Three-dimensional, Bayesian image reconstruction from sparse and noisy data sets: Near-infrared fluorescence tomography

Abstract

A method for inverting measurements made on the surfaces of tissues for recovery of interior optical property maps is demonstrated for sparse near-infrared (NIR) fluorescence measurement sets on large tissue-simulating volumes with highly variable signalto-noise ratio. A Bayesian minimum-variance reconstruction algorithm compensates for the spatial variability in signal-to-noise ratio that must be expected to occur in actual NIR contrast-enhanced diagnostic medical imaging. Image reconstruction is demonstrated by using frequency-domain photon migration measurements on 256-cm 3 tissue-mimicking phantoms containing none, one, or two 1-cm 3 heterogeneities with 50-to 100-fold greater concentration of Indocyanine Green dye over background levels. The spatial parameter estimate of absorption owing to the dye was reconstructed from only 160 to 296 surface measurements of emission light at 830 nm in response to incident 785-nm excitation light modulated at 100 MHz. Measurement error of acquired fluence at fluorescent emission wavelengths is shown to be highly variable. Convergence and quality of image reconstructions are improved by Bayesian conditioning incorporating (i) experimentally determined measurement error variance, (ii) recursively updated estimates of parameter uncertainty, and (iii) dynamic zonation. The results demonstrate that, to employ NIR fluorescence-enhanced optical imaging for large volumes, reconstruction approaches must account for the large range of signal-to-noise ratio associated with the measurements.

Tomographic imaging of oxygen by phosphorescence lifetime

“…49,50 MEM is usually described within the Bayesian framework, 26 and Bayesian reconstruction has been applied in diffuse optical tomography and in FLI in particular. 31,51 In an earlier work we developed a simple and compact recursive algorithm of the MEM 52 and used it to analyze phosphorescence lifetime distributions in solutions 13 and biological tissue. 53 In this paper the same recursive procedure was implemented for the inversion of Eq.…”

Fluorescence spectra provide information on the depth of fluorescent lesions in tissue

“…Fully threedimensional reconstruction methods are being developed by some groups. They are commonly based on use of diffusion theory as the forward model, [7][8][9][10][11] but an algorithm based on the discrete-ordinates solution of the transport equation has also been proposed. 12 Many combinations of light source and detection points are needed for full reconstruction, which implies a high complexity of both the instrumentation and the reconstruction algorithm.…”

Visualization of antitumor treatment by means of fluorescence molecular tomography with an annexin V–Cy5.5 conjugate

“…Fluorescence tomography of whole animals and human organs is feasible in the near-IR region where the lower tissue attenuation allows the penetration of photons over several centimeters (13). Considerable literature exists in theoretical models of photon propagation in diffuse media but, despite original experimental studies with phantoms (14)(15)(16)(17), the in vivo demonstration of tomographic utility over existing imaging methods is limited. A few fiber-based systems for fluorescence tomography were recently reported (18)(19)(20) and the feasibility for in vivo imaging of proteases was demonstrated (21).…”