Denervation impacts muscle quality and knee bone mineral density after spinal cord injury.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To compare muscle size, body composition, bone mineral density (BMD), and metabolic profiles in denervated versus innervated individuals with spinal cord injury (SCI). SETTING: Hunter Holmes McGuire Veterans Affairs (VA) Medical Center. METHODS: Body composition, bone mineral density (BMD), muscle size, and metabolic parameters were collected in 16 persons with chronic SCI (n = 8 denervated, n = 8 innervated) using dual-energy x-ray absorptiometry (DXA), magnetic resonance imaging (MRI), and fasting blood samples. BMR was measured by indirect calorimetry. RESULTS: Percent differences of the whole thigh muscle cross-sectional area (CSA; 38%), knee extensor CSA (49%), vasti CSA (49%), and rectus femoris CSA (61%) were smaller in the denervated group (p < 0.05). Leg lean mass was also lower (28%) in the denervated group (p < 0.05). Whole muscle intramuscular fat (IMF%; 15.5%), knee extensor IMF% (22%), and % fat mass (10.9%) were significantly greater in the denervated group (p < 0.05). Knee distal femur and proximal tibia BMD were lower in the denervated group, 18-22% and 17-23%; p < 0.05. Certain indices of metabolic profile were more favorable in the denervated group though were not significant. CONCLUSIONS: SCI results in skeletal muscle atrophy and dramatic changes in body composition. Lower motor neuron (LMN) injury results in denervation of the lower extremity muscles which exacerbates atrophy. Denervated participants exhibited lower leg lean mass and muscle CSA, greater muscle IMF, and reduced knee BMD compared to innervated participants. Future research is needed to explore therapeutic treatments for the denervated muscles after SCI.

Characterization of patient dose distributions and probabilistic risk analysis in cardiovascular catheterization laboratories.

Purpose: Patient radiation doses in cardiovascular and interventional radiology are highly variable for similar procedures. This random nature may be better described by a distribution function, compared to a linear regression. This study develops a distribution function to characterize patient dose distributions and estimate probabilistic risk.Methods: Reference air kerma from 8647 patients over six years were retrospectively collected from an EP lab and two Cath labs. Data was first sorted into low dose (<100mGy) and high dose cases (>100mGy), and histograms of the data created. Dagum and Inverse gamma distributions were chosen to initially fit to both low and high dose cases. Fits between model and the data was optimized, and a linear regression analysis performed to obtain R squared values and standard errors for the correlation between model and data. Risk probabilities were estimated according to the modeled distribution function. BMI and time distributions were analyzed to understand their influence on the inverse gamma distribution error found in the data. 75th percentiles from both descriptive statistics and model were calculated.Results: The inverse gamma distribution can be used to characterize radiation dose distributions. Model predicted cases for radiation dose 3000mGy< x <5000mGy and >5000mGy are approximately 42 and 0 for 3651 cases for lab#1, and 14 and 1 for 3197 cases for lab#2, respectively, while the actual cases are 10 and 0, and 16 and 2. Descriptive and model statistics generated different 75th percentile levels for sorted data compared to unsorted data. Time has a greater influence on inverse gamma distribution function than BMI.Conclusion: This study creates a framework to understand the random error present in radiology practices that cause wide variations in patient radiation doses. It also provides an approach to evaluate different IR areas in terms of effectiveness of dose reduction measures.

Skeletal muscle stiffness as measured by magnetic resonance elastography after chronic spinal cord injury: a cross-sectional pilot study.

Skeletal muscle stiffness is altered after spinal cord injury (SCI). Assessing muscle stiffness is essential for rehabilitation and pharmaceutical interventions design after SCI. The study used magnetic resonance elastography to assess the changes in stiffness after chronic SCI compared to matched able-bodied controls and determine its association with muscle size, spasticity, and peak torque in persons with SCI. Previous studies examined the association between muscle stiffness and spasticity, however, we are unaware of other studies that examined the effects of muscle composition on stiffness after SCI. Ten participants (one female) with chronic SCI and eight (one female) matched able-bodied controls participated in this cross-sectional study. Magnetic resonance elastography was utilized to monitor stiffness derived from shear waves propagation. Modified Ashworth scale was used to evaluate spasticity scores in a blinded fashion. Peak isometric and isokinetic torques were measured using a biodex dynamometer. Stiffness values were non-significantly lower (12.5%; P = 0.3) in the SCI group compared to able-bodied controls. Moreover, stiffness was positively related to vastus lateralis whole muscle cross-sectional area (CSA) (r2 = 0.64, P < 0.005) and vastus lateralis absolute muscle CSA after accounting for intramuscular fat (r2 = 0.78, P < 0.0007). Stiffness was also positively correlated to both isometric (r2= 0.55-0.57, P < 0.05) and isokinetic peak (r2= 0.46-0.48, P < 0.05) torques. Our results suggest that larger clinical trial is warranted to confirm the preliminary findings that muscle stiffness is altered after SCI compared to healthy controls. Stiffness appeared to be influenced by infiltration of intramuscular fat and modestly by the spasticity of the paralyzed muscles. The preliminary data indicated that the relationship between muscle stiffness and peak torque is not altered with changing the frequency of pulses or angular velocities. All study procedures were approved by the Institutional Review Board at the Hunter Holmes McGuire VA Medical Center, USA (IRB #: 02314) on May 3, 2017.

Semi-automated segmentation of magnetic resonance images for thigh skeletal muscle and fat using threshold technique after spinal cord injury.

Magnetic resonance imaging is considered the "gold standard" technique for quantifying thigh muscle and fat cross-sectional area. We have developed a semi-automated technique to segment seven thigh compartments in persons with spinal cord injury. Thigh magnetic resonance images from 18 men (18-50 years old) with traumatic motor-complete spinal cord injury were analyzed in a blinded fashion using the threshold technique. The cross-sectional area values acquired by thresholding were compared to the manual tracing technique. The percentage errors for thigh circumference were (threshold: 170.71 ± 38.67; manual: 169.45 ± 38.27 cm2) 0.74%, subcutaneous adipose tissue (threshold: 65.99±30.79; manual: 62.68 ± 30.22) 5.2%, whole muscle (threshold: 98.18 ± 20.19; manual: 98.20 ± 20.08 cm2) 0.13%, femoral bone (threshold: 6.53 ± 1.09; manual: 6.53 ± 1.09 cm2) 0.64%, bone marrow fat (threshold: 3.12 ± 1.12; manual: 3.1 ± 1.11 cm2) 0.36%, knee extensor (threshold: 43.98 ± 7.66; manual: 44.61 ± 7.81 cm2) 1.78% and % intramuscular fat (threshold: 10.45 ± 4.29; manual: 10.92 ± 8.35%) 0.47%. Collectively, these results suggest that the threshold technique provided a robust accuracy in measuring the seven main thigh compartments, while greatly reducing the analysis time.

Contrast use in relation to the arterial access site for percutaneous coronary intervention: A comprehensive meta-analysis of randomized trials.

AIM: To compare the amount of contrast used during percutaneous coronary intervention (PCI) via trans-radial access (TRA) vs trans-femoral access (TFA). METHODS: Scientific databases and websites were searched for:randomizedcontrolledtrials (RCTs). Data were extracted by two independent reviewers and was summarized as the weighted mean difference (WMD) of contrast used with a 95%CI using a random-effects model. RESULTS: The meta-analysis included 13 RCTs with a total of 3165 patients. There was no difference between the two strategies in the amount of contrast used (WMD = - 0.65 mL, 95%CI: -10.94-9.46 mL; P = 0.901). CONCLUSION: This meta-analysis shows that in patients undergoing PCI, the amount of contrast volume used was not different between TRA and TFA.

Liver Adiposity and Metabolic Profile in Individuals with Chronic Spinal Cord Injury.

PURPOSE: To quantify liver adiposity using magnetic resonance imaging (MRI) and to determine its association with metabolic profile in men with spinal cord injury (SCI). MATERIALS AND METHODS: MRI analysis of liver adiposity by fat signal fraction (FSF) and visceral adipose tissue (VAT) was completed on twenty participants. Intravenous glucose tolerance test was conducted to measure glucose effectiveness (Sg) and insulin sensitivity (Si). Lipid panel, fasting glucose, glycated hemoglobin (HbA1c), and inflammatory cytokines were also analyzed. RESULTS: Average hepatic FSF was 3.7% ± 2.1. FSF was positively related to TG, non-HDL-C, fasting glucose, HbA1c, VAT, and tumor necrosis factor alpha (TNF-α). FSF was negatively related to Si and testosterone. FSF was positively related to VAT (r = 0.48, p = 0.032) and TNF-α (r = 0.51, p = 0.016) independent of age, level of injury (LOI), and time since injury (TSI). The associations between FSF and metabolic profile were independent of VAT. CONCLUSIONS: MRI noninvasively estimated hepatic adiposity in men with chronic SCI. FSF was associated with dysfunction in metabolic profile, central adiposity, and inflammation. Importantly, liver adiposity influenced metabolic profile independently of VAT. These findings highlight the significance of quantifying liver adiposity after SCI to attenuate the development of metabolic disorders.

An 81-year-old man with an abnormal right-sided heart shadow on chest radiograph.

An 81-year-old man presented with a 1-week history of dry cough. He also complained of mild dyspnea, wheezing, and low-grade fever. He denied hemoptysis, fever, rashes, or chest pain. The patient's medical history included coronary artery bypass surgery, hypertension, gastroesophageal reflux disease, and COPD. The patient was a retired welder and an ex-smoker.