Let’s face it: Mammograms are slightly unpleasant. But they’re a small price to pay for catching breast cancer early — assuming you get an accurate result. One downfall of this screening tool is the dreaded “false positive,” a finding of cancer that’s not really there, which can lead to unnecessary biopsies and other follow-up testing. And of course, mammograms don’t catch all cancers that do exist.

3-D mammography may improve the picture. Advocates say it is vastly superior to the typical 2-D mammograms most women get. Research suggests it can detect more cancers, especially in women with dense breasts, and leads to fewer false positive results.

How do you know if you have dense breasts? Ask the doctor who ordered your mammogram or who manages your overall care. Or check the last letter sent to you about your mammogram results. At least 19 states have enacted laws requiring that women be given details about their breast tissue density. The denser the breast tissue, the more difficult it is to spot cancer on a conventional mammogram.

The technology for 3-D mammograms is not widespread yet, but it's becoming more available. About 1,500 3-D systems are in use in the United States, says Jim Culley of Hologic, which makes a 3-D system. Every state has at least one.

Here’s what you need to know about the benefits, the risks and the costs.

Related: 6 Powerful Ways to Reduce Your Cancer Risk

How it works

The first 3-D system, more accurately termed breast tomosynthesis, was approved by the FDA in 2011. A second was approved in 2014. The technique is no longer considered investigational, according to a position statement from the American College of Radiology.

In a regular mammogram, breast tissue is compressed between two plates and two views are taken of each breast. Most mammograms are now done and stored digitally, rather than on film. 3-D mammography ''is an advanced application of digital mammography," says Barbara Monsees, MD, chair of the breast imaging committee of the American College of Radiology and the Evens Professor of Women's Health at Washington University in St. Louis. The breast is compressed and the machine moves around it in an arc, taking many x-ray images.

If conventional mammography is like looking at a loaf of bread, Monsees says, 3-D mammography is like looking at the individual slices of bread, with the ability to zero in on individual slices. The radiation dose is higher if you add 3-D, she says, but ''both exposures, standard and tomosynthesis, are within what the FDA stipulates is allowed for mammography."

The benefits of 3-D

3-D mammograms beat conventional mammograms at detecting breast cancer in women with dense breasts according to a study presented at the annual meeting of the Radiological Society of North America in December, 2014. The researchers compared cancer detection in more than 25,000 women and found that while the regular mammogram found 59 percent of the 132 cancers in women with dense breasts, the 3-D mammogram found 80 percent of them.

3d scan (Photo: Hologic) 

An earlier study published in 2014 compared using both 3-D and 2-D exams (performed with the same machine) with using just 2-D. Using the combo reduced the rate of women being recalled for further testing by 15 percent. (When doctors aren't sure about whether they see cancer on a mammogram, women are called back for more testing, such as additional mammogram views or a biopsy.) The combination of 2-D and 3-D also increased the rate of detection of invasive cancer, defined as cancer that has spread from where it began in the breast, by 41 percent.

Related: 10 Health Symptoms Women Should Never Ignore

What else to know about 3-D

While the law dictates that regular mammograms be covered in full by insurance, for now you may have to pay something out of pocket for a 3-D exam, depending on your insurance plan. Medicare reimburses doctors only $57 for the exams. But some health insurance plans for younger women are beginning to cover 3-D, according to the American College of Radiology. Contact your health plan administrator to find out specifics.

Expert say you should ask your doctor for advice about getting the 3-D test. Be sure he knows your family history, personal history and breast density status. 

Kathleen Doheny is a Los Angeles journalist specializing in health, behavior and fitness topics.