Aaron Fenster PhD, FCCPM : Home Page

INTRODUCTION:

Breast cancer is the leading cause of death by disease in Canada for women aged 20 to 44, and is second only to lung cancer for women aged 45 to 64. Although cancer is supplanted by circulatory diseases after age 65 as a leading cause of death, nonetheless, 1993 statistics show breast cancer to be the leading cause of potential years of life lost for women. Key to improving the survival of women with breast cancer is early diagnosis. The 5-year survival rate for women diagnosed with localized breast cancer is 96%, whereas it is 75% if the cancer has spread regionally, and only 20% if there are distant metastases.

CLINICAL PROBLEM:

Women presenting with palpable lumps or those who are asymptomatic but are being screened for breast cancer will undergo various procedures in the evaluation of their health. After a physical examination of the breasts, an x-ray mammogram is usually conducted. While useful in identifying suspicious lesions, x-ray mammography is often not definitive, and further investigation is required. Ultrasound (used first if the woman is very young or has very dense breasts), can identify some lesions (i.e., cysts) as being benign, but very often the lesion must be biopsied to obtain a definitive diagnosis. In the past, this has required open surgical biopsy. However, there is a current trend toward the use of needle aspirations and needle biopsies which could eliminate the need for most surgical biopsies. As about 70% of biopsied lesions are negative for cancer, a reduction in surgical biopsies in favour of needle biopsies would greatly benefit women, by reducing surgery and the associated psychological trauma.

Needle biopsies are reliable only when the suspected tissue is sampled adequately. Proper placement of the needle into the tissue is essential, and needle guidance technology is required. To ensure that the lesion is sampled adequately, image guided breast biopsy techniques are being developed using magnetic resonance imaging, but such technology is expensive and not widely available.

The most common technique for needle biopsy is under ultrasound guidance. With the woman laying on her back, the medical practitioner finds the lesion under ultrasound and, with the ultrasound transducer in one hand providing an image of the relevant tissue, s/he guides the needle into the suspicious lesion with the other. In some cases, it is difficult to see the needle in the tissue, and the inherent two-dimensional nature of the imaging technique requires skill in appropriately moving the scanning transducer in coordination with needle insertion. Devices which fix to the transducer and offer needle guidance are generally not considered to be useful for the experienced practitioner, and are infrequently used. Thus, the conventional approach, which relies on the operator's skill and experience, results in potential variability and inaccuracy, requiring improved technology for the visualization and placement of the needle.

PROJECT GOAL:

Thus, the goal of this project is to develop a 3-dimensional ultrasound guided breast biopsy instrument involving an advanced imaging approach and sophisticated real-time image guidance. In this approach, a suspicious breast lesion, identified through traditional mammogram screening, would be located in 3-dimensions by ultrasound during the biopsy procedure. An automated system linked to the image analysis would then direct a needle, under operator control, to the lesion's core, allowing a biopsy to be taken accurately, swiftly and with minimal discomfort.

Investigators: Fenster A, Downey D.
Graduate Students: Surrey K.
Technicians: Mills, G.
Support: CIHR, ORDCF and IRIS

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