Development of a morphologically realistic mouse phantom for pre‐clinical photoacoustic imaging

Abstract

BackgroundCharacterizations based on anatomically realistic phantoms are highly effective to perform accurate technical validation of imaging systems. Specifically for photoacoustic imaging (PAI), although a variety of phantom models with simplified geometries are reported, an unmet need still exists to establish morphologically realistic heterogeneous pre‐clinical phantoms. So the development of a mouse‐mimicking phantom can reduce the use of animals for the validation and standardization studies of pre‐clinical PAI systems and thus eventually translate the PAI technology to clinical research.PurposeHere we designed, developed, and fabricated a stable phantom that mimics the detailed morphology of a mouse, to be used as a realistic tool for PAI.MethodsThe mouse phantom, has been designed by using a combination of image modeling and 3D‐printing techniques. As a tissue‐mimicking material, we have used copolymer‐in‐oil‐based material that was recently proposed by the International Photoacoustic Standardization Consortium (IPASC). In particular, the anatomically realistic phantom has been modeled by using the real atlas of a mouse as a reference. The mouse phantom includes a 3D‐printed skeleton and the main abdominal organs such as the liver, spleen, and kidneys obtained by using doped copolymer‐in‐oil material with 3D‐printed molds. In addition, the acoustic and optical properties of the tissue‐mimicking material and the long‐term stability have been broadly characterized.ResultsFurthermore, our studies showed that the phantom is durable and stable for more than 200 days, under normal storage and repeated use. Fabrication protocol is easy to reproduce. As a result, the proposed morphologically realistic mouse phantom offers durability, material compatibility, and an unprecedented realistic resemblance to the actual rodents’ anatomy in PAI.ConclusionThis durable morphologically realistic mouse phantom would minimize the animal experiments in compliance with the 3R principle of Replacement, Reduction, and Refinement. To our knowledge, this is the first time an anatomically realistic heterogeneous mouse phantom has been proposed for PAI in pre‐clinical animal imaging and tested its durability over 200 days.

Optical tuning of copolymer-in-oil tissue-mimicking materials for multispectral photoacoustic imaging

“…The creation of custom-made phantoms with desired shapes is highly desirable (Grasso et al 2023). The smiley phantoms showcased the potential use of SEBS-gel with added oil-based inks as custom-made TMMs.…”

“…Commercially available pigments have been employed as additives to tune absorption properties in mineral oil SEBS-gel and epoxy resins (Xu 2019, Grasso et al 2023. In addition, pigments have been used as additives in gel wax-based compounds (Maneas et al 2018).…”