Cardiac Imaging Issues with CT and MRI

Both CT and MRI modalities present risks, causing researchers to evaluate the safety of each when it comes to cardiac imaging.

MRI has always been thought to be a very safe modality, but putting certain devices such as a pacemaker, ICD, or aneurysm clip into the magnetic field produced by the MRI can certainly cause problems.

In addition, the FDA recently came out with an alert concerning the use of CT radiation or radiation in general and medical devices, such as pacemakers and neurostimulators.

Renal impairment and issues related to NSF with MRI is something to consider. The gadolinium-based contrast agent called ProHance appears to be very safe even in patients who have renal impairment.

The first is single-center studies where a number of devices have been evaluated, and found to be not exactly MRI safe, but maybe “MRI safer” than other devices.

Pacemakers are much less likely to be a serious concern to the patient than an ICD, although in both cases we are very concerned about the interaction with the magnetic field produced by the MRI.

There are newer types of pacemakers that seem to be more resistant to the magnetic field. In one of the studies at Hopkins, pacemakers that were manufactured after the year 2000 were more resistant to changes of the magnetic field and induced radiofrequency currents in those devices.

In more than 200 patients that we have done cardiac imaging on who have ICDs or pacemakers, more than 50% had a finding that significantly changed the therapy for that patient.

Patients with these devices really need their cardiac imaging examinations, and we need to be able to figure out how to do it more safely in patients using these devices, for better cardiac imaging.

In addition, we must also balance the need for better cardiac imaging through the use of gadolinium-based contrast agents, with the risks posed to some patients. Gadolinium-based contrast agents can reveal cardiovascular diseases that might not be as easily detected otherwise. Prohance has been shown to be well-tolerated even amongst renal patients.

Both CT and MRI modalities present risks, causing radiologists to constantly evaluate the safety of each when it comes to cardiac imaging. However, progress is being made to significantly improve the risk versus reward ratio when it comes to cardiac imaging to diagnose heart disease.

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Authors: Michal Macari, MD and David A. Bluemke, MD, PhD, MsB

Reference: FDA Public Health Notice: Possible Malfunction of Electronic Medical Devices Caused by Computed Tomography (CT) Scanning

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CME: Body Imaging: Abdominal, Thoracic and Vascular
University of California, San Francisco, Department of Radiology
This CME program carries 18.5 AMA PRA Category 1 Credits and is designed for the radiologist in clinical practice.

Hot topics include cardiac imaging, multidetector CT, CT/MR angiography, virtual colonoscopy, and tumor ablation.

Read more or order: Body Imaging: Abdominal, Thoracic and Vascular