A critical issue associated with the clinical translation of fluorescence molecular imaging relates to the reproducibility of the collected measurements. In particular, images acquired from the same target using different fluorescence cameras may vary considerably when the employed systems have markedly different specifications. Methods that standardize fluorescence imaging are therefore becoming necessary for assessing the performance of fluorescence systems and agents and for providing a reference to the data collected. In the work presented herein we propose a composite phantom for integrating multiple targets within the field of view of a fluorescence camera. Each quadrant of this phantom resolves different fluorescence features: (1) sensitivity as a function of the optical properties; (2) sensitivity as a function of the depth from the top surface; (3) resolution of the fluorescence and optical imaging; and (4) cross-talk from the excitation light. In addition, there exist structures in the phantom for assessing homogeneity of the incident illumination. In order to validate our main hypothesis that standardization of fluorescence imaging systems is feasible through imaging such a phantom, we employed two systems of different specifications and quantified all relevant performance metrics. The derived results showcase the feasibility of fluorescence cameras calibration. Additionally, we demonstrate a methodology of comparing fluorescence cameras by means of benchmarking scoring. We expect that such approaches will boost the clinical translation of fluorescence molecular imaging and will allow for the investigation of novel fluorescence agents.
Lack of standardization in fluorescence imaging challenges its clinical translation. We investigate the use of a composite phantom to perform standardization, which could serve as a framework toward the benchmarking of fluorescence imaging systems.
Despite recent advances in fluorescence imaging, standardization of systems remains an unmet need. We developed a new comprehensive phantom that resolves multiple system parameters simultaneously and could be used for system performance comparison.
Fluorescence molecular imaging (FMI) has shown potential to detect and delineate cancer during surgery or diagnostic endoscopy. Recent progress on imaging systems has allowed sensitive detection of fluorescent agents even in video rate mode. However, lack of standardization in fluorescence imaging challenges the clinical application of FMI, since the use of different systems may lead to different results from a given study, even when using the same fluorescent agent. In this work, we investigate the use of a composite fluorescence phantom, employed as an FMI standard, to offer a comprehensive method for validation and standardization of the performance of different imaging systems. To exclude user interaction, all phantom features are automatically extracted from the acquired epi-illumination color and fluorescence images, using appropriately constructed templates. These features are then employed to characterize the performance and compare different cameras to each other. The proposed method could serve as a framework toward the calibration and benchmarking of FMI systems, to facilitate their clinical translation.
Fluorescence imaging has been considered for over a half-century as a modality that could assist surgical guidance and visualization. The administration of fluorescent molecules with sensitivity to disease biomarkers and their imaging using a fluorescence camera can outline pathophysiological parameters of tissue invisible to the human eye during operation. The advent of fluorescent agents that target specific cellular responses and molecular pathways of disease has facilitated the intraoperative identification of cancer with improved sensitivity and specificity over nonspecific fluorescent dyes that only outline the vascular system and enhanced permeability effects. With these new abilities come unique requirements for developing phantoms to calibrate imaging systems and algorithms. We briefly review herein progress with fluorescence phantoms employed to validate fluorescence imaging systems and results. We identify current limitations and discuss the level of phantom complexity that may be required for developing a universal strategy for fluorescence imaging calibration. Finally, we present a phantom design that could be used as a tool for interlaboratory system performance evaluation.
The increasing demand of enhanced sensitivity in the detection of various biochemical analytes paves the way for the development of a new generation of biosensors. Label free multianalyte immunosensing methods utilizing photonic probing have proven to result in better sensitivity and reliability than other types of biosensing methods. Here we described a monolithic silicon optoelectronic transducer capable of label-free and multianalyte determinations. The transducer includes ten Mach-Zehnder interferometers each of which is coupled to its own broad band light emitting device. The adlayers on the sensing arm cause spectral shifts detected at the output of the interferometers by coupling a portable spectrometer through an external fiber. Fourier transform techniques are employed to determine with a high degree of accuracy the shifts of the sinusoidal spectral outputs. The microphotonic chip was integrated with a microfluidic module and a model binding assay (mouse-antimouse) was run to demonstrate the operation.