3D Fluorescence Molecular Tomography (FMT) is an important pre-clinical tool for quantifying and characterizing molecular markers for different diseases. Herein, we demonstrate, for the first time, 3D K-Space FMT reconstructions using a large time-gated SPAD camera, SwissSPAD2 (SS2). The 3D reconstruction results are obtained using traditional and Deep Neural Network-based inverse solvers. Moreover, the 3D reconstruction performance with SS2 is benchmarked against that obtained with a gated-ICCD camera. The reconstruction results obtained using SS2 are in good agreement with those obtained from the gated-ICCD.
Fluorescence lifetime (FLI) parameter estimation of a fluorescence inclusion inside a tissue remains challenging without due correction from Instrument Response function (IRF). Mathematical models, non-linear least-square-fit (‘reconvolution’), center-of-mass (CMM), and Phasor plot methods use IRF correction, however, recent machine learning (ML) models omit correction learning from IRF and often fails in in-vivo samples. Here, we use a transformer-ML model (MFLI-NET) which also takes temporal-point spread function (TPSF) and pixelwise IRF inputs to provide the offset correction due to depth. The MFLI-NET model showed high accuracy and robustness when tested with 1- and 2- exponential in vitro and in-vivo fluorescence samples.
KEYWORDS: Luminescence, Tomography, Fluorescence tomography, Inverse problems, 3D modeling, Spatial resolution, Monte Carlo methods, Biomedical optics, 3D image processing, 3D acquisition
We propose an end-to-end reconstruction approach for Mesoscopic Fluorescence Molecular Tomography (MFMT) using deep learning. Herein, an optimized deep network based on back-projection with Residual Channel Attention Mechanism architecture is implemented to directly output 3D reconstruction from 2D measurements and diminish the computational burden while overcoming the limitation of the PC's memory during reconstruction. The network is trained by producing a large synthetic dataset through Monte Carlo simulation and validated with in silico data and a phantom experiment. Our results suggest that this approach can reconstruct fluorescence inclusions in scattering media at a mesoscopic scale.
Reconstructions in 3D widefield Diffuse Optical Tomography (DOT) suffer from poor spatial resolution. Therefore, widefield DOT techniques benefit from incorporating structural priors from a complementary modality, such as the micro-CT. Unfortunately, traditional Laplacian-based methods to integrate the priors in the inverse problem are highly time-consuming. Therefore, we propose a Deep Neural Network based end-to-end inverse solver that combines features from AUTOMAP and Z-net and utilizes the micro-CT priors in the training stage. Initial in silico and experimental phantom results demonstrate that the proposed network accurately reconstructs, in 3D, the absorption contrast with a high resolution.
KEYWORDS: Monte Carlo methods, Data modeling, Luminescence, Computer simulations, Reflectivity, Sensors, In vivo imaging, Absorption, Diffuse optical tomography, 3D modeling
Significance: Deep learning (DL) models are being increasingly developed to map sensor data to the image domain directly. However, DL methodologies are data-driven and require large and diverse data sets to provide robust and accurate image formation performances. For research modalities such as 2D/3D diffuse optical imaging, the lack of large publicly available data sets and the wide variety of instrumentation designs, data types, and applications leads to unique challenges in obtaining well-controlled data sets for training and validation. Meanwhile, great efforts over the last four decades have focused on developing accurate and computationally efficient light propagation models that are flexible enough to simulate a wide variety of experimental conditions.
Aim: Recent developments in Monte Carlo (MC)-based modeling offer the unique advantage of simulating accurately light propagation spatially, temporally, and over an extensive range of optical parameters, including minimally to highly scattering tissue within a computationally efficient platform. Herein, we demonstrate how such MC platforms, namely “Monte Carlo eXtreme” and “Mesh-based Monte Carlo,” can be leveraged to generate large and representative data sets for training the DL model efficiently.
Approach: We propose data generator pipeline strategies using these platforms and demonstrate their potential in fluorescence optical topography, fluorescence optical tomography, and single-pixel diffuse optical tomography. These applications represent a large variety in instrumentation design, sample properties, and contrast function.
Results: DL models trained using the MC-based in silico datasets, validated further with experimental data not used during training, show accurate and promising results.
Conclusion: Overall, these MC-based data generation pipelines are expected to support the development of DL models for rapid, robust, and user-friendly image formation in a wide variety of applications.
Diffuse optical tomography, including fluorescence molecular tomography (FMT) have been greatly facilitated by the implementation of structured illumination (SI) strategies in recent years. In this work, we investigate the inverse problem in k-space reflectance fluorescence tomography. This in silico investigation leverages MCX, a Monte Carlo based platform, to generate large data sets for comparison between dAUTOMAP, a deep learning architecture, and commonly employed iterative solvers. We show that the proposed dAUTOMAP-based technique outperforms the traditional reconstruction algorithms. This new image formation approach is expected to facilitate imaging of sub-cutaneous tumors in live animals with enhanced resolution compared to the current gold standard.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.