Solid hydrogel coupling for ultrasound imaging and therapy

Abstract

The present invention employs hydrogels as acoustic couplings for clinical applications of ultrasound imaging and therapy, but is particularly applicable to high intensity focused ultrasound (HIFU) based therapy. While other materials can be used, it has been determined that polyacrylamide is sufficiently robust and transmissive to withstand the high temperatures encountered in HIFU therapy. One embodiment of a hydrogel coupling is configured in shape and size (length) to ensure that a focal region of an ultrasound transducer is disposed proximate the target area when the distal tip of the transducer is in contact with tissue. These couplings can be shaped to correspond to the beam focus characteristics of specific transducers. Water can be applied to hydrate the tip of the hydrogel coupling during use, and medication absorbed into the hydrogel material can be applied to the tissue in contact with the distal surface of the hydrogel.

Description

RELATED APPLICATIONS [0001] This application is a divisional application based on prior copending application Ser. No. 10 / 449,819 filed May 30, 2003, which itself is based on a prior copending provisional application, Ser. No. 60 / 384,566, filed on May 30, 2002, the benefit of the filing dates of which is hereby claimed under 35 U.S.C. §§ 119(e) and 120.GOVERNMENT RIGHTS [0002] The research for this invention was funded with grants from the National Institutes of Health (No. 5R01-HL064208-02) and from the Department of the Navy (No. N00014-96-1-0630). The U.S. government may have certain rights in this invention.FIELD OF THE INVENTION [0003] The present invention generally relates to a hydrogel based coupling for use in ultrasonic imaging and therapy, and method for use of the same, and more specifically, pertains to a dimensionally stable hydrogel that remains stable when transmitting relatively high intensity ultrasound to a therapy site, and a method for using the same. BACKGROUND...

AI Technical Summary

Benefits of technology

[0021] In at least one embodiment, the dimensionally stable hydrogel mass is substantially transparent, to avoid blocking a view of a target when in use. This characteristic facilitates the use of the hydrogel coupling, since a clinician will be able to see through the dimensionally stable hydrogel mass, to verify where the outer extent of the distal surface is contacting the boundary or the target.

[0037] Additional steps can include hydrating the distal surface of the dimensionally stable hydrogel mass, to prevent damage to the distal surface of the dimensionally stable hydrogel mass by the HIFU, and / or delivering a medicinal agent to at least one of the target and the physical boundary, after coupling the distal surface of the dimensionally stable hydrogel mass to at least one of the target and the physical boundary.

[0043] In at least one embodiment, the mold includes reservoir and a mold volume which are in fluid communication. The mold volume conforms to the desired size and shape of the dimensionally stable hydrogel mass to be produced. In such an embodiment, the mixture is introduced into the mold via the reservoir, until the mold volume is filled with the mixture, and additional mixture is in the reservoir. Polymerization of the mixture in the reservoir is inhibited, while polymerization of the mixture in the mold volume is allowed. The polymerization reduces the volume of the mixture in the mold volume, so that more of the mixture in the reservoir flows into the mold volume and polymerizes. Once the mold volume is filled with a polymerized dimensionally stable hydrogel mass, the mixture in the reservoir volume is allowed to polymerize. The dimensionally stable hydrogel mass is removed from the mold, and any undesired portion of the dimensionally stable hydrogel mass (i.e. the portion corresponding to the reservoir) is removed.

Problems solved by technology

Many studies have shown that these sound waves are harmless and may be used with complete safety, even to visualize the fetus in pregnant women, where the use of X-rays would be inappropriate.

While the treatment was quite successful, monitoring and guidance of the HIFU lesion formation was not easily achieved (as reported by N. T. Sanghvi and R. H. Hawes, (1994) “High-intensity focused ultrasound,”Gastrointestinal Endoscopy Clinics of North America, 4: 383-95).

While this coupling method has been useful for hemostasis experiments, it has many drawbacks that would make it impractical for a clinical setting.

These disadvantages include degassing, sterilization, circulation, and containment issues.

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