Breast Health Significance
Mammography is the pre-eminent screening procedure for breast cancer that has very high sensitivity but its lower specificity is well documented. With medical and societal emphasis on early detection of breast cancer, it appears the emphasis to avoid missing a malignant lesion may have led to a low positive biopsy rate for cancer, between 10-31%. Apparently, in standard clinical practice, if a lesion appears solid or indeterminate, biopsy is recommended and breast biopsy serves as the key diagnostic standard for evaluation of breast masses for malignancy. Unfortunately, breast biopsy is neither a noninvasive nor an inexpensive procedure. Besides affecting patients physically and emotionally, the procedure frequently causes internal scarring which may obscure the results of future mammograms.
Ultrasound (US) is widely regarded as the adjunct procedure of choice to mammography, especially for distinguishing cystic from solid masses where accuracy is 96-100%. However, earlier studies, in which ultrasound was evaluated largely as a primary screening tool, reported a wide variance in Positive Predictive Value (PPV) and an unsettling range of False Negative (FN) rate ranging from 0.3-30%. These results led to many recommendations still extant that breast ultrasound be used only to determine cyst from solid and/or for needle guidance. Furthermore, even with combined information from mammography and ultrasound, each radiologist may apply a different decision threshold to recommend biopsy of a suspicious mass.
The American College of Radiology (ACR) developed the Breast Imaging Reporting and Data System (BI-RADS) program to guide interpretation and reporting of breast ultrasound exams. The ACR also manages a program to accredit the clinical practice of breast ultrasound. Similarly, in 1998 the American Institute of Ultrasound in Medicine launched a program to accredit the breast ultrasound practices of radiologists and sonographers. These steps by professional organizations are designed to improve the quality and uniformity of care.
Acceptance and utilization of BI-RADS for ultrasound is increasing but the research literature, including our own reports, shows it is difficult to uniformly apply the method and there is considerable variability of lesion description and assessment between radiologists. Many authors report that some radiologists remain uncomfortable with the number of benign and malignant masses that overlap in appearance. The American College of Radiology Imaging Network (ACRIN) Research Protocol 6666, entitled Breast Cancer: Ultrasound Screening, is examining many aspects of breast ultrasound interpretation in whole-breast screening of high-risk women that may eventually lead to more uniform practice. Early results from this large study reveal that breast screening with sonography has considerable merit but there are many practical impediments to its widespread use. These include, among others, the great length of time needed to perform and interpret the study, the need for a radiologist to be involved in the performance of the exam, the large number of images that must be reviewed, and the need for highly expert operators.