TY - JOUR
T1 - Sensitive ultrasonic delineation of steroid treatment in living dystrophic mice with energy-based and entropy-based radio frequency signal processing
AU - Wallace, Kirk D.
AU - Marsh, Jon N.
AU - Baldwin, Steven L.
AU - Connolly, Anne M.
AU - Keeling, Richard
AU - Lanza, Gregory M.
AU - Wickline, Samuel A.
AU - Hughes, Michael S.
N1 - Funding Information:
Manuscript received October 1, 2006; accepted May 21, 2007. This work was funded by NIH R01-HL042950, R01-HL073646, and U54-CA119342. The authors are with the Washington University School of Medicine, Washington University, St. Louis, MO (e-mail: kirk.wallace@wustl.edu). Digital Object Identifier 10.1109/TUFFC.2007.533
PY - 2007/11
Y1 - 2007/11
N2 - Duchenne muscular dystrophy is a severe wasting disease, involving replacement of necrotic muscle tissue by fibrous material and fatty infiltrates. One primary animal model of this human disease is the X chromosomelinked mdx strain of mice. The goals of the present work were to validate and quantify the capability of both energy and entropy metrics of radio-frequency ultrasonic backscatter to differentiate among normal, dystrophic, and steroidtreated skeletal muscle in the mdx model. Thirteen 12month-old mice were blocked into three groups: 4 treated mdx-dystrophic that received daily subcutaneous steroid (prednisolone) treatment for 14 days, 4 positive-control mdx-dystrophic that received saline injections for 14 days, and 5 negative-control animals. Biceps muscle of each animal was imaged in vivo using a 40-MHz center frequency transducer in conjunction with a Vevo-660 ultrasound system. Radio-frequency data were acquired (1 GHz, 8 bits) corresponding to a sequence of transverse images, advancing the transducer from "shoulder" to "elbow" in 100-micron steps. Data were processed to generate both "integrated backscatter" (log energy), and "entropy" (information theoretic receiver, H f) representations. Analyses of the integrated-backscatter values delineated both treatedand untreated-mdx biceps from normal controls (p < 0.01). Complementary analyses of the entropy images differentiated the steroid-treated and positive-control mdx groups (p < 0.01). To our knowledge, this study represents the first reported use of quantitative ultrasonic characterization of skeletal muscle in mdx mice. Successful differentiation among dystrophic, steroid-treated, and normal tissues suggests the potential for local noninvasive monitoring of disease severity and therapeutic effects.
AB - Duchenne muscular dystrophy is a severe wasting disease, involving replacement of necrotic muscle tissue by fibrous material and fatty infiltrates. One primary animal model of this human disease is the X chromosomelinked mdx strain of mice. The goals of the present work were to validate and quantify the capability of both energy and entropy metrics of radio-frequency ultrasonic backscatter to differentiate among normal, dystrophic, and steroidtreated skeletal muscle in the mdx model. Thirteen 12month-old mice were blocked into three groups: 4 treated mdx-dystrophic that received daily subcutaneous steroid (prednisolone) treatment for 14 days, 4 positive-control mdx-dystrophic that received saline injections for 14 days, and 5 negative-control animals. Biceps muscle of each animal was imaged in vivo using a 40-MHz center frequency transducer in conjunction with a Vevo-660 ultrasound system. Radio-frequency data were acquired (1 GHz, 8 bits) corresponding to a sequence of transverse images, advancing the transducer from "shoulder" to "elbow" in 100-micron steps. Data were processed to generate both "integrated backscatter" (log energy), and "entropy" (information theoretic receiver, H f) representations. Analyses of the integrated-backscatter values delineated both treatedand untreated-mdx biceps from normal controls (p < 0.01). Complementary analyses of the entropy images differentiated the steroid-treated and positive-control mdx groups (p < 0.01). To our knowledge, this study represents the first reported use of quantitative ultrasonic characterization of skeletal muscle in mdx mice. Successful differentiation among dystrophic, steroid-treated, and normal tissues suggests the potential for local noninvasive monitoring of disease severity and therapeutic effects.
UR - http://www.scopus.com/inward/record.url?scp=37049039436&partnerID=8YFLogxK
U2 - 10.1109/TUFFC.2007.533
DO - 10.1109/TUFFC.2007.533
M3 - Article
C2 - 18051163
AN - SCOPUS:37049039436
SN - 0885-3010
VL - 54
SP - 2291
EP - 2299
JO - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
JF - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
IS - 11
ER -