Multimodal imaging combining time-domain near-infrared optical tomography and continuous-wave fluorescence molecular tomography

Abstract

Fluorescence molecular tomography (FMT) emerges as a powerful non-invasive imaging tool with the ability to resolve fluorescence signals from sources located deep in living tissues. Yet, the accuracy of FMT reconstruction depends on the deviation of the assumed optical properties from the actual values. In this work, we improved the accuracy of the initial optical properties required for FMT using a new-generation time-domain (TD) near-infrared optical tomography (NIROT) system, which effectively decouples scattering and absorption coefficients. We proposed a multimodal paradigm combining TD-NIROT and continuous-wave (CW) FMT. Both numerical simulation and experiments were performed on a heterogeneous phantom containing a fluorescent inclusion. The results demonstrate significant improvement in the FMT reconstruction by taking the NIROT-derived optical properties as prior information. The multimodal method is attractive for preclinical studies and tumor diagnostics since both functional and molecular information can be obtained.

Non-invasive visualization of amyloid-beta deposits in Alzheimer amyloidosis mice using magnetic resonance imaging and fluorescence molecular tomography

“…As the highly scattering nature of tissue renders FMT an ill-posed problem, implementing such prior information significantly improves the registration results (Arridge and Schotland, 2009). We have demonstrated the robustness and accuracy of the FMT-MRI method by using tissue-mimicking phantoms (Ren et al, 2020b) and in biological studies using a tumor-bearing mouse model (Ren et al, 2020a) or ex vivo intervertebral discs (Ren et al, 2021a).…”

“…A homebuilt non-contact FMT system was used for data acquisition (Ren et al, 2020b). The system is equipped with a 16-bit charge-coupled device (CCD) camera (ANDOR, Belfast, Northern Ireland), a galvanometric driven mirror system (ScanLab, Puchheim, Germany), a solid-state laser generator with 670 nm wavelength for illumination (B&W Tek, Newark, USA), and custom-made animal support.…”

“…To merge the FMT-MRI images and analyse the results, a linear interpolation scheme was used to transform from the mesh coordinates used for reconstructing the dye distribution to Cartesian grid coordinates of the anatomical reference image. A Tikhonov regularization term was introduced to the reconstruction, and the inverse problem was solved using the conjugation gradient (CG) method (Ren et al, 2020a;Ren et al, 2020b). Quantitative analysis was carried out following FMT reconstruction.…”

Recent Technical Advances in Accelerating the Clinical Translation of Small Animal Brain Imaging: Hybrid Imaging, Deep Learning, and Transcriptomics

“…The irregularly shaped boundary and heterogeneous inner structure can be rendered by CT and used for more accurate FMT image reconstruction ( 52 ). The FMT image quality is significantly improved with prior information from CT ( 53 , 54 ). The FMT-CT hybrid system has been used for the detection of amyloid-β deposition in mouse models of Alzheimer’s disease and lung cancer ( 50 , 55 – 59 ).…”

Multifunctional optical tomography system combining surface extraction and 3D fluorescence reconstruction

“…Optical imaging at a macroscopic level has become an essential tool for biomedical research and clinical applications due to its non-invasive nature, high sensitivity, non-ionizing radiation and cost effectiveness [1]. Traditional 2D optical imaging techniques such as fluorescence reflectance imaging (FRI) are widely used and provide fast visualization regarding functional and molecular information, but they are limited to planar images and lack depth information [2].…”