Chicago ? An experimental ultrasound technique that measures how easily breast lumps compress and bounce back could enable doctors to determine instantly whether a woman has cancer or not – without having to do a biopsy.

In a small study of 80 women, the technique, called “elastography,” distinguished harmless lumps from malignant ones with nearly 100 percent accuracy. Cancerous tumors are firmer than benign ones.

If the results hold up in a larger study, elastography could save thousands of women from the waiting, cost, discomfort and anxiety of a biopsy, in which cells are removed from the breast – sometimes with a needle, sometimes with a scalpel – and examined under a microscope.

Up to 1 million biopsies are performed each year on suspicious breast tissue detected by mammograms and self-exams, but as many as eight out of 10 of these biopsies find that the lumps are benign.

Biopsies can cost $200 to $1,000, depending on whether some fluid or an entire lump is removed, and it can take days or weeks to get the results. The cost of elastography is not yet clear, but some experts said the procedure might run $100 to $200. And it can yield results in minutes.

When checked against biopsies of women’s breast tissue, the ultrasound technique correctly identified 17 out of 17 cancerous tumors, and 105 out of 106 harmless lesions. The findings were reported at a national radiology meeting in Chicago this week.

Scientists said the approach may also be used someday to rapidly diagnose damaged hearts and guide the treatment of prostate cancer.