Mayo Clinic Health Letter, February 2012 Highlights: Molecular Breast Imaging: A Better Cancer Screening Tool for Dense Breast Tissue; Recognizing the Signs and Controlling the Risk of Stroke

Here are highlights from the February issue of Mayo Clinic Health

Letter. You may cite this publication as often as you wish.

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Molecular Breast Imaging: Better Way to Spot Cancer in Dense Breast


Mayo Clinic researchers have developed a new tool to better identify

tumors in women with dense breast tissue. The February issue of Mayo

Clinic Health Letter covers this technology, called molecular breast

imaging (MBI).

Breasts are a mixture of fatty and dense tissue. About one-half of women

younger than age 50 have breast tissue considered dense on mammogram

images. The same is true for about one-third of women over 50. On a

mammogram, dense tissue and tumors both appear white. Spotting a tumor

in dense tissue has been compared to looking through a frosted glass


MBI offers a clearer picture and detects three times as many cancers in

women with dense breast tissue than traditional mammography does. Like

mammography, MBI requires that the breast be compressed between two

plates. However, MBI needs only about one-third of the pressure used for

a mammogram. Prior to the imaging, a short-lived radioactive tracer is

injected into the woman’s arm vein. Two 10-minute images are taken of

each breast using gamma radiation. (Radiation levels from MBI are

comparable to the dose that’s delivered from one digital screening

mammogram.) If tumor cells are present, they absorb the tracer like a

sponge and illuminate on the image.

MBI supplements — rather than replaces — mammography, which remains an

accurate screening tool in women with non-dense breasts. The Food and

Drug Administration approved MBI as a screening tool in 2010. While MBI

is not widely available at all medical centers, that is expected to

change over the next few years. MBI costs around $600.

Strokes: Recognizing Signs, Controlling Risks

Strokes are the fourth-leading cause of death and the leading cause of

disability in the United States. The February issue of Mayo Clinic

Health Letter includes an eight- page Special Report on stroke,

covering risk factors, prevention, warning signs and treatment options.

Here are some highlights:

What happens: A stroke occurs when the blood supply to parts of the

brain is suddenly altered. Ninety percent of strokes are ischemic

strokes. They occur when the arteries to the brain are narrowed or

blocked, causing severely reduced blood flow. Equally serious, though

less common, are hemorrhagic strokes — occurring when a blood vessel in

the brain bursts or bleeding starts in the artery of the brain. Both

types of strokes can cause brain cells to die or become damaged,

resulting in temporary or permanent changes to the mind and body.

Warning signs: Symptoms may occur suddenly and sometimes last just a

short time. They can occur in different combinations. Traditional

symptoms include numbness, weakness or paralysis on one side of the face

or body; difficulty speaking or trouble understanding others; blurred,

decreased or double vision; dizziness, trouble walking or loss of

balance; and rapid onset of a severe headache.

Emergency treatment: The success of treatment depends on promptness. One

of the most effective medications for ischemic stroke must be

administered within 4.5 hours after the stroke begins.

TIAs: A transient ischemic attack (TIA), sometimes called a ministroke,

is a brief episode of stroke-like symptoms. Like an ischemic stroke, a

TIA occurs when a clot or plaque blocks blood flow to part of the brain.

The blockage is temporary, and symptoms typically disappear within an

hour. Some symptoms may last a few minutes. But fleeting symptoms should

not be ignored. It’s possible to be having a stroke even when symptoms

disappear. Anyone with stroke symptoms should seek emergency care.

Risk factors: Some risk factors can’t be changed. Family history plays a

role and so does age. The stroke risk doubles in every decade after age

55. Men are at higher risk than women. American blacks are more likely

to have strokes than other ethnic groups. Unmanaged diabetes, heart

disease and obstructive sleep apnea increase the risk of stroke.

Controllable risk factors include hypertension, unhealthy cholesterol

levels, heavy alcohol use and inactivity.

A second stroke: A stroke survivor is at increased risk for a second

stroke. Within five years, 24 percent of women and 42 percent of men

will have another one.

Prevention: Strokes and recurrent strokes often can be prevented by

reducing risk factors and undergoing preventive treatment. It’s wise to

talk with a doctor about personal stroke risks and prevention strategies.

Mayo Clinic Health Letter is an eight-page monthly newsletter of

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