Spatial frequency domain imaging for monitoring palpable breast lesions

We describe a novel approach for monitoring breast lesions, utilizing spatial frequency domain imaging, a diffuse optical imaging method to detect hemoglobin contrast, in combination with mechanical compression of the tissue. The project is motivated by the growing rate of unnecessary breast biopsies, caused by uncertainty in X-ray mammographic diagnoses. We believe there is a need for an alternate means of tracking the progression palpable lesions exhibiting probably benign features, that can be performed non-invasively and hence frequently: at home or in the clinic. The proposed approach capitalizes on two distinguishing properties of cancerous lesions, namely the relative stiffness with respect to surrounding tissue and the optical absorption due to the greater vascularization, hence hemoglobin concentration. The current research project is a pilot study to evaluate the principle on soft, breast tissue-mimicking phantoms containing stiffer, more highly absorbing inclusions. Spatial frequency domain imaging was performed by projecting onto the phantom a series of wide-field patterns at multiple spatial frequencies. Image analysis then was performed to map absorption and scattering properties. The results of the study demonstrate that compression significantly increases the optical contrast observed for inclusions located 10 and 15 mm beneath the surface. In the latter case, the inclusion was not detectable without compression.