Ultrasound-Guided Optical Tomographic Imaging of Malignant and Benign Breast Lesions: Initial Clinical Results of 19 Cases

Abstract

The diagnosis of solid benign and malignant tumors presents a unique challenge to all noninvasive imaging modalities. Ultrasound is used in conjunction with mammography to differentiate simple cysts from solid lesions. However, the overlapping appearances of benign and malignant lesions make ultrasound less useful in differentiating solid lesions, resulting in a large number of benign biopsies. Optical tomography using near-infrared diffused light has great potential for imaging functional parameters of 1) tumor hemoglobin concentration, 2) oxygen saturation, 3) metabolism, as well as other tumor distinguishing characteristics. These parameters can differentiate benign from malignant lesions. However, optical tomography, when used alone, suffers from low spatial resolution and target localization uncertainty due to intensive light scattering. Our aim is to combine diffused light imaging with ultrasound in a novel way for the detection and diagnosis of solid lesions. Initial findings of two earlystage invasive carcinomas, one combined fibroadenoma and fibrocystic change with scattered foci of lobular neoplasia/lobular carcinoma in situ, 16 benign lesions are reported in this paper. The invasive cancer cases reveal about two-fold greater total hemoglobin concentration (mean 119 μmol) than benign cases (mean 67 μmol), suggest that the discrimination of benign and malignant breast lesions might be enhanced by this type of achievable optical quantification with ultrasound localization. Furthermore, the small invasive cancers are well localized and have wavelength-dependent appearance in optical absorption maps, whereas the benign lesions appear diffused and relatively wavelength-independent.

Keywords

• breast cancer detection and diagnosis
• optical tomography
• ultrasound imaging
• tumor angiogenesis
• image reconstruction