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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

This study describes how to obtain high quality musculoskeletal images using the extended field-of-view ultrasound (EFOV-US) method for the purpose of making muscle fascicle length measures. We apply this method to muscles with fascicles that extend past the field-of-view of common traditional ultrasound (T-US) probes.

Abstract

Muscle fascicle length, which is commonly measured in vivo using traditional ultrasound, is an important parameter defining a muscle’s force generating capacity. However, over 90% of all upper limb muscles and 85% of all lower limb muscles have optimal fascicle lengths longer than the field-of-view of common traditional ultrasound (T-US) probes. A newer, less frequently adopted method called extended field-of-view ultrasound (EFOV-US) can enable direct measurement of fascicles longer than the field-of-view of a single T-US image. This method, which automatically fits together a sequence of T-US images from a dynamic scan, has been demonstrated to be valid and reliable for obtaining muscle fascicle lengths in vivo. Despite the numerous skeletal muscles with long fascicles and the validity of the EFOV-US method for making measurements of such fascicles, few published studies have utilized this method. In this study, we demonstrate both how to implement the EFOV-US method to obtain high quality musculoskeletal images and how to quantify fascicle lengths from those images. We expect that this demonstration will encourage the use of the EFOV-US method to increase the pool of muscles, both in healthy and impaired populations, for which we have in vivo muscle fascicle length data.

Introduction

Fascicle length is an important parameter of skeletal muscle architecture, which overall is indicative of a muscle’s ability to produce force1,2. Specifically, a muscle’s fascicle length provides insight into the absolute range of lengths over which a muscle can generate active force3,4. For example, given two muscles with identical values for all isometric force-generating parameters (i.e., average sarcomere length, pennation angle, physiological cross sectional area, contraction state, etc.) except for fascicle length, the muscle with the....

Protocol

Northwestern University’s Institutional Review Board (IRB) approved the procedures of this study. All participants enrolled in this work gave informed consent prior to beginning the protocol detailed below.
NOTE: The specific ultrasound system used in this study had EFOV-US capabilities and was adopted because we were able to review details about and validity assessments for the algorithm in the scientific literature22,26; multiple other systems with .......

Representative Results

Extended field-of-view ultrasound (EFOV-US) was implemented to obtain images from the long head of the biceps brachii and the tibialis anterior in 4 healthy volunteers (Table 1). Figure 1 shows what EFOV-US images of both muscles imaged in this representative imaging session and highlights important aspects of each image such as muscle aponeurosis, central tendon, fascicle path, etc. After the imaging session was over, 3 qualitatively “good” images (

Discussion

Critical steps in the protocol.

There are a few critical components to obtaining quality EFOV-US images that yield valid and reliable fascicle length measures. First, as indicated in method 1.1.2 it is essential that the sonographer take time to become familiar with the anatomy of the muscle being imaged as well as surrounding muscles, bones, and other soft tissue structures. This will improve the sonographer’s ability to image the correct muscle and determine if multipl.......

Acknowledgements

We would like to thank Vikram Darbhe and Patrick Franks for their experimental guidance. This work is supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1324585 as well as NIH R01D084009 and F31AR076920. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation or NIH.

....

Materials

NameCompanyCatalog NumberComments
14L5 linear transducersSiemens10789396
Acuson S2000 Ultrasound SystemSiemens10032746
Adjustable chair (Biodex System)Biodex Medical SystemsSystem Pro 4
Skin Marker Medium TipSportSafen/aMulti-color 4 Pack recommended
Ultrasound Gel - Standard 8 Ounce Non-Sterile Fragrance Free Glacial TintMediChoice, Owens &MinorM500812

References

  1. Gans, C., Bock, W. J. The functional significance of muscle architecture: a theoretical analysis. Advances in Anatomy, Embryology and Cell Biology. 38, 115-142 (1965).
  2. Gans, C. Fiber architecture and muscle function.

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