Thermo-responsive ultrasound coupling gel, and methods and uses thereof
Inventors
Bigeleisen, Paul E. • KENNEY, Kyle • Shirtliff, Mark E.
Assignees
University of Maryland Baltimore
Publication Number
US-12193874-B2
Publication Date
2025-01-14
Expiration Date
2039-03-06
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Abstract
A thermo-responsive ultrasound coupling gel that contains a thermo-responsive polymer such as poly(n-isopropyl acrylamide), the gel having a phase shift at a temperature in the range of 32 to 35° C. such that the gel has a loss factor G″/G′ of >1 at <32° C. and a loss factor G″/G′ of <1 at >35° C. The gel can also contain at least one of a solvent and gelling agent. Methods and uses for the thermo-responsive ultrasound coupling gel in an ultrasound and/or ultrasound guided procedure.
Core Innovation
The invention is a thermo-responsive ultrasound coupling gel containing a thermo-responsive polymer, such as poly(n-isopropyl acrylamide), which exhibits a phase shift within the temperature range of 32 to 35°C. At temperatures below 32°C, the gel behaves as a viscoelastic liquid with high tack (loss factor G″/G′ > 1), while at temperatures above 35°C, it behaves as an elastic solid with low tack (loss factor G″/G′ < 1). This enables the gel to transition between being slippery for probe movement to sticky for stabilizing the probe during procedures.
The problem addressed is that standard ultrasound gels have low adhesivity, which can result in unintentional movement of the ultrasound probe, known as drift, during medical imaging and ultrasound-guided procedures such as biopsies and catheter placements. This drift complicates maintaining accurate probe positioning, especially in invasive procedures where precise targeting is critical. Additionally, the lubricity of conventional gels can change with applied pressure, further increasing the risk of probe drift.
The core innovation involves the use of a three-component solution—comprising a thermo-responsive polymer, a solvent, and a gelling agent—which enables the coupling gel to be applied in a slippery state (allowing easy probe movement) and then, after brief cooling to skin temperature, changes to a tackier, viscoelastic liquid that inhibits drift and stabilizes the probe. The temperature-dependent properties of the gel are not significantly affected by applied pressure, and its formulation can include additional components like preservatives, antioxidants, or pH control agents.
Claims Coverage
There is one independent claim in this patent, focused on a method of conducting an ultrasound using a thermo-responsive ultrasound coupling gel.
Method of conducting an ultrasound using a thermo-responsive ultrasound coupling gel
The inventive method involves: 1. Heating a thermo-responsive ultrasound coupling gel to a temperature ≥ 35°C. The gel comprises: - A thermo-responsive polymer solution containing 1-10 wt% of a thermo-responsive polymer and water. - A solvent solution containing 10-30 wt% of a solvent and water. - A gelling agent solution containing 10-30 wt% of a gelling agent and water. 2. Applying the gel to a patient at a temperature ≥ 35°C. 3. Cooling the ultrasound coupling gel to a temperature < 35°C. 4. Performing an ultrasound guided procedure while the gel is at a temperature < 35°C. The gel exhibits a phase shift at a temperature in the range of 32 to 35°C, such that it has: - A loss factor (G″/G′) > 1 at temperatures below 32°C - A loss factor (G″/G′) < 1 at temperatures above 35°C
The claims provide coverage for a method using a thermo-responsive ultrasound coupling gel, defined by its temperature-induced phase shift and specific compositional parameters, to enhance ultrasound and ultrasound-guided procedures.
Stated Advantages
The gel reduces drift of the ultrasound probe, allowing more accurate guidance of instruments such as biopsy needles during ultrasound-guided procedures.
The gel allows easy initial scanning and positioning due to its low tack at elevated temperatures and quickly transitions to a higher tack state, enhancing probe stability within 1 to 2 minutes.
The gel’s properties are substantially unaffected by applied pressure, ensuring consistent performance regardless of probe pressure adjustments.
The coupling gel maintains clear ultrasound imaging quality, with little to no discernable difference compared to standard ultrasound gels.
The gel is capable of being sterilized using ultraviolet light and remains stable in packaging, maintaining sterility and preventing evaporation.
The gel can be easily removed from the skin or phantom surface with standard cleaning methods.
Documented Applications
Use in medical ultrasound imaging procedures to couple the probe to the patient’s skin.
Use in ultrasound-guided medical procedures such as nerve blocks, placement of nerve block catheters, biopsy of the liver and kidneys, and cannulation of arteries and veins.
Use in standard, non-invasive ultrasound procedures.
Use in industrial applications, such as machinery inspections involving ultrasound-based evaluation.
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