Ultrasonic systems and methods for fluid perfusion and flow rate measurement

A method for determining the perfusion rate of a fluid in an analysis region, comprising:

• introducing an ultrasound contrast agent into the fluid at an upstream site from the analysis region;
• monitoring ultrasonic backscatter from structures distal to the analysis region to determine an initial level of posterior backscatter;
• applying a pulse of ultrasonic energy sufficient to modify the contrast agent such that the contrast-agent attenuation is reduced in the analysis region, thereby increasing the posterior backscatter from the distal structures;
• and
• monitoring the backscatter from the structures distal to the analysis region to determine a time required for the posterial backscatter level to be restored to the initial level.

A method for determining the flow rate of a fluid in a conduit, comprising:

• introducing an ultrasound contrast agent into the fluid at an upstream location of the conduit;
• applying a pulse of ultrasonic energy sufficicnt to physically modify the contrast agent at a first downstream location of the conduit, thereby establishing a zone of reduced ultrasonic backscatter in the fluid at the first downstream location;
• and
• monitoring;
• a second location of the conduit, downstream from the first downstream location, to determine a time required for the zone of reduced ultrasonic backscatter to reach said second location.

A method for determining the flow rate of a fluid in a conduit, comprising:

• introducing an ultrasound contrast agent into the conduit at an upstream location;
• applying ultrasonic energy sufficient to physically modify the contrast agent in at least a first downstream location and second downstream location of the conduit, thereby establishing at least two zones of reduced ultrasonic backscatter in the fluid separated by a predetermined distance defined by the first downstream location and second downstream location;
• and
• monitoring, a third location downstream from the first and second downstream locations, to determine a time period between the first and second zones of reduced ultrasonic backscatter reaching said third location.

An ultrasonic apparatus for performing flow rate measurements of a fluid carrying a contrast agent in a conduit, the apparatus comprising:

• a first ultrasound transducer, said first ultrasound transduceer for proving a focused pulse of ultrsound energy at a frequency and magnitude sufficient to physically modify at least a portion of the contrast agent in a first target area;
• a second ultrasound transducer, said second ultrasound transducer operation at frequency and magnitude which does not substantially physically modify the contrast agent, said second ultrasound transducer for monitoring a second target area, the second target area being a predetermined distance downstream of the first transducer;
• and
• a processor operatively coupled to and controlling the first and second ultrasound transducers, wherein the first transducer is operable by the controller to modify at least a portion of the contrast agent in the first target area thereby creating a zone of reduced ultrasonic backscatter in the fluid stream and the second transducer is operable by the processor to monitor the backscatter level of contrast agent in the second target area to detect the zone of reduced ultrasonic backscatter, said processor calculating the time required for the zones of reduced ultrasonic backscatter to pass the second target area and calculating the flow rate of the fluid based on the predetermined distance separating said first and second target areas and the calculated time.

An ultrasonic apparatus for performing flow rate measurements of a fluid carry a contrast agent in a conduit, the apparatus comprising:

• a first ultrasound transducer arrangement, said first ultrasound transducer arrangement for providing a focused pulse of ultrasound energy at a frequency and magnitude sufficient to modify at least a portion of the contrast agent in at least a first target area and second target area, the first and second target areas being separated by a predetermined distance;
• a second ultrasound transducer, said second ultrasound transducer operating at frequency and magnitude which does not substantially modify the contrast agent, said second ultrasound transducer for monitoring a third target area, downstream of the first transducer;
• and
• a processor operatively coupled to and controlling the first ultrasound transducer arrangement and said second ultrasound transducer, wherein the first transducer arrangement is operably by the processor to simultaneously modify at least a portion of the contrast agent from the first and second target areas thereby creating at least first and second zones of reduced ultrasonic backscatter in the fluid stream and the second transducer is operable by the processor to monitor the backscatter level of contrast agent in the third target area to detect the zones of reduced ultrasonic backscatter, said processor calculating the time required for the first and second zones of reduced ultrasonic backscatter to pass the third target area and calculating the flow rate of the fluid based on the predetermined distance separating the first and second zones of reduced ultrasonic backscatter and the calculated time.