Near-infrared fluorescence (NIRF) angiography has been applied for intraoperative visualization of neurovascular circulation and pathologies such as aneurysms, as well as to enhance contrast in clinical imaging of retinal fundus microvasculature. The ability to quantitatively evaluate and compare the performance of NIRF imaging devices including contrast, resolution and linearity under biologically realistic, yet reproducible conditions would facilitate innovation and clinical translation of this technology. Towards development of methods that can fill this role, we have generated 3D-printed, image-defined tissue simulating phantoms at macro and micro scales. The macro-scale phantom was developed based on an MRI image volume of a human head. This map was segmented into white matter, gray matter and vessel regions and edited to provide a suitable file for 3D printing. The phantom was then printed with an Objet260 Connex3 printer using a material with a biologically relevant NIR scattering coefficient. The micro-scale phantom is based on a fundus camera image of a human retina. This phantom was printed using a Nanoscribe Photonic Professional GT printer with sub-micron resolution, but a maximum print volume of approximately 1 mm3. To demonstrate the neurovascular phantoms for NIRF imaging system, channels were injected with a solution of hemoglobin and Indocyanine Green and then imaged with CCD-based macro- and micro- NIRF imaging system. Overall, these approaches for fabricating biomimetic phantoms hold significant promise for evaluation of NIRF angiography devices image quality in a standardized, yet realistic manner.
|