A phantom to assess the accuracy of tumor delineation using MRSI
Background. Studies have demonstrated that magnetic resonance spectroscopic imaging (MRSI) can detect regions of abnormal activity (tumor) that would not have been covered using conventional imaging and contouring methods. With increased interest in MRSI it is important that its accuracy in tumor delineation be investigated. While some effort has been made to design phantoms to examine the performance of MRSI sequences, most phantoms rely on using traditional glass or acrylic as the phantom building material.
Material and methods. In this work, a gel-based detail phantom has been developed to assess the ability of the spectroscopic imaging sequences to accurately represent the geometry of tumors. The gel-based phantom is used as an alternative to conventional acrylic or glass based phantoms for use with MRSI.
Results. Gel-based phantoms have the advantage of having a magnetic susceptibility close to that of water. In addition, we demonstrate the benefits of having no finite wall thickness separating phantom compartments. The utility of the phantom was illustrated in comparisons between different MRSI sequences of the same nominal resolution as well as different filtering parameters.
Conclusions. Due to their ease of construction and the reduced artifacts, gel phantoms are a reliable tool for assessing the performance of MRSI sequences.
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