Breast Sonography: Not Just for "Cyst vs. Solid" Anymore
Since October is both Medical Ultrasound Awareness Month and Breast Cancer Awareness Month, it seems fitting to extol the virtues of diagnostic medical sonography for breast applications. In the past, sonographic examinations of the breast were primarily performed to determine if a previously detected mass was a cyst or a solid lesion. Thus, many in the field had low expectations of the modality and didn't consider it very important. However, as a result of significant advances in technology, improved classification systems and recognition of its diagnostic value, sonography is rapidly gaining a reputation as vital imaging modality in the fight against breast cancer. Of course sonography professionals already know this but The Breast Ultrasound Exam and Women's Health Information Hub is devoted to patient education about breast sonography.
Sonography has been proven to be particularly valuable for evaluation of patients with dense breast tissue and / or patients who have breast implants. Virtually all high-volume breast imaging centers include sonography services and some centers employ dedicated breast sonographers. Typically, sonography is used to gain additional diagnostic information about a lesion that is identified by palpation or mammography (i.e., a focused sonogram). However, there are reports that suggest there are benefits to using sonography for screening purposes. As described on The Society of Breast Imaging website, a published study that included 42,838 examinations from six centers found that "...screening breast sonography is capable of detecting some cancers that are undetected by mammography and physical examination."
There have been vast improvements in image quality and advanced signal processing schemes that have resulted in more accurate assessments of lesions and improved detection of microcalcifications using conventional hand-held transducers. To improve and standardize diagnostic breast sonography interpretations the American College of Radiology developed a lexicon of descriptors and assessment categories called the BI-RADS® - US (The Breast Imaging and Reporting Data System - Ultrasound). The use of computer-aided diagnosis of breast scans is enhancing breast lesion detection and improving the interpretation of breast sonograms.
An exciting area of technology is the commercial availability of automated breast ultrasound scanners. These systems utilize automated image acquisition techniques which produce volume data that can be viewed off-line on a workstation. Review of data on the workstation allows the interpreting physician or other operator to select specific image planes which may not be obtainable using conventional sonography as well as be more comparable to mammography images. Furthermore, the automated scanner would be ideal for screening sonograms.
The use of sonography has gone beyond examinations of breast lesions. As reported this month by Reuters Health, sonography of lymph nodes can reduce the need for surgery. A study done in the United Kingdom and presented earlier this month at the 2009 Breast Cancer Symposium in San Francisco found that sonography combined with fine-needle aspiration cytology of lymph nodes (which can be done as an out-patient procedure) can obviate the need to perform surgical sentinel lymph node biopsies in nearly 30% of node-positive, early breast cancer patients. Unfortunately ultrasound-guided FNAC cannot accurately detect micro-metastases.
Described above are just a few of the recent advances in breast sonography. I believe that in the future sonography will be even more valuable in the fight against breast cancer.