PVCP-based anthropomorphic breast phantoms containing structures similar to lactiferous ducts for ultrasound imaging: A comparison with human breasts

Tissue-Mimicking Materials for Breast Ultrasound Elastography Phantoms: A Systematic Review

Breast ultrasound elastography phantoms are valued for their ability to mimic human tissue, enabling calibration for quality assurance and testing of imaging systems. Phantoms may facilitate the development and evaluation of ultrasound techniques by accurately simulating the properties of breasts. However, selecting appropriate tissue-mimicking materials for realistic and accurate ultrasound exams is crucial to ensure the ultrasound system responds similarly to real breast tissue. We conducted a systematic review of the PubMed, Scopes, Embase, and Web of Sciences databases, identifying 928 articles in the initial search, of which 19 were selected for further evaluation based on our inclusion criteria. The chosen article focused on tissue-mimicking materials in breast ultrasound elastography phantom fabrication, providing detailed information on the fabrication process, the materials used, and ultrasound and elastography validation of phantoms. The phantoms fabricated from Polyvinyl Chloride Plastisol, silicon, and paraffin were best suited for mimicking breast, fatty, glandular, and parenchyma tissues. Adding scatterers to these materials facilitates accurate fatty and glandular breast tissue simulations, making them ideal for ultrasound quality assurance and elastography training. Future research should focus on developing more realistic phantoms for advanced medical training, improving the practice of difficult procedures, enhancing breast cancer detection research, and providing tailored tissue characteristics.

Fabrication and evaluation of breast tissue equivalent phantoms for image quality assessment in ultrasound imaging

INTRODUCTION

Phantom materials with tissue-equivalent physical properties that require regular evaluation using patented phantoms are essential for medical device quality assurance programs. This study evaluated phantom materials for tissue equivalence and their use in image quality assessment for breast ultrasound scanner performance testing using two custom-made phantoms.

METHODS

Two types of phantoms were developed: phantoms A and B. Phantom A was made from a base material consisting of polyvinyl chloride-plastisol with the addition of glycerol, whereas phantom B consisted of polyvinyl chloride-plastisol with the addition of graphite. Each phantom had a stiff and soft lesion shaped like a sphere, with a diameter of 1.4 cm. The phantoms were cuboids with dimensions of 10 × 10 cm2 and a thickness of 5 cm. A series of phantom evaluations was performed, consisting of density, elasticity, acoustic properties, B-mode ultrasound images, and strain ratio.

RESULTS

The characterisation results show that background A closely resembles fibroglandular tissue in terms of density and acoustic properties (<5% variation); background B only resembles fibroglandular tissue in terms of density (-1.8% variation). In terms of elasticity, both backgrounds were close to the minimum value of fibroglandular tissue elasticity. The soft lesion on the phantom had a slightly lower density and elasticity than the carcinoma, whereas its acoustic properties (speed of sound and attenuation coefficient) were slightly higher than those of the reference carcinoma. Both phantoms were consistent with the literature in terms of strain ratio, geometric accuracy, lesion detection, and mean pixel value and showed good potential stability over one year.

CONCLUSION

This study successfully described the fabrication and evaluation sequence of a phantom equivalent to breast fibroglandular tissue and its evaluation via ultrasound imaging.

IMPLICATIONS FOR PRACTICE

This study offers proprietary information essential for the fabrication of phantoms that can be used for quality assurance and control in ultrasound imaging.

Design and evaluation of an anthropomorphic neck phantom for improved ultrasound diagnostics of thyroid gland tumors

PURPOSE

Thyroid cancer is one of the most common cancers worldwide, with ultrasound-guided biopsy being the method of choice for its early detection. The accuracy of diagnostics directly depends on the qualifications of the ultrasonographers, whose performance can be enhanced through training with phantoms. The aim of this study is to propose a reproducible methodology for designing a neck phantom for ultrasound training and research from widely available materials and to validate its applicability.

METHODS

The phantom was made using polyvinyl chloride mixed with additives to reproduce different levels of brightness on ultrasound screens. 3D printing and casting were used to create the neck model and various structures of the neck, including bones, cartilage, arteries, veins, lymph nodes, thyroid gland, and soft tissues. The small objects, such as tumor and lymph node models, were shaped manually. All the phantom's materials were carefully selected to match the ultrasonic speed and attenuation values of real soft tissues and bones.

RESULTS

The thyroid gland contains models of a cancerous and cystic nodule. In the neck, there are models of carotid arteries and jugular veins filled with ultrasound-transparent gel. Additionally, there are replicas of lymph nodes and bone structures such as hyoid bone, thyroid cartilage, trachea, and vertebrae. The resulting phantom covers the entire neck area and has been positively received by practicing ultrasound specialists.

CONCLUSIONS

The proposed manufacturing technology offers a reliable and cost-effective approach to produce an anthropomorphic neck phantom for ultrasound diagnosis of the thyroid gland. The realistic simulation provided by the phantom enhances the quality and accuracy of ultrasound examinations, contributing to better training for medical professionals and improved patient care. Subsequent research efforts can concentrate on refining the fabrication process and exploring additional features to enhance the phantom's capabilities.

Agar-based Phantom for Evaluating Targeting of High-intensity Focused Ultrasound Systems for Breast Ablation

AIM

Phantoms are often utilized for the preclinical evaluation of novel high-intensity focused ultrasound (HIFU) systems, serving as valuable tools for validating efficacy. In the present study, the feasibility of a homogeneous agar-based breast-shaped phantom as a tool for the preclinical evaluation of HIFU systems dedicated to breast cancer was assessed. Specifically, the effect of the increased phantom curvature on temperature increase was examined through sonications executed on two sides having varied curvatures.

MATERIALS AND METHODS

Assessment was performed utilizing a 1.1 MHz focused transducer. Sonications on the two phantom sides were executed at varied acoustical power in both a laboratory setting and inside a 1.5 T magnetic resonance imaging scanner. Sonications were independently performed on two identical phantoms for repeatability purposes.

RESULTS

Temperature changes between 7.1°C-34.3°C and 5.1°C-21.5°C were recorded within the decreased and increased curvature sides, respectively, for acoustical power of 3.75-10 W. High-power sonications created lesions which were approximately symmetrically formed around the focal point at the decreased curvature side, while they were shifted away from the focal point at the increased curvature side.

CONCLUSIONS

The present findings indicate that increased curvature of the breast phantom results in deformed focal shapes and decreased temperatures induced at the focal area, thus suggesting treatment correction requirements in the form of focus control or accurate robotic movement. The developed breast-shaped phantom can be utilized as an evaluation tool of HIFU systems dedicated to breast cancer since it can visually verify the efficacy of any system.

Tissue-Mimicking Material Fabrication and Properties for Multiparametric Ultrasound Phantoms: A Systematic Review

Medical imaging has allowed for significant advancements in the field of ultrasound procedures over the years. However, each imaging modality exhibits distinct limitations that differently affect their accuracy. It is imperative to ensure the quality of each modality to identify and eliminate these limitations. To achieve this, a tissue-mimicking material (TMM) phantom is utilised for validation. This study aims to perform a systematic analysis of tissue-mimicking materials used for creating ultrasound phantoms. We reviewed 234 studies on the use of TMM phantoms in ultrasound that were published from 2013 to 2023 from two research databases. Our focus was on studies that discussed TMMs' properties and fabrication for ultrasound, elastography, and flow phantoms. The screening process led to the selection of 16 out of 234 studies to include in the analysis. The TMM ultrasound phantoms were categorised into three groups based on the solvent used; each group offers a broad range of physical properties. The water-based material most closely aligns with the properties of ultrasound. This study provides important information about the materials used for ultrasound phantoms. We also compared these materials to real human tissues and found that PVA matches most of the human tissues the best.

Development of an anatomical breast phantom from polyvinyl chloride plastisol with lesions of various shape, elasticity and echogenicity for teaching ultrasound examination

PURPOSE

The WHO reported an increasing trend in the number of new cases of breast cancer, making it the most prevalent cancer in the world. This fact necessitates the availability of highly qualified ultrasonographers, which can be achieved by the widespread implementation of training phantoms. The goal of the present work is to develop and test an inexpensive, accessible, and reproducible technology for creating an anatomical breast phantom for practicing ultrasound diagnostic skills in grayscale and elastography imaging, as well as ultrasound-guided biopsy sampling.

METHODS

We used FDM 3D printer and PLA plastic for printing an anatomical breast mold. We made a phantom using a mixture of polyvinyl chloride plastisol, graphite powder, and metallic glitter to simulate soft tissues and lesions. Various degrees of elasticity were imparted using plastisols of stiffness ranging from 3 to 17 on the Shore scale. The lesions were shaped by hand. The materials and methods used are easily accessible and reproducible.

RESULTS

Using the proposed technology, we have developed and tested a basic, differential, and elastographic versions of the breast phantom. The three versions of the phantom are anatomical and intended for use in medical education: the basic version is for practicing primary hand-eye coordination skills; the differential one is for practicing the differential diagnosis skills; the elastographic version helps developing the skills needed for assessing the stiffness of tissues.

CONCLUSION

The proposed technology allows the creation of breast phantoms for practicing hand-eye coordination and develop the critical skills for navigation and assessment of the shape, margins, and size of the lesion, as well as performing an ultrasound-guided biopsy. It is cost-effective, reproducible, and easily implementable, and could be instrumental in generating ultrasonographers with crucial skills for accurate diagnosis of breast cancer, especially in low-resource settings.

A Review of Low-Cost Ultrasound Compatible Phantoms

Ultrasound-compatible phantoms are used to develop novel US-based systems and train simulated medical interventions. The price difference between lab-made and commercially available ultrasound-compatible phantoms lead to the publication of many papers categorized as low-cost in the literature. The aim of this review was to improve the phantom selection process by summarizing the pertinent literature. We compiled papers on US-compatible spine, prostate, vascular, breast, kidney, and li ver phantoms. We reviewed papers for cost and accessibility, providing an overview of the materials, construction time, shelf life, needle insertion limits, and manufacturing and evaluation methods. This information was summarized by anatomy. The clinical application associated with each phantom was also reported for those interested in a particular intervention. Techniques and common practices for building low-cost phantoms were provided. Overall, this article aims to summarize a breadth of ultrasound-compatible phantom research to enable informed phantom methods selection.

Custom-made flow phantoms for quantitative ultrasound microvessel imaging

Morphologically realistic flow phantoms are essential experimental tools for quantitative ultrasound-based microvessel imaging. As new quantitative flow imaging tools are developed, the need for more complex vessel-mimicking phantoms is indisputable. In this article, we propose a method for fabricating phantoms with sub-millimeter channels consisting of branches and curvatures in various shapes and sizes suitable for quantifying vessel morphological features. We used different tissue-mimicking materials (TMMs) compatible with ultrasound imaging as the base and metal wires of different diameters (0.15-1.25 mm) to create wall-less channels. The TMMs used are silicone rubber, plastisol, conventional gelatin, and medical gelatin. Mother channels in these phantoms were made in diameters of 1.25 mm or 0.3 mm and the daughter channels in diameters 0.3 mm or 0.15 mm. Bifurcations were created by soldering wires together at branch points. Quantitative parameters were assessed, and accuracy of measurements from the ground truth were determined. Channel diameters were seen to have increased (76-270%) compared to the initial state in the power Doppler images, partly due to blood mimicking fluid pressure. Amongst the microflow phantoms made from the different TMMs, the medical gelatin phantom was selected as the best option for microflow imaging, fulfilling the objective of being easy to fabricate with high transmittance while having a speed of sound and acoustic attenuation close to human tissue. A flow velocity of 0.85 ± 0.01 mm/s, comparable to physiological flow velocity was observed in the smallest diameter phantom (medical gelatin branch) presented here. We successfully constructed more complex geometries, including tortuous and multibranch channels using the medical gelatin as the TMM. We anticipate this will create new avenues for validating quantitative ultrasound microvessel imaging techniques.

Sodium Alginate Ultrasound Phantom for Medical Education

The ultrasound phantoms used to educate medical students should not only closely mimic the ultrasound characteristics of human soft tissues but also be inexpensive and easy to manufacture. I have been studying handmade ultrasound phantoms and proposed an ultrasound phantom comprising calcium alginate hydrogel that met these requirements but caused a speckle pattern similar to that observed in ultrasound images of liver. In this study, I show that adding ethanol to the precursors used to fabricate the phantom reduces the speckle pattern. The ultrasound propagation velocity and attenuation coefficient of the phantom were 1561 ± 8 m/s and 0.54 ± 0.18 dB/cm/MHz, respectively (mean ± standard deviation), which are within the ranges of those in human soft tissues (1530-1600 m/s and 0.3-1.0 dB/cm/MHz, respectively). This phantom is easy to fabricate without special equipment, is inexpensive, and is suitable for elementary training on ultrasound diagnosis, operation of ultrasound-guided needles, and blind catheter insertion.