Contrast agent for ultrasonic imaging

Details Contrast agent for ultrasonic imaging Contrast agent for ultrasonic imaging

1998-10-14

2001-05-15

Lateef, Marvin M. (Department: 3737)

Surgery

Diagnostic testing

Detecting nuclear, electromagnetic, or ultrasonic radiation

Reexamination Certificate

active

06231513

ABSTRACT:

FIELD OF THE INVENTION
The present invention is directed to the field of diagnostic imaging. Specifically, the invention provides apparatuses and methods for delivery of a gaseous contrast media to a fluid containing medium for detection using ultrasonic imaging.
BACKGROUND OF THE INVENTION
The injection of minute gas bubbles into a patient's bloodstream for measuring pressure and flow characteristics of blood are disclosed in, for example, DE 29 46 662 A1 and U.S. Pat. No. 3,640,271. In German patent application DE 29 46 662 A1, the velocity of gas bubbles in the bloodstream is measured using ultrasound techniques and from this measurement, the velocity of the bloodstream is determined.
In U.S. Pat. No. 3,640,271, bubbles are sequentially injected into the bloodstream and the velocity of the bubbles is measured using ultrasound imaging procedures. The velocity of blood flow is determined by calculations using equations disclosed in the patent. The bubbles are formed by agitating a container holding a blood compatible solution, such as a saline solution, and a blood compatible gas. The bubbles are withdrawn from the container using a hypodermic needle having a filter such that only bubbles of less than 0.0025 cm are drawn into the syringe. The collected bubbles are then injected into the bloodstream and flow characteristics are measured using sound wave technology including Doppler and ultrasonic techniques.
U.S. Pat. No. 5,249,579 discloses an apparatus for controlled injection of carbon dioxide gas into an animal's vascular system. The apparatus includes a mechanism for controlling the flow rate at which the gas is delivered so that the flow rate of the gas correlates to the flow rate of the blood in the animal's vascular system.
The injected CO
2
functions as a blood displacement media or a contrast medium.
U.S. Pat. No. 5,264,421 discloses an ultrasound structure having a wire for transmission of high power ultrasonic energy. The ultrasonic energy is applied to a vascular occlusion at a duration and intensity sufficient to substantially break up the occlusion and recanalize the patient's artery.
The entire disclosure of each of the references disclosed in the present specification are incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention is directed to apparatuses and methods for forming gas bubbles which can be used as a contrast agent. In one embodiment, the invention provides for delivery of gaseous microbubbles that can be detected by ultrasound techniques to study interior surface contours within vessel walls.
An apparatus of the invention provides for delivering a contrast agent into a patient's vessel. The apparatus comprises a tube having a lumen extending from a proximal end to a distal end of the tube and a microbubble forming arrangement at the distal end of the lumen. The microbubble forming arrangement includes microholes which cause formation of microbubbles when a gas is passed through the microbubble forming arrangement.
The tube of the apparatus can be, for example, a catheter, a needle, or other hollow structure. The microbubble forming arrangement can be a porous matrix having microholes or microchannels throughout or a membrane having microholes therethrough. According to the invention, a porous matrix can be of a material selected from ceramics, sintered alloys, sintered nickel-titanium, sintered polytetrafluoroethylene (PTFE), etc.
The invention also provides methods for delivering microbubbles to the interior surface of a vessel for imaging the vessel wall or determining fluid flow characteristics within the vessel.


REFERENCES:
patent: 3640271 (1972-02-01), Horton
patent: 5163421 (1992-11-01), Bernstein et al.
patent: 5236693 (1993-08-01), Lee
patent: 5249579 (1993-10-01), Hobbs et al.
patent: 5599296 (1997-02-01), Spears
patent: 5833613 (1998-11-01), Averkiou et al.
patent: 5869538 (1999-02-01), Van Liew et al.
patent: 29 46 662 A1 (1981-05-01), None

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