In vivo imaging of blood flow in the mouse Achilles tendon using high-frequency ultrasound.
OBJECTIVE
Achilles tendinitis is a common clinical problem with many treatment modalities, including physical therapy, exercise and therapeutic ultrasound. However, evaluating the effects of current therapeutic modalities and studying the therapeutic mechanism(s) in vivo remains problematic. In this study, we attempted to observe the morphology and microcirculation changes in mouse Achilles tendons between pre- and post-treatment using high-frequency (25 MHz) ultrasound imaging. A secondary aim was to assess the potential of high-frequency ultrasound in exploring therapeutic mechanisms in small-animal models in vivo.


METHODS
A collagenase-induced mouse model of Achilles tendinitis was adopted, and 5 min treatment of continuous-mode low-frequency (45 kHz) ultrasound with 47 mW/cm(2) maximum intensity and 16.3 cm(2) effective beam radiating area was applied. The B-mode images showed no focal hypoechoic regions in normal Achilles tendons either pre- or post-treatment. The Doppler power energy and blood flow rate were measured within the peritendinous space of the Achilles tendon.


CONCLUSIONS
An increase in the microcirculation was observed soon after the low-frequency ultrasound treatment, which was due to immediate induction of vascular dilatation. The results suggest that applying high-frequency Doppler imaging to small-animal models will be an invaluable aid in explorations of the therapeutic mechanism(s). Our future work includes using imaging to assess microcirculation changes in tendinitis between before and after treatment over a long time period, which is expected to yield useful physiological data for future human studies.
Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC. ckyeh@mx.nthu.edu.tw
Chih-Kuang
CK
Yeh
Jia-Jiun
JJ
Chen
Meng-Lin
ML
Li
Jer-Junn
JJ
Luh
Jia-Jin Jason
JJ
Chen
D000125:Achilles Tendon / Q000098:blood supply* / Q000000981:diagnostic imaging*; D000818:Animals; D001783:Blood Flow Velocity; D004195:Disease Models, Animal; D051379:Mice; D008810:Mice, Inbred C57BL; D008833:Microcirculation; D052256:Tendinopathy / Q000000981:diagnostic imaging* / Q000628:therapy*; D014464:Ultrasonic Therapy / Q000379:methods*; D018615:Ultrasonography, Doppler, Color / Q000379:methods*