HOPKINTON, MassA new breast mapping system under development by Assurance Medical is designed to provide physicians with an objective, quantitative approach to the clinical breast examination. In essence, it allows the physician to visualize what is felt on the manual exam.
The physician uses a hand-held device, the Electronic Tactile Sensor Array (see figure), comprised of more than 400 miniature pressure sensors, to electronically palpate the breast. On the computer, the physician is then able to view a focus area via an image that reflects the mechanical properties of the underlying breast tissue. This image and associated parameters can be recorded and retrieved for serial comparison to determine changes over time in the area of focus (see illustration ).
Unique Pressure Signatures
The pressure sensors can show such palpable properties of tissue as hardness, stiffness, size, and discreteness. Initial studies indicate that different tissue structures within the breast (eg, cysts, fibro-adenomas, and cancers) exhibit unique pressure signatures, and the device may be effective at differentiating the pressure signatures of abnormal breast lesions from those of normal breast tissue, Joel B. Weinstein, vice-president of sales and marketing for Assurance Medical, said in an interview.
The intent of the productthe BreastView Visual Mapping Systemis to provide an extension of the physical exam and specifically to make it more objective and better documented, Mr. Weinstein said. The investigational device is not designed to replace existing screening modalities, he said, but rather to be used as an adjunct.
It allows the physician to objectively follow women with abnormal findings, such as fibrocystic tissue, that may not warrant starting a routine of diagnostic mammography and potentially biopsy, he noted.
Assurance Medical demonstrated the new device to physicians at their exhibit at the 21st Annual San Antonio Breast Cancer Symposium.
Edward Dalton, MD, of Northern New England Surgical Associates, Manchester, New Hampshire, who participated in the initial trials of the device, said that the ideal candidate for breast mapping is the high-risk woman with a dense mammogram and a focally difficult breast exam. These women often appear repeatedly, referred by an insecure primary care physician.
The BreastView device, Dr. Dalton said, has been an excellent way to improve the documentation and record keeping surrounding a focally difficult exam. The software can also store ultrasound images, x-ray reports, and communications and recommendations to a referring physician.
In early studies in which the results were interpreted via a visual display of the pressure signals, the system showed an overall sensitivity of 92% (detecting 108 of 118 palpable and nonpalpable lesions) vs 86% for the physicians exams (102 of 118 lesions). The device correctly detected all eight palpable cancers found in the study population and two of three nonpalpable cancers.
A phase III feasibility study employed advanced computer algorithms to identify the nature of specific structures by quantifying the tissues palpable characteristics. This program causes the sensor to emit an audible tone when a suspicious feature is found. In this study, the device detected 70 of the 75 lesions that were 1 cm or larger in diameter (93% sensitivity). Four cancerous lesions were found in the study, and the BreastView system accurately detected both of the two lesions that were within the devices intended range of 1 to 2.5 cm in size, Mr. Weinstein said.
The company has now performed a clinical study on 100 women to confirm the accuracy and reproducibility of the device. The results showed that the device is very accurate in terms of sizing lesions when compared with the actual excised lesions, Mr. Weinstein said.
The results showed a high level of reproducibilitywithin a couple of millimetersfor the mapping system. Furthermore, he said, the BreastView system was able to identify 35 structures that were not visualized on mammography, including five cancers.
The company is now moving forward with a formal FDA clinical study of the device, which is expected to begin in March 1999, Mr. Weinstein said. He anticipates that, when available, the complete systemsensor, software, computer, and printerwill cost under $10,000.