Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-10-12
2001-04-03
Lateef, Marvin M. (Department: 3757)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
Reexamination Certificate
active
06210333
ABSTRACT:
BACKGROUND
This invention relates to a medical diagnostic ultrasound system and method for automated triggering, such as for use in perfusion imaging or studies. In particular, automated triggering is used for determining perfusion using contrast agents.
Various methods of imaging contrast agents have been proposed for measuring perfusion or perfusion-related parameters. For example, a method is described by Dr. Wei in “Quantification of Myocardial Blood Flow with Ultrasound-Induced Destruction of Microbubbles Administered as a Constant Venous Infusion”, Circulation, volume 97, pp. 473-487, 1998. Using an ECG signal, images of microbubbles are generated by an ultrasound system at fixed trigger intervals. As each image is generated after a trigger interval, the microbubbles are destroyed. The amount of contrast agent that reflows into a region of interest during the trigger interval as represented on the subsequent image is measured. A fixed trigger interval is then manually changed and the measurement is repeated. Based on these measurements, a re-flow curve showing the amount of contrast agent flowing into a region as a function of the trigger interval is plotted. Due to the manual change of the trigger interval, an unnecessarily long amount of time is required to acquire the images and measure the amount of contrast agent re-flow.
Other triggering schemes for imaging contrast agents are known, such as shown in U.S. Pat. No. 5,833,613. An ultrasonic transmission is triggered off of an ECG signal to destroy contrast agent. Within the same heartbeat, an image is generated at a certain time after transmission of the destructive ultrasonic energy. The time between the transmission for destruction and transmissions for imaging is varied within the heartbeat. Other triggering schemes are shown for example in U.S. Pat. No. 5,686,310.
To assist a clinician during trigger imaging of contrast agent, images generated using low-power transmission may be interleaved with the trigger or destructive transmissions. The images allow the user to maintain the transducer in the correct position relative to the region of interest with reduced destruction of the contrast agents. Such imaging is taught, for example, in U.S. Pat. No. 6,110,120 (U.S. application Ser. No. 08/838,919), filed Apr. 11, 1997.
BRIEF SUMMARY
The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiments described below include a method and system for triggering to determine perfusion in a body. A region of interest in the body is imaged using at least two different trigger intervals between images. Imaging automatically switches from one trigger interval to another in response to a user command, such as depressing a button. This automation avoids cumbersome manual changes of the trigger intervals. Perfusion is measured in a shorter time in this way, reducing the effects of breathing and transducer movement.
Variation of the trigger intervals allows for a convenient determination of perfusion. For example, the trigger intervals are varied from one heart cycle to two heart cycles and then to other integer numbers of heart cycles.
In one aspect, a medical diagnostic ultrasound system for triggering to determine perfusion in a body is provided. A triggering device, responsive to a periodic signal source, is operable to provide trigger signals. A transmitter transmits pulses in response to the trigger signals. A user interface is operable to receive triggering input, where the triggering device automatically switches from a first predetermined interval between trigger signals to a second, different predetermined interval in response to the triggering input. A method corresponding to the system described above is also provided.
In a second aspect, a medical diagnostic ultrasound system for transmitting pulses to determine perfusion in a body during an imaging session is provided. A triggering device, responsive to an ECG signal source, is operable to provide triggering signals. A transmitter transmits pulses in response to the trigger signals. During the imaging session, the triggering device automatically switches from a first predetermined integer heart cycle interval between trigger signals to a second predetermined integer heart cycle interval, where one of the first and second predetermined integer heart cycle intervals is a greater number of heart cycles than the other.
Further aspects and advantages of the invention are discussed below in conjunction with the preferred embodiments.
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Kevin Wei, MD.,Quantification of Myocardial Blood Flow With Ultrasound-Induced Destruction of Microbubbles Administered as a Constant Venous Infusion, Sep. 30, 1997, pp. 473-483.
Gardner Edward A.
Krishnan Sriram
Sponheim Nils
Acuson Corporation
Brinks Hofer Gilson & Lione
Imam Ali M.
Lateef Marvin M.
Summerfield, Esq. Craig A.
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