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Biophan’s innovative technologies promise to make implanted medical devices safe with MRI. In order to demonstrate the safety of new devices, safety testing must be performed to accurately reveal problems and potential safety concerns. Biophan is working closely with the FDA, consultants, and customers to ensure that MRI devices are truly safe for patients. Biophan’s overarching objectives are to assure that MRI safety testing is performed at the highest professional level; to make MRI examinations available to the many patients who are currently shut out from them because of safety concerns; and to eliminate the serious risks from induced voltage and tissue heating that can occur during an MRI examination to patients with implanted medical devices.
FDA Comments on MRI Safety
Respected industry colleagues share important viewpoints on MRI Safety in the Journal of Neuromodulation. Click here to read Letters to the Editor by Dr. Wolfgang Kainz and Dr. Frank G. Shellock.
FDA Research Partnership
Biophan recently announced a research partnership with the US Food and Drug Administration (FDA) to help improve patient safety in magnetic resonance imaging (MRI) environments. Under a Cooperative Research and Development Agreement (CRADA), Biophan is collaborating with the FDA’s Science and Engineering Laboratories in the Center for Devices and Radiological Health to develop guidelines and standards for assessing the safety of implanted cardiac pacemaker and neurostimulation systems when in the MRI environment. The CRADA is part of the government’s initiative to address MRI related patient safety concerns.
CRADA Workshop
Biophan Technologies, Inc. and the United States Food and Drug Administration (FDA) co-hosted a Workshop on October 9, 2006. The purpose of the workshop was to assemble a team of experts to outline necessary research and improvements in testing methods for measuring certain aspects of MRI safety of medical implants. Read the complete summary from the initial workshop.
Testing GuidelinesBiophan is also collaborating with MR:comp GmbH a leading German testing company focused on MRI safety. MR:comp uses standardized test methods for evaluating MR safety and compatibility of implants, based on ASTM standards, and assists Biophan in developing testing methods. Biophan’s testing methods aim to encompass all clinically relevant conditions, to determine the range of possible effects on patients.
Testing MRI solutions is made complicated by a number of variables that affect the voltage and temperature generated by the MRI scanner around an implanted device, such as the location of the patient and device within the MRI chamber. The graph below shows that the increase in temperature around a pacing system’s lead tip depends on the location of the lead tip within the MRI chamber.
Location of the lead within MRI affects heating measurement dramatically
Source: Biophan Technologies R&D
As shown here, moving the pacemaker lead’s tip as little as 1.3 inches within the MRI system can result in an increase in lead temperature by more than 8 degrees Celsius, enough to cause significant tissue damage in the patient.
The temperature-probe design and placements also affect the accuracy of MRI safety measurements. In another Biophan study, shown here, MRI-induced lead heating data was collected with two different temperature probe designs, both of them acceptable according to the “Standard Test Method for Measurement of Radio Frequency Induced Heating Near Passive Implants During Magnetic Resonance Imaging” (ASTM F2182-02a ).
Probe design also affects MRI testing accuracy
Source: Biophan Technologies R&D
Note that probe design type #1 has the sensing material at the very tip of the probe, while with probe type #2, the sensing material is offset by about 0.5 mm from the tip. However, with probe design type #2, the exact position of the sensing material is not visible, so the exact position of the sensing material cannot be determined. That is why attempts to position both probes’ sensing material in the same location resulted in a large temperature difference of 8 degrees Celsius in the test shown above. To investigate MRI-induced heating around implants more thoroughly, Biophan has developed a computer model of the temperature distribution around the tip of an “active fixation” (screws into the heart) pacing lead. The results are shown in this cross-section view of the leads, which shows the temperature distribution (red hottest, green coolest) around the corkscrew tip of the pacemaker lead.
Temperature probe placement model shows probe location is critical
Source: Biophan Technologies R&D
The temperature profile clearly shows that placement of the temperature probe near the distal (furthest) tip of the device can result in temperature differences of up to 10 degrees Celsius with minor changes in probe position. Sub-millimeter movements in temperature probe location can, surprisingly, result in significant effects on the measured MRI induced temperature increase. By incorporating these findings in state-of-the-art safety testing methodologies, Biophan has set a new standard of excellence in the industry. Biophan is committed to continuing to work with the FDA and medical device manufacturers to ensure that testing methods are of the highest standard to validate the MRI safety of implantable medical devices, taking into account the worst-case, clinically relevant conditions.
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