There’s no need to let fear of electronic interference between computed tomography and electronic medical devices preclude the ordering of such scans for patients with insulin pumps, cardiac implantable electronic devices, or neurostimulators, the Food and Drug Administration said in a written notification.
“The probability of an adverse event being caused by exposing these devices to CT irradiation is extremely low, and it is greatly outweighed by the clinical benefit of a medically indicated CT examination,” according to the new notification, which updates and replaces a preliminary health notification released on July 14, 2008.
The preliminary notification said there was a “possibility that the x-rays used during CT examinations may cause some implanted and external electronic medical devices to malfunction.” It also included recommendations to reduce the potential risk of such events from occurring and cited adverse events experienced by a few patients with medical devices who had undergone CT scanning, including unintended shocks from neurostimulators, malfunctions of insulin infusion pumps, and transient changes in pacemaker output pulse rate.
The new notification says there is an extremely low probability that a CT scanner directly irradiating the circuitry of certain implantable or wearable electronic medical devices can cause sufficient electronic interference to affect the function and operation of the medical device, and this probability is even lower when the radiation dose and the radiation dose rate are reduced. The FDA also notes that the interference is completely avoided when the medical device is outside of the primary x-ray beam of the CT scanner.
The update, which provides additional reports of adverse events by patients with electronic medical devices who had CT scans, states that the number of such events was small, compared with the number of patients with insulin pumps, cardiac implantable electronic devices, and neurostimulators who were scanned without adverse effects.
The FDA encourages health care providers and patients who suspect a problem with a medical imaging device to file a voluntary report through MedWatch, the FDA Safety Information and Adverse Event Reporting Program.