Women's Health

Reading a large volume of mammograms is only one factor influencing radiologists' accuracy

Radiologists who examine more than 5,000 mammograms a year are more likely to accurately interpret them than radiologists who read a low volume of mammograms. However, experience is a multidimensional factor not adequately described by a single measure of annual mammograms read, says Joann G. Elmore, M.D., at the University of Washington School of Medicine. Her project to study variability in community mammography is supported by the Agency for Healthcare Research and Quality (HS10591).

In a recent editorial, Dr. Elmore and her colleagues question whether the recent volume of mammograms read, number of years of experience reading mammograms, or even lifetime number of mammograms interpreted should be used to determine the experience of a radiologist in this area. They also question whether having radiologists read the same mammogram during an experiment on mammogram interpretative accuracy reflects real-world community practice. For example, two to six cases of breast cancer are typically detected per 1,000 mammograms in a screened population compared with 64 of 148 mammograms used to test radiologists' accuracy in one recent study (less than 1 percent vs. 43 percent).

Other factors also influence radiologists' mammogram interpretation accuracy. For instance, fear of medical malpractice may prompt a radiologist to overinterpret a mammogram. The population of women screened also influences accuracy. For instance, women who take hormone replacement therapy, which may increase breast density that could reduce mammogram accuracy, may need additional imaging or breast ultrasound. Also, accuracy is more likely if menstruating women have a mammogram during the first or second week of the menstrual cycle, when breast tissue is less dense. Finally, women are more likely to get accurate mammograms if they go to the same facility and/or ensure that prior films are available for the radiologist to compare.

More details are in "Does practice make perfect when interpreting mammography? Part II," by Dr. Elmore, Diana L. Miglioretti, Ph.D., and Patricia A. Carney, Ph.D., in the February 19, 2003, Journal of the National Cancer Institute 95(4), pp. 250-252.

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