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Quality Definitions and Methodology

Use of Medical Imaging

The four outpatient imaging efficiency measures (OP-8 through OP-11) are produced from Medicare administrative claims for the fee-for-service population and no additional data submission is required by hospitals. The OIE measures are not risk adjusted; they are calculated as raw/observed rates after the exclusion and inclusion criteria are applied.

The purpose of these measures is to promote high-quality efficient care. Specifically, each of the following measures was created to reduce unnecessary exposure to contrast materials and /or radiation, ensure adherence to evidence-based medicine and practice guidelines, and promote efficiency defined as "absence of waste".

OP-8. MRI Lumbar Spine for Low Back Pain
What does this measure tell you about a hospital’s use of MRIs for low back pain?

Although MRIs can be helpful for diagnosing low back pain, MRIs can be used too much.

  • Usually, low back pain improves or goes away within six weeks and an MRI is not needed.
  • Standards of care say that most patients with low back pain should start with treatment such as physical therapy or chiropractic care, and have an MRI only if the treatment doesn’t help.
  • Finding out whether treatment helps before having an MRI is better and safer for most patients because it avoids the stress, risk, and cost of doing MRIs that patients don’t need.

If a number is high, it may mean that the facility is doing unnecessary MRIs for low back pain. For some patients with certain conditions, getting an MRI right away is appropriate care. Patients with these conditions are not included in this measure.

If you have low back pain, you, your doctor, and the medical imaging facility staff should all talk about the best time to do an MRI if you need one.

What is an MRI?

An MRI (magnetic resonance imaging) is a test that uses a powerful magnetic field and a computer to produce detailed pictures of the inside of the body (bones, organs, and other body parts).

What are the risks of having an MRI?
  • Since MRIs use magnets rather than x-rays, there is no radiation risk. However, because the magnets attract some kinds of metal, it’s important for the technician to know if there are any metal objects or implants inside the patient’s body, such as pacemakers, artificial joints, screws, stents, plates, or staples. Metal objects can pose serious risk to the patient and interfere with the test.
  • For some MRIs, a substance called "contrast" is injected before the test to make parts of the body stand out more clearly on the images. Risks of contrast include possible harm to the kidneys or allergic reactions. Contrast shouldn’t be used if it isn’t needed.
  • Having the test can be stressful for some people. Patients must hold still for about 15 to 45 minutes while lying on a table that moves inside a large scanning machine. While images are being taken, the machine makes loud noises.
OP-9. Mammography Follow-up Rates
What does this measure tell you about a hospital's follow-up for screening mammograms?

When a screening mammogram shows signs of possible breast cancer, the patient is asked to come back for a follow-up appointment. A follow-up usually means having more tests (mammograms, an ultrasound, or both).

Medical research shows that there may be a problem if a facility has either very low or very high numbers of follow-ups (Note: The numbers that follow are most appropriately applied to women who are 65 or older who have Original Medicare):

  • A number much lower than 8% may mean there's not enough follow-up and it's possible that signs of cancer are being missed.
  • A number much higher than 14% may mean the facility is doing too much unnecessary follow-up.
  • Reasons could include poor technique (blurry X-rays that need to be repeated) or a lack of skill or experience interpreting the screening mammograms.
  • Whatever the reason, unnecessary follow-up is stressful to patients and results in needless exposure to radiation. (There is no radiation exposure for ultrasounds because they don’t use x-rays.)
  • If you are going to have a screening mammogram, talk with your doctor about the results you see here and what a facility's results mean for you and your care.
What is a "screening" mammogram?

A screening mammogram is an x-ray of the breast to check for possible breast cancer.

OP-10. Abdomen CT - Use of Contrast Material
What is a "combination" CT scan?
  • For some CT scans, a substance called "contrast" is put into the patient’s body before the scan begins, to help make parts of the body stand out more clearly on the x-rays. Contrast can be either swallowed or injected into a vein.
  • "Combination" CT scan means that the patient gets two CT scans – one scan without contrast followed by a second scan with contrast.
What does this measure tell you about the hospital imaging facility’s use of CT scans of the abdomen?

Combination scans involve additional radiation exposure and risks associated with use of contrast.

For this measure, if a number is very close to 1, it may mean that the facility is routinely giving patients combination CT scans of the abdomen when a single scan is all they need.

Giving patients two scans when they only need one needlessly doubles their exposure to radiation:

  • Radiation exposure from a single CT scan of the abdomen is about 11 times higher than for an ordinary x-ray of the abdomen.
  • For a combination CT scan, radiation exposure is 22 times higher than for an x-ray of the abdomen because the patient is given two scans.

Risks of injected contrast include possible harm to the kidneys or allergic reactions. Contrast shouldn’t be used if it isn’t needed.

CT scans of the abdomen are one of the most commonly requested imaging procedures. If you need to have a CT scan of the abdomen, talk to your doctor about what’s best for your medical condition:

  • Do you need a single scan - either with or without contrast - or is a combination scan necessary?
  • Is using contrast appropriate for your medical condition?

The information that follows shows hospital imaging facilities’ use of CT scans of the abdomen. Talk with your doctor about the results you see here and what a facility’s results mean for you and your care.

What is a "CT scan"?

A CT scan (also called a CAT scan) uses multiple x-rays to produce detailed pictures of the inside of the body (bones, organs, and other body parts).

OP-11. Thorax CT - Use of Contrast Material
What is a "combination" CT scan?
  • For some CT scans, a substance called "contrast" is put into the patient’s body before the scan begins, to help make parts of the body stand out more clearly. Contrast can be either swallowed or injected into a vein.
  • "Combination" CT scan means that the patient gets two CT scans – one scan without contrast followed by a second scan with contrast.
What does this measure tell you about hospital imaging facilities’ use of CT scans of the chest?

Standards of quality care say that most patients who are getting a CT scan of the chest should be given a single CT scan rather than a "combination" CT scan. (Although combination CT scans are appropriate for some parts of the body and some medical conditions, combination scans are usually not appropriate for the chest.)

The range for this measure is 0 to 1. If a number is very close to 1, it may mean that the facility is routinely giving patients combination CT scans of the chest when a single scan is all they need.

Giving patients two scans when they only need one needlessly doubles their exposure to radiation:

  • Radiation exposure from a single CT scan of the chest is about 350 times higher than for an ordinary chest x-ray.
  • For combination CT scans, radiation exposure is 700 times higher than for a chest x-ray because the patient is given two scans.

When contrast is used, there are risks that can include possible harm to the kidneys or allergic reactions (especially if the contrast is injected). To avoid unnecessary risk, contrast should be used only when it is needed. If you need to have a CT scan of the chest, talk with your doctor about what’s best for your medical condition:

  • Do you need a single scan - either with or without contrast - or is a combination scan necessary?
  • Is using contrast appropriate for your medical condition?

The information that follows shows hospital imaging facilities’ use of CT scans of the chest. Talk with your doctor about the results shown here and what a facility’s results mean for you and your care.

OP-13. Outpatients who got cardiac imaging stress tests before low-risk outpatient surgery
OP-14. Outpatients with brain CT scans who got a sinus CT scan at the same time