Search

Purpose: Concussion management is shifting away from a rest-is-best approach, as data now suggest that exercise-is-medicine for this mild brain injury. Despite this, we have limited data on habitual physical activity following concussion. Therefore, our objective was to quantify accelerometer-measured physical activity and sedentary time in children with concussion (within the first month of injury) and healthy controls. We hypothesized that children with concussion would be less active than their healthy peers. Methods: We performed a secondary analysis of prospectively collected accelerometer data. Our sample included children with concussion (n = 60, 31 females) and historical controls (n = 60) matched for age, sex, and season of accelerometer wear. Results: Children with concussion were significantly more sedentary than controls (mean difference [MD], 38.3 min/d, P =.006), and spent less time performing light physical activity (MD, −19.5 min/d, P =.008), moderate physical activity (MD, −9.8 min/d, P <.001), and vigorous physical activity (MD, −12.0 min/d, P <.001); these differences were observed from 8:00 AM to 9:00 PM. Sex-specific analyses identified that girls with concussion were less active and more sedentary than both boys with concussion (P =.010) and healthy girls (P <.010). Conclusion: There is an activity deficit observed within the first month of pediatric concussion. Physical activity guidelines should address this while considering sex effects. [ABSTRACT FROM AUTHOR]

Background: Recent scientific evidence has challenged the traditional "rest-is-best" approach for concussion management. It is now thought that "exercise-is-medicine" for concussion, owing to dozens of studies which demonstrate that sub-maximal, graded aerobic exercise can reduce symptom burden and time to symptom resolution. However, the primary neuropathology of concussion is altered functional brain activity. To date, no studies have examined the effects of sub-maximal aerobic exercise on resting state functional brain activity in pediatric concussion. In addition, although exercise is now more widely prescribed following concussion, its cardiopulmonary response is not yet well understood in this population. Our study has two main goals. The first is to understand whether there are exercise-induced resting state functional brain activity differences in children with concussion vs. healthy controls. The second is to profile the physiological response to exercise and understand whether it differs between groups. Methods: We will perform a single-center, controlled, prospective cohort study of pediatric concussion at a large, urban children's hospital and academic center. Children with sport-related concussion (aged 12–17 years) will be recruited within 4-weeks of injury by our clinical study team members. Key inclusion criteria include: medical clearance to exercise, no prior concussion or neurological history, and no implants that would preclude MRI. Age- and sex-matched healthy controls will be required to meet the same inclusion criteria and will be recruited through the community. The study will be performed over two visits separated by 24–48 h. Visit 1 involves exercise testing (following the current clinical standard for concussion) and breath-by-breath gas collection using a metabolic cart. Visit 2 involves two functional MRI (fMRI) scans interspersed by 10-minutes of treadmill walking at an intensity calibrated to Visit 1 findings. To address sub-objectives, all participants will be asked to self-report symptoms daily and wear a waist-worn tri-axial accelerometer for 28-days after Visit 2. Discussion: Our study will advance the growing exercise-concussion field by helping us understand whether exercise impacts outcomes beyond symptoms in pediatric concussion. We will also be able to profile the cardiopulmonary response to exercise, which may allow for further understanding (and eventual optimization) of exercise in concussion management. Trial registration: Not applicable. [ABSTRACT FROM AUTHOR]

Although hyperpolarized (HP) 129Xe ventilation MRI can be carried out within a breath hold, it is still challenging for many sick patients. Compressed sensing (CS) is a viable alternative to accelerate this approach. However, undersampled images with identical sampling ratios differ from one another. Twenty subjects (n = 10 healthy and n = 10 patients with asthma) were scanned using a GE MR750 3 T scanner, acquiring fully sampled 2D multi‐slice HP 129Xe lung ventilation images (10 s breath hold, 128 × 80 (FE × PE—frequency encoding × phase encoding) and 16 slices). Using fully sampled data, 500 variable‐density Cartesian random undersampling patterns were generated, each at eight different sampling ratios from 10% to 80%. The parallel imaging and compressed sensing (PICS) command from BART was employed to reconstruct undersampled data. The signal to noise ratio (SNR), structural similarity index measurement (SSIM) and sidelobe to peak ratio of each were subsequently compared. There was a high degree of variation in both SNR and SSIM results from each of the 500 masks of each sampling rate. As the undersampling increases, there is more variation in the quantifying metrics, for both healthy and asthmatic individuals. Our study shows that random undersampling poses a significant challenge when applied at sampling ratios less than 60%, despite fulfilling CS's incoherency criteria. Such low sampling ratios will result in a large variety of undersampling patterns. Therefore, skipped segments of k‐space cannot be allowed to happen randomly at low sampling rates. By optimizing the sampling pattern, CS will reach its full potential and be able to be applied to a highly undersampled 129Xe lung dataset. [ABSTRACT FROM AUTHOR]

The human brain is an exceptionally complex organ that is comprised of billions of neurons. Therefore, when a traumatic event such as a concussion occurs, somatic, cognitive, behavioral, and sleep impairments are the common outcome. Each concussion is unique in the sense that the magnitude of biomechanical forces and the direction, rotation, and source of those forces are different for each concussive event. This helps to explain the unpredictable nature of post-concussion symptoms that can arise and resolve. The purpose of this narrative review is to connect the anatomical location, healthy function, and associated post-concussion symptoms of some major cerebral gray and white matter brain regions and the cerebellum. As a non-exhaustive description of post-concussion symptoms nor comprehensive inclusion of all brain regions, we have aimed to amalgamate the research performed for specific brain regions into a single article to clarify and enhance clinical and research concussion assessment. The current status of concussion diagnosis is highly subjective and primarily based on self-report of symptoms, so this review may be able to provide a connection between brain anatomy and the clinical presentation of concussions to enhance medical imaging assessments. By explaining anatomical relevance in terms of clinical concussion symptom presentation, an increased understanding of concussions may also be achieved to improve concussion recognition and diagnosis. [ABSTRACT FROM AUTHOR]

White matter (WM) injury is frequently observed along with dementia. Positron emission tomography with amyloid-ligands (Aβ-PET) recently gained interest for detecting WM injury. Yet, little is understood about the origin of the altered Aβ-PET signal in WM regions. Here, we investigated the relative contributions of diffusion MRI-based microstructural alterations, including free water and tissue-specific properties, to Aβ-PET in WM and to cognition. We included a unique cohort of 115 participants covering the spectrum of low-to-severe white matter hyperintensity (WMH) burden and cognitively normal to dementia. We applied a bi-tensor diffusion-MRI model that differentiates between (i) the extracellular WM compartment (represented via free water), and (ii) the fiber-specific compartment (via free water-adjusted fractional anisotropy [FA]). We observed that, in regions of WMH, a decrease in Aβ-PET related most closely to higher free water and higher WMH volume. In contrast, in normal-appearing WM, an increase in Aβ-PET related more closely to higher cortical Aβ (together with lower free water-adjusted FA). In relation to cognitive impairment, we observed a closer relationship with higher free water than with either free water-adjusted FA or WM PET. Our findings support free water and Aβ-PET as markers of WM abnormalities in patients with mixed dementia, and contribute to a better understanding of processes giving rise to the WM PET signal. [ABSTRACT FROM AUTHOR]

Introduction: The ideal contrast agents for ventilation SPECT and MRI are Technegas and 129Xe gas, respectively. Despite increasing interest in the clinical utility of ventilation imaging, these modalities have not been directly compared. Therefore, our objective was to compare the ventilation defect percent (VDP) assessed by Technegas SPECT and hyperpolarized 129Xe MRI in patients scheduled to undergo lung cancer resection with and without pre-existing obstructive lung disease. Methods: Forty-one adults scheduled to undergo lung cancer resection performed same-day Technegas SPECT, hyperpolarized 129Xe MRI, spirometry, and diffusing capacity of the lung for carbon monoxide (DLCO). Ventilation abnormalities were quantified as the VDP using two different methods: adaptive thresholding (VDPT) and k-means clustering (VDPK). Correlation and agreement between VDP quantified by Technegas SPECT and 129Xe MRI were determined by Spearman correlation and Bland-Altman analysis, respectively. Results: VDP measured by Technegas SPECT and 129Xe MRI were correlated (VDPT: r = 0.48, p = 0.001; VDPK: r = 0.63, p < 0.0001). A 2.0% and 1.6% bias towards higher Technegas SPECT VDP was measured using the adaptive threshold method (VDPT: 23.0% ± 14.0% vs. 21.0% ± 5.2%, p = 0.81) and k-means method (VDPK: 9.4% ± 9.4% vs. 7.8% ± 10.0%, p = 0.02), respectively. For both modalities, higher VDP was correlated with lower FEV1/FVC (SPECT VDPT: r = -0.38, p = 0.01; MRI VDPK: r=-0.46, p = 0.002) and DLCO (SPECT VDPT: r=-0.61, p < 0.0001; MRI VDPK: r = -0.68, p < 0.0001). Subgroup analysis revealed that VDP measured by both modalities was significantly higher for participants with COPD (n = 13) than those with asthma (n = 6; SPECT VDPT: p = 0.007, MRI VDPK: p = 0.006) and those with no history of obstructive lung disease (n = 21; SPECT VDPT: p = 0.0003, MRI VDPK: p = 0.0003). Discussion: The burden of ventilation defects quantified by Technegas SPECT and 129Xe MRI VDP was correlated and greater in participants with COPD when compared to those without. Our observations indicate that, despite substantial differences between the imaging modalities, quantitative assessment of ventilation defects by Technegas SPECT and 129Xe MRI is comparable. [ABSTRACT FROM AUTHOR]

Pediatric concussion has a rising incidence and can lead to long-term symptoms in nearly 30% of children. Resting state functional magnetic resonance imaging (rs-fMRI) disturbances are a common pathological feature of pediatric concussion, though no studies have explicitly examined sex-differences with respect to this outcome, precluding a sex-specific understanding of the functional neuropathology of pediatric concussion. Therefore, we performed a secondary data analysis of rs-fMRI data collected on children with concussion (n = 29) recruited from in a pediatric hospital setting, with greater than 12:1 matched control data accessed from the open-source ABIDE-II database. Seed-based and region of interest (ROI) analyses were used to examine sex-based rs-fMRI differences; threshold-free cluster enhancement (TFCE) and a family-wise error (FWE) corrected p-values were used to identify significantly different clusters. In comparing females with concussion to healthy females, groupwise differences were observed irrespective of seed selected. Notably, we observed (in order of largest effect) hypo-connectivity between the anterior cingulate cortex of the salience network and the thalamus and precuneus (TFCE = 1473.5, p-FWE < 0.001) and the cingulate gyrus (TFCE = 769.3, p-FWE = 0.009), and the seed (posterior cingulate cortex (PCC)) of the default mode network and the paracingulate gyrus (TFCE = 1275.7, p-FWE < 0.001), occipital pole right (TFCE = 1045.0, p-FWE = 0.001), and sub-callosal cortex (TFCE = 844.9, p-FWE = 0.005). Hyper-connectivity was observed between the salience network seed and the cerebellum (TFCE = 1719.3, p-FWE < 0.001) and the PCC and the thalamus (TFCE = 1198.3, p-FWE < 0.001), cuneal cortex (1070.9, p-FWE = 0.001), and lateral occipital cortex left (TFCE = 832.8, p-FWE = 0.006). ROI analyses showed 10 and 5 significant clusters of hypo- and hyper-connectivity in females, respectively. Only one cluster of difference was found between males with concussion and healthy males on seed-based analyses, and 3 clusters on ROI analyses. There are alterations in rs-fMRI in females with concussion at one-month post-injury that are minimally present in males, which provides further evidence that recovery timelines in pediatric concussion may differ by sex. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Diabetes is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents a study that aims at exploring the relationship between resting-state intra-network connectivity and accelerometer-measured physical activity in pediatric concussion. Presents the preliminary findings that suggest that there is a positive association between the intra-network connectivity of the DMN and device-measured physical activity in children with concussion.

Objective: This proof-of-principle study integrates joint reaction forces (JRFs) and bone shape to assess acute cartilage changes from walking and cycling. Methods: Sixteen women with symptomatic knee osteoarthritis were recruited. Biomechanical assessment estimated JRFs during walking and cycling. Subsamples had magnetic resonance imaging (MRI) performed before and after a 25-min walking (n = 7) and/or cycling (n = 9) activity. MRI scans were obtained to assess cartilage shape and composition (T2 relaxation time). Bone shape was quantified using a statistical shape model built from 13 local participants and 100 MRI scans from the Osteoarthritis Initiative. Statistical parametric mapping quantified cartilage change and correlations between cartilage change with JRFs and statistical shape model features. Results: Cartilage thickness (interior lateral, Δ − 0.10 mm) and T2 (medial, Δ − 4 ms) decreased on the tibial plateau. On the femur, T2 change depended on the activity. Greater tibiofemoral JRF was associated with more cartilage deformation on the lateral femoral trochlea after walking (r − 0.56). Knees more consistent with osteoarthritis showed smaller decreases in tibial cartilage thickness. Discussion: Walking and cycling caused distinct patterns of cartilage deformation, which depended on knee JRFs and bone morphology. For the first time, these results show that cartilage deformation is dependent on bone shapes and JRFs in vivo. [ABSTRACT FROM AUTHOR]

Childhood obesity is a growing worldwide problem. In adults, lower cold-induced brown adipose tissue (BAT) activity is linked to obesity and metabolic dysfunction; this relationship remains uncertain in children. In this cross-sectional study, we compared cold-induced supraclavicular (SCV) BAT activity (percent change in proton density fat fraction [PDFF]) within the SCV region after 1 h of whole-body cold exposure (18°C), using MRI in 26 boys aged 8-10 years: 13 with normal BMI and 13 with overweight/obesity. Anthropometry, body composition, hepatic fat, visceral adipose tissue (VAT), and pre- and postcold PDFF of the subcutaneous adipose tissue (SAT) in the posterior neck region and the abdomen were measured. Boys with overweight/obesity had lower cold-induced percent decline in SCV PDFF compared with those with normal BMI (1.6 ± 0.8 vs. 4.7 ± 1.2%, P = 0.044). SCV PDFF declined significantly in boys with normal BMI (2.7 ± 0.7%, P = 0.003) but not in boys with overweight/obesity (1.1 ± 0.5%, P = 0.053). No cold-induced changes in the PDFF of either neck SAT (-0.89 ± 0.7%, P = 0.250, vs. 0.37 ± 0.3%, P = 0.230) or abdominal SAT (-0.39 ± 0.5%, P = 0.409, and 0.25 ± 0.2%, P = 0.139, for normal BMI and overweight/obesity groups, respectively) were seen. The cold-induced percent decline in SCV PDFF was inversely related to BMI (r = -0.39, P = 0.047), waist circumference (r = -0.48, P = 0.014), and VAT (r = -0.47, P = 0.014). Thus, in young boys, as in adults, BAT activity is lower in those with overweight/obesity, suggesting that restoring activity may be important for improving metabolic health. [ABSTRACT FROM AUTHOR]

Magnetic Resonance Imaging (MRI) is well‐suited for imaging peripheral blood flow due to its non‐invasive nature and excellent spatial resolution. Although MRI is routinely used in adults to assess physiological changes in chronic diseases, there are currently no MRI‐based data quantifying arterial flow in pediatric or adolescent populations during exercise. Therefore the current research sought to document femoral arterial blood flow at rest and following exercise in a pediatric‐adolescent population using phase contrast MRI, and to present test‐retest reliability data for this method. Ten healthy children and adolescents (4 male; mean age 14.8 ± 2.4 years) completed bloodwork and resting and exercise MRI. Baseline images consisted of PC‐MRI of the femoral artery at rest and following a 5 × 30 s of in‐magnet exercise. To evaluate test‐retest reliability, five participants returned for repeat testing. All participants successfully completed exercise testing in the MRI. Baseline flow demonstrated excellent reliability (ICC = 0.93, p = 0.006), and peak exercise and delta rest‐peak flow demonstrated good reliability (peak exercise ICC = 0.89, p = 0.002, delta rest‐peak ICC = 0.87, p = 0.003) between‐visits. All three flow measurements demonstrated excellent reliability when assessed with coefficients of variance (CV's) (rest: CV = 6.2%; peak exercise: CV = 7.3%; delta rest‐peak: CV = 7.1%). The mean bias was small for femoral arterial flow. There was no significant mean bias between femoral artery flow visits 1 and 2 at peak exercise. There were no correlations between age or height and any of the flow measurements. There were no significant differences between male and female participants for any of the flow measurements. The current study determined that peripheral arterial blood flow in children and adolescents can be evaluated using non‐invasive phase contrast MRI. The MRI‐based techniques that were used in the current study for measuring arterial flow in pediatric and adolescent patients demonstrated acceptable test‐retest reliability both at rest and immediately post‐exercise. [ABSTRACT FROM AUTHOR]

Overuse knee injuries are common in bicycling and are often attributed to poor bicycle-fit. Bicycle-fit for knee health focuses on setting saddle height to elicit a minimum knee flexion angle of 25-40°. Equations to predict saddle height include a single input, resulting in a likely suboptimal bicycle-fit. The purpose of this work was to develop an equation to predict saddle height from anthropometrics, bicycle geometry, and user-defined joint kinematics. Methods: Forty healthy adults (17 women, 23 men; mean (SD): 28.6 (7.2) years; 24.2 (2.6) kg/m2) participated. Kinematic analyses were conducted for 18 three-minute bicycling bouts including all combinations of 3 horizontal and 3 vertical saddle positions, and 2 crank arm lengths. For both minimum and maximum knee flexion, predictors were identified using Least Absolute Shrinkage and Selection Operator (LASSO) regression, and final models were fit using linear regression. Secondary analyses determined if saddle height equations were sex dependent. Results: The equation to predict saddle position from minimum knee flexion angle (R2=0.97; root mean squared error (RMSE) = 1.15 cm) was: Saddle height (cm) = 7.41 + 0.82(inseam cm) – 0.1(minimum knee flexion °) + 0.003(inseam cm)(seat tube angle °). The maximum knee flexion equation (R2=0.97; RMSE=1.15 cm) was: Saddle height (cm) = 41.63 + 0.78(inseam cm) – 0.25(maximum knee flexion °) + 0.002(inseam cm)(seat tube angle °). The saddle height equations were not dependent on sex. Conclusions: These equations provide a novel, practical strategy for bicycle-fit that accounts for rider anthropometrics, bicycle geometry and user-defined kinematics. Highlights This work developed simple equations to prescribed bicycle saddle height that elicits desired knee kinematics. Separate equations are presented for prescribing minimum or maximum knee flexion angle. Equations can be generalized to riders of both sexes, and a breadth of anthropometrics and ages. [ABSTRACT FROM AUTHOR]

Despite the technical challenges that require lengthy acquisitions to overcome poor signal‐to‐noise ratio (SNR), sodium (23Na) magnetic resonance imaging (MRI) is an intriguing area of research due to its essential role in human metabolism. Low SNR images can impact the measurement of the point‐spread function (PSF) by adding uncertainty into the resulting quantities. Here, we present methods to calculate the PSF by using the modulation transfer function (MTF), and a 3D‐printed line‐pair phantom in the context of 23Na MRI. A simulation study investigated the effect of noise on the resulting MTF curves, which were derived by direct modulation (DM) and a method utilizing Fourier harmonics (FHs). Experimental data utilized a line‐pair phantom with nine spatial frequencies, filled with different concentrations (15, 30, and 60 mM) of sodium in 3% agar. MTF curves were calculated using both methods from data acquired from density‐adapted 3D radial projections (DA‐3DRP) and Fermat looped orthogonally encoded trajectories (FLORET). Simulations indicated that the DM method increased variability in the MTF curves at all tested noise levels over the FH method. For the experimental data, the FH method resulted in PSFs with a narrower full width half maximum with reduced variability, although the improvement in variability was not as pronounced as predicted by simulations. The DA‐3DRP data indicated an improvement in the PSF over FLORET. It was concluded that a 3D‐printed line‐pair phantom represents a convenient method to measure the PSF experimentally. The MTFs from the noisy images in 23Na MRI have reduced variability from a FH method over DM. [ABSTRACT FROM AUTHOR]

The most common cause of chronic musculoskeletal pain is chronic myofascial pain syndrome (MPS). MPS often presents with increased muscle stiffness, and the myofascial trigger point (MTrP). Imaging modalities have been used to identify the MTrP, but their role in the detection and diagnosis of MPS remains unclear. The purpose of this review was to identify evidence in literature for the use of imaging in the role of classifying and explaining the physiology of MTrPs. Since few imaging techniques have been performed on MTrPs, we explored the imaging techniques that can effectively image complex skeletal muscle microstructure, and how they could be used. As part of a scoping review, we conducted a systematic search from three medical databases (CINAHL, EMBASE and MEDLINE) from year to year to analyze past MTrP imaging, as well as analyzing imaging techniques performed on the microstructure of muscle. Previously, ultrasound has been used to differentiate active, latent MTrPs, but these studies do not adequately address their underlying anatomical structure. MRI remains the standard method of imaging skeletal muscle. The existing MRI literature suggests that the DTI technique can quantify muscle injury, strain, and structure. However, theoretically, HARDI and DKI techniques seem to provide more information for complex structural areas, although these modalities have a disadvantage of longer scan times and have not been widely used on skeletal muscle. Our review suggests that DTI is the most effective imaging modality that has been used to define the microstructure of muscle and hence, could be optimal to image the MTrP. HARDI and DKI are techniques with theoretical potential for analysis of muscle, which may provide more detailed information representative of finer muscle structural features. Future research utilizing MRI techniques to image muscle are necessary to provide a more robust means of imaging skeletal muscle and the MTrP. [ABSTRACT FROM AUTHOR]

Aerobic exercise has both neuroprotective and neurorehabilitative benefits. However, the underlying mechanisms are not fully understood and need to be investigated, especially in postmenopausal women, who are at increased risk of age-related disorders such as Alzheimer's disease and stroke. To advance our understanding of the potential neurological benefits of aerobic exercise in aging women, we examined anatomical and functional responses that may differentiate women of varying cardiorespiratory fitness using neuroimaging and neurophysiology. A total of 35 healthy postmenopausal women were recruited (59 ± 3 years) and cardiorespiratory fitness estimated (22–70 mL/kg/min). Transcranial magnetic stimulation was used to assess -aminobutyric acid (GABA) and glutamate (Glu) receptor function in the primary motor cortex (M1), and magnetic resonance spectroscopy (MRS) was used to quantify GABA and Glu concentrations in M1. Magnetic resonance imaging was used to assess mean cortical thickness (MCT) of sensorimotor and frontal regions, while the microstructure of sensorimotor and other white matter tracts was evaluated through diffusion tensor imaging. Regression analysis revealed that higher fitness levels were associated with improved microstructure in pre-motor and sensory tracts, and the hippocampal cingulum. Fitness level was not associated with MCT, MRS, or neurophysiology measures. These data indicate that, in postmenopausal women, higher cardiorespiratory fitness is linked with preserved selective white matter microstructure, particularly in areas that influence sensorimotor control and memory. [ABSTRACT FROM AUTHOR]

Background: Post-concussive depression describes an elevation of depressive symptoms following concussion that occurs in conjunction with other symptoms of concussion. Children with concussion are more likely to diagnosed with depression. The overlapping symptoms between clinical depression and concussion make the diagnosis of depression difficult. The purpose of this study is to explore how post-concussive depression relates to post-concussion symptoms and cognition by investigating symptom-reporting in youth with post-concussive depression and executive function. Methods: Adolescents (age 10–17 years) diagnosed with concussion were divided into two groups based on depression scores on the Children's Depression Inventory (post-concussion depression; non-depression groups). Symptom reporting on the Post-Concussion Symptom Inventory and performance on Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) were compared. Results: Participants with post-concussive depression had heightened emotionality, irritability, and nervousness. Sadness and fatigue were reported by both groups. ImPACT was unable to distinguish between groups but the group overall demonstrated severe neurocognitive deficits. Conclusion: Reports of greater emotionality, irritability, and nervousness on concussion symptom scales may be indicators of post-concussion depression. It is important for clinicians to take note when an adolescent with concussion scores high on these three emotional symptoms as they may be indicative of greater emotional distress. [ABSTRACT FROM AUTHOR]

Context In rodents, cold exposure induces the activation of brown adipose tissue (BAT) and the induction of intracellular triacylglycerol (TAG) lipolysis. However, in humans, the kinetics of supraclavicular (SCV) BAT activation and the potential importance of TAG stores remain poorly defined. Objective To determine the time course of BAT activation and changes in intracellular TAG using MRI assessment of the SCV (i.e., BAT depot) and fat in the posterior neck region (i.e., non-BAT). Design Cross-sectional. Setting Clinical research center. Patients or Other Participants Twelve healthy male volunteers aged 18 to 29 years [body mass index = 24.7 ± 2.8 kg/m2 and body fat percentage = 25.0% ± 7.4% (both, mean ± SD)]. Intervention(s) Standardized whole-body cold exposure (180 minutes at 18°C) and immediate rewarming (30 minutes at 32°C). Main Outcome Measure(s) Proton density fat fraction (PDFF) and T2* of the SCV and posterior neck fat pads. Acquisitions occurred at 5- to 15-minute intervals during cooling and subsequent warming. Results SCV PDFF declined significantly after only 10 minutes of cold exposure [−1.6% (SE: 0.44%; P = 0.007)] and continued to decline until 35 minutes, after which time it remained stable until 180 minutes. A similar time course was also observed for SCV T2*. In the posterior neck fat (non-BAT), there were no cold-induced changes in PDFF or T2*. Rewarming did not result in a change in SCV PDFF or T2*. Conclusions The rapid cold-induced decline in SCV PDFF suggests that in humans BAT is activated quickly in response to cold and that TAG is a primary substrate. [ABSTRACT FROM AUTHOR]

Purpose: Dynamic phosphorus MR spectroscopic imaging (31P‐MRSI) experiments require temporal resolution on the order of seconds to concurrently assess different muscle groups. A highly accelerated pulse sequence combining flyback echo‐planar spectroscopic imaging (EPSI) and compressed sensing was developed and tested in a phantom and healthy humans during an exercise‐recovery challenge of the lower leg muscles, using a clinical 3T MRI. Methods: A flyback EPSI readout designed to achieve 2.25 × 2.25 cm2 resolution over a 18 × 18 cm2 field of view (i.e., 8 × 8 matrix) was combined with compressed sensing through the inclusion of pseudorandom gradient blips to sub‐sample the ky‐kt dimensions by a factor of 2.7×, achieving a temporal resolution of 9 s. The sequence was first tested in a phantom to assess performance compared to fully sampled EPSI (fidEPSI) and phase encoded chemical shift imaging (fidCSI). Then, tests were performed in 11 healthy volunteers during an exercise‐recovery challenge of the lower leg muscles. Voxels containing tissue from different muscle groups were evaluated measuring percentage phosphocreatine (%PCr) depletion, time constant of PCr recovery (τPCr) and intracellular pH at rest and following exercise. Results: The sequence was capable to track the dynamic PCr response of multiple muscles simultaneously. No statistical differences were found in the metabolite ratio, pH or linewidth when compared with fidEPSI and fidCSI in the phantom study. Dynamic experiments showed differences in PCr depletion when comparing soleus with gastrocnemius muscles. Intracellular pH, τPCr and %PCr decrease were consistent with reported values. Conclusion: Highly accelerated 31P‐MRSI combining flyback EPSI and compressed sensing is capable of assessing concurrent energy metabolism in multiple muscle groups using a clinical 3T MR system. [ABSTRACT FROM AUTHOR]

Object: To present and evaluate a fast phosphorus magnetic resonance spectroscopic imaging (MRSI) sequence using echo planar spectroscopic imaging with flyback readout gradient trajectories.Materials and Methods: Waveforms were designed and implemented using a 3 Tesla MRI system. 31P spectra were acquired with 2 × 2 cm2 and 3 × 3 cm2 resolution over a 20- and 21-cm field of view and spectral bandwidths up to 1923 Hz. The sequence was first tested using a 20-cm-diameter phosphate phantom, and subsequent in vivo tests were performed on healthy human calf muscles and brains from five volunteers.Results: Flyback EPSI achieved 10× and 7× reductions in acquisition time, with 68.0 ± 1.2 and 69.8 ± 2.2% signal-to-noise ratio (SNR) per unit of time efficiency (theoretical SNR efficiency was 74.5 and 76.4%) for the in vivo experiments, compared to conventional phase-encoded MRSI for the 2 × 2 cm2 and 3 × 3 cm2 resolution waveforms, respectively. Statistical analysis showed no difference in the quantification of most metabolites. Time savings and SNR comparisons were consistent across phantom, leg and brain experiments.Conclusion: EPSI using flyback readout trajectories was found to be a reliable alternative for acquiring 31P-MRSI data in a shorter acquisition time. [ABSTRACT FROM AUTHOR]

The activation of brown adipose tissue (BAT) is associated with reductions in circulating lipids and glucose in rodents and contributes to energy expenditure in humans indicating the potential therapeutic importance of targetting this tissue for the treatment of a variety of metabolic disorders. In order to evaluate the therapeutic potential of human BAT, a variety of methodologies for assessing the volume and metabolic activity of BAT are utilized. Cold exposure is often utilized to increase BAT activity but inconsistencies in the characteristics of the exposure protocols make it challenging to compare findings. The metabolic activity of BAT in response to cold exposure has most commonly been measured by static positron emission tomography of 18F-fluorodeoxyglucose in combination with computed tomography (18F-FDG PET-CT) imaging, but recent studies suggest that under some conditions this may not always reflect BAT thermogenic activity. Therefore, recent studies have used alternative positron emission tomography and computed tomography (PET-CT) imaging strategies and radiotracers that may offer important insights. In addition to PET-CT, there are numerous emerging techniques that may have utility for assessing BATmetabolic activity including magnetic resonance imaging (MRI), skin temperaturemeasurements, near-infrared spectroscopy (NIRS) and contrast ultrasound (CU). In this review, we discuss and critically evaluate the various methodologies used to measure BAT metabolic activity in humans and provide a contemporary assessment of protocols which may be useful in interpreting research findings and guiding the development of future studies. [ABSTRACT FROM AUTHOR]

Objective: Certain exercises could overload the osteoarthritic knee. We developed an exercise program from yoga postures with a minimal knee adduction moment for knee osteoarthritis. The purpose was to compare the effectiveness of this biomechanically-based yoga exercise (YE), with traditional exercise (TE), and a no-exercise attention-equivalent control (NE) for improving pain, self-reported physical function and mobility performance in women with knee osteoarthritis. Design: Single-blind, three-arm randomized controlled trial. Setting: Community in Southwestern Ontario, Canada. Participants: A convenience sample of 31 women with symptomatic knee osteoarthritis was recruited through rheumatology, orthopaedic and physiotherapy clinics, newspapers and word-of-mouth. Interventions: Participants were stratified by disease severity and randomly allocated to one of three 12-week, supervised interventions. YE included biomechanically-based yoga exercises; TE included traditional leg strengthening on machines; and NE included meditation with no exercise. Participants were asked to attend three 1-hour group classes/sessions each week. Measurements: Primary outcomes were pain, self-reported physical function and mobility performance. Secondary outcomes were knee strength, depression, and health-related quality of life. All were assessed by a blinded assessor at baseline and immediately following the intervention. Results: The YE group demonstrated greater improvements in KOOS pain (mean difference of 22.9 [95% CI, 6.9 to 38.8; p = 0.003]), intermittent pain (mean difference of -19.6 [95% CI, -34.8 to -4.4; p = 0.009]) and self-reported physical function (mean difference of 17.2 [95% CI, 5.2 to 29.2; p = 0.003]) compared to NE. Improvements in these outcomes were similar between YE and TE. However, TE demonstrated a greater improvement in knee flexor strength compared to YE (mean difference of 0.1 [95% CI, 0.1 to 0.2]. Improvements from baseline to follow-up were present in quality of life score for YE and knee flexor strength for TE, while both also demonstrated improvements in mobility. No improvement in any outcome was present in NE. Conclusions: The biomechanically-based yoga exercise program produced clinically meaningful improvements in pain, self-reported physical function and mobility in women with clinical knee OA compared to no exercise. While not statistically significant, improvements in these outcomes were larger than those elicited from the traditional exercise-based program. Though this may suggest that the yoga program may be more efficacious for knee OA, future research studying a larger sample is required. Trial registration: ClinicalTrials.gov () [ABSTRACT FROM AUTHOR]

Background: Brain connectivity in autism spectrum disorders (ASD) has proven difficult to characterize due to the heterogeneous nature of the spectrum. Connectivity in the brain occurs in a complex, multilevel and multi-temporal manner, driving the fluctuations observed in local oxygen demand. These fluctuations can be characterized as fractals, as they auto-correlate at different time scales. In this study, we propose a model-free complexity analysis based on the fractal dimension of the rs-BOLD signal, acquired with magnetic resonance imaging. The fractal dimension can be interpreted as measure of signal complexity and connectivity. Previous studies have suggested that reduction in signal complexity can be associated with disease. Therefore, we hypothesized that a detectable difference in rs-BOLD signal complexity could be observed between ASD patients and Controls. Methods and findings: Anatomical and functional data from fifty-five subjects with ASD (12.7 ± 2.4 y/o) and 55 age-matched (14.1 ± 3.1 y/o) healthy controls were accessed through the NITRC database and the ABIDE project. Subjects were scanned using a 3T GE Signa MRI and a 32-channel RF-coil. Axial FSPGR-3D images were used to prescribe rs-BOLD (TE/TR = 30/2000ms) where 300 time points were acquired. Motion correction was performed on the functional data and anatomical and functional images were aligned and spatially warped to the N27 standard brain atlas. Fractal analysis, performed on a grey matter mask, was done by estimating the Hurst exponent in the frequency domain using a power spectral density approach and refining the estimation in the time domain with de-trended fluctuation analysis and signal summation conversion methods. Voxel-wise fractal dimension (FD) was calculated for every subject in the control group and in the ASD group to create ROI-based Z-scores for the ASD patients. Voxel-wise validation of FD normality across controls was confirmed, and non-Gaussian voxels were eliminated from subsequent analysis. To maintain a 95% confidence level, only regions where Z-score values were at least 2 standard deviations away from the mean (i.e. where |Z| > 2.0) were included in the analysis. We found that the main regions, where signal complexity significantly decreased among ASD patients, were the amygdala (p = 0.001), the vermis (p = 0.02), the basal ganglia (p = 0.01) and the hippocampus (p = 0.02). No regions reported significant increase in signal complexity in this study. Our findings were correlated with ADIR and ADOS assessment tools, reporting the highest correlation with the ADOS metrics. Conclusions: Brain connectivity is best modeled as a complex system. Therefore, a measure of complexity as the fractal dimension of fluctuations in brain oxygen demand and utilization could provide important information about connectivity issues in ASD. Moreover, this technique can be used in the characterization of a single subject, with respect to controls, without the need for group analysis. Our novel approach provides an ideal avenue for personalized diagnostics, thus providing unique patient specific assessment that could help in individualizing treatments. [ABSTRACT FROM AUTHOR]

Objectives Myofascial pain syndrome is one of the most common causes of chronic pain and is highlighted by the presence of myofascial trigger points. The current practice of diagnosing myofascial pain syndrome among clinicians involves manual detection of myofascial trigger points, which can be inconsistent. However, the detection process can be strengthened with the assistance of ultrasound (US). Therefore, this study aimed to characterize the upper trapezius by using quantitative techniques in healthy asymptomatic individuals with neck pain. Methods Study participants were recruited on the basis of the inclusion and exclusion criteria established, and US images of the trapezius, along the axial and longitudinal orientations, were obtained. Each set was obtained by 2 investigators: experienced and inexperienced personnel. Results Fifteen participants were recruited. The mean gray scale US echo intensity distribution obtained was 41.9. A paired t test of the global mean echo intensity value obtained for each image from the US operators did not show any significant difference ( P = .77). A t test was performed, comparing the echo intensity of the group of patients with neck pain and healthy control participants, and the difference was found to be significant ( P = .052). The median blob area was 2.71. The quartile range for the blob area was 1.72 for the 25th percentile to 4.90 for the 75th percentile. Conclusions This study demonstrated that quantitative analysis of the echo intensity of US images can provide important information. However, further research is necessary to explore the relationships among sex, age, blob area, count, body mass index, regional anatomy, and extent of training or exercise of the particular muscle. [ABSTRACT FROM AUTHOR]

Background: Obesity is associated with cardiometabolic disturbances, which may have significant implications for musculoskeletal health and exercise tolerance. Objective: We sought to determine the association between muscle structure, function, and metabolism in adolescents across the weight spectrum. Methods: This cross‐sectional case–control study included overweight and obese participants (n = 24) 8–18 years of age with a body mass index (BMI) ≥ 85th percentile for age and gender, and non‐obese participants (n = 24) with a BMI < 85th percentile. Body composition, physical activity, peak aerobic capacity, cardiometabolic blood markers and insulin resistance (measured by the homeostatic model assessment of insulin resistance, HOMA‐IR), skeletal muscle mitochondrial oxidative capacity (via 31Phosphorous‐Magnetic Resonance Spectroscopy, 31P‐MRS, to assess phosphocreatine (PCr) recovery after exercise), and extramyocellular and intramyocellular lipid (IMCL) levels (via 1Hydrogen‐MRS) were assessed. Stepwise regression was performed to examine the factors associated with oxidative capacity. Results: bese and overweight patients had similar age, height, and physical activity to non‐obese controls, but obese and overweight participants exhibited higher insulin resistance. Obese and overweight participants had longer PCr recovery than non‐obese controls following 5x30s of moderate‐intensity exercise (51.2 ± 20.1 s vs. 23.9 ± 7.5 s, p = 0.004). In univariate correlation analysis, impaired PCr recovery was associated with a higher BMI z‐score (rs = 0.51, p < 0.001), circulating triglycerides (rs = 0.41, p = 0.005), and HOMA‐IR (rs = 0.46, p = 0.001). In stepwise multivariate regression analysis, impaired PCr recovery was associated with a higher BMI z‐score (β = 0.47, p = 0.002), but not insulin resistance (β = 0.07, p = 0.07) or circulating triglycerides (β = 0.16 p = 0.33). Conclusion: A slower phosphocreatine recovery following aerobic exercise is strongly associated with increasing adiposity. A slower metabolic recovery following aerobic exercise stress suggests that endurance exercise training in obese adolescents may be an optimal strategy to target exercise intolerance in this cohort. [ABSTRACT FROM AUTHOR]

Background: Conventional imaging techniques are unable to detect abnormalities in the brain following mild traumatic brain injury (mTBI). Yet patients with mTBI typically show delayed response on neuropsychological evaluation. Because fractal geometry represents complexity, we explored its utility in measuring temporal fluctuations of brain resting state blood oxygen level dependent (rs-BOLD) signal. We hypothesized that there could be a detectable difference in rs-BOLD signal complexity between healthy subjects and mTBI patients based on previous studies that associated reduction in signal complexity with disease. Methods: Fifteen subjects (13.4 ± 2.3 y/o) and 56 age-matched (13.5 ± 2.34 y/o) healthy controls were scanned using a GE Discovery MR750 3T MRI and 32-channel RF-coil. Axial FSPGR-3D images were used to prescribe rs-BOLD (TE/TR = 35/2000ms), acquired over 6 minutes. Motion correction was performed and anatomical and functional images were aligned and spatially warped to the N27 standard atlas. Fractal analysis, performed on grey matter, was done by estimating the Hurst exponent using de-trended fluctuation analysis and signal summation conversion methods. Results and Conclusions: Voxel-wise fractal dimension (FD) was calculated for every subject in the control group to generate mean and standard deviation maps for regional Z-score analysis. Voxel-wise validation of FD normality across controls was confirmed, and non-Gaussian voxels (3.05% over the brain) were eliminated from subsequent analysis. For each mTBI patient, regions where Z-score values were at least 2 standard deviations away from the mean (i.e. where |Z| > 2.0) were identified. In individual patients the frequently affected regions were amygdala (p = 0.02), vermis(p = 0.03), caudate head (p = 0.04), hippocampus(p = 0.03), and hypothalamus(p = 0.04), all previously reported as dysfunctional after mTBI, but based on group analysis. It is well known that the brain is best modeled as a complex system. Therefore a measure of complexity using rs-BOLD signal FD could provide an additional method to grade and monitor mTBI. Furthermore, this approach can be personalized thus providing unique patient specific assessment. [ABSTRACT FROM AUTHOR]

Purpose: To develop an inexpensive magnetic resonance imaging (MRI)-compatible electrical muscle stimulation (EMS) unit and test it for safety and efficacy.Materials and Methods: A simple MRI-compatible EMS device was developed using radiofrequency (RF) translucent electrodes at 3T. RF heating concerns were assessed using optical temperature measurements at electrode sites, during scanning of a phantom. EMS efficacy and consistency was investigated through in vivo (n = 5) measures of 31 P-MRS phosphocreatine (PCr) reduction, and altered blood oxygen level-dependent (BOLD) signal and the results were compared to effects from equivalent voluntary effort on the same subjects.Results: The presence of an EMS pulse did not interfere with the T2 * signal in a phantom. However, signal-to-noise ratio (SNR) was reduced by 70% at electrode sites, but only by 10% 4 cm distally. Under RF intense conditions, the temperature at the electrode site increased by only 4.7°C over a 16-minute time span. In vivo muscle stimulation resulted in 13.5 ± 1.8% reduction in PCr, which was not significantly (P < 0.195) different from voluntary contraction. Reproducible muscle BOLD signal changes following EMS were noted, with a maximal increase of 10.0 ± 2.6% seen in the central soleus. For soleus and gastrocnemius compartments, EMS produced significantly higher BOLD signal change compared to voluntary contraction (P < 0.05).Conclusion: A safe and inexpensive MRI-compatible EMS unit can be easily built for evaluating muscle function and metabolism within a 3T MRI scanner. Clinical applications might include evaluating skeletal muscle function in patients with limited or absent voluntary skeletal motor function or inadequate exercise capacity. J. Magn. Reson. Imaging 2016;44:1530-1538. [ABSTRACT FROM AUTHOR]

A cadmium zinc telluride (CZT) based detector system has been developed with the goal of combining molecular breast imaging (MBI) and magnetic resonance imaging (MRI) to address shortcomings of each modality. The CZT detector system is comprised of four CZT modules tiled in a $2\times 2$ array. Each module consists of 256 pixels ( $16\times 16$ , 2.4 mm pixels) and features a built-in ASIC and FPGA. A custom digital readout circuit board was designed to interface the four modules with a microcontroller to a data acquisition PC. The system was placed within the bore of a 3 T GE Discovery MR750 and imaging performance of each modality evaluated using both sequential and simultaneous imaging protocols. The mean energy resolution of the gamma camera both inside and outside the MRI is 7.3% at 140 keV. The maximum increase in the integral uniformity was 3% when using a gradient echo MRI sequence while the mean differential uniformity when inside the MRI increased by 1%. Spatial resolution varied in a predictable manner from 2.4 mm FWHM at the collimator face to 6.9 mm at 10 cm from the collimator. Performance of the 3 T GE Discovery MR750 using a 16-channel breast RF coil array was measured with and without the gamma camera present using a gradient echo and spoiled gradient echo imaging sequence. A realistic 99mTc-filled breast-like phantom containing two lesions (30:1 lesion to background ratio) was used to assess the feasibility of both serial and simultaneous hybrid imaging. Sequential imaging resulted in a reduction in MRI SNR of 70-80% and a further decrease of 93-98% was observed when performing simultaneous MR/scintigraphy imaging, likely a result of RF interference originating from the CZT detector modules and associated analog electronics. Co-registered scintigraphic and MRI images display negligible geometric distortion when imaged with both simultaneous and serial imaging modes, thus indicating the feasibility of combining MBI with breast MRI. [ABSTRACT FROM AUTHOR]

Purpose: To explore the effect of diffusion tensor imaging (DTI) acquisition parameters on principal and minor eigenvector stability within human lower leg skeletal muscles.Materials and Methods: Lower leg muscles were evaluated in seven healthy subjects at 3T using an 8-channel transmit/receive coil. Diffusion-encoding was performed with nine signal averages (NSA) using 6, 15, and 25 directions (NDD). Individual DTI volumes were combined into aggregate volumes of 3, 2, and 1 NSA according to number of directions. Tensor eigenvalues (λ1 , λ2 , λ3 ), eigenvectors (ε1 , ε2 , ε3 ), and DTI metrics (fractional anisotropy [FA] and mean diffusivity [MD]) were calculated for each combination of NSA and NDD. Spatial maps of signal-to-noise ratio (SNR), λ3 :λ2 ratio, and zenith angle were also calculated for region of interest (ROI) analysis of vector orientation consistency.Results: ε1 variability was only moderately related to ε2 variability (r = 0.4045). Variation of ε1 was affected by NDD, not NSA (P < 0.0002), while variation of ε2 was affected by NSA, not NDD (P < 0.0003). In terms of tensor shape, vector variability was weakly related to FA (ε1 :r = -0.1854, ε2 : ns), but had a stronger relation to the λ3 :λ2 ratio (ε1 :r = -0.5221, ε2 :r = -0.1771). Vector variability was also weakly related to SNR (ε1 :r = -0.2873, ε2 :r = -0.3483). Zenith angle was found to be strongly associated with variability of ε1 (r = 0.8048) but only weakly with that of ε2 (r = 0.2135).Conclusion: The second eigenvector (ε2 ) displayed higher directional variability relative to ε1 , and was only marginally affected by experimental conditions that impacted ε1 variability. [ABSTRACT FROM AUTHOR]

Objective Decline in cognitive function begins by the 40s, and may be related to future dementia risk. We used data from a community-representative study to determine whether there are age-related differences in simple cognitive and gait tests by the 40s, and whether these differences were associated with covert cerebrovascular disease on magnetic resonance imaging (MRI). Methods Between 2010 and 2012, 803 participants aged 40 to 75 years in the Prospective Urban Rural Epidemiological (PURE) study, recruited from prespecified postal code regions centered on 4 Canadian cities, underwent brain MRI and simple tests of cognition and gait as part of a substudy (PURE-MIND). Results Mean age was 58 ± 8 years. Linear decreases in performance on the Montreal Cognitive Assessment, Digit Symbol Substitution Test (DSST), and Timed Up and Go test of gait were seen with each age decade from the 40s to the 70s. Silent brain infarcts were observed in 3% of 40- to 49-year-olds, with increasing prevalence up to 18.9% in 70-year-olds. Silent brain infarcts were associated with slower timed gait and lower volume of supratentorial white matter. Higher volume of supratentorial MRI white matter hyperintensity was associated with slower timed gait and worse performance on DSST, and lower volumes of the supratentorial cortex and white matter, and cerebellum. Interpretation Covert cerebrovascular disease and its consequences on cognitive and gait performance and brain atrophy are manifest in some clinically asymptomatic persons as early as the 5th decade of life. Ann Neurol 2015;77:251-261 [ABSTRACT FROM AUTHOR]

Objective: Multiple sclerosis (MS) is a chronic neurodegenerative disease of the CNS. Recently a controversial vascular hypothesis for MS, termed chronic cerebrospinal venous insufficiency (CCSVI), has been advanced. The objective of this study was to evaluate the relative prevalence of the venous abnormalities that define CCSVI. Methods: A case-control study was conducted in which 100 MS patients aged between 18–65 y meeting the revised McDonald criteria were randomly selected and stratified into one of four MS subtypes: relapsing/remitting, secondary progressive, primary progressive and benign. Control subjects (16–70 y) with no known history of MS or other neurological condition were matched with the MS cases. All cases and controls underwent ultrasound imaging of the veins of the neck plus the deep cerebral veins, and magnetic resonance imaging of the neck veins and brain. These procedures were performed on each participant on the same day. Results: On ultrasound we found no evidence of reflux, stenosis or blockage in the internal jugular veins (IJV) or vertebral veins (VV) in any study participant. Similarly, there was no evidence of either reflux or cessation of flow in the deep cerebral veins in any subject. Flow was detected in the IJV and VV in all study participants. Amongst 199 participants there was one MS subject who fulfilled the minimum two ultrasound criteria for CCSVI. Using MRI we found no significant differences in either the intra- or extra-cranial venous flow velocity or venous architecture between cases and controls. Conclusion: This case-control study provides compelling evidence against the involvement of CCSVI in multiple sclerosis. [ABSTRACT FROM AUTHOR]

Introduction: Structural evidence of exercise-induced muscle disruption has traditionally involved histological analysis of muscle tissue obtained by needle biopsy, however, there are multiple limitations with this technique. Recently, diffusion tensor magnetic resonance imaging (DT-MRI) has been successfully demonstrated to noninvasively assess skeletal muscle abnormalities induced by traumatic injury. Methods: To determine the potential for DT-MRI to detect musculoskeletal changes after a bout of eccentric exercise, 10 healthy men performed 300 eccentric actions on an isokinetic dynamometer. DT-MRI measurements and muscle biopsies from the vastus lateralis were obtained before and 24 h post-exercise. Results: Z-band streaming was higher 24 h post-exercise compared with baseline ( P < 0.05). The histological indices of damage coincided with changes in DT-MRI parameters of fractional anisotropy (FA) and apparent diffusion coefficient; reflecting altered skeletal muscle geometry ( P < 0.05). Z-band streaming quantified per fiber correlated with FA (r = −0.512; P < 0.05). Conclusions: DT-MRI can detect changes in human skeletal muscle structure following eccentric exercise. Muscle Nerve 46: 42-50, 2012 [ABSTRACT FROM AUTHOR]

Purpose: To measure interindividual, repositioning, and time-of-day effects of single voxel PRESS ( Point RESolved Spectroscopy) proton magnetic resonance spectroscopy (1H-MRS) acquisition of the anterior cingulate cortex (AC) in healthy human subjects. Materials and Methods: AC 1H-MRS measurements were performed in 15 healthy adult volunteers using a short echo PRESS sequence (GE Healthcare 3 Tesla, TE/TR = 30/2500 ms, 192 acquisitions, 6 cm3 voxels). For each individual, a total of eight spectra were obtained during two identical scanning sessions separated by 3.5 h. In each, two consecutive AC spectra were acquired. After the first two scans, the subject left the scanner, then immediately returned for repositioning and acquisition of two more consecutive spectra. The subject then left the imaging centre to return 3.5 h later for a repeated procedure. Spectroscopic postprocessing was done using LCmodel. Interindividual, repositioning and time-of-day effects were measured using restricted maximum likelihood (REML) models of variance components analysis, where response variables were levels of creatine/phosphocreatine (Cr), N-acetyl-aspartate (NAA), myo-inositol (mI), choline (Cho), and the glutamate-glutamine complex (Glx). Results: Interindividual effects were markedly higher than time-of-day and repositioning effects for all metabolites. Conclusion: Our findings show that 1H-MRS measurements of the AC are sensitive to interindividual differences, while time of day and repositioning are markedly less important. J. Magn. Reson. Imaging 2010;32:276-282. © 2010 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]