High Frequency Spectral Ultrasound Imaging Detects Early Post Traumatic Muscle Fibrosis in Rodents

Johanna Nunez, Nicole J. Edwards, Geoffrey E. Hespe, Cassie Rowe, Amanda K. Huber, Chase Pagani, Ashish R. Chowdary, Jan P. Stegemann, Cheri X. Deng, Thomas Davis, Benjamin Levi

Research output: Contribution to conferenceAbstractpeer-review

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Abstract

Purpose: Muscle fibrosis is a devastating condition that can
occur following traumatic injury leading to loss of function
and poor outcomes. Limited noninvasive modalities exist to diagnose and characterize the extent of muscle damage.
Here we investigate spectral ultrasound imaging (SUSI),
a quantitative imaging technique which detects tissue
parameters based on intrinsic structure and composition,
to identify early muscle fibrosis based on fibrotic changes
established in a rat model. We hypothesize that SUSI will
detect early traumatic muscle fibrosis in a clinically translational
rat muscle injury model.
Methods: Adult male Sprague Dawley rats were sedated,
prepped, and underwent a soft tissue crush injury that generated
20lbs/in² of pressure using a digital force gauge.
A superficial 1.5 cm incisional wound was then made
over the quadriceps and closed. Injured and contralateral
uninjured hind limbs were collected and fixed for SUSI
imaging. Imaging was performed with a VisualSonics
VEVO770 high resolution small animal ultrasound
imaging system, using a 30 MHz center frequency single
element transducer. Injured muscles were imaged at the
crush injury and the corresponding place on the contralateral
limb. Analysis of radiofrequency data was done as
previously described in literature and SUSI parameters
were calculated using the average acoustic concentration
(AAC) of the fibrotic region and the corresponding region
in the contralateral muscle. AAC values were grouped by
time point and tissue type for statistical comparison using
unpaired t tests.
Results: In our rodent model, SUSI identified muscle
fibrosis as early as 7 days post injury. The average AAC of
injured fibrotic versus uninjured muscle was significantly
increased at post injury day 7 (36.33 vs 18.36 db/mm3,
injured versus uninjured, p = 0.003) and day 28 (54.64
vs 28.29 db/mm3, injured versus uninjured, pThough not statistically significant at day 14 (38.69 vs
27.61 db/mm3, injured vs uninjured, p=0.14) the fibrotic
muscle did trend toward a higher AAC value. These results
indicate that at day 7 and 28, the SUSI measurement AAC
can be used to distinguish injured fibrotic muscle from
uninjured muscle.
Conclusions: SUSI offers a portable, non-invasive,
and safe diagnostic modality to detect muscle fibrosis,
making it an ideal modality for post traumatic injuries.
Here, we show SUSI distinguishes muscle fibrosis from
healthy tissue at day 7 and 28 post injury in our model
allowing for early treatment. Unlike qualitative grayscale
imaging, SUSI determines unique parameters of the tissue
based on a calibrated spectrum related to the inherent
properties of the tissue, making it less user-dependent
and more reproducible.
Original languageAmerican English
StatePublished - 1 Jun 2022
Event17th Annual Academic Surgical Congress - Hilton Buena Vista Palace, Orlando, United States
Duration: 1 Feb 20223 Feb 2022

Conference

Conference17th Annual Academic Surgical Congress
Country/TerritoryUnited States
CityOrlando
Period1/02/223/02/22

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