Akito Yoshiko

Intramuscular adipose tissue determined by T1-weighted MRI at 3T primarily reflects extramyocellular lipids.

PURPOSE The purpose of this study was to assess relationships between intramuscular adipose tissue (IntraMAT) content determined by MRI and intramyocellular lipids (IMCL) and extramyocellular lipids (EMCL) determined by (1)H magnetic resonance spectroscopy ((1)H MRS) or echo intensity determined by B-mode ultrasonography of human skeletal muscles. METHODS Thirty young and elderly men and women were included. T1-weighted MRI was taken from the right mid-thigh to measure IntraMAT content of the vastus lateralis (VL) and biceps femoris (BF) using a histogram shape-based thresholding technique. IMCL and EMCL were measured from the VL and BF at the right mid-thigh using (1)H MRS. Ultrasonographic images were taken from the VL and BF of the right mid-thigh to measure echo intensity based on gray-scale level for quantitative analysis. RESULTS There was a significant correlation between IntraMAT content by MRI and EMCL of the VL and BF (VL, r=0.506, P<0.01; BF, r=0.591, P<0.001) and between echo intensity and EMCL of the VL and BF (VL, r=0.485, P<0.05; BF, r=0.648, P<0.01). IntraMAT content was also significantly correlated with echo intensity of the VL and BF (VL, r=0.404, P<0.05; BF, r=0.493, P<0.01). CONCLUSION Our study suggests that IntraMAT content determined by T1-weighted MRI at 3T primarily reflects extramyocellular lipids, not intramyocellular lipids, in human skeletal muscles.

Effect of 12-month resistance and endurance training on quality, quantity, and function of skeletal muscle in older adults requiring long-term care

ABSTRACT Older adults requiring long‐term care will experience age‐associated deterioration of the quality and quantity of skeletal muscle if no interventions are performed. Long‐term training is considered a typical intervention method and is effective for improvement of both muscle quantity and physical function. However, how such training affects muscle quality [i.e., fat‐to‐muscle ratio as determined by echo intensity (EI)] in older adults requiring long‐term care remains unclear. The purpose of this study was to investigate the effects of a 12‐month physical training intervention on the quality and quantity of skeletal muscle, physical function, and blood chemistry in older adults requiring long‐term care. Seventeen older adults requiring long‐term care (Tr‐group) and 15 healthy older adults (Cont‐group) participated in this study. Patients in the Tr‐group performed exercises consisting of resistance and endurance training once or twice a week for 12 months. The EI and muscle thickness of the thigh were calculated from the rectus femoris and biceps femoris using B‐mode transverse ultrasound images. Physical functions (isometric knee extension peak torque, sit‐to‐stand test, 5‐m normal/maximal speed walking, handgrip strength, and timed up and go test) and blood lipid components including adipocytokines were measured at three points, i.e. baseline and 6 and 12 months after. The thigh EI was significantly lower after 6 months of training than baseline, and it returned to the initial level after 12 months of training (baseline, 70.2 ± 8.3 a.u.; 6 months, 64.1 ± 11.2 a.u.; 12 months, 72.3 ± 7.2 a.u.). The thigh muscle thickness, 5‐m maximal speed walking, and knee extension torque were significantly improved after 12 months of training (P < 0.05). The blood chemistry parameters did not significantly change. These results demonstrate that a 12‐month training intervention contributes to improvement of muscle quantity and function with tentative changes in muscle quality but has no effect on blood chemistry in older adults requiring long‐term care. We conclude that this type of training has the potential to restore the muscle functional abilities of older adults requiring long‐term care. HighlightsThe effect of 12‐month training was investigated in older adults with long‐term care.Long‐term training improved physical function and muscle quantity.Once improved, muscle quality then returned to the baseline level.Blood lipid components did not change throughout the training intervention.This type of training was mainly effective for muscle quantity and physical function.

Muscle atrophy and recovery of individual thigh muscles as measured by magnetic resonance imaging scan during treatment with cast for ankle or foot fracture

Purpose: We aimed to longitudinally investigate individual thigh muscle changes using magnetic resonance imaging (MRI) during treatment with cast of ankle or foot fracture. Moreover, we aimed to demonstrate whether measurements of muscle cross-sectional area (CSA) are sensitive to muscle changes, contributing to simpler methods in clinical application . Methods: Ten patients undergoing treatment with cast of acute ankle or foot fractures were studied. Axial MRI (1.5 T) was conducted around the affected mid-thigh region after the injury (Pre), after maintaining a nonweight-bearing (NWB) period (approximately 28 days), and after finishing rehabilitation (recovery). Regarding individual thigh muscles, the total CSAs corresponding to 40% of the femoral length (FL) and the CSAs at 5% interval of the FL were longitudinally measured. Standardized response means (SRMs) were accessed for sensitivity in the muscle changes. Results: The total CSAs at NWB were significantly lower than those at Pre in vastus lateralis (10.9% ± 5.4%), vastus intermedius (8.4% ± 6.7%), and vastus medialis (11.2% ± 6.9%) (p < 0.01 for all). In contrast, at recovery, the only significant muscle atrophy relative to that at Pre was observed in the semitendinosus of the proximal 15% and 10% CSAs (p < 0.01 and p = 0.01, respectively). In all muscles, SRM using a single-slice CSA at or near the muscle belly was high. Conclusion: Thigh muscle changes differ according to the variations in individual muscles. CSA measurements at or near the muscle belly are simple methods and sensitive indicators of these muscle changes.

Estimation of individual thigh muscle volumes from a single-slice muscle cross-sectional area and muscle thickness using magnetic resonance imaging in patients with knee osteoarthritis:

Purpose: This study aimed to identify the best single-slice anatomical muscle cross-sectional area (CSA) and muscle thickness (MT) on magnetic resonance imaging (MRI) to estimate the overall individual muscle volumes (MVs) of knee extensors and flexors in patients with knee osteoarthritis (KOA). Methods: Twelve patients (24 legs; 4 men and 8 women) with KOA underwent a 1.5-Tesla axial MRI scan in the femoral region of interest (ROI), between the lesser trochanter and rectus femoris tendon. Individual MVs were calculated by numerical integration based on individual CSAs analyzed at the ROI. The best slice was determined as follows: coefficient of determination (R 2) between MVs measured and those estimated from the femoral length (FL) × CSAs or FL × MTs measured at each 10% interval level of the ROI. These estimation equations were applied for a cross-validation group (24 KOA patients: 12 men and 12 women). Results: Estimated individual MVs of knee extensors and flexors, based on the CSAs at the distal 10% level, significantly correlated with each of the measured individual MVs (R 2: 0.79–0.96, p < 0.05 for all). Similarly, estimated individual knee extensor MVs, based on MTs at the mid-slice, significantly correlated with each of the measured individual MVs (R 2: 0.77–0.84, p < 0.05 for all). The application of the developed regression equation to the cross-validation group did not exhibit any systematic bias. Conclusion: These simple methods could be applied in prospective research with a larger number of patients with KOA.