Next to lung cancer, breast cancer is the leading cause of cancer death in women, according to the American Cancer Society. That's why so many medical professionals encourage women to get mammograms, even though the tests are imperfect at best: only a minority of suspicious mammograms actually leads to a cancer diagnosis. That results in lots of needless worry for women and their families -- not to mention the time, discomfort and expense of additional tests, including ultrasounds and biopsies. Recently, a different type of test, ultrasound elastography, has been used to pinpoint possible tumors throughout the body, including in the breast. Those images can be breathtakingly clear: Jiang shows one elastogram in which the tumor is as different from normal breast tissue as a yolk is from the white in a fried egg. However, not all images are that precise.