In-vivo Assessment of Taut Bands and Myofascial Trigger Points using Shear
Wave Elastography
1.
Research Objectives
The primary aim of this study is to evaluate the feasibility of using shear wave elastography
(SWE) to quantify taut band (TB) and myofascial trigger points (MTrP);
Our secondary aims are to evaluate the effect of Nimmo treatment on elasticity of TB/MTrP site;
evaluate the test-retest reliability of SWE for muscle hardness measurements; compare the
hardness of TB/MTrP with their surrounding muscle fibers in tibialis anterior muscle; and
compare the hardness of the tibialis anterior (TA) muscles in subjects with and without TB/MTrP.
2.
Past Experimental and/or Clinical Findings
Myofascial pain syndrome (MPS) is estimated to affect as many as nine million people in the
United States [1, 2]. Despite its high prevalence, the characteristics of MPS remain highly
debated as its hallmark findings of taut bands (TBs) (localized areas of increased muscle tone
and tenderness) and myofascial trigger points (MTrPs) (hard and localized nodules of increased
tenderness within the taut bands) [3] depend very much on the examiner’s clinical skills for
identification. Currently, we still lack objective and quantitative evidence to confirm MTrP and
TB as a clinical entity. Ironically, accurate localization of MTrP and TB is vital to the diagnosis
and treatment of myofascial pain [4].
Recently, elastography imaging techniques have been applied to identify taut bands and/or
myofascial trigger points with some success [3, 5-7]. Chen and his co-workers [6, 7] utilized a
non-invasive MR-based phase contrast imaging technique, namely magnetic resonance
elastography (MRE), to image taut bands at the upper trapezius. They noted a signature
“chevron-shaped” shear wave front in the region of taut band palpated by a physician but MTrP
was not identified within the taut band, most likely because of the limited resolution of the
technique. In addition, MRE acquisition requires the subject to stay still for a long time. Any
subtle motion during the acquisition could compromise the image quality.
Shah and his co-workers utilized B-mode ultrasound imaging and vibration sonoelastography
(VSE) to visualize MTrPs [3, 5]. Their preliminary findings appear to show that MTrPs are focal,
hypoechoic regions on B-mode ultrasound, indicating local changes in tissue echogenicity, and
focal regions of reduced vibration amplitude on VSE, indicating a localized, stiff nodule.
However, Shah admitted that the amount of pressure and the angle at which the ultrasound
transducer head is held to scan the tissue is difficult to control, which may substantially affect the
results. Although more quantitative measurement (i.e. trigger point area) has also been extracted
from VSE images to quantify MTrPs [5], area measurement suffers from subjectivity related to
threshold settings, and hence, VSE and B-mode ultrasound can provide at best semi-quantitative
information of MTrP.
A technique that can provide quantitative elastography images and elasticity values at the MTrP,
TB, and its surrounding soft tissues will advance our understanding on MTrP and TB to a new
level. Such information may aid proper diagnosis of myofascial pain syndrome and help to
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determine the underlying mechanisms relevant to the development, amplification, and resolution
of MTrP and TB.
Shear wave Elastography (SWE) is the current state-of-the-art technology that uses acoustic
radiation force induced by ultrasound beams to perturb underlying tissues [8]. This force induces
shear waves which propagate transversely in the tissue. By focusing the push forces at different
depths in tissues at high speed, shear waves are coherently summed, which substantially increase
the propagation distance (Figure 1). As the shear waves propagate, they are captured by the
ultrasound at a frame rate up to 20,000 Hz (Figure 2). Shear wave propagation speed (𝑉) is then
estimated at each pixel. Tissue elasticity (E) can then be directly deduced from the following
equation:
𝐸 = 3𝜌𝑉 2
(1)
where 𝜌 is the density of tissue expressed in kg/m3.
SWE can provide quantitative elasticity maps in real time with color scale expressed in kPa
(Figure 3), which does not requires external compression and/or vibration, and hence, it supposes
to be less skill-dependent as compared with other elastography modalities. SWE has been shown
to be highly reproducible in breast mass [9].
Figure 2: Plane shear wave in a medium
containing a harder inclusion (red circle). The
plane shear wave front is deformed because
the shear wave travels faster in the harder
inclusion. (From: SuperSonic Imagine white
paper)
Figure 1: Principle of plane shear
wave generation using radiation
force. (From: SuperSonic Imagine
white paper)
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Figure 3: Map of the elasticity image deduced from the velocity movie as shown in figure 2.
We propose to investigate the feasibility of using shear wave elastography to quantify MTrPs
and TBs, compare the hardness of TB/MTrP, and thier surrounding muscle fibers, and compare
the hardness of TB/MTrP and normal sites. If successful, it will provide groundbreaking data to
support MTrP and TB as real clinical entities. We hypothesize that shear wave elastography is a
reliable imaging modality. We further hypothesize that using shear wave elastography, normal
and TB/MTrP sites can be consistently differentiated from each other.
3.
Subject Population
Two groups of subjects (i.e. runner and non-runner groups) will be recruited. Each group
consists of 15 subjects. Participants must fulfill all inclusion criteria and do not meet any of the
exclusion criteria listed below. A clinician will take a thorough history and perform a physical
examination to determine their eligibility. Subjects with chronic posttraumatic pain will also be
included in the study unless they meet the exclusion criteria.
Runner group
o Inclusion criteria:
 18-65 years of age
 With running habit, running at least 5 miles a week
 Pain or discomfort in lower extremity while running or walking
 With palpable myofascial trigger point in at least one tibialis anterior muscle
(TA)
o Exclusion criteria:
 Diagnosis of stress fracture or compartment syndrome within the last 12
months
 Pain or discomfort due to an acute injury
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With delayed onset muscle sore at the time of testing
Fibromyalgia
A history of myopathy
A history of cancer
Females, if pregnant or there is a possibility that they are pregnant
Females, if the lower extremity pain/discomfort is associated with their
menstrual cycle
Non-runner group
o Inclusion criteria:
 18-65 years of age.
 Without running habit
 No pain or discomfort in lower extremity while running or walking
o Exclusion criteria:
 Diagnosis of stress fracture or compartment syndrome within the last 12
months
 With delayed onset muscle sore at the time of testing
 Fibromyalgia
 A history of myopathy
 A history of cancer
 Females, if pregnant or there is a possibility that they are pregnant
 Females, if the lower extremity pain/discomfort is associated with their
menstrual cycle
4.
Recruitment of Subjects
We will try to recruit subjects from the students and staff population at New York Chiropractic
College (NYCC). Additional subjects will be recruited from the community if we are unable to
recruit enough subjects on campus. We will post recruitment announcements for this research
project throughout campus. We will ask willing faculty members to announce this research
project to students in their classes. We will provide these faculty members with sign-up sheets to
obtain the students’ phone numbers for scheduling and informational purposes. We may also ask
willing faculty members to allow us to announce this research project to students in their classes.
All subjects will undergo a verbal description of their participation requirements and the nature
of the procedures. A written informed consent will be signed by all participants, which will
outline risks and benefits of participation. All participation is strictly voluntary and subjects may
withdraw from the study at any time. Subjects will be screened for the inclusion and exclusion
criteria by an experience clinician prior to enrollment. Emails of advertisement to recruit subjects
will be sent by the principle investigator. Pre-screening for inclusion and exclusion criteria will
be done by one of the investigators.
5.
Study Design
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This feasibility study will explore whether shear wave elastography (SWE) could be used to
quantify MTrP and TB. The study will be carried out at the Biodynamic Laboratory of the New
York Chiropractic College. Convenient samples of 15 runners and 15 non-runners who fulfill the
inclusion criteria and do not meet any of the exclusion criteria will be recruited in a first-comefirst-serve basis. An experienced clinician will palpate for the most prominent MTrP in each
tibialis anterior muscle (TA). Each MTrP site will be classified as either active or latent. Active
site has at least 1 palpable nodule, and palpation reproduces or exacerbates the patient’s
spontaneous pain. Latent site has at least 1 palpable nodule; although tender to palpation, this
maneuver did not reproduce or exacerbate the patient’s spontaneous pain. Taut band along the
MTrP will also be identified by palpation. If no MTrP can be found, that TA is denoted as a
control. Subjects and examiners will be aware of the clinical diagnosis of each site. Each
participant will be tested using the same testing protocol and Nimmo receptor tonus technique
will be used to resolve the MTrP. Comparisons of the elastography images and quantitative
parameters will be made between MTrP/TB site and its nearby normal site.
6.
Research procedure(s)
Protocol for Imaging the MTrP and Tuat Band Sites
Each subject will be instructed to completely relax and sit comfortably on an assessment chair of
the Biodex machine (Biodex Medical Systems, Inc., Shirley, NY) with his/her foot secured on a
foot plate which is connected to the Biodex dynamometer (Figure 4). Each MTrP/taut band site
will be tested with the ankle positioned at 0, 10, 20, 30, 40, and 50 plantarflexion (or 90%
of the maximum plantarflexion whatever smaller) respectively. Ankle positions will be
measured by an electrogoniometer (Biometrics Ltd, UK). Hardware and software stops will be
setup to constraint the ankle to rotate within its normal range of motion. All measurements will
start at 50 plantarflexion or 90% of the maximum plantarflexion whatever smaller. A clinician
with 30+ years’ experience in locating MTrP and TB will palpate for the most prominent MTrP
and its corresponding TB in each tibialis anterior muscle. Reasons for selection of TA in this
study are because (1) it is a common place with MTrP [10], and (2) our pilot study shows that
more reliable elastography images can be obtained in TA. MTrP and taut band locations will be
marked on the skin using an oil-based marker. A line (60 mm long) centered at the palpable
MTrP/TB will then be drawn along muscle fiber direction (MTrP/TB site). A parallel line at the
same level of the MTrP/TB line will also be marked along the normal muscle fibers (i.e. normal
site). A 50mm, 15-4 MHz linear array transducer of the shear wave elastography machine
(Aixplorer®, Supersonic Imagine Inc, France) will be placed along the lines in a random order.
No pressure will be induced by the transducer at all measurement sites. Surface
electromyographic (sEMG) electrodes will be placed on the distal tibialis anterior to monitor
muscle activation of the TA during elasticity measurements. SEW images will be acquired when
the sEMG signal is smaller than 1% of the maximal level reached during maximal isometric
contraction. At each measurement site, the SWE image will be frozen and saved after a few
seconds of immobilization to allow the SWE image to stabilize. Three SWE images will be
acquired in each measurement site at each ankle position. Right after the elastography
measurements, a Nimmo doctor (Cohen) will treat the MTrP using Nimmo technique. The
treatment will involve applying precise pressure for 5-7 seconds to the MTrP site for up to 3
times. Elastography measurements will be repeated at the MTrP/TB site right after the treatment.
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Altogether, 90 SWE images (i.e. 3 repetitions per sites x 2 sites x 6 ankle positions x 2 sessions
(Pre-treatment) + 3 repetitions per sites x 1 site x 6 ankle positions x 1 session (Post-treatment))
will be saved. All SWE images will be acquired with the transducer perpendicular to the skin.
Figure 5 summarizes the experimental protocol for imaging the MTrP and TB sites.
Biodex dynamometer
Foot plate
Mechanical Constraints
Surface EMG electrodes
Ultrasound transducer
Adjustable bars
Axis of
rotation
Figure 4: Experimental setup.
Protocol for Imaging the Normal Sites
For a normal side, 2 muscle bands of the TA at one-third of the shank will be imaged using SWE
with the ankle at 0, 10, 20, 30, 40, and 50 plantarflexion (or 90% of the maximum
plantarflexion whatever smaller). The same protocol as described above will be employed for
SWE imaging of the normal sites except that there will be no treatment involved and hence, no
post-treatment measurements. Altogether, 36 SWE images (i.e. 3 repetitions per sites x 2 sites x
6 ankle positions x 2 sessions) will be saved.
Instrumentation
All instruments to be used in this study, including shearwave elastography, Biodex
dynamometer, and surface EMG, have been used in previous approved IRB projects (IRB 08-07,
10-01, 12-01, 12-05). Nimmo treatment has also been studied in a previous approved IRB study
(IRB 10-01). No adverse events have been reported in these studies.
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(1) Palpate for the most prominent MTrP or TB in the left tibialis anterior muscle
(2) Mark a “X” at the MTrP or TB site and draw a line centered at “X” and along muscle fiber
direction (Taut band site)
(3) Draw a line along the normal fiber (Normal site)
(4) Position the ankle to 50 plantarflexion or 90% of the maximum plantarflexion whatever
smaller
(5) Place an ultrasound transducer along a measurement site. Freeze and save the SWE image
at the same site for 3 times.
(6) Repeat the measurements at 40, 30, 20, 10, and 0 plantarflexion respectively
(7) Repeat steps 5-6 at the other site
(8) Treat the TrP/TB site using Nimmo Technique
(9) Repeat elastography measurement at TrP/TB site
Figure 5: Experimental protocol for quantifying the MTrP/TB site using shear wave
elastography.
Data Analysis
(A) Quantitative Measures
Based on a region of interest (ROI) placed at the center of the SWE image of each measurement
site, the following parameters will be determined:
Emax(MTrP) - Maximum elasticity value in the ROI of the MTrP
Emean(MTrP) – Mean elasticity value in the ROI of the MTrP
Emax(Sur) - Maximum elasticity value in the ROI of the normal tissue surrounding the MTrP
Emean(Sur) – Mean elasticity value in the ROI of the normal tissue surrounding the MTrP
Eratio – Ratio of Emean(MTrP) to Emean(Sur)
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Similarly, based on a ROI placed at the center of the SWE image of each normal site, the
following parameters will also be determined:
Emax(Norm) - Maximum elasticity value in the ROI of the normal site
Emean(Norm) – Mean elasticity value in the ROI of the normal site
(B) Qualitative Measures
The following qualitative SWE features will be assessed and recorded:
(1) Percentage of MTrP sites with focal high stiffness region
(2) Percentage of normal sites with focal high stiffness region
(3) Homogeneity of elasticity of the MTrP sites (Not homogeneous, reasonable homogeneous,
very homogeneous)
(4) Homogeneity of elasticity of the normal sites (Not homogeneous, reasonable homogeneous,
very homogeneous)
(5) MTrP appearance (Single or multiple loci, oval, round, irregular, etc.)
(C) Repeatability and Reliability
Based on the three SWE images captured in the same plane, image repeatability (i.e. all images
very similar, reasonably similar, some images are similar (two of the three), and images very
dissimilar) will be assessed.
Intraclass correlation coefficients (ICCs) will be calculated for each quantitative parameter
defined above.
(D) Statistical Analysis
Paired t-tests of Emax and Emean for the MTrP region versus the surrounding normal tissue will be
performed. Two-sample t-tests of Emax and Emean, assuming unequal variances for the MTrP
region versus the contralateral normal site will be performed. Eratio, Emean, and Emax will be
compared between active and latent MTrP sites and between upper trapezius and gluteal muscle
using two-sample t-tests. A confidence level of 0.05 is chosen for all statistical tests.
7.
Potential Risks
The procedures as outlined above pose no known significant risks to the patient.
Minor bruising and soreness after a Nimmo treatment intervention has been reported in the past
as evidenced by over 20 years of clinical experience by CoI.
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Shear wave elastography is a safe imaging modality which meets acoustic output limitations
defined by international standards [11]. It has been used in vivo for breast [12] and liver [13]
imaging and have been cleared by FDA for clinical use. To our knowledge, there is no adverse
effect reported in the past.
There is a very small possibility that some subjects may have a mild dermal allergic response to
ultrasound gels or surface EMG electrodes. This is quite rare and usually only results in a focus
of mild irritation at the site of placement. In PI’s experience using similar gels over the past ten
years, no significant allergic response has been encountered.
Theoretically, there is a small possibility that the ankle joint may be over-stretched by the Biodex
machine. This is very unlikely because the mechanical constraints built-in to the Biodex machine
will limit the ankle range of motion within a safety limit even woth machine failure.
Minor discomfort and/or fatigue may result from the testing protocol.
There also may be risks and discomforts which are not yet known.
8.
Procedures for Protecting Against and Minimizing Any Potential Risks
In the event a subject was to note intolerance to the testing protocol, voluntary withdrawal from
participation can be obtained. In the event of an allergic response to ultrasound gels and/or
surface electrode, the subject will be immediately withdrawn from participation and monitored
by the PI as to their condition. Both hardware and software constraints will be properly setup
within the Biodex machine to minimize ankle over-stretching
9.
Anticipated Benefit
Although there is no direct benefit to the participants, the data obtained in this study may allow
us to confirm MTrPs and TB as real clinical entities.
10.
Incentives for Participation
We will offer participants $10 per hour to defray the time for participating the study.
11.
Sources of Data
Data collection will involve B-mode and elastography images, quantitative elasticity values, and
demographic data. All data and record will be secured as part of the subject's data records. The
confidentially of all sources of materials will be secured by identifying data records by subject
number and group number. Informed consent forms and other data record sheets containing the
names of the subjects as well as their age, height, weight, and clinical data findings will be stored
in a locked cabinet whose access is limited to the PI. The cabinet will be located in the research
building whose access is limited to research personnel. All personal data collected in this study
will be destroyed 5 years after completion of the study.
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12.
Brief CV
See attached.
13.
Data and Safety Monitoring Plan
The proposed study is associated with relatively little risk to a small number of participants (see
Potential Risks above). Thus it does not require extensive monitoring by a Data and Safety
Monitoring Board. The Principal Investigator (Koo) and Co-Investigator (Guo) will be
responsible for overseeing the conduct of the research project to ensure the safety of participants
and the validity and integrity of the data. The Data and Safety Monitoring Plan will include
monthly assessment of data quality, participant recruitment, accrual and retention, and any
anticipated and unanticipated events that may affect the risk to study participants. Further we
will monitor adverse events that are possibly, probably, or definitely related to study procedures.
For this study, we will define an adverse event as any unfavorable or unintended sign, symptom,
or disease that arises immediately after a study procedure and persists for more than 24 hours,
and could reasonably be related to study procedures. Subjects will be asked to report any adverse
events to the principal investigator as soon as possible. Once an adverse event is reported, study
clinician will assess whether an adverse event is: 1) mild, moderate, severe, or serious; 2)
expected (disclosed in the Consent Form) or unexpected (more serious than expected, or not
disclosed in the Consent Form), and 3) unrelated, unlikely related, possibly related, probably
related and definitely related to study procedures. Any adverse events will be reported to IRB
committee within 48 hours.
A chiropractor (Cohen) with 30+ years of clinical experience will screen all subjects to make
sure that they do not meet any of the exclusion criteria before the subjects being recruited. In
case of doubt, the subject will be excluded from the subject. Throughout the experiment, subjects
will be regularly reminded that they may withdraw from the study at any time if they don’t feel
well to ensure the safety of participants.
14.
References
[1] R. D. Gerwin, Classification, epidemiology, and natural history of myofascial pain
syndrome. Curr Pain Headache Rep 5, 412-420 (2001).
[2] D. J. Alvarez and P. G. Rockwell, Trigger points: diagnosis and management. Am Fam
Physician 65, 653-660 (2002).
[3] S. Sikdar, J. P. Shah, T. Gebreab, R. H. Yen, E. Gilliams, J. Danoff and L. H. Gerber,
Novel applications of ultrasound technology to visualize and characterize myofascial
trigger points and surrounding soft tissue. Arch Phys Med Rehabil 90, 1829-1838
(2009).
[4] C. L. Graboski, D. S. Gray and R. S. Burnham, Botulinum toxin A versus bupivacaine
trigger point injections for the treatment of myofascial pain syndrome: a randomised
double blind crossover study. Pain 118, 170-175 (2005).
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[5] J. J. Ballyns, J. P. Shah, J. Hammond, T. Gebreab, L. H. Gerber and S. Sikdar, Objective
sonographic measures for characterizing myofascial trigger points associated with
cervical pain. J Ultrasound Med 30, 1331-1340 (2011).
[6] Q. Chen, J. Basford and K. N. An, Ability of magnetic resonance elastography to assess
taut bands. Clin Biomech (Bristol , Avon ) 23, 623-629 (2008).
[7] Q. Chen, S. Bensamoun, J. R. Basford, J. M. Thompson and K. N. An, Identification and
quantification of myofascial taut bands with magnetic resonance elastography. Arch
Phys Med Rehabil 88, 1658-1661 (2007).
[8] J. Bercoff, M. Tanter and M. Fink, Supersonic shear imaging: a new technique for soft
tissue elasticity mapping. IEEE Trans Ultrason Ferroelectr Freq Control 51, 396-409
(2004).
[9] D. O. Cosgrove, W. A. Berg, C. J. Dore, D. M. Skyba, J. P. Henry, J. Gay and C. CohenBacrie, Shear wave elastography for breast masses is highly reproducible. Eur Radiol
(2011).
[10] D. G. Simons, J. G. Travell and L. S. Simons, Travell & Simons' myofascial pain and
dysfunction: The trigger point manual, Williams & Wilkins, Baltimore 1999.
[11] IEC 60601-2-37:2001 + Amendment 1: 2004 + Amendment 2: 2005 Medical electrical
equipment - Part 2-37: Particular requirements for the safety of ultrasonic medical
diagnostic and monitoring equipment. 2005.
[12] A. Athanasiou, A. Tardivon, M. Tanter, B. Sigal-Zafrani, J. Bercoff, T. Deffieux, J. L.
Gennisson, M. Fink and S. Neuenschwander, Breast lesions: quantitative elastography
with supersonic shear imaging--preliminary results. Radiology 256, 297-303 (2010).
[13] E. L. Leen, C. J. Harvey and H. Wasan. Application of ShearWave™ Elastography
(SWE) in assessing the effect of systemic treatment of liver tumours. RSNA 2010 . 2011.
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Attachments
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Koo CV
Guo CV
Cohen CV
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