Do Medical Tests Give You Cancer?

MRI... CT... ultrasound... these and other imaging tests are now so commonplace that we tend to take their use for granted. And indeed, these sophisticated imaging technologies have advanced medicine in previously unimaginable ways by enabling doctors to look inside our bodies. But (isn’t there always a but?), it is important to be aware that everything has its price. Among the downsides to all this testing...
  • Cumulative exposure to radiation from imaging tests over your lifetime increases your risk for cancer.
  • Imaging equipment is expensive, and doctors and hospitals may need to recoup the investment as quickly as possible. Some experts believe that overuse has been a significant contributor to our exorbitant health-care costs.
  • The images are not as precise as we’d like to think... in fact, in many cases, they’re actually interpretations (based on calculations performed by computer software) and not pictures at all.
  • All this information adds up to many instances of "false positive" results, which in turn can lead to unnecessary anxiety and stress for patients and unnecessary (and often risky) medical procedures.
To Save Yourself from Unnecessary Tests
Once again, we need to advocate for ourselves. First and foremost, do not make the assumption that every imaging test suggested by your doctors is necessary and important. Knowing something about the risks and benefits of the different types will help you discuss intelligently with your doctor what’s right for you. Having this knowledge will also help you understand and keep track of your imaging-test history so that you don’t have radiation-based exams that are redundant or for problems that could be diagnosed with a different technique.
With that in mind, I spoke with E. Stephen Amis, Jr., MD, chair of radiology at both the Albert Einstein College of Medicine and Montefiore Medical Center in Bronx, New York, to learn what we should know about the five most common diagnostic imaging tests.
Ultrasound (also called sonography)
Ultrasound uses high-frequency sound waves to create real-time images of organs and blood as it flows through vessels. Commonly used to monitor fetal development, ultrasound can also be used to diagnose abdominal organ abnormalities, gallbladder or kidney stones or an aneurysm in the aorta.
Pros: Ultrasound requires no ionizing radiation and, Dr. Amis said, "presents no known dangers." The scans can be done quickly. Ultrasound is among the least expensive imaging procedures, and the machines it uses are small and portable.
Cons: Ultrasound scans show less detail than CT and MRI scans, and not all structures can be visualized with this technology.
Best used for: Ultrasound is best for evaluating abdominal and reproductive organs, the developing fetus, vascular structures (such as the abdominal aorta) and joints.
Magnetic Resonance Imaging (MRI)
This procedure uses a powerful magnet and radio frequency pulses to "view" most internal body structures. It utilizes a large scanner that transmits the data to a computer, providing a detailed interpretive image of the structures in the body. Sometimes a contrast dye is used to heighten image quality. MRI is especially useful in neurological, cardiovascular, musculoskeletal and oncological imaging.
Pros: MRI uses no ionizing radiation and produces sharp, high-contrast images of different tissues, especially valuable in visualizing the brain and its blood vessels.
Cons: Some people find having an MRI scan quite uncomfortable (two common complaints -- obese people don’t fit easily into the machines, and being inside can create claustrophobic feelings, for which some people require mild sedation). Scans take a long time -- often 30 minutes to an hour -- and patients must remain perfectly still and may be required to hold their breath for short periods. A small percentage of people are allergic to the contrast dye, and it’s not known whether MRI is totally safe for pregnant women. A particularly dangerous problem is that the magnets exert powerful force on anything and everything metallic that is on or in the body, and as a result, MRI scanners have been known to cause pacemakers to malfunction.
Best used for: MRI is the best choice for soft tissue imaging, including to diagnose cardiovascular disease, as well as for oncological and musculoskeletal imaging.
These are created by sending beams of radiation through the area of concern to capture an image on photographic film -- or these days, more typically on a digital image recording plate. To obtain real-time images of functioning organs or blood vessels, X-ray technology is sometimes combined with contrast dyes injected into the body (called fluoroscopy).
Pros: X-ray technology is relatively inexpensive, is easy to use and produces high-resolution images of bone with less radiation than CT scan.
Cons: The type of radiation used, called ionizing radiation, is carcinogenic, albeit weakly. The radiation accumulates over the course of a lifetime, and excessive doses are believed to increase risk for cancer.
Best used for: X-ray is typically the first choice for diagnosing or monitoring calcium-dense tissue (broken bones, dental cavities) and pneumonia and other chest diseases.
Computed Tomography (CT or CAT scan)
A CT scan is like an X-ray taken to the next level. The patient lies on a table that moves through a machine as numerous X-ray beams and electronic detectors rotate, following a spiral path, around the body. Computers use the resulting data to create two-dimensional cross-sectional views of parts of the body -- these can be further manipulated to create multidimensional views as well. CT scans are most widely used for diagnosing causes of abdominal pain, diseases of internal organsand injuries to the liver, spleen, etc.
Pros: Scans can be completed in a matter of seconds, making CT scans indispensable in emergencies. CT scans produce very detailed images of bone, soft tissue and blood vessels, and can be used in patients with pacemakers and other metallic implants.
Cons: CT scan delivers higher doses of ionizing radiation than X-ray... so with multiple scans, in particular, cancer risk is increased. X-rays, including CT scans, are not recommended for pregnant women -- in emergencies, however, they may be required.
Best used for: CT scan is the imaging test doctors use for diagnosing severe headache, chest pain, abdominal pain and trauma and generally in emergency-room settings. This technology is also often used for diagnostic "work-ups" for cancer, stroke and brain problems, among other illnesses and injuries.
Nuclear imaging
In nuclear imaging, patients are injected with (or, alternately, ingest or inhale) a minute amount of radioactive material. A scanner or camera is then used to gather images from specific organs in the body. The process is similar to an X-ray, but the radiation beams emanate from the inside out, which enables doctors to see clearly what’s deep inside the body. This technique is often used to diagnose or measure the progression of specific diseases, such as cancer or cardiovascular disease.
Pros: Nuclear images provide a view that no other technique can obtain.
Cons: It can take hours or days for the radioactive tracer to accumulate in the body and then additional hours to perform the imaging test. Image resolution may not be as clear as those taken with other forms of imaging. Though the radioactive contrast material is designed to exit the body via the urine or stool within a day or two, the radioactive waste then remains in leaching fields and septic systems and is unaffected by sewage treatment methods, so there are concerns about the cumulative environmental impact of this particular form of imaging. Also, it’s quite rare, but some patients have reactions to injected materials -- typically these are mild, though severe reactions have been reported.
Informed Decision Making
Patients aren’t the ones who should demand one type of imaging test over another -- even doctors, when they are patients, take counsel from their physicians. But, as a patient, you absolutely should feel comfortable questioning your doctors about the risks and benefits -- and necessity -- of any imaging study.
Important: Always bring up the scans you’ve had before -- the type, how many and what they were for -- so that your doctor can make an informed recommendation about what you need next. If you’re interested in learning more about imaging techniques, Dr. Amis recommends visiting, which is co-sponsored by the American College of Radiology and the Radiological Society of North America.
And look for more information in our upcoming special report on CT safety -- coming next week in Daily Health News.

Source(s): E. Stephen Amis, Jr., MD, FACR, professor and university chair, department of radiology, The Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, New York.