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Diffusion‐tensor magnetic resonance imaging (DT‐MRI) offers objective measures of muscle characteristics, providing insights into age‐related changes. We used DT‐MRI to probe skeletal muscle microstructure and architecture in a large healthy‐aging cohort, with the aim of characterizing age‐related differences and comparing these to muscle strength. We recruited 94 participants (43 female; median age = 56, range = 22–89 years) and measured microstructure parameters—fractional anisotropy (FA) and mean diffusivity (MD)—in 12 thigh muscles, and architecture parameters—pennation angle, fascicle length, fiber curvature, and physiological cross‐sectional area (PCSA)—in the rectus femoris (RF) and biceps femoris longus (BFL). Knee extension and flexion torques were also measured for comparison to architecture measures. FA and MD were associated with age (β = 0.33, p = 0.001, R2 = 0.10; and β = −0.36, p < 0.001, R2 = 0.12), and FA was negatively associated with Type I fiber proportions from the literature (β = −0.70, p = 0.024, and R2 = 0.43). Pennation angle, fiber curvature, fascicle length, and PCSA were associated with age in the RF (β = −0.22, 0.26, −0.23, and −0.31, respectively; p < 0.05), while in the BFL only curvature and fascicle length were associated with age (β = 0.36, and −0.40, respectively; p < 0.001). In the RF, pennation angle and PCSA were associated with strength (β = 0.29, and 0.46, respectively; p < 0.01); in the BFL, only PCSA was associated with strength (β = 0.43; p < 0.001). Our results show skeletal muscle architectural changes with aging and intermuscular differences in the microstructure. DT‐MRI may prove useful for elucidating muscle changes in the early stages of sarcopenia and monitoring interventions aimed at preventing age‐associated microstructural changes in muscle that lead to functional impairment. [ABSTRACT FROM AUTHOR]

Objective: To introduce cooled radiofrequency nerve ablation (C-RFA) as an alternative to managing symptomatically moderate to severe glenohumeral osteoarthritis (OA) in patients who have failed other conservative treatments and who are not surgical candidates or refuse surgery. Material and methods: This prospective pilot study includes a total of 12 patients experiencing chronic shoulder pain from moderate to severe glenohumeral OA. Patients underwent anesthetic blocks of the axillary, lateral pectoral, and suprascapular nerves to determine candidacy for C-RFA treatment. Adequate response after anesthetic block was over 50% immediate pain relief. Once patients were deemed candidates, they underwent C-RFA of the three nerves 2–3 weeks later. Treatment response was evaluated using the clinically validated American Shoulder and Elbow Surgeons (ASES) score and visual analog scale (VAS) to assess pain, stiffness, and functional activities of daily living. Follow-up outcome scores were collected up to 6 months after C-RFA procedure. Results: Twelve patients underwent C-RFA procedure for shoulder OA. VAS scores significantly improved from 8.8 ± 0.6 to 2.2 ± 0.4 6 months after the C-RFA treatment (p < 0.001). Patient's ASES score results significantly improved in total ASES from 17.2 ± 6.6 to 65.7 ± 5.9 (p < 0.0005). No major complications arose. No patients received re-treatment or underwent shoulder arthroplasty. Conclusion: Image-guided axillary, lateral pectoral, and suprascapular nerve C-RFA has minimal complications and is a promising alternative to treat chronic shoulder pain and stiffness from glenohumeral arthritis. [ABSTRACT FROM AUTHOR]

Objective: To establish the effectiveness of cooled radiofrequency ablation in managing hip pain from osteoarthritis at 6 months after receiving treatment in patients who failed conservative treatments and are not surgical candidates due to comorbidities or unwillingness to undergo arthroplasty surgery by targeting the femoral and obturator branches and assessing the degree of hip pain relief and change of function. Materials and methods: This prospective pilot study includes a total of 11 consecutive patients experiencing persistent chronic hip pain in the setting of advanced osteoarthritis. Patients initially underwent anesthetic blocks of the obturator and femoral nerve branches to determine cooled radiofrequency ablation candidacy. After adequate response to the anesthetic blocks (> 50% immediate pain relief), patients were subjected to the procedures 2–3 weeks later. Treatment response was evaluated utilizing clinically validated questionnaires and visual analog score in order to assess impact on pain severity, stiffness, and functional activities of daily living. Follow-up outcome scores were collected up to 6 months after cooled radiofrequency ablation procedure. Results: A total of 11 hips were treated consecutively between August 2019 and March 2020 (mean patient age 61.4 years; 8 M:3F). The mean total HOOS score improved significantly from baseline at 17.0 ± 6.0 to 52.9 ± 5.4 at a mean of 6.2 months after treatment (p < 0.0001), with significant improvement in mean pain score from 16.1 ± 6.6 to 53.4 ± 7.4 (p < 0.0001) and mean stiffness score from 15.0 ± 8.1 to 53.6 ± 11.0 (p < 0.0001). No major complications were encountered. No patients went on to re-treatment, surgery, or other intervention. Conclusion: Image-guided obturator and femoral nerve cooled radiofrequency ablation is effective and safe in treating chronic hip pain/stiffness in the setting of advanced osteoarthritis. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is globally the most prevalent joint disease and causes patients great pain, limited joint mobility, and psychological distress. Short- and long-term therapies like steroid injections and arthroplasty exist, respectively. Joint arthroplasty can effectively treat symptomatic end-stage OA, but most patients do not go through with surgery because they are not qualified, have comorbidities, or do not wish to undergo surgery. As a result, patients can turn to opioid agonists for pain relief, which contributes to the growing opioid epidemic that mars our communities. Cooled radiofrequency ablation (C-RFA) is an effective treatment modality that can alleviate the pain associated with moderate to severe OA, especially in patients who have tried and failed conservative therapy. This review article elucidates the benefits of C-RFA, while also walking through the technical steps to performing the procedure. For patients suffering from debilitating joint OA, especially of the knee, C-RFA is a minimally invasive procedure that ensures pain relief. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is the most common joint disease worldwide, leading to significant pain, restricted range of motion, and disability. A gap exists between short- and long-term symptom-relieving therapies. Although arthroplasty is an effective treatment for symptomatic end-stage disease, most patients ultimately do not receive a joint replacement due to suboptimal surgical qualifications, comorbidities, or an aversion to surgery. The lack of additional treatment options in this setting makes opioid agonists a commonly used pharmacologic agent, contributing to the addiction epidemic that greatly afflicts our communities. Cooled radiofrequency ablation (CRFA) has arisen as a treatment modality in the setting of moderate to severe OA among patients refractory to conservative management, generally showing greater efficacy compared with other existing strategies. This review focuses on the benefits of CRFA and its technical feasibility as a management option among patients experiencing debilitating large joint OA with limited clinical options. [ABSTRACT FROM AUTHOR]

Objective: To establish the effectiveness of cooled radiofrequency ablation in managing hip pain from osteoarthritis at 6 months after receiving treatment in patients who failed conservative treatments and are not surgical candidates due to comorbidities or unwillingness to undergo arthroplasty surgery by targeting the femoral and obturator branches and assessing the degree of hip pain relief and change of function. Materials and methods: This prospective pilot study includes a total of 11 consecutive patients experiencing persistent chronic hip pain in the setting of advanced osteoarthritis. Patients initially underwent anesthetic blocks of the obturator and femoral nerve branches to determine cooled radiofrequency ablation candidacy. After adequate response to the anesthetic blocks (> 50% immediate pain relief), patients were subjected to the procedures 2–3 weeks later. Treatment response was evaluated utilizing clinically validated questionnaires and visual analog score in order to assess impact on pain severity, stiffness, and functional activities of daily living. Follow-up outcome scores were collected up to 6 months after cooled radiofrequency ablation procedure. Results: A total of 11 hips were treated consecutively between August 2019 and March 2020 (mean patient age 61.4 years; 8 M:3F). The mean total HOOS score improved significantly from baseline at 17.0 ± 6.0 to 52.9 ± 5.4 at a mean of 6.2 months after treatment (p < 0.0001), with significant improvement in mean pain score from 16.1 ± 6.6 to 53.4 ± 7.4 (p < 0.0001) and mean stiffness score from 15.0 ± 8.1 to 53.6 ± 11.0 (p < 0.0001). No major complications were encountered. No patients went on to re-treatment, surgery, or other intervention. Conclusion: Image-guided obturator and femoral nerve cooled radiofrequency ablation is effective and safe in treating chronic hip pain/stiffness in the setting of advanced osteoarthritis. [ABSTRACT FROM AUTHOR]

Sarcopenia is associated with poor outcomes in a variety of conditions, including malignancy. Abdominal skeletal muscle area (SMA) segmentation using computed tomography (CT) has been shown to be an accurate surrogate for identifying sarcopenia. While magnetic resonance imaging (MRI) segmentation of SMA has been validated in cadaver limbs, few studies have validated abdominal SMA segmentation using MRI at lumbar level mid-L3. Our objective was to assess the reproducibility and concordance of CT and MRI segmentation analyses of SMA at mid-L3. This retrospective analysis included a random sample of 10 patients with renal cell carcinoma (RCC) and CT abdomen/pelvis, used to assess intra-observer variability of SMA measurements using CT. An additional sample of 9 patients with RCC and both CT and T2-weighted (T2w) MRI abdomen/pelvis was used to assess intra-observer variability of SMA using MRI and concordance of SMA between MRI and CT. SMA was segmented using Slice-O-Matic. SMA reproducibility was assessed using intraclass correlation coefficient (ICC). SMA concordance was analyzed using Bland–Altman plot and Pearson correlation coefficient. The intra-observer variability of CT and MRI SMA at mid-L3 was low, with ICC of 0.998 and 0.985, respectively. Bland–Altman analysis revealed bias of 0.74% for T2w MRI over CT. The Pearson correlation coefficient was 0.997 (p < 0.0001), demonstrating strong correlation between CT and T2w MRI. Abdominal SMA at mid-L3 is reproducibly segmented for both CT and T2w MRI, with strong correlation between the 2 modalities. T2w MRI can be used interchangeably with CT for assessment of SMA and sarcopenia. This finding has important clinical implications. [ABSTRACT FROM AUTHOR]

Background and Purpose: Myelin water fraction (MWF) mapping permits direct visualization of myelination patterns in the developing brain and in pathology. MWF is conventionally measured through multiexponential T2 analysis which is very sensitive to noise, leading to inaccuracies in derived MWF estimates. Although noise reduction filters may be applied during postprocessing, conventional filtering can introduce bias and obscure small structures and edges. Advanced nonblurring filters, while effective, exhibit a high level of complexity and the requirement for supervised implementation for optimal performance. The purpose of this paper is to demonstrate the ability of the recently introduced nonlocal estimation of multispectral magnitudes (NESMA) filter to greatly improve the determination of MWF parameter estimates from gradient and spin echo (GRASE) imaging data.Methods: We evaluated the performance of the NESMA filter for MWF mapping from clinical GRASE imaging data of the human brain, and compared the results to those calculated from unfiltered images. Numerical and in vivo analyses of the brains of three subjects, representing different ages, were conducted.Results: Our results demonstrated the potential of the NESMA filter to permit high-quality in vivo MWF mapping. Indeed, NESMA permits substantial reduction of random variation in derived MWF estimates while preserving accuracy and detail.Conclusions: In vivo estimation of MWF in the human brain from GRASE imaging data was markedly improved through use of the NESMA filter. The use of NESMA may contribute to the goal of high-quality MWF mapping in clinically feasible imaging times. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Brain glucose hypometabolism is a prominent feature of Alzheimer's disease (AD), and in this case–control study we used Magnetic Resonance Spectroscopy (MRS) to assess AD‐related differences in the posterior cingulate/precuneal ratio of glucose, lactate, and other metabolites. Methods: J‐modulated Point‐Resolved Spectroscopy (J‐PRESS) and Prior‐Knowledge Fitting (ProFit) software was used to measure glucose and other metabolites in the posterior cingulate/precuneus of 25 AD, 27 older controls, and 27 younger control participants. Clinical assessments for AD participants included cognitive performance measures, insulin resistance metrics and CSF biomarkers. Results: AD participants showed substantially elevated glucose, lactate, and ascorbate levels compared to older (and younger) controls. In addition, the precuneal glucose elevation discriminated well between AD participants and older controls. Myo‐inositol correlated with CSF p‐Tau181P, total Tau, and the Clinical Dementia Rating (CDR) sum‐of‐boxes score within the AD group. Interpretation: Higher glucose to creatine ratios in the AD brain likely reflect lower glucose utilization. Our findings reveal pronounced metabolic abnormalities in the AD brain and strongly suggest that brain glucose merits further investigation as a candidate AD biomarker. [ABSTRACT FROM AUTHOR]

Purpose We applied our recently introduced Bayesian analytic method to achieve clinically-feasible in-vivo mapping of the proteoglycan water fraction (PgWF) of human knee cartilage with improved spatial resolution and stability as compared to existing methods. Materials and methods Multicomponent driven equilibrium single-pulse observation of T 1 and T 2 (mcDESPOT) datasets were acquired from the knees of two healthy young subjects and one older subject with previous knee injury. Each dataset was processed using Bayesian Monte Carlo (BMC) analysis incorporating a two-component tissue model. We assessed the performance and reproducibility of BMC and of the conventional analysis of stochastic region contraction (SRC) in the estimation of PgWF. Stability of the BMC analysis of PgWF was tested by comparing independent high-resolution (HR) datasets from each of the two young subjects. Results Unlike SRC, the BMC-derived maps from the two HR datasets were essentially identical. Furthermore, SRC maps showed substantial random variation in estimated PgWF, and mean values that differed from those obtained using BMC. In addition, PgWF maps derived from conventional low-resolution (LR) datasets exhibited partial volume and magnetic susceptibility effects. These artifacts were absent in HR PgWF images. Finally, our analysis showed regional variation in PgWF estimates, and substantially higher values in the younger subjects as compared to the older subject. Conclusions BMC-mcDESPOT permits HR in-vivo mapping of PgWF in human knee cartilage in a clinically-feasible acquisition time. HR mapping reduces the impact of partial volume and magnetic susceptibility artifacts compared to LR mapping. Finally, BMC-mcDESPOT demonstrated excellent reproducibility in the determination of PgWF. [ABSTRACT FROM AUTHOR]

Skeletal muscle mitochondrial oxidative capacity declines with age and negatively affects walking performance, but the mechanism for this association is not fully clear. We tested the hypothesis that impaired oxidative capacity affects muscle performance and, through this mechanism, has a negative effect on walking speed. Muscle mitochondrial oxidative capacity was measured by in vivo phosphorus magnetic resonance spectroscopy as the postexercise phosphocreatine resynthesis rate, kPCr, in 326 participants (154 men), aged 24-97 years (mean 71), in the Baltimore Longitudinal Study of Aging. Muscle strength and quality were determined by knee extension isokinetic strength, and the ratio of knee extension strength to thigh muscle cross-sectional area derived from computed topography, respectively. Four walking tasks were evaluated: a usual pace over 6 m and for 150 s, and a rapid pace over 6 m and 400 m. In multivariate linear regression analyses, kPCr was associated with muscle strength (β = 0.140, P = 0.007) and muscle quality (β = 0.127, P = 0.022), independent of age, sex, height, and weight; muscle strength was also a significant independent correlate of walking speed ( P < 0.02 for all tasks) and in a formal mediation analysis significantly attenuated the association between kPCr and three of four walking tasks (18-29% reduction in β for kPCr). This is the first demonstration in human adults that mitochondrial function affects muscle strength and that inefficiency in muscle bioenergetics partially accounts for differences in mobility through this mechanism. [ABSTRACT FROM AUTHOR]

Background: Aerobic fitness and muscle bioenergetic capacity decline with age; whether such declines explain age-related slowing of walking speed is unclear. We hypothesized that muscle energetics and aerobic capacity are independent correlates of walking speed in simple and challenging performance tests and that they account for the observed age-related decline in walking speed in these same tests.Methods: Muscle bioenergetics was assessed as postexercise recovery rate of phosphocreatine (PCr), k PCr, using phosphorus magnetic resonance spectroscopy (31P-MRS) in 126 participants (53 men) of the Baltimore Longitudinal Study of Aging aged 26-91 years (mean = 72 years). Four walking tasks were administered-usual pace over 6 m and 150 seconds and fast pace over 6 m and 400 m. Separately, aerobic fitness was assessed as peak oxygen consumption (peak VO2) using a graded treadmill test.Results: All gait speeds, k PCr, and peak VO2 were lower with older age. Independent of age, sex, height, and weight, both k PCr and peak VO2 were positively and significantly associated with fast pace and long distance walking but only peak VO2 and not k PCr was significantly associated with usual gait speed over 6 m. Both k PCr and peak VO2 substantially attenuated the association between age and gait speed for all but the least stressful walking task of 6 m at usual pace.Conclusion: Muscle bioenergetics assessed using 31P-MRS is highly correlated with walking speed and partially explains age-related poorer performance in fast and long walking tasks. [ABSTRACT FROM AUTHOR]

Abstract: The balance between excitatory glutamatergic projection neurons and inhibitory GABAergic interneurons determines the function of cortical microcircuits. How these neurotransmitters relate to the functional status of an entire macro-scale network remains unknown. The posteromedial cortex (PMC) is the default mode network (DMN) node with the greatest functional connectivity; therefore, we hypothesized that PMC glutamate and GABA predict intrinsic functional connectivity (iFC) across the entire DMN. In 20 healthy men, we combined J-resolved magnetic resonance spectroscopy to measure glutamate and GABA in the PMC and resting fMRI followed by group Independent Components Analysis to extract the entire DMN. We showed that, controlling for age and partial GM volume in the MRS voxel, PMC glutamate and GABA explained about half of the variance of DMN iFC (represented by the network''s beta coefficient for rest). Glutamate correlated positively and GABA correlated negatively with DMN iFC; in an alternative statistical model which included the glutamate/GABA ratio, the ratio correlated positively with DMN iFC. Age had no independent association with DMN iFC. No other network was associated with PMC glutamate or GABA. We conclude that regional neurotransmitter concentrations in a network node strongly predict network but not global brain iFC. [Copyright &y& Elsevier]

Abstract: High resolution strain measurements are of particular interest in load bearing tissues such as the intervertebral disc (IVD), permitting characterization of biomechanical conditions which could lead to injury and degenerative outcomes. Magnetic resonance (MR) imaging produces excellent image contrast in cartilaginous tissues, allowing for image-based strain determination. Nonrigid registration (NRR) of MR images has previously demonstrated sub-voxel registration accuracy although its accuracy and precision in determining strain has not been evaluated. Accuracy and precision of NRR-derived strain measurements were evaluated using computer generated deformations applied to both computer generated images and MR images. Two different measures of registration similarity—the cost function which drives the registration algorithm—were compared: Mutual Information (MI) and Least Squares (LS). Strain error was evaluated with respect to signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and strain heterogeneity. Additionally, the creep strain response from an in vitro loaded porcine IVD is shown and comparisons between similarity measures are presented. MI showed a decrease in strain precision with increasing CNR and decreasing SNR while LS was insensitive to both. Both similarity measures showed a decrease in strain precision with increasing strain heterogeneity. When computer generated heterogeneous strains were applied to MR images of the IVD, LS showed substantially lower strain error in comparison to MI. Results suggest that LS-driven NRR provides a more accurate image-based method for mapping large and heterogeneous strain fields and this method can be applied to studies of the IVD and, potentially, other soft tissues which present sufficient image texture. [Copyright &y& Elsevier]

Abstract: Multiexponential transverse relaxation in tissue has been interpreted as a marker of water compartmentation. Articular cartilage has been reported to exhibit such relaxation in several studies, with the relative contributions of tissue heterogeneity and tissue microstructure remaining unspecified. In bovine nasal cartilage, conflicting data regarding the existence of multiexponential relaxation have been reported. Imaging and analysis artifacts as well as rapid chemical exchange between tissue compartments have been identified as potential causes for this discrepancy. Here, we find that disruption of cartilage microstructure by freeze-thawing can greatly alter the character of transverse relaxation in this tissue. We conclude that fresh cartilage exhibits multiexponential relaxation based upon its microstructural water compartments, but that multiexponentiality can be lost or rendered undetectable by freeze-thawing. In addition, we find that increasing chemical exchange by raising sample temperature from 4°C to 37°C does not substantially limit the ability to detect multiexponential relaxation. [Copyright &y& Elsevier]

Abstract: MRI analysis of cartilage matrix may play an important role in early detection and development of therapeutic protocols for degenerative joint disease. Correlations between MRI parameters and matrix integrity have been established in many studies, but the substantial overlap in values observed for normal and for degraded cartilage greatly limits the specificity of these analyses. We implemented established multiparametric analysis methods to define data clusters corresponding to control and degraded bovine nasal cartilage in two-, three-, and four-dimensional parameter spaces, and applied these results to discriminant analysis of a validation data set. Analyses were performed using the parameters (T 1, T 2, k m, ADC), where k m is the magnetization transfer rate and ADC is the apparent diffusion coefficient. Results were compared to univariate analyses. Multiparametric k-means clustering led to no improvement over univariate analyses, with a maximum sensitivity and specificity in the range of 60–70% for the detection of degradation using T 1, and in the range of 80% sensitivity but only 36% specificity using the parameter pair (T 1, k m). In contrast, model-based analysis using more general Gaussian clusters resulted in markedly improved classification, with sensitivity and specificity reaching levels of 80–90% using the pair (T 1, k m). Finally, a fuzzy clustering technique was implemented which may be still more appropriate to the continuum of degradation seen in degenerative cartilage disease. In view of its success in identifying mild cartilage degradation, the formal multiparametric approach implemented here may be applicable to the nondestructive evaluation of other biomaterials using MRI. [Copyright &y& Elsevier]

Presents a 2D optical method for measuring gross kinematics of porcine anterior column units (ACUs) exposed to swelling with no applied load. Detailed error analysis of the 2D optical measurement technique; 2D radiographic technique for measuring the distribution of x-ray intensity through an axial slice of the disc; Indication that the 2D optical technique was sufficient for detecting the flexion-extension behavior of the ACUs tested.

Purpose: To report normative stiffness parameters obtained using shear wave elastography in dorsiflexion from the Achilles tendons in asymptomatic professional ballet dancers and compare them with college-level athletes. Methods: An Institutional Review Board (IRB)-approved study consists of 28 professional ballet dancers and 64 asymptomatic collegiate athletes. The athletes were further subdivided into runner and non-runner disciplines. Shear wave elastography (SWE) measurements were made in maximum ankle dorsiflexion position. Results and discussion: Forty-eight (52%) males and 44 (48%) females were examined with an overall mean age of 22.2 (± 3.8 years). There were no significant SWE differences between dominant and non-dominant legs in both groups and comparing spin vs. non-spin leg of ballet dancers (p > 0.05). Ballet dancers had significantly higher short-axis velocity values than runners and non-runners (2.34 m/s increase and 2.79 m/s increase, respectively, p < 0.001). Long-axis velocity was significantly higher in ballet dancers compared to non-runners (by 0.80 m/s, p < 0.001), but was not different between ballet dancers and runners (p > 0.05). Short-axis modulus was significantly higher in dancers compared to runners and non-runners (by 135.2 kPa and 159.2 kPa, respectively, p < 0.001). Long-axis modulus (LAM) was not significantly different in ballet dancers when compared to runners. Conclusion: Asymptomatic professional ballet dancers exhibit greater short-axis tendon stiffness compared to athletes and greater long-axis tendon stiffness compared to non-runners but similar to runners. The functional benefit from elevated short-axis stiffness in dancers is not clear but may be related to greater axial loading and adaptations of the tendon matrix. [ABSTRACT FROM AUTHOR]

Presents the short story "Her Father's Daughter," by David P. Reiter.

Background: Adiposity and mitochondrial dysfunction are related factors contributing to metabolic disease development. This pilot study examined whether in vivo and ex vivo indices of mitochondrial metabolism were differentially associated with body composition in males and females. Methods: Thirty-four participants including 19 females (mean 27 yr) and 15 males (mean 29 yr) had body composition assessed by dual energy x-ray absorptiometry and magnetic resonance (MR) imaging. Monocyte reserve capacity and maximal oxygen consumption rate (OCR) were determined ex vivo using extracellular flux analysis. In vivo quadriceps mitochondrial function was measured using 31P-MR spectroscopy based on post-exercise recovery kinetics (τPCr). The homeostatic model assessment of insulin resistance (HOMA-IR) was calculated from fasting glucose and insulin levels. Variables were log-transformed, and Pearson correlations and partial correlations were used for analyses. Results: Mitochondrial metabolism was similar between sexes (p > 0.05). In males only, higher fat mass percent (FM%) was correlated with lower reserve capacity (r = − 0.73; p = 0.002) and reduced muscle mitochondrial function (r = 0.58, p = 0.02). Thigh subcutaneous adipose tissue was inversely related to reserve capacity in males (r = − 0.75, p = 0.001), but in females was correlated to higher maximal OCR (r = 0.48, p = 0.046), independent of FM. In females, lean mass was related to greater reserve capacity (r = 0.47, p = 0.04). In all participants, insulin (r = 0.35; p = 0.04) and HOMA-IR (r = 0.34; p = 0.05) were associated with a higher τPCr. Conclusions: These novel findings demonstrate distinct sex-dependent associations between monocyte and skeletal muscle mitochondrial metabolism with body composition. With further study, increased understanding of these relationships may inform sex-specific interventions to improve mitochondrial function and metabolic health. [ABSTRACT FROM AUTHOR]

This article focuses on the sculptor, Wilfried Penker, and presents a feature on his works. Wilfried lives in Graham Island, largest of the Queen Charlotte chain off the northern coast of British Columbia. Two sculpted cedar poles, long since exposed to the elements, confront one at the gate of his home. Wilfried was born in Austria. He speaks in a guttural accent about his childhood in the 1940s. Wilfried keeps a low fire going near the stumps where he does his carving. A brace of green tree limbs, with seal skins and deer hides tied to them for smoking, arc over the smoldering coals. He has gathered two of the hides from the town dump where they were discarded by hunters interested only in the venison. Wilfried is shy about his art. He claims to have no plans before he starts to carve, instead letting the natural lines of the wood participate in determining the ultimate form of his figures, especially the more abstract ones. He works with local woods. Some of his masks show a definite Haida influence. There are traditional ceremonial figures, like the transformation double mask, where the wearer can exhibit two faces at once.

Background: A common feature of hip arthritis is the presence of labra tears. Recent literature suggests against the use of magnetic resonance imaging (MRI) in patients aged >45 years for the assessment of hip pain related to arthritis.Purpose: To determine if radiographic features of osteoarthritis detectable on routine hip radiographs are accurate and reliable surrogate markers of degenerative acetabular labral tears identified on MR arthrography (MRA) and corroborated during arthroscopy.Material and Methods: A retrospective study involving 86 symptomatic patients (hip pain) with radiologic work-up included MRA and pelvic or hip radiographs that underwent hip arthroscopy within three months. Imaging characteristics assessed on hip radiographs include measurements of superior acetabular, femoral head osteophyte, cortical thickness of the femoral shaft, and minimum joint space as well as presence of subchondral sclerosis of the femoral head and acetabulum, femoral shaft buttressing, and grade of arthritis. Presence of a labral tear was determined by consensus between three readers as well as by surgical correlation. The Pearson's chi-squared and Fisher's exact tests were used to compare presence of labral tears with each radiographic feature.Results: Seventy-one patients (82.6%) had labral tears: 49 (69%) women and 22 (31%) men. Receiver operating characteristic analysis showed statistical significance (P<0.05) between presence of a labral tear and acetabular and femoral head osteophyte sizes but failed to demonstrate any significance regarding acetabular subchondral sclerosis, cortical thickness, buttressing, or minimum joint space.Conclusions: Radiographic markers such as the acetabular and femoral head osteophyte sizes demonstrated statistical significance with the presence of labral tears. [ABSTRACT FROM AUTHOR]

Context: The etiology of patellofemoral pain has remained elusive, potentially due to an incomplete understanding of how pain, motor control, and kinesiophobia disrupt central nervous system functioning. Objective: To directly evaluate brain activity during experimental knee pain and its relationship to kinesiophobia in patients with patellofemoral pain. Design: Cross-sectional. Methods: Young females clinically diagnosed with patellofemoral pain (n = 14; 14.4 [3.3] y; body mass index = 22.4 [3.8]; height = 1.61 [0.1 ] m; body mass = 58.4 [12.7] kg). A modified Clarke test (experimental pain condition with noxious induction via patella pressure and quadriceps contraction) was administered to the nondominant knee (to minimize limb dominance confounds) of patients during brain functional magnetic resonance imaging (fMRI) acquisition. Patients also completed a quadriceps contraction without application of external pressure (control contraction). Kinesiophobia was measured using the Tampa Scale of Kinesiophobia. The fMRI analyses assessed brain activation during the modified Clarke test and control contraction and assessed relationships between task-induced brain activity and kinesiophobia. Standard processing for neuroimaging and appropriate cluster-wise statistical thresholds to determine significance were applied to the 1MRI data (z > 3.1, P < .05). Results: The fMRI revealed widespread neural activation in the frontal, parietal, and occipital lobes, and cerebellum during the modified Clarke test (all zs > 4.4, all Ps < .04), whereas neural activation was localized primarily to frontal and cerebellar regions during the control contraction test (all zs > 4.4, all Ps < .01). Greater kinesiophobia was positively associated with greater activity in the cerebello-frontal network for the modified Clarke test (all zs > 5.0, all Ps < .01), but no relationships between kinesiophobia and brain activity were observed for the control contraction test (all zs < 3.1, all Ps > .05). Conclusions: Our novel experimental knee pain condition was associated with alterations in central nociceptive processing. These findings may provide novel complementary pathways for targeted restoration of patient function. [ABSTRACT FROM AUTHOR]

The poem "Extremis" by David Reiter is presented. First Line: Without Hope; Last Line: synapse to pixel = #Unreal.

The poem "The Pyramid at the End of the World" by David Reiter is presented. First Line: Every trap you walk; Last Line: for unconditional sight.

The poem "The Eater of Light" by David Reiter is presented. First Line: They will keep eating; Last Line: is resisting its music.

Study Design: This is a retrospective cohort study.Objective: The aim was to evaluate differences in readmission rates, number of debridements, and length of antibiotic therapy when comparing bacterial gram type following lumbar spinal fusion infections.Summary Of Background Data: Surgical site infections (SSIs) after spinal fusion serve as a significant source of patient morbidity. It remains to be elucidated how bacterial classification of the infecting organism affects the management of postoperative spinal SSI.Methods: Patients who underwent spinal fusion with a subsequent diagnosis of SSI between 2013 and 2019 were retrospectively identified. Patients were grouped based on bacterial infection type (gram-positive, gram-negative, or mixed infections). Poisson regressions analyzed the relationship between the type of bacterial infection and the number of irrigation and debridement (I&D) reoperations, and the duration of intravenous (IV) antibiotic therapy. Significance was set at P <0.05.Results: Of 190 patients, 92 had gram-positive (G+) infections, 57 had gram-negative (G-) infections, and 33 had mixed (M) infections. There was no difference in 30 or 90-day readmissions for infection between groups (both P =0.051). Patients in the M group had longer durations of IV antibiotic treatment (G+: 46.4 vs. G-: 41.0 vs. M: 55.9 d, P =0.002). Regression analysis demonstrated mixed infections were 46% more likely to require a greater number of debridements ( P =0.001) and 18% more likely to require an increased duration of IV antibiotic therapy ( P <0.001), while gram-negative infections were 10% less likely to require an increased duration of IV antibiotic therapy ( P <0.001) when compared with G- infections.Conclusion: Spinal SSI due to a mixed bacterial gram type results in an increased number of debridements and a longer duration of IV antibiotics required to resolve the infection compared with gram-negative or gram-positive infections.Level Of Evidence: Level III. [ABSTRACT FROM AUTHOR]

Study Design: The study design used was a retrospective cohort. Objective: The objective of this study is to determine if intraoperative improvements in sagittal alignment on the operating table persisted on postoperative standing radiographs. Summary of Background Data: Cervical sagittal alignment may be correlated to postoperative outcomes. Since anterior cervical discectomy and fusions (ACDFs) can restore some cervical lordosis through intervertebral grafts/cages, it is important to understand if intraoperative radiographic measurements correlate with persistent postoperative radiographic changes. Materials and Methods: Patients undergoing elective primary ACDF were screened for the presence of lateral cervical radiographs preoperatively, intraoperatively, and postoperatively. Patients were excluded if their first postoperative radiograph was more than 3 months following the procedure or if cervical lordosis was not able to be measured at each time point. Paired t-tests were utilized to compare differences in measurements between time points. Statistical significance was set at P < 0.05. Results: Of 46 included patients, 26 (56.5%) were female, and the mean age was 55.2 ± 11.6 years. C0-C2 lordosis significantly increased from the preoperative to intraoperative time point (delta [Δ] = 4.49, P = 0.029) and significantly decreased from the intraoperative to postoperative time period (Δ = −6.57, P < 0.001), but this resulted in no significant preoperative to postoperative change (Δ = −2.08, P = 0.096). C2 slope decreased from the preoperative to the intraoperative time point (Δ = −3.84, P = 0.043) and significantly increased from the intraoperative to the postoperative time point (Δ = 3.68, P = 0.047), which also resulted in no net change in alignment between the preoperative and postoperative periods (Δ = −0.16, P = 0.848). There was no significant difference in the C2-C7 SVA from the preoperative to intraoperative (Δ = 0.85, P = 0.724) or intraoperative to postoperative periods (Δ = 2.04, P = 0.401); however, the C2-C7 SVA significantly increased from the preoperative to postoperative period (Δ = 2.88, P = 0.006). Conclusions: Intraoperative positioning predominantly affects the mobile upper cervical spine, particularly C0-C2 lordosis and C2 slope, but these changes do not persist postoperatively. [ABSTRACT FROM AUTHOR]

The article presents the poem "John Ryan, Crown Prisoner," by David P. Reiter. First Line: only a dozen muskets and maybe less; Last Line: such a happy fate for prisoners of the crown.

The article presents the poem "Mr Flinders and the Aborigines," by David P. Reiter. First Line: At last the wind changed and we went in under topsails; Last Line: only darkening boulders I spied through my glass?

The article presents the poem "Snakes and Leeches," by David P. Reiter. First Line: she's an islander; Last Line: with the dark love of leeches.

The purpose of this retrospective cohort study was to investigate the impact of smoking on patient-reported outcome measures (PROMs) following elective posterior cervical decompression and fusion (PCF). Electronic medical records at a single institution were reviewed for patients undergoing elective PCF. Patients were grouped based on smoking history: current smokers, former smokers, and never smokers. A delta score (Δ) was calculated for all PROMs (postoperative minus preoperative scores). Continuous and categorical data were compared using analysis of variance or χ2 tests. Regression analysis controlled for demographics. Patients were then regrouped into current smokers and nonsmokers for reanalysis. A total of 195 patients were included, of whom 35 (22.1%) were current smokers, 51 (26.2%) were former smokers, and 101 (51.8%) were never smokers. Preoperative and postoperative Short-Form 12 Mental Component Score (MCS-12) were significantly lower in the current smoker group (preoperative: current 42.7, former 49.9, and never 46.6; P = 0.024; postoperative: current 44.6, former 53.7, and never 52.2; P = 0.003). Only never smokers improved in MCS-12 and Neck Disability Index following surgery. On regrouping, current smokers had significantly lower preoperative MCS-12 (42.7 vs. 47.7, P = 0.031), lower preoperative modified Japanese Orthopaedic Association (12.2 vs. 14.0, P = 0.039), greater preoperative visual analog scale Arm (6.39 vs. 4.94, P = 0.025), and lower postoperative MCS-12 (44.6 vs. 52.7, P = 0.001). Only the nonsmokers improved in MCS-12 and Neck Disability Index following surgery. On regression analysis, smoking was not an independent predictor of ΔPROMs. Univariate analysis found that smokers have worse symptoms at baseline. However, smoking status was not an independent predictor of improvement in ΔPROMs following elective PCF. [ABSTRACT FROM AUTHOR]

Abstract: The advancement of spectroscopy methods attained through increases in sensitivity, and often with the coupling of complementary techniques, has enabled real-time structure and function measurements of single cells. The purpose of this review is to illustrate, in light of advances, the strengths and the weaknesses of these methods. Included also is an assessment of the impact of the experimental setup and conditions of each method on cellular function and integrity. A particular emphasis is placed on noninvasive and nondestructive techniques for achieving single cell detection, including nuclear magnetic resonance, in addition to physical, optical, and vibrational methods. [Copyright &y& Elsevier]

Highlights: [•] We propose a method of stabilizing the inverse Laplace transform of 1D multiexponential NMR signals. [•] We examine simulated and experimental multiexponential NMR relaxation datasets. [•] Our method is based on conventional 2D relaxometry followed by 1D projection. [•] We compare these projections with 1D results on an equal experimental time basis. [•] We find markedly improved stability, accuracy, and insensitivity to regularization. [Copyright &y& Elsevier]

Objective: To assess the functional parameters of the Achilles tendons among asymptomatic college level athletes using shear wave elastography (SWE) and to describe the relationship to athlete demographics and anthropometric lower extremity measurements. Material and methods: Sixty-five athletes were included in this IRB-approved study. SWE measurements were made on two tendon positions (neutral state and active maximum dorsiflexion) with two different probe orientations (longitudinal and transverse). Associations were assessed with BMI, tibial/foot length, type of sports, and resting/maximal dorsiflexion-plantar flexion angles. Results: Thirty-five (53.8%) males and 30 (46.2%) females with an overall mean age of 20.9 years (± 2.8), mean height of 176 cm (± 0.11), and mean weight of 74.1 kg (± 12) were studied. In the neutral state, the mean wave velocity of 7.5 m sec−1 and the mean elastic modulus of 176.8 kPa were recorded. In active maximum dorsiflexion, the mean velocity was 8.3 m sec−1 and mean elastic modulus was 199 kPa. On the transverse view, the mean velocity and elastic measurements were significantly lower (p = 0.0001). No significant differences in SWE parameters were seen between male and female athletes regardless of probe orientation (p < 0.05) with SWE values being higher in the running group vs non-running group (p < 0.05). In neutral state, longitudinal SWE measurements correlated with the tibia-foot length whereas transverse measurements correlated with the tendon diameter and ankle resting angle (ARA) (p < 0.005). Conclusion: SWE can distinguish functional differences in Achilles tendon stiffness between athletes engaged in running-intensive sports compared with other athletes. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the safety and efficacy of image-guided genicular nerve cooled radiofrequency ablation (C-RFA) for the treatment of pain in non-surgical candidates with moderate to severe knee osteoarthritis (OA) and to compare three- vs four-needle technique. Method: This retrospective study included 50 consecutive patients with pain from moderate to severe knee OA refractory to anti-inflammatory analgesia that failed multiple intra-articular lidocaine-steroid injections and who were non-surgical total knee arthroplasty candidates because of comorbidities. Patients initially underwent anesthetic blocks of the superior medial/lateral femoral and inferior medial tibial genicular nerve branches and in some cases the suprapatellar genicular nerve branch. Radiofrequency ablations of the same nerve branches were performed 1–2 weeks after the nerve blocks. Follow-up outcome was collected at approximately 2 weeks, 1, 3, and 6 months after the C-RFA procedure utilizing VAS and clinically validated questionnaires. Results: A total of 77 knees were treated. The mean total KOOS score improved significantly from baseline at 24.7 ± 14.1 to 59.4 ± 26.5 at 6 months after treatment (p < 0.0001), with significant improvement in mean pain score from 25.5 ± 15.2 to 64.5 ± 25.2 (p < 0.0001) and mean stiffness score from 35.1 ± 21.9 to 65.8 ± 24.9 (p < 0.0001). At 6 months, 65% of all patients demonstrated decreased opiate medication usage, 79% of patients in the four-needle, and 45% of patients in the three-needle arms (p = 0.03). No complications were reported. Conclusions: The four-needle treatment approach offers an advantage in the overall efficacy in treating stiffness and pain in patients with moderate-to-severe OA refractory to conservative treatments leading to decreased opiate usage without complications. [ABSTRACT FROM AUTHOR]

Vascular impairment is closely related to increased mortality in chronic kidney disease (CKD). The objective of this study was to assess impairments in the regulation of peripheral microvascular perfusion in patients with CKD based on time-frequency spectral analysis of resting near-infrared spectroscopy (NIRS) signals. Total hemoglobin (tHb) concentration and tissue saturation index (TSI) signals were collected using NIRS for a continuous 5 mins at 10 Hz from the forearm of 55 participants (34 CKD including 5 with end-stage renal disease, and 21 age-matched control). Continuous wavelet transform-based spectral analysis was used to quantify the spectral amplitude within five pre-defined frequency intervals (I, 0.0095–0.021 Hz; II, 0.021–0.052 Hz; III, 0.052–0.145 Hz; IV, 0.145–0.6 Hz and V, 0.6–2.0 Hz), representing endothelial, neurogenic, myogenic, respiratory and heartbeat activity, respectively. CKD patients showed lower tHb average spectral amplitude within the neurogenic frequency interval compared with controls (p = 0.014), consistent with an increased sympathetic outflow observed in CKD. CKD patients also showed lower TSI average spectral amplitude within the endothelial frequency interval compared with controls (p = 0.046), consistent with a reduced endothelial function in CKD. These findings demonstrate the potential of wavelet analysis of NIRS to provide complementary information on peripheral microvascular regulation in CKD. • Wavelet analysis of resting NIRS in skeletal muscle quantifies diminished peripheral microvascular regulation in CKD. • Reduced tHb neurogenic spectral amplitude reflects increased sympathetic outflow and reduced neurovascular control in CKD. • Reduced endothelial spectral amplitude of tissue saturation in CKD is suggestive of impaired endothelial function. [ABSTRACT FROM AUTHOR]

Objective: This study aims to determine the accuracy of a novel ultrasonography (US) scanning and reporting protocol to detect recurrences. The secondary aim is to compare US and MRI accuracy and agreement. Materials and methods: In this IRB-approved prospective study, consecutive patients presenting for MRI surveillance after resection were enrolled and underwent same-day US. Blinded to clinical information and the MRI, the US scanner characterized lesions using a proposed novel lexicon. Outcome was defined either by histology or a subsequent MRI scan confirming the presence or absence of recurrence. Fisher's exact test and Kappa test were performed to assess of the significance and agreement between US, MRI, and outcome. Results: A total of 68 US scans were performed on 55 patients. The overall accuracy to diagnose recurrence was the same for US and MRI (92.6%) while US was less sensitive (75.0% vs. 91.7%) but more specific (97.6% vs. 92.9%) than MRI. The two lesions missed by US but not MRI were an entirely intraosseous metastasis and a subcentimeter skin nodule. There was strong agreement between US and MRI with outcome (k = 0.787 and 0.801, respectively). Conclusions: These pilot data suggest the accuracy of this novel US local recurrence surveillance method is comparable to MRI. A multi-institutional prospective trial would increase power and determine reproducibility. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) is the non-invasive modality of choice for body tissue composition analysis due to its excellent soft-tissue contrast and lack of ionizing radiation. However, quantification of body composition requires an accurate segmentation of fat, muscle, and other tissues from MR images, which remains a challenging goal due to the intensity overlap between them. In this study, we propose a fully automated, data-driven image segmentation platform that addresses multiple difficulties in segmenting MR images such as varying inhomogeneity, non-standardness, and noise, while producing a high-quality definition of different tissues. In contrast to most approaches in the literature, we perform segmentation operation by combining three different MRI contrasts and a novel segmentation tool, which takes into account variability in the data. The proposed system, based on a novel affinity definition within the fuzzy connectivity image segmentation family, prevents the need for user intervention and reparametrization of the segmentation algorithms. In order to make the whole system fully automated, we adapt an affinity propagation clustering algorithm to roughly identify tissue regions and image background. We perform a thorough evaluation of the proposed algorithm's individual steps as well as comparison with several approaches from the literature for the main application of muscle/fat separation. Furthermore, whole-body tissue composition and brain tissue delineation were conducted to show the generalization ability of the proposed system. This new automated platform outperforms other state-of-the-art segmentation approaches both in accuracy and efficiency. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the automatic detection of white and brown adipose tissues using Positron Emission Tomography/Computed Tomography (PET/CT) scans, and develop methods for the quantification of these tissues at the whole-body and body-region levels. We propose a patient-specific automatic adiposity analysis system with two modules. In the first module, we detect white adipose tissue (WAT) and its two sub-types from CT scans: Visceral Adipose Tissue (VAT) and Subcutaneous Adipose Tissue (SAT). This process relies conventionally on manual or semi-automated segmentation, leading to inefficient solutions. Our novel framework addresses this challenge by proposing an unsupervised learning method to separate VAT from SAT in the abdominal region for the clinical quantification of central obesity. This step is followed by a context driven label fusion algorithm through sparse 3D Conditional Random Fields (CRF) for volumetric adiposity analysis. In the second module, we automatically detect, segment, and quantify brown adipose tissue (BAT) using PET scans because unlike WAT, BAT is metabolically active. After identifying BAT regions using PET, we perform a co-segmentation procedure utilizing asymmetric complementary information from PET and CT. Finally, we present a new probabilistic distance metric for differentiating BAT from non-BAT regions. Both modules are integrated via an automatic body-region detection unit based on one-shot learning. Experimental evaluations conducted on 151 PET/CT scans achieve state-of-the-art performances in both central obesity as well as brown adiposity quantification. [ABSTRACT FROM AUTHOR]

Whether individuals with insulin resistance (IR) but without criteria for diabetes exhibit reduced mitochondrial oxidative capacity is unclear; addressing this question could guide research for new therapeutics. We investigated 248 participants without diabetes from the Baltimore Longitudinal Study of Aging (BLSA) to determine whether impaired mitochondrial capacity is associated with prediabetes, IR, and duration and severity of hyperglycemia exposure. Mitochondrial capacity was assessed as the postexercise phosphocreatine recovery time constant (τPCr) by 31P-magnetic resonance spectroscopy, with higher τPCr values reflecting reduced capacity. Prediabetes was defined using the American Diabetes Association criteria from fasting and 2-h glucose measurements. IR and sensitivity were calculated using HOMA-IR and Matsuda indices. The duration and severity of hyperglycemia exposure were estimated as the number of years from prediabetes onset and the average oral glucose tolerance test (OGTT) 2-h glucose measurement over previous BLSA visits. Covariates included age, sex, body composition, physical activity, and other confounders. Higher likelihood of prediabetes, higher HOMA-IR, and lower Matsuda index were associated with longer τPCr. Among 205 participants with previous OGTT data, greater severity and longer duration of hyperglycemia were independently associated with longer τPC In conclusion, in individuals without diabetes a more impaired mitochondrial capacity is associated with greater IR and a higher likelihood of prediabetes. [ABSTRACT FROM AUTHOR]

Diffusion tensor imaging (DTI) measures are commonly used as imaging markers to investigate individual differences in relation to behavioral and health-related characteristics. However, the ability to detect reliable associations in cross-sectional or longitudinal studies is limited by the reliability of the diffusion measures. Several studies have examined the reliability of diffusion measures within (i.e. intra-site) and across (i.e. inter-site) scanners with mixed results. Our study compares the test–retest reliability of diffusion measures within and across scanners and field strengths in cognitively normal older adults with a follow-up interval less than 2.25 years. Intra-class correlation (ICC) and coefficient of variation (CoV) of fractional anisotropy (FA) and mean diffusivity (MD) were evaluated in sixteen white matter and twenty-six gray matter bilateral regions. The ICC for intra-site reliability (0.32 to 0.96 for FA and 0.18 to 0.95 for MD in white matter regions; 0.27 to 0.89 for MD and 0.03 to 0.79 for FA in gray matter regions) and inter-site reliability (0.28 to 0.95 for FA in white matter regions, 0.02 to 0.86 for MD in gray matter regions) with longer follow-up intervals were similar to earlier studies using shorter follow-up intervals. The reliability of across field strengths comparisons was lower than intra- and inter-site reliabilities. Within and across scanner comparisons showed that diffusion measures were more stable in larger white matter regions (> 1500 mm 3 ). For gray matter regions, the MD measure showed stability in specific regions and was not dependent on region size. Linear correction factor estimated from cross-sectional or longitudinal data improved the reliability across field strengths. Our findings indicate that investigations relating diffusion measures to external variables must consider variable reliability across the distinct regions of interest and that correction factors can be used to improve consistency of measurement across field strengths. An important result of this work is that inter-scanner and field strength effects can be partially mitigated with linear correction factors specific to regions of interest. These data-driven linear correction techniques can be applied in cross-sectional or longitudinal studies. [ABSTRACT FROM AUTHOR]

R2304 --> 885.2 --> This study aims to evaluate the effectiveness of aerobic exercise training on microcirculatory function among individuals with chronic kidney disease (CKD). Microcirculatory dysfunction is a prevalent complication in CKD that progresses as CKD evolves. Endothelial dysfunction is an early manifestation of microvascular disease and contributes to increased cardiovascular‐related mortality in CKD. Evidence indicates that endothelial dysfunction might be linked to deficits in blood perfusion and oxygen delivery. Aerobic exercise has been shown to improve cardiorespiratory function and blood pressure control for adults with CKD. Previous work has validated correspondence of specific frequency intervals in resting microvascular blood flow fluctuations with physiological events. Specifically, the spectrum amplitude from three frequency intervals (0.0095 – 0.02 Hz, 0.02 – 0.06 Hz, 0.06 – 0.15 Hz) have been attributed to microvascular regulation by endothelial, neurogenic, and myogenic origins, respectively. We hypothesized that 12 weeks of aerobic exercise would improve endothelial function in CKD. Ten CKD participants (Table 1) were randomized into treatment and control groups that performed progressive aerobic cycling exercise (N = 5) for 20‐45 min up to 80% of heart rate reserve and non‐aerobic, stretching exercise (N = 5). Each group performed activities 3 days/week for 12 weeks. Resting microvascular blood flow was measured in the forearm for 5 minutes using total hemoglobin (tHb) signal from near‐infrared spectroscopy. Reactive hyperemic index (RHI) was measured using peripheral artery tonometry at the upper arm, providing an accepted, single‐value index of endothelial function. Both measures were obtained at the beginning (baseline) and end of the 12‐week intervention (EOS), respectively. The resting tHb signal was analyzed using wavelet transform to obtain time‐frequency information on microcirculation regulated by endothelial, neurogenic, and myogenic functions. Differences at baseline and EOS were assessed using pairwise Student's t‐test (statistical significance: p < 0.05). The Pearson correlation coefficient between RHI and individual mean spectral amplitude was also obtained. Endothelial spectral amplitudes significantly decreased (p = 0.007) in the stretching group over the 12‐week intervention, suggesting decreased endothelial function (Fig.1). There was no significant change in the endothelial spectral amplitude (p = 0.16) in the cycling group. Changes in individual endothelial spectral amplitude and RHI were moderately correlated (r = 0.57 and p = 0.02). In conclusion, spectral analysis of resting microvascular blood flow in CKD suggests preserved endothelial function over 12 weeks of progressive aerobic cycling exercise, compared with a decline in those who performed a non‐aerobic stretching exercise. Ongoing work focuses on adapting and applying this wavelet methodology to MRI‐derived signals that provide temporo‐spatially resolved information on tissue oxygenation and perfusion. Resting microcirculatory properties yielded from this work may be useful for monitoring disease progression and guiding targeted therapeutic strategies to improve microvascular function in CKD. [ABSTRACT FROM AUTHOR]

ABSTRACT This work evaluates the ability of quantitative MRI to discriminate between normal and pathological human osteochondral plugs characterized by the Osteoarthritis Research Society International (OARSI) histological system. Normal and osteoarthritic human osteochondral plugs were scored using the OARSI histological system and imaged at 3 T using MRI sequences producing T1 and T2 contrast and measuring T1, T2, and T2* relaxation times, magnetization transfer, and diffusion. The classification accuracies of quantitative MRI parameters and corresponding weighted image intensities were evaluated. Classification models based on the Mahalanobis distance metric for each MRI measurement were trained and validated using leave-one-out cross-validation with plugs grouped according to OARSI histological grade and score. MRI measurements used for classification were performed using a region-of-interest analysis which included superficial, deep, and full-thickness cartilage. The best classifiers based on OARSI grade and score were T1- and T2-weighted image intensities, which yielded accuracies of 0.68 and 0.75, respectively. Classification accuracies using OARSI score-based group membership were generally higher when compared with grade-based group membership. MRI-based classification-either using quantitative MRI parameters or weighted image intensities-is able to detect early osteoarthritic tissue changes as classified by the OARSI histological system. These findings suggest the benefit of incorporating quantitative MRI acquisitions in a comprehensive clinical evaluation of OA. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:640-650, 2015. [ABSTRACT FROM AUTHOR]

Courtney N. Gleason was incorrectly captured in the original manuscript. [ABSTRACT FROM AUTHOR]

Abstract: We present a fractional-order extension of the Bloch equations to describe anomalous NMR relaxation phenomena (T 1 and T 2). The model has solutions in the form of Mittag–Leffler and stretched exponential functions that generalize conventional exponential relaxation. Such functions have been shown by others to be useful for describing dielectric and viscoelastic relaxation in complex, heterogeneous materials. Here, we apply these fractional-order T 1 and T 2 relaxation models to experiments performed at 9.4 and 11.7 Tesla on type I collagen gels, chondroitin sulfate mixtures, and to bovine nasal cartilage (BNC), a largely isotropic and homogeneous form of cartilage. The results show that the fractional-order analysis captures important features of NMR relaxation that are typically described by multi-exponential decay models. We find that the T 2 relaxation of BNC can be described in a unique way by a single fractional-order parameter (α), in contrast to the lack of uniqueness of multi-exponential fits in the realistic setting of a finite signal-to-noise ratio. No anomalous behavior of T 1 was observed in BNC. In the single-component gels, for T 2 measurements, increasing the concentration of the largest components of cartilage matrix, collagen and chondroitin sulfate, results in a decrease in α, reflecting a more restricted aqueous environment. The quality of the curve fits obtained using Mittag–Leffler and stretched exponential functions are in some cases superior to those obtained using mono- and bi-exponential models. In both gels and BNC, α appears to account for micro-structural complexity in the setting of an altered distribution of relaxation times. This work suggests the utility of fractional-order models to describe T 2 NMR relaxation processes in biological tissues. [Copyright &y& Elsevier]

Recent literature has examined the importance of cervical alignment with regards to health-related quality-of-life outcomes. Several cervical alignment parameters have been identified as potential goals for correction of cervical spinal deformities. Of these parameters, the C2-7 sagittal vertical axis (SVA) has been utilized as a measure of global cervical alignment, and previous work has suggested that achieving a postoperative SVA of 4 cm or less is ideal with regard to patient outcomes. The purpose of this study was to determine the impact of SVA on postoperative neck pain scores after posterior cervical laminectomy and fusion for myelopathy. We performed a retrospective review of a multicenter prospective cohort of patients undergoing posterior cervical laminectomy and fusion from C2-T2 for subaxial cervical stenosis and degenerative cervical myelopathy from 2011-2018. A total of 173 patients were identified. SVA and VAS neck pain scores were recorded. We collected demographic information and assessed cervical alignment on standing radiographs performed preoperatively as well as at 6 months or greater postoperatively. The cohort was divided into 2 groups based on a postoperative SVA of <4 cm or ≥4 based on established criteria. We then examined differences between the groups with regard to preoperative and postoperative alignment, demographics, and neck pain scores as measured by the visual analog scale. A univariate analysis was performed to assess for differences between the 2 groups. All statistical analyses were performed with JMP®Pro 14.1.0. A total of 173 patients were identified for inclusion. In this cohort, 70 patients were identified as having a postoperative SVA <4 cm and 103 patients were identified as having an SVA ≥4cm. In both groups, the change in SVA showed a worsening of alignment. This was significantly higher in the SVA >4 cohort compared to the SVA <4 cohort (-11.6 vs -3.3, p<.001). There was also a significantly higher proportion of female patients in the SVA <4 cohort (54.3% vs 30.1%). Otherwise, there were no other significant differences in demographics between the 2 groups. Of the 173 patients, 108 patients (62.4%) had VAS neck pain scores recorded at greater than 6 months postoperatively. With regard to VAS neck pain scores, they improved in both groups with long-term follow-up. There was no significant difference between the cohorts with respect to neck pain scores at any time point. Using the established minimal clinically important difference for VAS neck pain following cervical surgery, we found that 61.9% of the SVA <4 cohort and 52.9% SVA >4 cohort achieved MCID with no significant difference between the groups (p =.432). The primary goal for posterior cervical laminectomy and fusion in the treatment of degenerative myelopathy is to achieve adequate decompression of the spinal cord and a stable, fused spine. While previous work has established the importance of SVA alignment in treatment of cervical deformity, in this multicenter cohort of patients undergoing C2-T2 posterior cervical fusion for degenerative myelopathy, postoperative SVA >4 cm was not associated with a significant difference in long-term patient-reported outcomes with regard to neck pain. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Surgical site infections (SSIs) pose a significant burden to both patients and the health care system with recent focus on the identification and modification of applicable risk factors in spine surgery. However, there is a paucity of literature evaluating the clinical outcomes of patients treated for infection after spine surgery. To compare the clinical outcomes of patients who developed SSI after thoracolumbar spine surgery to an aseptic control cohort. Retrospective propensity matched case-control study. Adult patients who underwent thoracolumbar spinal fusion between March 2014 and January 2020. Oswestry Disability Index (ODI), Visual Analog Scale (VAS) Back and Leg, Physical Component (PCS) and Mental Component (MCS) of the SF-12. Structured query language query (SQL) was used to identify patients and extract patient-reported outcome measures (PROMs). Demographic data was extracted through chart review. Patients who developed an SSI were matched to a control cohort based on age, sex, body mass index (BMI), diabetes status, smoking status and race through propensity score matching. A total of 176 patients (132 Control, 44 SSI) with a mean age of 66 years, body-mass index of 34, ASA of 2.76 were included in final analysis. Both groups demonstrated significant improvements in ODI (Control: p<0.001, SSI: p=0.006), VAS Back (Control: p<0.001, SSI: p=0.002), VAS Leg (Control and SSI:p<0.001), and PCS-12 (Control:p<0.009, SSI:p=0.01) after surgery. Despite comparable preoperative and ∆ODI scores, patients who had an SSI had significantly worse postoperative ODI scores (Control:28.5, SSI: 37.5, p=0.024). ∆VAS Leg, ∆VAS Back, ∆PCS-12, and ∆MCS-12 did not differ significantly between groups with no difference in the proportion of individuals meeting MCID for VAS Leg (60.6% vs 57.1%, p=0.899), VAS Back (Control: 63.6%, SSI: 57.1%, p=0.667), PCS-12 (Control: 22.1%, SSI: 26.1%, p=0.868) or MCS-12 (Control: 20.5%, SSI: 30.4%, p=0.427). Despite the associated morbidity of infection after spine surgery, the results of this study demonstrate that patients who sustain SSI after lumbar fusion can ultimately expect similar clinical outcomes as those without postoperative complications and can be used by surgeons to help counsel patients. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Impaired tissue perfusion underlies many chronic disease states and aging. Diffusion-weighted imaging (DWI) is a noninvasive MRI technique that has been widely used to characterize tissue perfusion. Parametric models based on DWI measurements can characterize microvascular perfusion modulated by functional and microstructural alterations in the skeletal muscle. The intravoxel incoherent motion (IVIM) model uses a biexponential form to quantify the incoherent motion of water molecules in the microvasculature at low b-values of DWI measurements. The fractional Fickian diffusion (FFD) model is a parsimonious representation of anomalous superdiffusion that uses the stretched exponential form and can be used to quantify the microvascular volume of skeletal muscle. Both models are established measures of perfusion based on DWI, and the prognostic value of model parameters for identifying pathophysiological processes has been studied. Although the mathematical properties of individual models have been previously reported, quantitative connections between IVIM and FFD models have not been examined. This work provides a mathematical framework for obtaining a direct, one-way transformation of the parameters of the stretched exponential model to those of the biexponential model. Numerical simulations are implemented, and the results corroborate analytical results. Additionally, analysis of in vivo DWI measurements in skeletal muscle using both biexponential and stretched exponential models is shown and compared with analytical and numerical models. These results demonstrate the difficulty of model selection based on goodness of fit to experimental data. This analysis provides a framework for better interpreting and harmonizing perfusion parameters from experimental results using these two different models. [ABSTRACT FROM AUTHOR]