NEW PARADIGMS FOR ULTRASOUND – PART II
Our previous blog opened a multi-part discussion on the expanding fields of ultrasound technology and potential applications in healthcare beyond interrogation and imaging for diagnostics. This material is adapted and condensed from presentations given at SDMS Conventions and the AVID Symposium in 2017. As stated previously, for those of you considering an entry into this profession, therapeutic ultrasound represents broader specialization possibilities, and wider opportunities for career advancement and success.
We noted with irony that many of the most exciting potential applications are based on utilizing properties of ultrasound that we have traditionally thought of as undesirable (i.e. Mechanical and Thermal Bioeffects). One of the more recent and promising fields of research involves harnessing the physical properties of ultrasound waves in service of more effective transdermal drug delivery, referred to as sonophoresis. Transdermal drug delivery was popularized in the 1990’s most notably associating with the Nicoderm patch. Today, for example, its application in the delivery of Fentanyl for treatment of chronic pain is well known.
Limitations exist to the effectiveness of transdermal delivery that leave it a distant third option to oral delivery and the often-loathed subdermal injection. Many of these relate to the non-uniform nature of different patients’ stratum corneum (the outer layer of the epidermis). Basically some of us are more “thin-skinned” or “thick-skinned” physically, rather than metaphorically.
Ultrasound, as with all sound waves, has an underlying wave force. Where researchers foresee promise is in using this wave force to “push” drug molecules through upper layers of the irregular epidermis to the subdermal layers where it can be absorbed. Obviously, a needle does the same thing only by a more intrusive and painful means.
This is potentially revolutionary if the technology advances to a point where it offers an alternative to the currently-prevalent subdermal needle injection by which most vaccines are delivered. Many patients would be more amenable to vaccination, if needles were not required. Additionally, needles represent an everyday biohazard in their disposal, and an infection source when the economically-disadvantaged are tempted to reuse them. Additionally, this technologically can prove extremely beneficial when injections are required on a daily basis such as with insulin for diabetics. Avoiding an occasional injection may be considered desirable, but avoiding repeated injections is significantly advantageous, especially if the transdermal approach can result in more effective control of blood glucose levels (as shown by this graph).
Another interesting field of study is advancing based on using the force of cavitation to drive localized drug delivery. This is especially promising where it is desirable to deliver a drug targeted to an infinitesimal mass (cancerous tissue or tumor). Again, as you may recall, because of the chaotic and intense energy (heat and pressure) associating with cavitation it is traditionally viewed as something to be controlled and minimized. This is based on both its effect on the tissue (thermal and mechanical) and the impact on the ultrasound image.
Until recently, channeling cavitational force intentionally within a living body would have been viewed like fishing with sticks of dynamite. However, because ultrasound force can now be delivered with more pin-point accuracy, this energy can be localized to activate drugs when in close proximity to a treatment site. Essentially, its power can be used to “herd” the drug toward its intended target, and/or activate it once there. By executing this reaction so precisely, the percentage of drug delivered to where it is actually needed can be enhanced to a point where it is more effective.
–Frank Miele, MSEE , President of Pegasus Lectures, Inc. Frank graduated cum laude from Dartmouth College with a triple major in physics, mathematics, and engineering. While at Dartmouth, he was a Proctor Scholar and received citations for academic excellence in comparative literature, atomic physics and quantum mechanics, and real analysis. Frank was a research and design engineer and project leader, designing ultrasound equipment and electronics for more than ten years at Hewlett Packard Company. As a designer of ultrasound, he has lectured across the country to sonographers, physicians, engineers and students on myriad topics.
*** A Special ‘Thank You‘ to Focused Ultrasound Foundation for use of images, statistical and industry research.