Chemical preservation of tail feathers fromAnchiornis huxleyi, a theropod dinosaur from the Tiaojishan Formation (Upper Jurassic, China)

AbstractA panel of geochemical techniques is used here to investigate the taphonomy of fossil feathers preserved in association with the skeleton of the Jurassic theropodAnchiornis huxleyi. Extant feathers were analysed in parallel to test whether the soft tissues morphologically preserved in the fossil also exhibit a high degree of chemical preservation. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) indicate that clays and iron oxide pseudomorphs occur in the surrounding sediment and also reveal the preservation of melanosome‐like microbodies in the fossil. Carbon gradient along a depth profile and co‐occurrence of carbon and sulphur are shown in the fossil by elastic backscattering (EBS) and particle‐induced x‐ray emission (PIXE), which are promising techniques for the elemental analysis of fossil soft tissues. The molecular composition of modern and fossil soft tissues was assessed from micro‐attenuated total reflectance fourier transform infrared spectroscopy (micro‐ATR FTIR), solid‐state13C nuclear magnetic resonance (CP‐MAS13C NMR) and pyrolysis gas chromatography mass spectrometry in the presence of TMAH (TMAH‐Py‐GC‐MS). Results indicate that the proteinaceous material that comprises the modern feathers is not present in the fossil feathers. The fossil feathers and the embedding sediment exhibit a highly aliphatic character. However, substantial differences exist between these samples, revealing that the organic matter of the fossil feathers is, at least partially, derived from original constituents of the feathers. Our results suggest that, despite the morphological preservation ofAnchiornisfeathers, original proteins, that is keratin, were probably not preserved in the 160‐myr‐old feathers.

Chemical signatures of soft tissues distinguish between vertebrates and invertebrates from the Carboniferous Mazon Creek Lagerstätte of Illinois.

The chemical composition of fossil soft tissues is a potentially powerful and yet underutilized tool for elucidating the affinity of problematic fossil organisms. In some cases, it has proven difficult to assign a problematic fossil even to the invertebrates or vertebrates (more generally chordates) based on often incompletely preserved morphology alone, and chemical composition may help to resolve such questions. Here, we use in situ Raman microspectroscopy to investigate the chemistry of a diverse array of invertebrate and vertebrate fossils from the Pennsylvanian Mazon Creek Lagerstätte of Illinois, and we generate a ChemoSpace through principal component analysis (PCA) of the in situ Raman spectra. Invertebrate soft tissues characterized by chitin (polysaccharide) fossilization products and vertebrate soft tissues characterized by protein fossilization products plot in completely separate, non-overlapping regions of the ChemoSpace, demonstrating the utility of certain soft tissue molecular signatures as biomarkers for the original soft tissue composition of fossil organisms. The controversial problematicum Tullimonstrum, known as the Tully Monster, groups with the vertebrates, providing strong evidence of a vertebrate rather than invertebrate affinity.

The impact of sample preparation on the elemental composition of soft tissues assessed by laser ablation ICP-MS

Oven drying and freeze drying may alter the elemental composition of soft tissues subjected to LA-ICP-MS or ICP-MS analysis.

Detailed analysis of dose difference in using water as tissue-equivalent material in 252Cf brachytherapy.

The purpose of this study is to analyse how small variations in the elemental composition of soft tissue lead to differences in dose distributions from a 252Cf brachytherapy source and to determine the error percentage in using water as a tissue-equivalent material. Water is normally used as a tissue-equivalent phantom material in radiotherapy dosimetry. Neutron energy spectra, neutron and gamma-ray dose rate distributions were calculated for a 252Cf AT source located at the center of a spherical phantom filled with various types of tissue compositions: adipose, brain, muscle, International Commission on Radiation Units and Measurements (ICRU) report No. 44 9-component soft tissue and water, using Monte Carlo simulation. The obtained results showed differences between total dose rates in various tissues relative to water varying between zero and 4.94%. The contributions of neutron and total gamma ray doses to these differences are, on average, 81% and 19%, respectively. It was found that the dose differences between various soft tissues and water depend not only on the soft tissue composition, but also on the beam type emitted from the 252Cf source and the distance from the source. Assuming water as a tissue-equivalent material, although leads to overestimation of dose rate (except in the case of adipose tissue), is acceptable and suitable for use in 252Cf brachytherapy treatment planning systems based on the recommendation by the ICRU that the uncertainties in dose delivery in radiotherapy should be lower than 5%.

Secondary particle production and physical properties during dose enhancement for spread-out Bragg peaks

Background: The proton therapy is a form of particle radiation therapy that dose enhancement to improve therapeutic ratio (TR) is obtained by high-Z materials. This study evaluated the physical properties of dose enhancement and the resulting changes in the secondary particle production using the spread-out Bragg peak (SOBP). Methods: Monte Carlo simulations were performed using the Geant4 software and the medical internal radiation dose head phantom. Gold and gadolinium were applied as enhancement materials at concentrations of 10, 20, and 30 mg/g in the tumor volume, and the composition of soft tissue was varied in parallel. The ratio of changes in the reaction caused by the interaction of the initial particles with the enhancement materials was calculated. Results: Among the physical interaction processes, inelastic Coulomb scattering by electrical action occurred with the highest frequency of 99.02%, and elastic collisions, nuclear inelastic collisions, and multiple Coulomb scatterings appeared with low frequencies of 0.633%, 0.334%, and 0.006%, respectively. The use of gold as the enhancement material increased the frequency of interactions by a factor of 1.14–1.18 for inelastic Coulomb scattering, 1.05–1.30 for elastic collision, and 1.03–1.37 for nuclear inelastic collision. Furthermore, the use of gadolinium as the enhancement material increased the frequency of interactions by a factor of 1.08–1.14 for inelastic Coulomb scattering, 1.03–1.25 for elastic collision, and 1.01–1.34 for nuclear inelastic collision. Regarding the dose by the production of secondary particles, the equivalent dose increased by a factor of 1.032–1.070 for alpha particles, 1.133–1.860 for neutrons, and 1.030–1.053 for deuterons when gold was used as the enhancement material. When gadolinium was used as the enhancement material, the equivalent dose increased by a factor of 1.015–1.043 for alpha particles, 1.075–1.478 for neutrons, and 1.021–1.036 for deuterons. Conclusions: Based on this study’s findings, the dose enhancement simulations correspond to the physical characteristics of energy transmission. The study’s results can be used as basic data for in vivo and in vitro experiments investigating the effects of dose enhancement.

Secondary particle production and physical properties during dose enhancement for spread-out Bragg peaks.

BackgroundThe proton therapy is a form of particle radiation therapy that dose enhancement to improve therapeutic ratio (TR) is obtained by high-Z materials. This study evaluated the physical properties of dose enhancement and the resulting changes in the secondary particle production using the spread-out Bragg peak (SOBP).MethodsMonte Carlo simulations were performed using the Geant4 software and the medical internal radiation dose head phantom. Gold and gadolinium were applied as enhancement materials at concentrations of 10, 20, and 30 mg/g in the tumor volume, and the composition of soft tissue was varied in parallel. The ratio of changes in the reaction caused by the interaction of the initial particles with the enhancement materials was calculated.ResultsAmong the physical interaction processes, inelastic Coulomb scattering by electrical action occurred with the highest frequency of 99.02%, and elastic collisions, nuclear inelastic collisions, and multiple Coulomb scatterings appeared with low frequencies of 0.633%, 0.334%, and 0.006%, respectively. The use of gold as the enhancement material increased the frequency of interactions by a factor of 1.14–1.18 for inelastic Coulomb scattering, 1.05–1.30 for elastic collision, and 1.03–1.37 for nuclear inelastic collision. Furthermore, the use of gadolinium as the enhancement material increased the frequency of interactions by a factor of 1.08–1.14 for inelastic Coulomb scattering, 1.03–1.25 for elastic collision, and 1.01–1.34 for nuclear inelastic collision. Regarding the dose by the production of secondary particles, the equivalent dose increased by a factor of 1.032–1.070 for alpha particles, 1.133–1.860 for neutrons, and 1.030–1.053 for deuterons when gold was used as the enhancement material. When gadolinium was used as the enhancement material, the equivalent dose increased by a factor of 1.015–1.043 for alpha particles, 1.075–1.478 for neutrons, and 1.021–1.036 for deuterons.ConclusionsBased on this study’s findings, the dose enhancement simulations correspond to the physical characteristics of energy transmission. The study’s results can be used as basic data for in vivo and in vitro experiments investigating the effects of dose enhancement.

Cross-Sectional Soft-Tissue Composition and the Distribution of Blue Cutaneous Discoloration in the Lower Eyelid after Hyaluronic Acid Injection.

The soft-tissue composition of the eyelid varies from lateral to medial, in that the orbicularis area (in square millimeters) is greatest medially and least laterally, whereas the reverse is true for the preauricularis and postorbicularis fat. The purpose of this study was to describe the relative contribution of tissue types to the volume of the lower eyelid-midface junction. This is an observational cohort study of 11 subjects (20 eyes) without a history of orbital or periorbital surgery or abnormality. Quasi-sagittal surface coil magnetic resonance imaging scans in planes parallel to the long axis of each orbit were obtained during central gaze fixation. Measurements of the tissue area (in square millimeters) of the skin, preorbicularis fat, orbicularis, and postorbicularis fat were obtained in the center, medial, and lateral eyelid regions. Differences in tissue area across the eyelid were assessed. The segmental cross-sectional area and percentage of total segment represented by the orbicularis muscle increased from the lateral (9.4 mm; 21.8 percent) to the central (14.1 mm; 35.0 percent) and to the medial (18.5 mm; 47.0 percent) eyelid (p < 0.01). The inverse pattern was noted for both preorbicularis and postorbicularis fat, each occupying less area (in square millimeters) from lateral to medial (p < 0.01). Skin thickness did not vary significantly across the eyelid. The soft-tissue composition of the eyelid varies from lateral to medial in that the orbicularis increases in area, whereas the reverse is true for the preorbicularis and postorbicularis fat. This anatomical progression may help to explain the stereotypical location of blue discoloration in some patients after hyaluronic acid filler injection.

The effect of excessive fat tissue on the measure of bone mineral density by dual X-ray absorptiometry: the impact of substantial weight loss following sleeve gastrectomy.

Dual-energy X-ray absorptiometry (DXA) is used in clinical routine to determine areal bone mineral density (aBMD). However, it is not clear whether excessive fat mass or substantial weight loss modify the aBMD measurements. The aim of this study was to evaluate the effect of soft tissue composition on aBMD measured by DXA using a clinical model (i.e. sleeve gastrectomy: SG) that induces substantial body weight loss. Areal bone mineral density and body composition (fat mass: FM and lean tissue mass: LTM) were determined by DXA in 41 obese patients (33 women, 80.5%) just before SG and 1month later. One month after SG, mean weight loss was -9.8±2.6kg, with a significant decrease in LTM and FM (kg) ranging from -7.3% to -9.5%. The relative variation in aBMD was increased at the lumbar spine (2.45±3.44%) and decreased at the hip (-1.47±2.28%), whereas no variation was observed for the whole body and radius. The variation in aBMD at the lumbar spine was inversely correlated with variations in weight, whole-body FM and trunk FM, but not LTM. This study shows evidence of a potential effect of body composition, particularly FM, on aBMD. However, given the modest change in aBMD, which was close to the precision error of aBMD measurements, it appears that significant weight loss does not have a clinically significant impact on the evaluation of aBMD using DXA.

Arachidonic acid status negatively associates with forearm bone outcomes and glucose homeostasis in children with an overweight condition or obesity.

Long-chain polyunsaturated fatty acids are implicated in musculoskeletal health in adults. This study examined whether fatty acid status relates to bone health outcomes in children with overweight condition or obesity (body mass index z score, 3.1 ± 0.1; age, 9.0 ± 0.2 years; n = 108). Nondominant forearm bone density (distal one-third), geometry (4% site), and soft tissue composition (66%) were assessed using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Red blood cell (RBC) fatty acid profile and indices of glucose homeostasis were measured. Differences in outcomes among RBC arachidonic acid (AA, C20:4n-6) tertiles were tested using mixed-model ANOVA. Ultra-, mid-, and total-distal forearm bone mineral content, adjusted for sex, age, percentage body fat, race, and forearm length, were 10% to 13% greater in children in the first AA tertile relative to the third. Children in the second tertile had the highest bone cross-sectional area and estimated strength at the 66% radius. Muscle cross-sectional area was 15% lower in the third tertile compared with the first, along with higher fasting insulin concentrations (27%) and homeostasis model of assessment estimate of insulin resistance (31%). Higher RBC AA status aligns with deficits in forearm bone mass, geometry, and muscle mass in children with excess adiposity and early signs of insulin resistance. Novelty Higher arachidonic acid status is associated with lower forearm bone mass in children with overweight condition or obesity. Children with higher arachidonic acid status had increased fasting insulin concentrations and indices of insulin resistance.

Lake Characteristics, Population Properties and Invasion History Determine Impact of Invasive Bivalves on Lake Nutrient Dynamics

Invasive species can have large impacts on ecosystems, including the cycling and distribution of nutrients. To determine the whole-ecosystem effects of invasive zebra mussels on lake nutrient dynamics, we sampled 10 invaded Minnesota lakes spanning a broad trophic status gradient. We conducted N and P excretion and biodeposition rate measurements and determined the C, N and P composition of dreissenid soft tissues and shell material in the study lakes. We also estimated the whole-lake biomass of live dreissenid mussels and their dead shell material, constructing comprehensive nutrient budgets for dreissenid populations in the study lakes. We used the results of our measurements and published data to estimate the contribution of dreissenids to P budgets in 24 additional lakes in Europe and North America. Results show that nutrient cycling rates and composition of soft tissues and shells vary with mussel size and lake trophic status. Zebra mussels made variable, but often large, contributions to cycling and storage of water column standing stocks of POC, PON and TP in the study and literature lakes. In some lakes, the effects of zebra mussels on P dynamics were also considerable in the context of estimated P external and internal loading, sediment sequestration and effects of other biota. We show that the impact of zebra mussels on whole-lake nutrient budgets depends on lake properties, dreissenid population characteristics and invasion history. This information can be used by ecosystem managers to prioritize invasion prevention efforts toward lakes likely to be most strongly impacted by zebra mussel invasions.

Feasibility of Dixon magnetic resonance imaging to quantify effects of physical training on muscle composition—A pilot study in young and healthy men

Changes in muscle-fat-composition affect physical performance and muscular function, like strength and power. The purpose of the present study was to investigate whether changes in soft tissue composition of the thigh and changes in muscle size and composition resulting from physical training were detectable with Dixon magnetic resonance imaging (MRI).A young and healthy subject population (n = 21, 29 ± 5 years) was split into a strength training (G_t, 11 subjects) and a control group (G_c, 10 subjects). The physical training intervention lasted over 13 weeks. Before and after this intervention a muscle performance exam and an MRI exam were conducted on all subjects. To evaluate muscle performance and the training effect, the jump height was measured using a mechanograph. Fascia, pure muscle and subcutaneous fat areas and proton density water fraction (PDWF) and proton density fat fraction (PDFF) of the left thigh were measured with a 6-point Dixon prototype MRI sequence.Muscle area changed by +7.1 ± 3.3% (p < 0.05) and +2.5 ± 5.6% (p > 0.05), and PDFF by -16.3 ± 10.4% (p < 0.05) and +5.4 ± 6.9% (p > 0.05) in G_t and G_c, respectively. Cross-sectional and longitudinal correlation coefficients R between PDFF and muscle performance were moderate (R = -0.43 and R = -0.51, respectively). The correlation was also moderate for muscle performance and a combined muscle fat per area ratio (R = -0.40 and R = -0.55, respectively).Dixon MRI is capable to measure training-related changes in muscle area and muscular fat. Both parameters correlate to muscle function. Muscle area per se does not always mirror functional parameters. Due to the complex interaction of muscle volume, muscle structure, and inter- and intramuscular coordination during muscle performance, multivariate muscle parameter models should be investigated in the future. Future studies will have to show if structural parameters mirror and explain functional muscle data both in the context of physical training and pathologies like sarcopenia.

Body composition and disability in people with multiple sclerosis: A dual-energy x-ray absorptiometry study

IntroductionBody composition refers to the relative distribution of different tissue types within the body, including fat, lean, and bone tissues. There is evidence for associations between body composition and the development of multiple sclerosis (MS). The relationship between body composition and disease progression and disability accumulation, however, is unclear. ObjectivesTo examine: a) differences in overall and regional body composition by disability status in persons with multiple sclerosis (MS); and b) the relationship between body composition and other outcomes reflecting impairments and limitations due to MS. MethodsCross-sectional investigation of 47 ambulatory persons with relapsing remitting MS who were grouped by Expanded Disability Status Scale (EDSS) scores as having mild (1.0–4.0; n = 26) or moderate (4.5–6.5; n = 21) disability. Main outcome measures were whole-body and regional soft tissue composition (%body fat (BF), fat mass (FM), and fat-free soft tissue mass (FFM)), bone mineral content (BMC), and bone mineral density (BMD) determined from dual-energy X-ray absorptiometry (DXA). Other outcomes included physical fitness, mobility, cognitive processing speed, symptoms, and health-related quality of life (HRQOL). ResultsWhole-body and regional %BF and FM were significantly higher, and whole-body and appendicular BMC and BMD were significantly lower in participants with moderate disability than those with mild disability (all p < .05). There were no significant differences in whole-body or regional FFM by disability status. In the overall sample, body fat correlated significantly with cardiorespiratory fitness (prs = −.52 to −.56), pain symptoms (prs = .32), and psychological HRQOL (prs = .34). FFM (prs = .38–.48) and BMC (prs = .53–.69) correlated primarily with measures of muscular strength. ConclusionsPersons with MS who have greater disability present with higher body fat and lower bone tissue content and density than those with mild disability. These findings highlight the need for strategies that address potential changes in body composition with disability accumulation.

Tissue composition effect on dose distribution in radiotherapy with a 6 MV photon beam of a medical linac.

The aim of this study is to evaluate soft-tissue composition effect on dose distribution for various soft tissues in radiotherapy with a 6 MV photon beam of a medical linac. The compositions of various soft tissues are different which could affect dose calculations. A phantom and Siemens Primus linear accelerator were simulated using MCNPX Monte Carlo code. In a homogeneous cubic phantom, six types of soft tissue and three types of tissue-equivalent materials were defined separately. The soft tissues were muscle (skeletal), adipose tissue, blood (whole), breast tissue, soft tissue (9-component), and soft tissue (4-component). The tissue-equivalent materials included water, A-150 tissue equivalent plastic and perspex. Photon dose relative to dose in 9-component soft tissue at various depths on the beam's central axis was determined for the 6 MV photon beam. The relative dose was also calculated and compared for various MCNPX tallies including *F8, F6, and *F4. The results of the relative photon dose in various materials relative to dose in 9-component soft tissue using different tallies are reported in the form of tabulated data. Minor differences between dose distributions in various soft tissues and tissue-equivalent materials were observed. The results from F6 and F4 were practically the same but differ with the *F8 tally. Based on the calculations performed, the differences in dose distributions in various soft tissues and tissue-equivalent materials are minor but they could be corrected in radiotherapy calculations to upgrade the accuracy of the dosimetric calculations.

Three-dimensional Distribution of Muscle and Adipose Tissue of the Thigh at CT: Association with Acute Hip Fracture.

Purpose To evaluate determinants of hip fracture by assessing soft-tissue composition of the upper thigh at CT. Materials and Methods In this retrospective analysis of prospectively collected data, CT studies in 55 female control participants (mean age, 73.1 years ± 9.3 [standard deviation]) were compared with those in 40 female patients (mean age, 80.2 years ± 11.0) with acute hip fractures. Eighty-seven descriptors of the soft-tissue composition were determined. A multivariable best subsets analysis was used to extract parameters best associated with hip fracture. Results were adjusted for age, height, and weight. Results of soft-tissue parameters were compared with bone mineral density (BMD) and cortical bone thickness. Areas under the receiver operating characteristic curve (AUCs) adjusted for multiple comparisons were determined to discriminate fracture. Results The hip fracture group was characterized by lower BMD, lower cortical thickness, lower relative adipose tissue volume of the upper thigh, and higher extramyocellular lipid (EML) surface density. The relative volume of adipose tissue combined with EML surface density (model S1) was associated with hip fracture (AUC, 0.85; 95% confidence interval [CI]: 0.78, 0.93), as well as trochanteric trabecular BMD combined with neck cortical thickness (model B2) (AUC, 0.84; 95% CI: 0.75, 0.92). The model including all four parameters provided significantly better (P < .01) discrimination (AUC, 0.92; 95% CI: 0.86, 0.97) than model S1 or B2. Conclusion In addition to bone mineral density and geometry of the proximal femur, the amount of adipose tissue of the upper thigh and the distribution of the adipocytes in the muscles are significantly associated with acute hip fracture at CT. © RSNA, 2018 Online supplemental material is available for this article.

Total and regional bone mineral and tissue composition in female adolescent athletes: comparison between volleyball players and swimmers

BackgroundExploring the osteogenic effect of different bone-loading sports is particular relevant to understand the interaction between skeletal muscle and bone health during growth. This study aimed to compare total and regional bone and soft-tissue composition between female adolescent swimmers (n=20, 15.71±0.93 years) and volleyball players (n=26, 16.20±0.77 years).MethodsDietary intake was obtained using food frequency questionnaires. Body size was given by stature, sitting height, and body mass. Six skinfolds were measured. Bone mineral content (BMC) and density (BMD), lean soft tissue, and fat tissue were assessed using dual-energy X-ray absorptiometry. Pearson’s product moment correlation coefficients were calculated to examine the relationships among variables, by type of sport. Comparisons between swimmers and volleyball players were performed using student t-tests for independent samples and multivariate analysis of covariance (controlling for age, training history and body size).ResultsSwimmers (BMC: 2328±338 g) and volleyball players (BMC: 2656±470 g) exceeded respectively by 2.1 and 2.8 standard deviation scores the average of international standards for whole body BMC of healthy adolescents. Years of training in swimmers were positively related to the upper limbs BMC (r=+0.49, p<0.05). In volleyball players, years of training correlated significantly with lower limbs BMD (r=+0.43, p<0.05). After adjustments for potential confounders, moderate differences (ES-r=0.32) between swimmers and volleyball players were noted in BMD at the lower limbs (volleyball players: +0.098 g∙cm-2, +7.8%).ConclusionsYouth female athletes who participate in high-intensity weight-loading activities such as volleyball exhibit moderately higher levels of BMD at the lower limbs compared to non-loading sports such as swimming.

Trabecular Bone Score and Vertebral Fracture Assessment in Portuguese Premenopausal Women with Hyperthyroidism

Hyperthyroidism is a risk factor for reduced bone mineral density (BMD) and osteoporotic fractures. Vertebral fracture assessment (VFA) detects vertebral fractures and trabecular bone score (TBS) is an index of bone micro-architecture. We aimed to evaluate the effects of hyperthyroidism on BMD, soft body tissue composition, prevalence of silent vertebral fractures and TBS. Eighty Portuguese pre-menopausal women were divided and matched in overt hyperthyroidism (n=40) and control (n=40) groups. BMD (g/cm2) at lumbar spine, hip, radius 33% and whole body and the total body masses (Kg) were studied by DXA. VFA was used to detect fractures and those were classified by Genant´s semi-quantitative method and confirmed by X-ray. TBS was obtained from lumbar spine DXA images. No patient had previously been treated for hyperthyroidism, osteoporosis or low bone mass. Adequate statistical tests were used. In the hyperthyroidism group, the mean BMD (total hip, femoral neck and whole body), the total lean mass and TBS were significantly lower; according to ISCD classification, there was a trend for a higher prevalence of low BMD; vertebral fractures were significantly higher. These results suggest that in a group of hyperthyroid pre-menopausal women there are significantly lower BMD, lean mass and TBS. The prevalence of silent vertebral fractures is also significantly higher. All patients and controls gave their informed consent, according to the approved protocol by the ethic committee of the institution and based on Helsinki declaration. Declaration of Interest: We declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported. Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

MRI analysis of peripheral soft tissue composition, not body mass index, correlates with outcomes following anterior cruciate ligament reconstruction

To utilize MRI to assess the relationship between BMI, peripheral soft tissue composition about the knee, and surgical outcomes in patients undergoing primary ACL reconstruction. It was hypothesized that a fatty periarticular soft tissue composition may be better than BMI at predicting poor outcomes after ACL reconstruction. Fifty-eight patients who underwent primary acute ACL reconstruction were identified from the surgical database and their data were retrospectively reviewed. Patients were selected based on availability of 2-year IKDC outcome scores, BMI data, and preoperative MRI studies. To approximate peripheral soft tissue composition, novel measurements of axial MRI images were employed using PACS ROI measurement tool. Relationships were assessed between IKDC outcome scores and measures of body habitus including BMI, total knee area, knee fatty-connective tissue area, and fatty-connective tissue to bone size ratio. The median BMI was 24.3kg/m2 (range 18.5-36.9). Median IKDC score was 81.0 (range 46-100). BMI was correlated with total knee area (R = 0.72) and periarticular fat (R = 0.53). Neither continuous BMI (n.s.) nor total knee area (n.s.) was predictor of IKDC outcomes scores. Periarticular fatty-connective tissue trended towards predicting negative outcomes (n.s.). Periarticular fatty-connective tissue to bone size ratio was a significant negative predictor of IKDC scores (p = 0.03). Patients with more fat than bone on axial MRI (ratio > 1, N = 34) reported a lower mean IKDC score compared to patients with a ratio < 1 (N = 24) (77.2 vs. 87.7, p = 0.0028). The top quartile (N = 14) of these ratios reported a mean IKDC score of 68.9, compared to 87.3 of the bottom quartile (p = 0.0001). Periarticular soft tissue composition, as approximated by the novel MRI analysis of this study, is a better predictor of outcomes following ACL reconstruction than is BMI. This information can be utilized in guiding surgeon and patient expectations following surgery, either via a direct application of these measurements or heightened awareness of the importance of peripheral body habitus. III.

Validation of Peripheral Quantitative Computed Tomography–Derived Thigh Adipose Tissue Subcompartments in Young Girls Using a 3 T MRI Scanner

The ability to assess skeletal muscle adipose tissue is important given the negative clinical implications associated with greater fat infiltration of the muscle. Computed tomography and magnetic resonance imaging (MRI) are highly accurate for measuring appendicular soft tissue and muscle composition, but have limitations. Peripheral quantitative computed tomography (pQCT) is an alternative that investigators find valuable because of its low radiation, fast scan time, and comparatively lower costs. The present investigation sought to assess the accuracy of pQCT-derived estimates of total, subcutaneous, skeletal muscle, intermuscular, and calculated intramuscular adipose tissue areas, and muscle density in the midthigh of young girls using the gold standard, 3 T MRI, as the criterion. Cross-sectional data were analyzed for 26 healthy girls aged 9–12 years. Midthigh soft tissue composition was assessed by both pQCT and 3 T MRI. Mean tissue area for corresponding adipose compartments by pQCT and MRI was compared using t tests, regression analysis, and Bland-Altman plots. Muscle density was regressed on MRI skeletal muscle adipose tissue, intermuscular adipose tissue, and intramuscular adipose tissue, each expressed as a percentage of total muscle area. Correlations were high between MRI and pQCT for total adipose tissue (r2 = 0.98), subcutaneous adipose tissue (r2 = 0.95), skeletal muscle adipose tissue (r2 = 0.83), and intermuscular adipose tissue (r2 = 0.82), and pQCT muscle density correlated well with both MRI skeletal muscle adipose tissue (r2 = 0.70) and MRI intermuscular adipose tissue (r2 = 0.70). There was a slight, but statistically significant underestimation by pQCT for total and subcutaneous adipose tissue, whereas no significant difference was observed for skeletal muscle adipose tissue. Both pQCT-estimated intramuscular adipose tissue and muscle density were weakly correlated with MRI-intramuscular adipose tissue. We conclude that pQCT is a valid measurement technique for estimating all adipose subcompartments, except for intramuscular adipose tissue, for the midthigh region in young/adolescent girls.

Simulation of the upper airways in patients with obstructive sleep apnea and nasal obstruction: A novel finite element method.

ObjectiveTo evaluate the biomechanical properties of the soft palate and velopharynx in patients with obstructive sleep apnea (OSA) and nasal obstruction.Study designProspective experimental study.Materials and methodsTwo finite element (FE) models of the soft palate were created in six patients undergoing nasal surgery, one homogeneous model based on CT images, and one layered model based on soft tissue composition. The influence of anatomy on displacement caused by a gravitational load and closing pressure were evaluated in both models. The strains in the transverse and longitudinal direction were obtained for each patient.ResultsThe individual anatomy influences both its structural stiffness and its gravitational displacement. The soft palate width was the sole anatomical parameter correlated to the critical closing pressure, but the maximal displacement due to gravity may have a relationship to closing pressure of possibly an exponential order. The airway occlusion occurred mainly at the lateral attachments of the soft palate. The total transverse strain showed a strong correlation with maximal closing pressure. There was no relationship between the critical closing pressure and the preoperative AHI levels, or the change in AHI after surgery.ConclusionHyperelastic FE models both in the homogeneous and layered model represent a novel method of evaluating soft tissue biomechanics of the upper airway. The obstruction occurs mainly at the level of the lateral attachments to the pharyngeal wall, and the width of the soft palate is an indicator of the degree of critical closing pressure. A less negative closing pressure corresponds to small total transverse strain. The effect of nasal surgery on OSA is most likely not explained by change in soft palate biomechanics.Level of EvidenceNA.

New interaction between galectin-3 and cystinosin reveals a role of inflammation in kidney pathogenesis in cystinosis

Changes in muscle-fat-composition affect physical performance and muscular function, like strength and power. The purpose of the present study was to investigate whether changes in soft tissue composition of the thigh and changes in muscle size and composition resulting from physical training were detectable with Dixon magnetic resonance imaging (MRI).A young and healthy subject population (n = 21, 29 ± 5 years) was split into a strength training (G_t, 11 subjects) and a control group (G_c, 10 subjects). The physical training intervention lasted over 13 weeks. Before and after this intervention a muscle performance exam and an MRI exam were conducted on all subjects. To evaluate muscle performance and the training effect, the jump height was measured using a mechanograph. Fascia, pure muscle and subcutaneous fat areas and proton density water fraction (PDWF) and proton density fat fraction (PDFF) of the left thigh were measured with a 6-point Dixon prototype MRI sequence.Muscle area changed by +7.1 ± 3.3% (p < 0.05) and +2.5 ± 5.6% (p > 0.05), and PDFF by -16.3 ± 10.4% (p < 0.05) and +5.4 ± 6.9% (p > 0.05) in G_t and G_c, respectively. Cross-sectional and longitudinal correlation coefficients R between PDFF and muscle performance were moderate (R = -0.43 and R = -0.51, respectively). The correlation was also moderate for muscle performance and a combined muscle fat per area ratio (R = -0.40 and R = -0.55, respectively).Dixon MRI is capable to measure training-related changes in muscle area and muscular fat. Both parameters correlate to muscle function. Muscle area per se does not always mirror functional parameters. Due to the complex interaction of muscle volume, muscle structure, and inter- and intramuscular coordination during muscle performance, multivariate muscle parameter models should be investigated in the future. Future studies will have to show if structural parameters mirror and explain functional muscle data both in the context of physical training and pathologies like sarcopenia.