Review of consensus test methods in medical imaging and current practices in photoacoustic image quality assessment

Abstract

. Significance : Photoacoustic imaging (PAI) is a powerful emerging technology with broad clinical applications, but consensus test methods are needed to standardize performance evaluation and accelerate translation. Aim : To review consensus image quality test methods for mature imaging modalities [ultrasound, magnetic resonance imaging (MRI), x-ray CT, and x-ray mammography], identify best practices in phantom design and testing procedures, and compare against current practices in PAI phantom testing. Approach : We reviewed scientific papers, international standards, clinical accreditation guidelines, and professional society recommendations describing medical image quality test methods. Observations are organized by image quality characteristics (IQCs), including spatial resolution, geometric accuracy, imaging depth, uniformity, sensitivity, low-contrast detectability, and artifacts. Results : Consensus documents typically prescribed phantom geometry and material property requirements, as well as specific data acquisition and analysis protocols to optimize test consistency and reproducibility. While these documents considered a wide array of IQCs, reported PAI phantom testing focused heavily on in-plane resolution, depth of visualization, and sensitivity. Understudied IQCs that merit further consideration include out-of-plane resolution, geometric accuracy, uniformity, low-contrast detectability, and co-registration accuracy. Conclusions : Available medical image quality standards provide a blueprint for establishing consensus best practices for photoacoustic image quality assessment and thus hastening PAI technology advancement, translation, and clinical adoption.

Evaluation of standardized performance test methods for biomedical Raman spectroscopy

“…Phantoms are objects used to mimic the relevant properties of human tissues, specific to a medical imaging modality, to ensure that systems and methods are operating correctly. 9 To date, most commonly used phantoms in Raman spectroscopy can be designed to mimic the optical absorption and scattering of tissue, but do not exhibit the Raman spectral components associated with the intended tissue type. [10][11][12][13] Our laboratory has recently reported on a 3D-printed phantom based on polyacrylate resins with biologically relevant absorption and scattering properties, as well as a Raman spectrum similar to that of tissue.…”

Photoacoustic imaging phantoms for assessment of object detectability and boundary buildup artifacts

“…In addition to well-characterized TMMs, it is equally important to carefully design reproducible phantom geometries, target inclusion sizes and patterns, and image acquisition and analysis protocols. We recently reviewed common practices in PAI phantom design and testing, and compared them to standardized IQC test methods used for mature imaging modalities [40] . Several understudied IQCs were identified, including: size-dependent low-contrast object detectability; geometric accuracy (the ability to accurately represent real dimensions of imaged features); and artifacts.…”

“…Ideally, imaging targets would be solid inclusions made of tunable TMM, which could be prepared with variable shapes and dimensions, and could represent small assemblies of small absorbers (e.g., arterioles and capillaries). Most reported PAI phantoms use tubes or wall-less channels filled with contrast media such as dyes, blood, or nanoparticles [29] , [30] , [40] , [42] . However, tubes are often only available in relatively large sizes representative of larger blood vessels, rather than smaller vasculature.…”

“…These phantoms are composed of multiple layers of PVCP breast-mimicking TMMs embedding spherical inclusions and wall-less channels for absorber injection. Although anthropomorphic phantoms can produce more life-like image features, image quality phantoms generally rely on idealized targets such as cylinders and spheres for objective, quantitative image quality assessment [40] . This latter phantom paradigm is more consistent with standardized phantom-based image quality test methods for mature modalities such as CT, mammography, MRI, and ultrasound.…”

“…To the best of our knowledge, these are the first well-characterized image quality phantom targets prepared with a TMM that generates “filled-in” PAI features. Similarly, the phantom designs and test methods proposed here are a first attempt to evaluate understudied PAI IQCs we previously identified through literature review [40] . Finally, to encourage adoption of the phantoms proposed in this study, all 3D-printer designs are readily available through the NIH 3D-File Exchange website [45] .…”