MR elastography-based slip interface imaging (SII) for functional assessment of myofascial interfaces: A feasibility study.

PURPOSE: Abnormal adherence at functional myofascial interfaces is hypothesized as an important phenomenon in myofascial pain syndrome. This study aimed to investigate the feasibility of MR elastography (MRE)-based slip interface imaging (SII) to visualize and assess myofascial mobility in healthy volunteers. METHODS: SII was used to assess local shear strain at functional myofascial interfaces in the flexor digitorum profundus (FDP) and thighs. In the FDP, MRE was performed at 90 Hz vibration to each index, middle, ring, and little finger. Two thigh MRE scans were performed at 40 Hz with knees flexed and extended. The normalized octahedral shear strain (NOSS) maps were calculated to visualize myofascial slip interfaces. The entropy of the probability distribution of the gradient NOSS was computed for the two knee positions at the intermuscular interface between vastus lateralis and vastus intermedius, around rectus femoris, and between vastus intermedius and vastus medialis. RESULTS: NOSS map depicted distinct functional slip interfaces in the FDP for each finger. Compared to knee flexion, clearer slip interfaces and larger gradient NOSS entropy at the vastus lateralis-vastus intermedius interface were observed during knee extension, where the quadriceps are not passively stretched. This suggests the optimal position for using SII to visualize myofascial slip interface in skeletal muscles is when muscles are not subjected to any additional force. CONCLUSION: The study demonstrated that MRE-based SII can visualize and assess myofascial interface mobility in extremities. The results provide a foundation for investigating the hypothesis that myofascial pain syndrome is characterized by changes in the mobility of myofascial interfaces.

Magnetic Resonance Elastography in the Study of Neurodegenerative Diseases.

Neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD) present a major health burden to society. Changes in brain structure and cognition are generally only observed at the late stage of the disease. Although advanced magnetic resonance imaging (MRI) techniques such as diffusion imaging may allow identification of biomarkers at earlier stages of neurodegeneration, early diagnosis is still challenging. Magnetic resonance elastography (MRE) is a noninvasive MRI technique for studying the mechanical properties of tissues by measuring the wave propagation induced in the tissues using a purpose-built actuator. Here, we present a systematic review of preclinical and clinical studies in which MRE has been applied to study neurodegenerative diseases. Actuator systems for data acquisition, inversion algorithms for data analysis, and sample demographics are described and tissue stiffness measures obtained for the whole brain and internal structures are summarized. A total of six animal studies and eight human studies have been published. The animal studies refer to 123 experimental animals (68 AD and 55 PD) and 121 wild-type animals, while the human studies refer to 142 patients with neurodegenerative disease (including 56 AD and 17 PD) and 166 controls. The animal studies are consistent in the reporting of decreased stiffness of the hippocampal region in AD mice. However, in terms of disease progression, although consistent decreases in either storage modulus or shear modulus magnitude are reported for whole brain, there is variation in the results reported for the hippocampal region. The clinical studies are consistent in reports of a significant decrease in either whole brain storage modulus or shear modulus magnitude, in both AD and PD and with different brain structures affected in different neurodegenerative diseases. MRE studies of neurodegenerative diseases are still in their infancy, and in future it will be interesting to investigate potential relationships between brain mechanical properties and clinical measures, which may help elucidate the mechanisms underlying onset and progression of neurodegenerative diseases. EVIDENCE LEVEL: 1. TECHNICAL EFFICACY: Stage 2.

Feasibility study of the application of magnetic resonance elastography (MRE) to measure oral posture related changes in stiffness of zygomaticus major muscle.

PURPOSE: Development of a technique for measuring the mechanical properties of zygomaticus major (ZM) may aid advances in clinical treatments for correcting abnormal oral posture. The objective of this work was to demonstrate the feasibility of measuring the stiffness of ZM using an MR elastography technique that incorporates a custom local driver and a phase-gradient (PG) inversion. METHODS: 2D MRE investigations were performed for 3 healthy subjects using a vibration frequency of 90 Hz to test the prediction that the stiffness of ZM would be greater in the mouth-open compared to the mouth-closed position. MRE wave images were acquired along the long axis of ZM and processed using a 2D spatial-temporal directional filter applied in the direction of wave propagation along the long axis of the muscle. Stiffness measurements were obtained by applying the PG technique to a 1D-profile drawn in the phase image of the first harmonic of the wave images and a one-tailed paired t-test was used to compare the ZM stiffness between the two mouth postures (p < 0.05). RESULTS: The mean stiffness and standard deviation (SD) of ZM across the three participants in the mouth-closed and mouth-open postures was 6.75 kPa (SD 3.36 kPa) and 15.5 kPa (SD 5.15 kPa), respectively. Changes of ZM stiffness were significantly greater in the mouth-open than the mouth-closed posture (p = 0.038). CONCLUSION: The feasibility of using the PG MRE technique to measure stiffness changes in a small muscle such as ZM for different mouth postures has been demonstrated. Further investigations are required in a larger cohort of participants to investigate the sensitivity and reproducibility of the technique for potential clinical application as well as in health and beauty related studies.

The benefits of Shuai Shou Gong (SSG) demonstrated in a Randomised Control Trial (RCT) study of older adults in two communities in Thailand.

INTRODUCTION: Shuai Shou Gong (SSG) is a type of Arm Swing Exercise (ASE) developed and practiced especially by older people in China for over one thousand years to maintain physical health and well-being. Until now the potential benefits of SSG have not been investigated in a Randomised Control Trial (RCT). MATERIALS AND METHODS: Fifty six older women were recruited from each of two urban communities in Khon Kaen, Thailand. One community was randomly assigned as the Exercise Group (mean age 68.3 years, standard deviation 5.6 years) and the other as the Control Group (69.4 years, 4.4 years). The Exercise Group performed SSG for 40 minutes, three days per week for two months, whereas the Control Group maintained their usual daily life. Measurements of Posture (C7 to Wall Distance (C7WD), Standing Height (SH), Flexibility (Back Scratch of Left and Right arms (BSL and BSR) and Chair Sit and Reach of Left and Right legs (CSRL and CSRR), Gait (Timed Up and Go (TUG)), and Cognition (Barthel Activities of Daily Living Index (BADL) and Rosenberg Self Esteem Scale (RSES) questionnaires) were recorded for each group prior to, on day 1, week 4, and week 8 of the SSG training. RESULTS: The 8 week SSG training course produced a significant interaction between group and time for the combined set of all outcome measures (C7WD, SH, BSL, BSR, CSRL, CSRR, TUG, BADL, and BSES) (Modified ANOVA-Type Statistic (MATS) p-value < 0.001) and for the four categories of Posture, Flexibility, Gait, and Cognition (all Wald-Type Statistic (WTS) p-values < 0.05) and in all cases the changes in the Exercise Group were in the direction predicted to be beneficial. No significant interaction effect between time and group was found after either one session or four weeks of SSG training for any of the categories (all WTS p > 0.05) with significant effects only arising after eight weeks (all WTS p < 0.05). Thus although alterations were shown to be increasingly beneficial over time the minimum period required to produce a statistically significant benefit from performing SSG training was 8 weeks. For the Control Group no significant changes were identified for Posture, Flexibility and Cognition however a significant deterioration was observed in TUG (WTS p = 0.003). CONCLUSIONS: SSG is a holistic, gentle, rhythmic, whole body sequence of movements that may be readily learned and enjoyed in a group setting and has been confirmed in an RCT study of older adult females to produce significant benefits in Posture, Flexibility, Gait and Cognition.