Radiology - Juanito Villanueva, MD

Ask A Doctor
Juanito Villanueva, MD
FAQs About Radiology

Q: I’ve heard of X-ray, CT, and MRI; how many different ways are there to take X-rays?
A: These types of imaging studies use different technologies. X-ray studies use what is called “ionizing radiation” to reveal certain body parts for viewing either on film or computer screen. Don’t be afraid of the word “radiation” here as the amounts used are generally very small. X-rays are the best way to look at bones in your body. The way an x-ray study is done for any part of your body uses pretty much the same equipment but the differences are where it is focused and how you are positioned. For example, in an x-ray of the knee, depending on which direction the x-ray is pointed, the physician can look for fluid in the joint, look for arthritis, and of course look for fractures. In a typical 3 view study of the knee, any one of these things may show up on only one of the views.

CT also uses “ionizing radiation” to look at internal body parts. The main difference from x-ray is that it is more sensitive and gives a better view of the non-bony parts of the body. It also lets the radiologist look at the images in three-dimensions instead of two.

MRI uses magnetic fields to look at body parts. The magnetic fields look at the water molecules in your cells and the water molecule will respond differently depending on what cell it is in and what other molecules are around it. The computer looks for the slight differences in the way the water molecules respond to paint a picture of your internal body parts. Interestingly, MRI is not nearly as good at looking at bone in general as CT or X-ray.

Q: I think I have a contrast allergy and my doctor wants me to have a contrast study. What are my options?
A: Make sure that the ordering doctor knows you have the contrast allergy. Often, there are alternative ways to help answer the clinical question. Also, it is important to know the exact circumstance which led to you being told you have a contrast allergy. A “reaction” to a contrast injection – for example feeling warm or nauseated – might not be an allergic response at all.

If you have a true allergic response to contrast, and there are no alternative studies that can be done, you can receive medication in advance to decrease the risk for allergic response. Be assured that if the facility that does your study knows of a previous allergic reaction they will be prepared with additional medications and treatments in the unlikely event you would need it.

Q: My sister recently had an early cancer detected by digital mammography and she told me I should get one done. What is digital mammography?
A: Let’s start with the mammography part. For someone without symptoms you would get a “screening mammogram”. Despite the numerous studies performed world-wide over the years, there is still no set-in-stone rule for when to get screening mammograms done. Pretty much all agree to have screenings started by age 50, and some recommend starting at age 40. The recommendations for screening change when you have a close relative diagnosed as having breast cancer. It’s best to discuss these specifics with your primary physician.

Digital mammography is simply a high tech method for performing mammograms. In the past, the only way to do them was on film (called film-screen mammography) for viewing on light-boxes. Now images can be captured electronically for viewing on a computer screen. This electronic method is what is referred to as Digital Mammography.

The issues around the differences between digital mammography and film-screen mammography are too expansive to cover well here. The most important aspect of your question is that your sister has breast cancer. You should definitely have a mammography screening. If digital is not available to you, get film-screen.

Q: I’ve been suffering headaches and my doctor ordered a CT. Now I need to have an MRI. If the CT wasn’t good enough, why didn’t I just have the MRI in the first place?
A: Headaches are common. If your doctor ordered a CT it was out of concern for something unusual in your specific symptoms. One of the most frequent concerns along these lines is that bleeding in the head may be the cause for the headache. CT is the best non-invasive way to look for bleeding in the head. If the CT happens to find something else that may be worrisome, an MRI might be ordered to evaluate it further. MRI is not often used as the first study to evaluate headaches mainly because it takes longer than a CT, is very sensitive to patient movement, is less available, more expensive, and may miss small amounts of bleeding on the surface of the brain that CT excels at finding.

Bio:
Juanito Villanueva, MD, was born in the Philippines and moved to California at the age of seven. He earned his undergraduate degree from the California Institute of Technology and medical degree from the University of California San Francisco.

Dr. Villanueva’s extensive training includes an internship in medicine with the University of California Irvine/VA Long Beach Healthcare System, radiology residency at the Los Angeles County/USC Medical Center, and fellowship in MRI and Interventional Radiology at the St. Mary Medical Center in Long Beach.

Following his training, Dr. Villanueva joined Affiliates in Imaging and worked in the Bay Area. He then went on to serve as medical director of an outpatient imaging center in Vacaville and worked in interventional radiology at the Sutter Medical Center of Santa Rosa. Dr. Villanueva is now back with Affiliates in Imaging, currently serving as medical director for diagnostic imaging at Sonora Regional Medical Center.

Away from work, Dr. Villanueva enjoys many interests including gardening, motorcycling, woodworking, skiing and flying and is also developing an online staff scheduling program called Calcentrix.