Preclinical Ultrasound Imaging—A Review of Techniques and Imaging Applications

Abstract

Ultrasound imaging is a well-established clinical imaging technique providing real-time, quantitative anatomical and physiological information in humans. The lack of ionizing radiation and relative low purchase and maintenance costs results in it being one of the most frequently used clinical imaging techniques with increasing use for guiding interventional clinical procedures. Until 20 years ago, translation of clinical ultrasound practices to preclinical applications proved a significant technological challenge due to the smaller size (25 g vs. 70 kg) and rapid conscious heart-rate (500-700 bpm vs. 60 bpm) of the mouse requiring an increase in both spatial and temporal resolution of 10-20-fold in order to achieve diagnostic information comparable to that achieved clinically. Since 2000 [1], these technological challenges have been overcome and commercial high frequency ultrasound scanners have enabled longitudinal studies of disease progression in small animal models to be undertaken. Adult, neonatal and embryonic rats, mice and zebrafish can now be scanned with resolutions down to 30 microns and with sufficient temporal resolution to enable cardiac abnormalities in all these species to be identified. In mice and rats, quantification of blood flow in cardiac chambers, renal, liver and uterine vessels, and intra-mural tissue movements can be obtained using the Doppler technique. Ultrasonic contrast microbubbles used routinely for clinical applications are now being further developed to include targeting mechanisms and drug-loading capabilities and the results in animal models bode well for translation for targeted drug delivery in humans.

Assessment of myocardial viscoelasticity with Brillouin spectroscopy in myocardial infarction and aortic stenosis models

“…In addition, it depends on the operator´s pressure, presenting high intra and inter-operator variability 39 . Therefore, strain analysis of the myocardium using ultrasound is generally performed with speckle tracking techniques 40 , as we did in this report to validate mBS. The correlation between speckle tracking and mBS stiffness estimation argues in favour of the reliability of this technique.…”

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“…Smart theranostic systems need to combine contrast agents for distinct imaging modalities, a targeting strategy, therapy effectors and responsive moieties. Adapted with permission from 42 - 46 , copyright 2020 Moran and Thomson, 2018 Stylogiannis et al, 2020 Picillo et al, 2013 Cheng et al, 2016 Tang et al…”

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