Agarose and Wax Tissue-Mimicking Phantom for Dynamic Magnetic Resonance Imaging of the Liver (original) (raw)
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Advanced Research in Gastroenterology & Hepatology
Background: Hepatocellular carcinoma (HCC) is one of the most common cause of cancer-related deaths worldwide. The objective of this study is to detect the various stages of HCC through the utilization of a dynamic liver phantom with MRI. Methods: Three liver phantoms composed of different gelatin concentrations (2.5%wt, 4.0%wt, and 5.0%wt) and fixed agar concentrations were used. The HCC samples consisted of agarose and glycerol and were of varying sizes (0.5,1.0, and 2.0cm). The chemical, mechanical, electrical, and imaging properties of the phantoms were examined. The consistency of T1 and T2 signal intensities over a six-week period was studied. In addition, dynamic contrast-enhanced MRI was used to detect the HCC samples through the Dixon sequence. Results: The gelatin concentration of 5%wt was the most stable in regard to density, exhibited the lowest average compressive strength of 0.22MPa, and had the lowest electrical conductivity over the course of a six-week period. Durin...
Dynamic Hepatocellular Carcinoma Model Within a Liver Phantom for Multimodality Imaging
European Journal of Radiology Open, 2020
Hepatocellular carcinoma (HCC) is one of the most common cancer in the world, and the effectiveness of its treatment lies in its detection in its early stages. The aim of this study is to mimic HCC dynamically through a liver phantom and apply it in multimodality medical imaging techniques including magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound. Methods and materials: The phantom is fabricated with two main parts, liver parenchyma and HCC inserts. The liver parenchyma was fabricated by adding 2.5 wt% of agarose powder combined with 2.6 wt% of wax powder while the basic material for the HCC samples was made from polyurethane solution combined with 5 wt% glycerol. Three HCC samples were inserted into the parenchyma by using three cylinders implanted inside the liver parenchyma. An automatic injector is attached to the input side of the cylinders and a suction device connected to the output side of the cylinders. After the phantom was prepared, the contrast materials were injected into the phantom and imaged using MRI, CT, and ultrasound. Results: Both HCC samples and liver parenchyma were clearly distinguished using the three imaging modalities: MRI, CT, and ultrasound. Doppler ultrasound was also applied through the HCC samples and the flow pattern was observed through the samples. Conclusion: A multimodal dynamic liver phantom, with HCC tumor models have been fabricated. This phantom helps to improve and develop different methods for detecting HCC in its early stages.
MR relaxation times of agar‐based tissue‐mimicking phantoms
Journal of Applied Clinical Medical Physics
Agar gels were previously proven capable of accurately replicating the acoustical and thermal properties of real tissue and widely used for the construction of tissue-mimicking phantoms (TMPs) for focused ultrasound (FUS) applications. Given the current popularity of magnetic resonance-guided FUS (MRgFUS), we have investigated the MR relaxation times T1 and T2 of different mixtures of agar-based phantoms. Nine TMPs were constructed containing agar as the gelling agent and various concentrations of silicon dioxide and evaporated milk. An agar-based phantom doped with wood powder was also evaluated. A series of MR images were acquired in a 1.5 T scanner for T1 and T2 mapping. T2 was predominantly affected by varying agar concentrations. A trend toward decreasing T1 with an increasing concentration of evaporated milk was observed. The addition of silicon dioxide decreased both relaxation times of pure agar gels.The proposed phantoms have great potential for use with the continuously emerging MRgFUS technology. The MR relaxation times of several body tissues can be mimicked by adjusting the concentration of ingredients, thus enabling more accurate and realistic MRgFUS studies.
Multimodal Phantom of Liver Tissue
PLoS ONE, 2013
Medical imaging plays an important role in patients' care and is continuously being used in managing health and disease. To obtain the maximum benefit from this rapidly developing technology, further research is needed. Ideally, this research should be done in a patient-safe and environment-friendly manner; for example, on phantoms. The goal of this work was to develop a protocol and manufacture a multimodal liver phantom that is suitable for ultrasound, computed tomography, and magnetic resonance imaging modalities. The proposed phantom consists of three types of mimicked soft tissues: liver parenchyma, tumors, and portal veins, that are made of six ingredients: candle gel, sephadexH, agarose, glycerol, distilled water, and silicone string. The entire procedure is advantageous, since preparation of the phantom is simple, rather costeffective, and reasonably quick -it takes around 2 days. Besides, most of the phantom's parts can be reused to manufacture a new phantom. Comparison of ultrasound images of real patient's liver and the developed phantom shows that the phantom's liver tissue and its structures are well simulated.
Tissue mimicking materials for imaging and therapy phantoms: a review
Physics in Medicine & Biology
Tissue mimicking materials (TMMs), typically contained within phantoms, have been used for many decades in both imaging and therapeutic applications. This review investigates the specifications that are typically being used in development of the latest TMMs. The imaging modalities that have been investigated focus around CT, mammography, SPECT, PET, MRI and ultrasound. Therapeutic applications discussed within the review include radiotherapy, thermal therapy and surgical applications. A number of modalities were not reviewed including optical spectroscopy, optical imaging and planar x-rays. The emergence of image guided interventions and multimodality imaging have placed an increasing demand on the number of specifications on the latest TMMs. Material specification standards are available in some imaging areas such as ultrasound. It is recommended that this should be replicated for other imaging and therapeutic modalities. Materials used within phantoms have been reviewed for a series of imaging and therapeutic applications with the potential to become a testbed for cross-fertilization of materials across modalities. Deformation, texture, multimodality imaging and perfusion are common themes that are currently under development.
Multimodal Imaging of Hepatocellular Carcinoma Using Dynamic Liver Phantom
Hepatocellular Carcinoma - Challenges and Opportunities of a Multidisciplinary Approach, 2021
Liver phantom is used at various medical levels, such as detecting hepatocellular carcinoma (HCC) in the early stages, training medical staff to deal with HCC by taking biopsies, developing new sequences on medical imaging devices, confirming the image quality, applying treatments to HCC, and others. All of the trials should be applied before entering the real human body. The phantom includes properties very similar to those of the human body, as well as the properties of liver cancer and how it is treated within the body through its biological form. Therefore, the present chapter aims to provide comprehensive information to consider when fabricating HCC-containing phantoms and the characteristics of those phantoms in proportion to multimodal medical imaging to aid in understanding the main target of dynamic phantom for HCC.
Tissue mimicking materials for a multi-imaging modality prostate phantom
Medical Physics, 2001
Materials that simultaneously mimic soft tissue in vivo for magnetic resonance imaging ͑MRI͒, ultrasound ͑US͒, and computed tomography ͑CT͒ for use in a prostate phantom have been developed. Prostate and muscle mimicking materials contain water, agarose, lipid particles, protein, Cu ϩϩ , EDTA, glass beads, and thimerosal ͑preservative͒. Fat was mimicked with safflower oil suffusing a random mesh ͑network͒ of polyurethane. Phantom material properties were measured at 22°C. ͑22°C is a typical room temperature at which phantoms are used.͒ The values of material properties should match, as well as possible, the values for tissues at body temperature, 37°C. For MRI, the primary properties of interest are T1 and T2 relaxations times, for US they are the attenuation coefficient, propagation speed, and backscatter, and for CT, the x-ray attenuation. Considering the large number of parameters to be mimicked, rather good agreement was found with actual tissue values obtained from the literature. Using published values for prostate parenchyma, T1 and T2 at 37°C and 40 MHz are estimated to be about 1100 and 98 ms, respectively. The CT number for in vivo prostate is estimated to be 45 HU ͑Hounsfield units͒. The prostate mimicking material has a T1 of 937 ms and a T2 of 88 ms at 22°C and 40 MHz; the propagation speed and attenuation coefficient slope are 1540 m/s and 0.36 dB/cm/MHz, respectively, and the CT number of tissue mimicking prostate is 43 HU. Tissue mimicking ͑TM͒ muscle differs from TM prostate in the amount of dry weight agarose, Cu ϩϩ , EDTA, and the quality and quantity of glass beads. The 18 m glass beads used in TM muscle increase US backscatter and US attenuation; the presence of the beads also has some effect on T1 but no effect on T2. The composition of tissue-mimicking materials developed is such that different versions can be placed in direct contact with one another in a phantom with no long term change in US, MRI, or CT properties. Thus, anthropomorphic phantoms can be constructed.
Development of a Computerized 4-D MRI Phantom for Liver Motion Study
Technology in cancer research & treatment, 2017
To develop a 4-dimensional computerized magnetic resonance imaging phantom with image textures extracted from real patient scans for liver motion studies. The proposed phantom was developed based on the current version of 4-dimensional extended cardiac-torso computerized phantom and a clinical magnetic resonance scan. Initially, the extended cardiac-torso phantom was voxelized in abdominal-chest region at the end of exhalation phase. Structures/tissues were classified into 4 categories: (1) Seven key textured organs, including liver, gallbladder, spleen, stomach, heart, kidneys, and pancreas, were mapped from a clinical T1-weighted liver magnetic resonance scan using deformable registration. (2) Large textured soft tissue volumes were simulated via an iterative pattern generation method using the same magnetic resonance scan. (3) Lung and intestine structures were generated by assigning uniform intensity with proper noise modeling. (4) Bony structures were generated by assigning the...