A digital x-ray tomosynthesis coupled near infrared spectral tomography system for dual-modality breast imaging

Venkataramanan Krishnaswamy,Ian Shaw,Keith D Paulsen,Steven P Poplack,Ken Brooks,Ken Defrietas,Brian W Pogue,Kelly E Michaelsen

doi:10.1364/oe.20.019125

Abstract

A Near Infrared Spectral Tomography (NIRST) system has been developed and integrated into a commercial Digital Breast Tomosynthesis (DBT) scanner to allow structural and functional imaging of breast in vivo. The NIRST instrument uses an 8-wavelength continuous wave (CW) laser-based scanning source assembly and a 75-element silicon photodiode solid-state detector panel to produce dense spectral and spatial projection data from which spectrally constrained 3D tomographic images of tissue chromophores are produced. Integration of the optical imaging system into the DBT scanner allows direct co-registration of the optical and DBT images, while also facilitating the synergistic use of x-ray contrast as anatomical priors in optical image reconstruction. Currently, the total scan time for a combined NIRST-DBT exam is ~50s with data collection from 8 wavelengths in the optical scan requiring ~42s to complete. The system was tested in breast simulating phantoms constructed using intralipid and blood in an agarose matrix with a 3 cm x 2 cm cylindrical inclusion at 1 cm depth from the surface. Diffuse image reconstruction of total hemoglobin (HbT) concentration resulted in accurate recovery of the lateral size and position of the inclusion to within 6% and 8%, respectively. Use of DBT structural priors in the NIRST reconstruction process improved the quantitative accuracy of the HbT recovery, and led to linear changes in imaged versus actual contrast, underscoring the advantages of dual-modality optical imaging approaches. The quantitative accuracy of the system can be further improved with independent measurements of scattering properties through integration of frequency or time domain data.

Highlights

Digital Breast Tomosynthesis (DBT) is an emerging FDA-approved imaging modality for breast cancer screening [1,2,3]
In a recently published study, the Massachusetts General Hospital (MGH) system examined 125 women and the results showed statistically significant differences in hemoglobin concentration in malignant versus benign masses relative to the fibroglandular region in the same breast [7]
This paper describes the design, development and integration of Near Infrared Spectral Tomography (NIRST) into a commercial DBT scanner

Summary

Introduction

Digital Breast Tomosynthesis (DBT) is an emerging FDA-approved imaging modality for breast cancer screening [1,2,3]. The technique is similar to conventional mammography in that it images variations in breast density using x-ray attenuation and requires significant compression to enhance soft tissue contrast. DBT extends the capabilities of conventional mammography by acquiring x-ray projection data at a limited set of angular views, which allows 3D reconstruction of tissue density over the imaged breast volume. DBT provides superior lateral resolution, but its depth discrimination is relatively. DBT provides depth-resolved 3-D structural images of the breast at a dose comparable to digital mammography, but with improved diagnostic power [4]

Methods

Results

Discussion

Conclusion