Abstract:.
Microscopic and mesoscale optical imaging techniques allow for three-dimensional (3-D) imaging of biological tissue across millimeter-scale regions, and imaging phantom models are invaluable for system characterization and clinical training. Phantom models that replicate complex 3-D geometries with both structural and molecular contrast, with resolution and lateral dimensions equivalent to those of imaging techniques (
), have proven elusive. We present a method for fabricating phant… Show more
“…While final cured polyurethane is chemically inert, some of its unreacted ingredients such as isocyanates are toxic 134 . RTV silicone 40,135,[144][145][146][147][148][149][136][137][138][139][140][141][142][143] exhibits similar properties to resin-based materials, but allows greater versatility in phantom design. It is composed of liquid polyorganosiloxanes that crosslink upon addition of a catalyst and is widely available in different hardness shores.…”
Section: Non-water-based Materialsmentioning
confidence: 99%
“…Albumen 44,284 Bovine Serum Albumin (BSA) [285][286][287][288] Melting temperature Formaldehyde 79 TiO2 40,138,139,141,145,147,149,152,289 , Al2O3…”
The reliability and reproducibility of experimental results are crucial in the development and regulatory approval of medical technologies, yet represent a challenge for biophotonic instrumentation due to a lack of accepted standards and phantoms suitable for successful technical validations. Here, we discuss the general design considerations for the preparation of tissue-mimicking biophotonic phantoms and then critically review the existing literature on phantom materials and fabrication across the field in light of these criteria and of recent developments at the state-of-the-art. We then focus on three representative examples of biophotonic standardisation related to different modalities, presented in order of their relative maturity: diffuse optical imaging and spectroscopy, fluorescence guided surgery, and photoacoustic imaging. Finally, we provide a perspective on future phantom development and the unmet needs of the biophotonic field, identifying a set of criteria, termed the "4Cs", for biophotonic standardisation which highlight the need for characterisation, collaboration, communication and commitment to maximise the achievements of ongoing standardisation efforts.Optical imaging biomarkers enable disease diagnosis and treatment in real-time at relatively low cost, leading to an increase in the use of optical imaging methods in clinical practice 1 . Despite the increasing number of available optical-imaging biomarkers and their significant potential for improving clinical outcomes, published standards for performance evaluation of optical imaging devices are still lacking 2 . As a result, technological progress in the respective imaging communities is hampered by a lack of transparency and comparability between system performance evaluations reported in the literature. The lack of consensus standards alsoimpacts the clinical translation process because regulatory bodies often recognize such standards and/or use them to guide policy. Without technical guidance on performance testing, the execution of clinical studies and the approval of new biophotonic devices may be slower and inconsistent.Test objects to calibrate optical systems have an important subset known as tissuemimicking phantoms, which are used for performance evaluation of a given technology by mimicking light-tissue interactions of human tissue, as well as other crucial elements of the process 3,4 . The diverse landscape of biophotonic applications means that it is likely impossible to have an all-encompassing phantom that fulfils the needs of every optical sub-speciality. As such, a wide range of biophotonic phantoms have been proposed 5,6 , but there has been no consensus on a widely applicable material type nor fabrication method to produce such phantoms. Nevertheless, finding consensus on broadly applicable materials would be beneficial to enable comparison of devices between vendors and institutions; advance hybrid modalities; allow complementary use of different modalities within one clinical session; and further the development of inte...
“…While final cured polyurethane is chemically inert, some of its unreacted ingredients such as isocyanates are toxic 134 . RTV silicone 40,135,[144][145][146][147][148][149][136][137][138][139][140][141][142][143] exhibits similar properties to resin-based materials, but allows greater versatility in phantom design. It is composed of liquid polyorganosiloxanes that crosslink upon addition of a catalyst and is widely available in different hardness shores.…”
Section: Non-water-based Materialsmentioning
confidence: 99%
“…Albumen 44,284 Bovine Serum Albumin (BSA) [285][286][287][288] Melting temperature Formaldehyde 79 TiO2 40,138,139,141,145,147,149,152,289 , Al2O3…”
The reliability and reproducibility of experimental results are crucial in the development and regulatory approval of medical technologies, yet represent a challenge for biophotonic instrumentation due to a lack of accepted standards and phantoms suitable for successful technical validations. Here, we discuss the general design considerations for the preparation of tissue-mimicking biophotonic phantoms and then critically review the existing literature on phantom materials and fabrication across the field in light of these criteria and of recent developments at the state-of-the-art. We then focus on three representative examples of biophotonic standardisation related to different modalities, presented in order of their relative maturity: diffuse optical imaging and spectroscopy, fluorescence guided surgery, and photoacoustic imaging. Finally, we provide a perspective on future phantom development and the unmet needs of the biophotonic field, identifying a set of criteria, termed the "4Cs", for biophotonic standardisation which highlight the need for characterisation, collaboration, communication and commitment to maximise the achievements of ongoing standardisation efforts.Optical imaging biomarkers enable disease diagnosis and treatment in real-time at relatively low cost, leading to an increase in the use of optical imaging methods in clinical practice 1 . Despite the increasing number of available optical-imaging biomarkers and their significant potential for improving clinical outcomes, published standards for performance evaluation of optical imaging devices are still lacking 2 . As a result, technological progress in the respective imaging communities is hampered by a lack of transparency and comparability between system performance evaluations reported in the literature. The lack of consensus standards alsoimpacts the clinical translation process because regulatory bodies often recognize such standards and/or use them to guide policy. Without technical guidance on performance testing, the execution of clinical studies and the approval of new biophotonic devices may be slower and inconsistent.Test objects to calibrate optical systems have an important subset known as tissuemimicking phantoms, which are used for performance evaluation of a given technology by mimicking light-tissue interactions of human tissue, as well as other crucial elements of the process 3,4 . The diverse landscape of biophotonic applications means that it is likely impossible to have an all-encompassing phantom that fulfils the needs of every optical sub-speciality. As such, a wide range of biophotonic phantoms have been proposed 5,6 , but there has been no consensus on a widely applicable material type nor fabrication method to produce such phantoms. Nevertheless, finding consensus on broadly applicable materials would be beneficial to enable comparison of devices between vendors and institutions; advance hybrid modalities; allow complementary use of different modalities within one clinical session; and further the development of inte...
“…Compared to our previous work 39 , refractive indices closer to the case of biological tissue have been used and the interferometer setup has been included rigorously according to Maxwell’s equations. With the obtained results, it is possible to explain the structure of experimental tomogram images presented elsewhere 62 .Figure 4Comparison between tomograms simulated for ( a , b ) perpendicular polarisation and ( c , d ) parallel polarisation for an infinitely long cylindrical scatterer with a = 5 μ m radius. The scatterer, distorted according to the refractive index ratio, is indicated by a black line.…”
An algorithm for the simulation of two-dimensional spectral domain optical coherence tomography images based on Maxwell’s equations is presented. A recently developed and modified time-harmonic numerical solution of Maxwell’s equations is used to obtain scattered far fields for many wave numbers contained in the calculated spectrum. The interferometer setup with its lenses is included rigorously with Fresnel integrals and the Debye-Wolf integral. The implemented model is validated with an existing FDTD algorithm by comparing simulated tomograms of single and multiple cylindrical scatterers for perpendicular and parallel polarisation of the incident light. Tomograms are presented for different realisations of multiple cylindrical scatterers. Furthermore, simulated tomograms of a ziggurat-shaped scatterer and of dentin slabs, with varying scatterer concentrations, are investigated. It is shown that the tomograms do not represent the physical structures present within the sample.
“…Previous studies already demonstrated the association between OCT imaging signals and the corresponding atherosclerotic tissues [ 68 , 69 ]: for example, lipid-rich plaques show diffuse borders with signal-poor regions, while fibrous plaques show homogeneous and signal-rich regions, meaning that lipid-rich plaques have higher attenuation and backscattering coefficients than fibrocalcific and fibrous plaques [ 69 ]. For this reason, including adequate structural and molecular sources of contrast into the biomodel is crucial, so the OCT phantoms can accurately mimic realistic pathologic conditions [ 70 ].…”
Section: Applications Of Biomimetic Vascular Models For Atherosclerosismentioning
Atherosclerosis represents the etiologic source of several cardiovascular events, including myocardial infarction, cerebrovascular accidents, and peripheral artery disease, which remain the leading cause of mortality in the world. Numerous strategies are being delineated to revert the non-optimal projections of the World Health Organization, by both designing new diagnostic and therapeutic approaches or improving the interventional procedures performed by physicians. Deeply understanding the pathological process of atherosclerosis is, therefore, mandatory to accomplish improved results in these trials. Due to their availability, reproducibility, low expensiveness, and rapid production, biomimicking physical models are preferred over animal experimentation because they can overcome some limitations, mainly related to replicability and ethical issues. Their capability to represent any atherosclerotic stage and/or plaque type makes them valuable tools to investigate hemodynamical, pharmacodynamical, and biomechanical behaviors, as well as to optimize imaging systems and, thus, obtain meaningful prospects to improve the efficacy and effectiveness of treatment on a patient-specific basis. However, the broadness of possible applications in which these biomodels can be used is associated with a wide range of tissue-mimicking materials that are selected depending on the final purpose of the model and, consequently, prioritizing some materials’ properties over others. This review aims to summarize the progress in fabricating biomimicking atherosclerotic models, mainly focusing on using materials according to the intended application.
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