Laser treatment of cutaneous vascular lesions

Abstract

Methods for treating maladies such as cutaneous vascular lesions. A patient in need of vascular lesion treatment is identified. A hyperosmotic agent is administered to a region adjacent the lesion. Blood flow velocity is slowed within the region using the hyperosmotic agent, and the lesion is exposed to laser radiation.

Description

[0001] This application claims priority to, and incorporates by reference, U.S. Provisional Patent Application Ser. No. 60 / 363,726 filed Mar. 12, 2002 entitled “Laser Treatment of Cutaneous Vascular Lesions.”[0002] Aspects of this invention were made with government support of the National Science Foundation, grant number BES9986296. Further support has been provided by Texas Higher Education Coordinating Board, grant number BER-ATP-253. Accordingly, the government may have certain rights in this invention.BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates generally to biomedical engineering, imaging, medicine, and medical treatment. More particularly, it concerns clinical laser treatment of cutaneous vascular lesions using chemical agents that not only increase light penetration but also decrease blood flow velocity. [0005] 2. Description of Related Art [0006] Cutaneous vascular lesions can be classified into two main categories. The f...

AI Technical Summary

Benefits of technology

[0015] Procedures described herein are able to reduce the laser dose required for irreversible photocoagulation of blood vessels in tissue. Each of the two main limitations of conventional techniques, discussed above, are addressed by using a specific class of chemical agents together with application of laser radiation to blood vessels. Required fluences for the permanent destruction of blood vessels in the skin are significantly lower with the techniques of this disclosure as compared to cases where no chemical agents are used. Experimental results substantiating the assertions of this disclosure are presented in the Examples section.

[0017] These recently-discovered morphological effects of glycerol (and other agents) on blood flow velocity, coupled with glycerol's ability to increase light transmission within turbid media (i.e., glycerol's “optical clearing” properties), serve as one basis for an effective, new methodology for vastly improved laser treatment of cutaneous vascular lesions. First, increased light penetration due to glycerol and other hyperosmotic agents allows for better localization of light on deep blood vessels that previously would not have been targeted. Second, decrease in blood flow velocity due to glycerol allows for significantly lower radiant light exposures to be used for blood vessel photocoagulation.

[0018] In one embodiment, the invention is a method for reducing the amount of radiation required to destroy a blood vessel of a cutaneous vascular lesion. The method involves administering a hyperosmotic agent to the blood vessel to slow blood flow velocity prior to exposure to laser radiation.

Problems solved by technology

Some of these lesions, such as the port wine stain (PWS), can be quite traumatic for a patient, resulting in serious psychological and social problems [Lanigan et al., 1989; Tan, 1992; Morelli et al., 1992; Masciarelli, 1992; van Gemert, 1992].

When lesions are located near joints, lips, or the eyes they can also interfere with normal functions and lead to serious problems such as hypertrophy of skeletal tissue or more severe conditions [Mulliken, 1992].

Blood vessels are damaged by the increase in temperature resulting from absorption of pulsed laser light.

A number of shortcomings exist in current clinical treatments due to the lack of parameter optimization and sufficient delivery of light to deep lying blood vessels.

Unfortunately, because the treatment parameters governing the effectiveness of laser therapies vary greatly from patient to patient, many instances of incomplete destruction of abnormal vessels and clearing of the lesion occur.

In general, low treatment success rates remain a problem with existing laser treatments of vascular lesions.

This low success rate is due to at least two main limitations: (a) restrictions in the achievable penetration depth of light in biological tissue and (b) insufficient increase in blood vessel temperatures associated with high flow velocities.

The first limitation (limitation (a)) in the laser treatment of cutaneous vascular lesions involves rapid attenuation of incident light with depth.

In many cases, deep blood vessels in a lesion are not sufficiently heated by incident light due to competition from absorption and scattering by other tissue constituents.

The second limitation (limitation (b)) in the laser treatment of vascular lesions involves the lack of control of blood flow velocity.

Despite this realization, current laser treatment techniques have not been able to fully capitalize upon the benefits afforded by controlling blood flow velocity during treatment.

The referenced shortcomings of conventional methodologies mentioned above are not intended to be exhaustive, but rather are among many that tend to impair the effectiveness of previously known techniques concerning the laser treatment of cutaneous vascular lesions.

Other noteworthy problems may also exist; however, those mentioned here are sufficient to demonstrate that methodology appearing in the art have not been altogether satisfactory and that a significant need exists for the techniques described and claimed herein.

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