Trending
DEAR DR. ROACH: I have a pacemaker that was installed in January 2024. This is a newer model that's said to be safe for those who need an MRI. I have a neoplasm that was recently discovered in the parotid gland on the right side of my head.
The doctors at a referral hospital attempted to do a biopsy on the mass in the center of the gland. But the biopsy failed as the tissue samples were only obtained from benign tissue surrounding the neoplasm, not from the mass.
My doctor doesn't want to attempt another biopsy, as the biopsy procedure that failed was very lengthy and lasted for most of the day. She said the mass is in an area that's very hard to reach.
The doctor who ordered the biopsy now wants to monitor the parotid gland through periodic scans. She suggested periodic MRIs. I demurred and suggested that the monitoring can be done by CT scans.
The reason I don't want to have periodic MRIs is that I've read that the newer pacemakers, such as the one I have, reduce the risk of having an MRI. However, the key word here is "reduce," not eliminate.
What's your opinion about having regular MRIs versus regular CT scans, with the acknowledgement that CT scans come with the risk of radiation, while continued MRIs offer some risk to my pacemaker and the wires leading into my heart?
I want to add that neoplasms are said to be benign 80% of the time. It's the other 20% that cause concern.
-- J.B.
ANSWER: With parotid masses, it can be difficult to tell how likely they are to be malignant, and a biopsy is the only definitive diagnostic tool. But I understand that biopsies can be challenging and respect the surgeon's decision about attempting a biopsy again.
When comparing MRIs versus CT scans as it pertains to accuracy for the evaluation of parotid masses, there's no question that an MRI is superior. It's more likely to correctly diagnose cancer and less likely to falsely state that cancer is there when it isn't. As you mention, an MRI doesn't have ionizing radiation (as CT scans do), which is a real issue when multiple scans have to be done over time.
The issue with MRIs and pacemakers is the pacemaker construction. An MRI uses powerful magnetic fields to take pictures of the inside of the body, and it's especially useful for soft tissue, such as brain and glandular tissue (like the parotid gland, in your case — the major salivary gland).
However, the MRI field affects ferromagnetic metals such as iron (or any alloy such as steel), nickel and cobalt. Not only can the magnetic field move these objects inside the body, it can also heat them up to a point that they can damage surrounding tissue.