Near Infrared/ Ultrasound Dual Modal Imaging for Breast Cancer Diagnosis

Breast cancer is the leading cause of cancer among women in the United States. It has always been the hope that devising methods of earlier detection would lead to improvement of long-term survival. Therefore, the development of novel, more selective, and noninvasive diagnostic techniques is a priority. Mammography is currently the most commonly used breast imaging modality for both screening and diagnostic purposes. Additionally, breast ultrasound imaging and breast magnetic resonance imaging (MRI) are generally used to supplement or help confirm any indeterminate or suspicious finding prior to consideration of a breast biopsy. However, these conventional imaging methods lack information about tissue function and have lower diagnostic accuracy. Most recently, near infrared (NIR, of wavelength 700-900 nm) optical diffuse spectroscopic imaging has been investigated as a novel diagnostic tool for breast cancer. In the near-infrared (NIR) light spectrum, oxygenated hemoglobin and deoxygenated hemoglobin are the major chromospheres in tissue, and the absorption spectrums of the two hemoglobin states differ across these wavelengths. Thus, there have been many contemporary attempts to use the intra-tissue absorption and scattering of NIR light to quantify functional tissue parameters such as hemoglobin concentration (HbT) and oxygen saturation (StO2), including tumor differentiation within the human breast. To a very good approximation, NIR photons diffuse through relatively thick tissues, such as several centimeters of a human breast. Functional imaging with NIR light offers several novel tissue parameters that differentiate tumors from normal breast tissue. For example, hemoglobin de-saturation in tumors may be increased due to the high oxygen demand of cancers and blood volume may be increased over that of normal background tissue due to the greater vascularization and metabolic needs of cancers. While NIR imaging provides additional physiological parameters that potentially help to improve the specificity of breast cancer diagnosis, its relatively low spatial resolution makes it unsuitable for morphological analysis. The resolution of a NIR system is intrinsically limited by the diffusive nature of the near infrared light in tissue. Currently, typical instruments can distinguish simple structures of approximately 1 cm in size; sharp edges are typically blurred by a few millimeters. It was proposed that the imaging technique combining near infrared and ultrasound modalities has the potential to fully utilize their complementary features and overcome their deficiencies. This protocol defines the clinical study to prove the concept of the near infrared/ ultrasound dual modal imaging and to evaluate its sensitivity and specificity for breast cancer diagnosis.