Page 371 - Biomedical Engineering and Design Handbook Volume 2, Applications

CHAPTER 12

BREAST IMAGING SYSTEMS:

DESIGN CHALLENGES
FOR ENGINEERS

Mark B. Williams
University of Virginia, Charlottesville, Virginia

Laurie L. Fajardo
University of Iowa, Iowa City, Iowa

12.1 INTRODUCTION 349 12.4 NEW AND DEVELOPING BREAST
12.2 BREAST ANATOMY 350 IMAGING MODALITIES 356
12.3 CURRENT CLINICAL BREAST 12.5 FUTURE DIRECTIONS 366
IMAGING 350 REFERENCES 367

12.1 INTRODUCTION

Breast cancer is the second greatest cause (after lung cancer) of cancer-related death among
American women, accounting for approximately 40,000 deaths each year. At the present time, early
detection and characterization of breast cancers is our most effective weapon, since local disease is
in most cases curable. Breast imaging systems can thus be potentially useful if they either are
(1) useful for detection of cancers or (2) useful for characterization of suspicious lesions that may or
may not be cancerous. Similarly, from a clinical perspective, methodologies used for breast cancer
diagnosis (as opposed to therapy) fall into one of two broad categories: screening or diagnostic.
Screening pertains to the population of women exhibiting no symptoms. Diagnostic imaging (other-
wise known as problem-solving imaging) is used when there is some suspicion of disease, as a result
of the manifestation of some physical symptom, of a physical exam, or of a screening study. The rel-
ative effectiveness of a given imaging modality at the tasks of detection and characterization deter-
mines whether it will be employed primarily in a screening or diagnostic context. At the present time,
x-ray mammography is the only FDA-approved modality for screening, and is by far the most effec-
tive modality because of its ability to detect small cancers when they are most treatable (i.e., prior to
metastasis). The sensitivity (fraction of all cancers that are detected) by screen-film mammography
is approximately 85 percent. Ultrasound, MRI, breast specific gamma imaging, positron emission
mammography, and electrical impedance scanning are FDA approved as diagnostic procedures fol-
lowing detection of an abnormality via x-ray mammography.
When designing a system for either screening or diagnostic imaging of the breast, several char-
acteristics of the breast itself present unique engineering challenges. First, unlike parts of the body
supported by bone, the breast is a malleable organ. Thus obtaining the exact same configuration for

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