Multitask Deep Learning Reconstruction and Localization of Lesions in
Limited Angle Diffuse Optical Tomography
Abstract
Diffuse optical tomography (DOT) leverages near-infrared light
propagation through tissue to assess its optical properties and identify
abnormalities.
DOT image reconstruction from limited-angle data acquisition is severely
ill-posed due to the highly scattered photons in the medium and the
relatively small number of collected projections. Reconstructions are
thus commonly marred by artifacts and, as a result, it is difficult to
obtain accurate reconstruction of target objects, e.g., malignant
lesions.
Reconstruction does not always ensure good localization of small
lesions. Furthermore, conventional optimization-based reconstruction
methods are computationally expensive, rendering them too slow for
real-time imaging applications.
Our goal is to develop a fast and accurate image reconstruction method
using deep learning, where multitask learning ensures accurate lesion
localization in addition to improved reconstruction.
We apply spatial-wise attention and a distance transform based loss
function in a novel multitask learning formulation to improve
localization and reconstruction compared to single-task optimized
methods.
Given the scarcity of real-world sensor-image pairs required for
training supervised deep learning models,
we leverage physics-based simulation to generate synthetic datasets and
use a transfer learning module to align the sensor domain distribution
between in silico and real-world data, while taking advantage of
cross-domain learning.
Both quantitative and qualitative results on phantom and real data
indicate the superiority of our multitask method in the reconstruction
and localization of lesions in tissue compared to state-of-the-art
methods.
The results demonstrate that multitask learning provides sharper and
more accurate reconstruction.