Quantitative contrast-enhanced optical coherence tomography

Abstract

We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects. V C 2016 AIP Publishing LLC.

Gold Nanoprisms as Optical Coherence Tomography Contrast Agents in the Second Near Infrared Window for Enhanced Angiography in Live Animals

“…However, strong OCT signals of GNPRs were imaged in whole blood at concentrations ≥250 pM. We showed that the OCT signal of GNPRs in blood increased with concentration, and the experimental data matched well with the prediction of our physical model 26 (Figure 1d). We calculated the detection limit of GNPRs in blood to be 206 pM at a signal-to-noise ratio of 3.…”

“…However, the increase of OCT amplitude with each injection was not significant for GNPR concentrations in blood ≥0.75 nM, which can be explained by a multi-scattering effect according to our physical model. 26 Next we investigated OCT angiograms of healthy mouse ears (Figure 3a-c) with increasing concentrations of GNPRs. We obtained the OCT angiograms by detecting the blood vessels with NSV followed by segmenting the vessels with a hybrid intensity/shape-based compounding algorithm.…”

Characterizing relationship between optical microangiography signals and capillary flow using microfluidic channels

“…For simplicity, we do not take into the consideration of the DC, mutual cross-correlation, and noise components in the OCT signal formulation because they are not relevant to our discussion. The OCT signal can be described as the superposition of all the light fields reflected from the scatters within an imaging voxel (coherent volume) in the medium [21]. Because the light field is treated as a vector of magnitude and angle (phasor) that are time-variant due to a random arrangement of the scattering particles within the imaging voxel, the OCT signal can be expressed as a sum of many random phasors as…”

“…According to Winertraub et al [21], with the simplified assumptions: 1) single scattering regime, 2) reflections modeled by ray optics and 3) all particles having the same reflectance in the imaging voxel, the OCT signal detected from the scattering particle is proportional to a square root of the number of particles (N) within the imaging voxel that is given by [21] …”

Characterizing physical properties and in vivo OCT imaging study of Cu-Sn-S nanocrystals

“…The advantages of LSPR make Cu-Sn-S nanocrystals can serve as a contrast-enhanced molecular imaging for cancer detection in clinical setting. Such as Optical Coherence Tomography (OCT), [28][29][30][31][32] magnetic resonance imaging (MRI) and positron emission tomography (PET). As we know, there are many researches have reported the synthesis and characterization of Cu-Sn-S nanocrystals.…”