expert type icon EXPERT

Sean L. Johnston

Radiologist

Dr. Sean Johnston is a radiologist practicing in Burbank, California. Dr. Johnston specializes in diagnosing and treating injuries and diseases using medical imaging techniques such as X-Rays, magnetic resonance imaging and computed tomography exams. These techniques offer accurate visibility to the inside of the patients body and help to detect otherwise hidden illnesses so that they can be treated quickly and efficiently.
Sean L. Johnston
  • Burbank, California
  • Mayo Clinic
  • Accepting new patients

Why is a CT scan necessary for pneumonia?

In general, a CT scan is not necessary for this indication. Typically, just a chest X-ray will do. However, if he is worried about an atypical infection (walking pneumonia) or READ MORE
In general, a CT scan is not necessary for this indication. Typically, just a chest X-ray will do. However, if he is worried about an atypical infection (walking pneumonia) or other types of lung disease, a CT is better. Just ask your provider what's on his mind!

Is an MRI scan painful?

No, but it is loud, and if you have claustrophobia, it will not be pleasant for you as the tube is tight. Your technologist will provide you with ear protection but know in advance READ MORE
No, but it is loud, and if you have claustrophobia, it will not be pleasant for you as the tube is tight. Your technologist will provide you with ear protection but know in advance it is not a quiet procedure. Best of luck!

What are MRI results supposed to indicate?

That's actually a much larger question. Please consult with your ordering physician what they are interested in finding. Any radiological examination provides a tremendous amount READ MORE
That's actually a much larger question. Please consult with your ordering physician what they are interested in finding. Any radiological examination provides a tremendous amount of information, designed to aid referrings into making the best treatment choices, MRI included.

My son has been having bad headaches. His neurologist is sending him to a radiologist. What can we expect next?

Most likely the neurologist requested an MRI. Your son will be given a set of headphones to cover his ears and placed in a fairly tight tube. If he is claustrophobic he will READ MORE
Most likely the neurologist requested an MRI. Your son will be given a set of headphones to cover his ears and placed in a fairly tight tube. If he is claustrophobic he will not like the procedure, as his head will have to be in the tube. The scan actually takes around a half hour, and the test results will depend on his ability to hold still. Too much motion will cause blurring on the images, which will make interpretation difficult. That being said, the test will be over shortly and you will receive the results most likely within a day. good luck!

I accompanied my mother for her X-ray and I didn’t know I was pregnant then. What should I do?

The risk of radiation effects on a fetus for a back radiograph series on a person standing away from the patient is extremely, extremely low. You actually receive over twenty READ MORE
The risk of radiation effects on a fetus for a back radiograph series on a person standing away from the patient is extremely, extremely low. You actually receive over twenty times more background radiation from radon sources in your home than you will from that single medical exposure. So, rest assured and congratulations!

How can I ensure no other cancer cells are present in my body?

The best way to check for distant metastases is a separate scan called a PET-CT, which helps detect the presence of cancer cells throughout the body. Periodic surveillance will READ MORE
The best way to check for distant metastases is a separate scan called a PET-CT, which helps detect the presence of cancer cells throughout the body. Periodic surveillance will be necessary, so be sure to keep your appointments and follow the recommendations of your oncologist. Best of luck.


Sean L. Johnston, MD, PhD

What if I'm allergic to contrast?

Contrast allergies should always be taken seriously. While most people have a similar level of reaction, there are cases where a person with a minor allergy at one session had READ MORE
Contrast allergies should always be taken seriously. While most people have a similar level of reaction, there are cases where a person with a minor allergy at one session had a major reaction (as in airway compromise) at a later setting. If you need a CT with contrast in the future, you should ask your primary care physician to prescribe the pre-treatment protocol that is in place at your local hospital or imaging center. This usually involves a short course of steroids prior to the administration, which stops the allergic reaction from even starting.

Is pregnancy possible after chemotherapy?

It is possible, although much less likely, as chemotherapy tends to hamper fertility. Doesn't make it impossible, but your sister needs to know the odds are a bit against her READ MORE
It is possible, although much less likely, as chemotherapy tends to hamper fertility. Doesn't make it impossible, but your sister needs to know the odds are a bit against her at this point. Breast feeding will be fine, as the radiation does not cover the opposite breast. Best of luck!

Airport security and being pregnant

Hello- Yes, you may go through the scanner at the airport. The radiation dosage is so low that it doesn't pass through the skin, and therefore does not provide any significant READ MORE
Hello-


Yes, you may go through the scanner at the airport. The radiation dosage is so low that it doesn't pass through the skin, and therefore does not provide any significant increased risk to your fetus. Congratulations!


Sean L. Johnston, MD, PhD