Controlling telemetry during magnetic resonance imaging

#The invention relates to magnetic resonance imaging (MRI) techniques.

#Magnetic resonance imaging (MRI) techniques make use of electromagnetic fields to create images of a patient. MRI techniques permit the generation of high-quality two- or three-dimensional images of a patient's body, which can then be examined by a physician for diagnosis purposes. In particular, MRI techniques permit the generation of internal images of a patient's flesh, blood, bones, cartilage, blood vessels, organs, and the like. The generated images can then be examined by physicians in order to diagnose disease, disorders or injuries and facilitate patient care.

#MRI devices typically subject a patient to a very strong static magnetic field and a pulsed gradient magnetic field, and then apply pulses or bursts of electromagnetic radiation (typically radio frequency (RF) radiation bursts) to an area of the patient to be imaged. The strong magnetic field generally orients the protons of the patient's tissue in particular directions. However, the RF radiation bursts cause some of the patient's protons to resonate, or spin, at a particular frequency depending on the local magnetic field during application of the radiation burst. The resonance frequency in MRI is referred to as the Larmour frequency, which has a relationship with the local magnetic field. When the RF radiation burst is terminated, the resonating protons reorient themselves in accordance with the strong magnetic field of the MRI device, giving off energy in the process. The MRI device can detect the energy given off by the reorienting protons in order to create a high quality image of the patient's tissue.

#FIG. 1 is a conceptual diagram illustrating a magnetic resonance imaging (MRI) device, an implantable medical device (IMD), and a programmer communicating via telemetry.

#FIG. 2 is a functional block diagram of a MRI device, an IMD, and a programmer communicating via telemetry

#FIGS. 3-6 are flow diagrams illustrating techniques for coordinating medical device telemetry with MRI techniques according to embodiments of the invention.

#The invention is directed to the coordination of telemetry of medical devices with magnetic resonance imaging (MRI) techniques. By adjusting telemetry during MRI, the use of telemetry during MRI may be facilitated. In one example, information indicative of electromagnetic radiation bursts in MRI techniques can be communicated to the medical device prior to application of the bursts. Also, information indicative of application of magnetic gradients may be communicated. The medical device can adjust telemetry according to the received information. In another example, the medical device may identify the electromagnetic radiation bursts, e.g., by measuring for the presence of such bursts. In either case, the medical device can adjust its telemetry to improve telemetric communication during MRI.

#The medical device may adjust its telemetry in any of a number of different ways, upon identifying information associated with MRI electromagnetic radiation bursts (and possibly application of gradient fields). In one example, the medical device can blank or otherwise disable one or more telemetry components of the medical device specifically during the electromagnetic radiation bursts and/or application of gradient fields. In another example, the medical device can increase power of telemetry signals during the electromagnetic radiation bursts. In another example, the medical device can select a packet size for more effective communication between burst intervals. In these or other ways, a medical device may adjust its telemetry upon receiving information indicative of MRI electromagnetic radiation bursts, or upon measuring the presence of such radiation bursts.

#FIG. 1 is a conceptual diagram of a system 30 including a magnetic resonance imaging (MRI) device 20, an implantable medical device (IMD) 10, and a programmer 50 communicating via telemetry. MRI device 20, IMD 10 and programmer 50 are all examples of medical devices, and will be referred to collectively as such. Programmer 50 and MRI device 20 communicate via telemetry signals 21A, MRI device 20 and IMD 10 communicate via telemetry signals 21B, and programmer 50 and IMD 10 communicate via telemetry signals 21C. In other embodiments, some of the respective connections may be wired connections, e.g., programmer 50 and MRI device 20 may have a wired connection instead of using telemetry. In any event, any or all of the telemetry between respective medical devices 10, 20 and 50 can be defined or adjusted specifically for compatibility with MRI techniques.