Characterisation Of Agarose Gel As Breast Mimicking Material

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Date
2016-01
Authors
Jamil, Munirah
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Publisher
Universiti Sains Malaysia
Abstract
Breast MRI has become an essential element in breast imaging. A phantom is a mass of materials that are used to investigate the effects of radiation on human. The aims of this study were to fabricate an agarose phantom as breast mimicking material for MRI and to evaluate agarose gel concentration that has a similar SPGR T1 and T2 relaxation times for normal and abnormal breast tissues. The breast mimicking materials consisted of agarose and gelatine mixture as the background material, which mimics the breast tissue. The background solution composed of 30% of agarose solution and 70% of gelatine solution. Different concentrations of agarose were set at 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0% and 3.5%. Besides, there are different types of materials that were used to mimic abnormal tissue characteristics in the sample such as polyacrylamide crystal soils (PCS) to mimic cysts, eggshells to mimic calcifications and crushed eggshells (CrE) to mimic microcalcifications. Selection of the MRI parameters was based on routine clinical MRI breast imaging protocols that used SPGR T1 and T2 for 1.5T. In SPGR T1 relaxation time, 2.0% of the agarose concentration batch gave the lowest value compared to other agarose concentration batches. The SPGR T1 relaxation time for control, PCS, CrE and eggshell samples were 48.18 ms, 43.41 ms, 47.15 ms and 44.38 ms, respectively. In T2 relaxation time, 3.0% of agarose concentration batch gave the lowest T2 value compared to other batches. The T2 relaxation time for control, PCS, CrE and eggshell samples were 1134.2 ms, 2839.1 ms, 185.5 ms and 265.2 ms, respectively. However, no sample batches give similar T2 relaxation time as reported in previous studies. Gelatine was not a suitable material to mimic fat because no fat images appear in SPGR T1WI and T2WI. In addition, NaCl can act as conductivity as well as a modifier to the agarose concentration. Selection of the suitable material and its size also needs to be considered for phantom fabrication to get a similar relaxation time to those of breast tissue.
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Keywords
Characterisation of agarose gel as , breast mimicking material
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