Estimation and imaging of breast lesions using a two-layer tissue structure by ultrasound-guided optical tomography

Abstract

A new two-step estimation and imaging method is developed for a two-layer breast tissue structure consisting of a breast tissue layer and a chest wall underneath. First, a smaller probe with shorter distance source-detector pairs was used to collect the reflected light mainly from the breast tissue layer. Then, a larger probe with 9×14 source-detector pairs and a centrally located ultrasound transducer was used to collect reflected light from the two-layer tissue structure. The data collected from the smaller probe were used to estimate breast tissue optical properties. With more accurate estimation of the average breast tissue properties, the second layer properties can be assessed from data obtained from the larger probe. Using this approach, the unknown variables have been reduced from four to two and the estimated bulk tissue optical properties are more accurate and robust. In addition, a two-step reconstruction using a genetic algorithm and conjugate gradient method is implemented to simultaneously reconstruct the absorption and reduced scattering maps of targets inside a two-layer tissue structure. Simulations and phantom experiments have been performed to validate the new reconstruction method, and a clinical example is given to demonstrate the feasibility of this approach.

Improving breast cancer diagnosis by reducing chest wall effect in diffuse optical tomography

“…We have tried to remove the chest wall effect by using shorter source-detector measurements. 27,[29][30][31] Results show that although the correlation coefficient was smaller when shorter sourcedetector measurements were selected, the fitted μ a was still correlated with the chest wall depth but not μ 0 s for the source and detector range we have.…”

“…27,28 We have developed several methods to minimize the chest wall effect, including a two-layer modeling 29 and a two-layer reconstruction method, 30 and a two-step fitting and reconstruction with a dual-probe measurements (a small probe for the first layer and a larger probe for both layers). 31 Despite the promising results, the clinical application of these methods is limited due to their intense computation and a slower convergence rate. 29,31 In a recent paper, Yoshizawa et al reported the effect of chest wall on light reflectance measurements using their TR-DOS system with a 3 cm source-to-detector distance, and showed a function characterizing the tHb concentration in terms of chest wall depth.…”

“…31 Despite the promising results, the clinical application of these methods is limited due to their intense computation and a slower convergence rate. 29,31 In a recent paper, Yoshizawa et al reported the effect of chest wall on light reflectance measurements using their TR-DOS system with a 3 cm source-to-detector distance, and showed a function characterizing the tHb concentration in terms of chest wall depth. 32 Based on their measurements, they reported the tHb concentration ranging between 10 and 90 μM, and this range reduced to 10 to 30 μM by taking out cases whose chest wall depths were smaller than 2 cm.…”

Review of optical breast imaging and spectroscopy

“…114 In more recent work, theoretical and experimental attempts have been undertaken to account for the influence of the chest wall that can strongly contribute to the measured signals in the supine position. 115…”

Review of breast screening: Toward clinical realization of microwave imaging

“…Many breast cancer studies in the literature have reported significant improvement in diagnostic performance of one modality when adjunctive data from another modality is used. Here are some examples of such hybrid studies: ultrasound‐guided optical tomography, combined optical and X‐ray tomosynthesis, combined optical imaging and mammography, MRI‐guided optical spectroscopy, ultrasound‐guided microwave imaging, combined microwave tomography and MRI and microwave‐induced thermos‐acoustics . Haynes et al have also implemented real‐time (1 frame per second) MI system to monitor thermal breast cancer therapy .…”