Why isn’t MRI the tool of choice for chronic subdural hematoma since the CT scan emits radiation?

A brain bleed might require many follow-up imagings during the course of treatment and recovery.

“CT or MRI may be used for evaluation of a subdural hematoma, depending on the clinical situation,” begins Resham Mendi, MD, a renowned expert in the field of medical imaging, and the medical director of Bright Light Medical Imaging.

My mother must have received about 10 CT scans of her head in connection with a chronic subdural hematoma that had been caused by a fall in her bathroom.

That day and the day after she underwent a head CT scan that was negative for bleeding in the brain.

Six weeks later she was suddenly symptomatic (very bad headache, one-sided lower extremity weakness, nausea) and a CT scan revealed a chronic subdural hematoma.

Between that point and several weeks, there were at least half a dozen CT scans because there were complications: a recurrence and steroid psychosis.

After eight weeks there must have been 10 CT scans. I wondered why an MRI wasn’t used for the follow-ups.

It’s understandable when a CT scan is used when a patient presents to the ER with symptoms suggestive of a stroke or other brain injury. You’d want a diagnosis as fast as possible.

The treatment for a stroke is not the same as for a chronic subdural hematoma.

Both conditions, which have significantly overlapping symptoms, need prompt evaluation and a fast treatment plan.

“In some cases CT may be used because it is much faster (30 seconds as opposed to 30 minutes for MRI), which is vital for a sick patient or someone who cannot hold still for an MRI,” says Dr. Mendi.

But what about the follow-ups in which there is no urgent situation or possible subsequent injury?

Dr. Mendi explains, “We do not worry about the radiation dose from a CT brain as much as we may worry about the dose to other organs, as the brain is considered ‘low radiosensitivity,’ meaning that it is not very susceptible to the bad effects of radiation.

“Of course, no matter what, we try to minimize radiation to the best of our ability.

“Sometimes MRI is the right choice and sometimes it’s CT, and that is based on each individual patient.

“CT also shows new blood very clearly, and is better than MRI for detecting skull fractures.

“Also, if there is a patient who needs medical equipment to bring into the room during the exam, this is much easier with CT. MRI is also more costly.”

The fee for 10 MRI’s is much greater than for 10 CT scans.

dr. mendi
Dr. Mendi has published several articles in radiology journals and has expertise in MRI, women’s imaging, musculoskeletal, neurological and body imaging.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  



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