Photoacoustic tomography and fluorescence molecular tomography: A comparative study based on indocyanine green

Abstract

Purpose: Both photoacoustic tomography (PAT) and fluorescence molecular tomography (FMT) can be used for molecular imaging when contrast agents are administrated. The goal of this work is to comparatively evaluate the performance of reflection-mode PAT and FMT in common phantom when indocyanine green (ICG) was used as a contrast agent. Methods: Reflection-mode PAT and FMT systems were developed. Target embedded in a background phantom with different ICG concentration, size, and depth location was examined. Comparisons were made in terms of target morphology, spatial resolution, and sensitivity between the two modalities. Results: Phantom results showed that PAT and FMT gave different image morphology. PAT offered higher spatial resolution, while FMT provided higher sensitivity. Thus, improved target detection could be achieved by correlating the complementary information obtained from the two modalities. Conclusions: The combination of high resolution PAT and high sensitivity FMT will provide a more complete range of pathology spectra for more reliable target detection, suggesting a potentially better diagnostic tool when this combination coupled with the administration of ICG as contrast agent is applied to clinical problems in the future.

The evaluation of NIR-absorbing porphyrin derivatives as contrast agents in photoacoustic imaging

“…10 ICG and ICG derivatives were utilized as rare molecular NIR PAI contrast agents even though there are other photophysical parameters – like the significant fluorescence of ICG derivatives, see below – that do not make them ideal PAI contrast agents. 11 Irrespective of the shortcomings, the utilization of ICG suggests its use as the benchmark dye.…”

Molecular photoacoustic tomography of breast cancer using receptor targeted magnetic iron oxide nanoparticles as contrast agents

“…This shows the potential for us to combine fluorescence molecular tomography (FMT) with photoacoustic tomography. While FMT has lower spatial resolution than PAT, it has higher specificity than photoacoustic imaging techniques and the combination of PAT and FMT would provide complementary information for breast cancer detection [26]. …”

HER-2/neu targeted delivery of a nanoprobe enables dual photoacoustic and fluorescence tomography of ovarian cancer

“…However, PAT has relatively low sensitivity compared to pure optical imaging due to the limitations of acoustic transducers. 23 Additionally, the presence of endogenous photoacoustic signals in some normal organs, such as the kidney, liver, spleen and heart, may interfere with specificity of PAT imaging.…”

“…24 In contrast to conventional two-dimensional (2D) fluorescence molecular imaging, FMT provides improved localization and quantification in deep tissues. 23–25 Previously, we reported that FMT was more sensitive and specific for the detection of low concentration contrast agents in tissues compared with PAT. 23 However, FMT has limited spatial resolution.…”

“…23–25 Previously, we reported that FMT was more sensitive and specific for the detection of low concentration contrast agents in tissues compared with PAT. 23 However, FMT has limited spatial resolution. Hence the combination of these two modalities with targeted nanoprobes should allow noninvasive imaging of ovarian tumors with high resolution, specificity and sensitivity.…”