{"title":"在具有挑战性的条件下定量敏感性测绘重建精度的说明:幻影测量和模拟","authors":"Lundberg A, L. E., K. L., Wirestam R","doi":"10.17727/jmsr.2022/10-21","DOIUrl":null,"url":null,"abstract":"Magnetic susceptibility can be assessed by quantitative susceptibility mapping (QSM), based on measured magnetic resonance imaging (MRI) phase data. The QSM reconstruction process is, however, mathematically challenging and still not fully robust. A signal-generating holmium [Ho(III)] aqueous solution with air-equivalent magnetic susceptibility was prepared, and used as a surrounding medium in a water phantom with tubes filled with a solution of gadolinium contrast agent at various concentrations. Extended analyses under controlled conditions were accomplished by simulations of the phantom construction. Without surrounding holmium solution, a gadolinium tube positioned centrally, parallel with B0, showed a susceptibility difference that agreed well with theoretical values, whereas a peripheral parallel tube position showed larger deviation. Orientation perpendicular to B0 resulted in less variation between the internal tube positions. Air-equivalent magnetic susceptibility corresponded to 16.5 mM Ho(III) solution. With surrounding holmium solution, several post-processing steps became challenging. Simulations indicated higher degree of underestimation when the theoretical susceptibility difference increased. Details in the mathematical implementation, for example, background field removal can strongly influence the result. Simulated results were, in part, unexpected, and provided awareness of limitations in the reconstruction technique, mainly related to conditions with large susceptibility differences between compartments.","PeriodicalId":32890,"journal":{"name":"Journal of Medical and Scientific Research","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Notes on quantitative susceptibility mapping reconstruction accuracy under challenging conditions: Phantom measurements and simulations\",\"authors\":\"Lundberg A, L. E., K. L., Wirestam R\",\"doi\":\"10.17727/jmsr.2022/10-21\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Magnetic susceptibility can be assessed by quantitative susceptibility mapping (QSM), based on measured magnetic resonance imaging (MRI) phase data. The QSM reconstruction process is, however, mathematically challenging and still not fully robust. A signal-generating holmium [Ho(III)] aqueous solution with air-equivalent magnetic susceptibility was prepared, and used as a surrounding medium in a water phantom with tubes filled with a solution of gadolinium contrast agent at various concentrations. Extended analyses under controlled conditions were accomplished by simulations of the phantom construction. Without surrounding holmium solution, a gadolinium tube positioned centrally, parallel with B0, showed a susceptibility difference that agreed well with theoretical values, whereas a peripheral parallel tube position showed larger deviation. Orientation perpendicular to B0 resulted in less variation between the internal tube positions. Air-equivalent magnetic susceptibility corresponded to 16.5 mM Ho(III) solution. With surrounding holmium solution, several post-processing steps became challenging. Simulations indicated higher degree of underestimation when the theoretical susceptibility difference increased. Details in the mathematical implementation, for example, background field removal can strongly influence the result. Simulated results were, in part, unexpected, and provided awareness of limitations in the reconstruction technique, mainly related to conditions with large susceptibility differences between compartments.\",\"PeriodicalId\":32890,\"journal\":{\"name\":\"Journal of Medical and Scientific Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2022-07-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Medical and Scientific Research\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.17727/jmsr.2022/10-21\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Medical and Scientific Research","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.17727/jmsr.2022/10-21","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
摘要
磁化率可以通过定量磁化率图(QSM)来评估,基于测量的磁共振成像(MRI)相位数据。然而,QSM重建过程在数学上具有挑战性,并且仍然不是完全健壮。制备了一种具有空气等效磁化率的产生信号的钬[Ho(III)]水溶液,并将其用作水幻影的周围介质,水幻影的管中填充了不同浓度的钆造影剂溶液。在控制条件下的扩展分析是通过模拟的幻影结构完成的。在没有周围钬溶液的情况下,与B0平行放置在中心位置的钆管的磁化率差异与理论值吻合较好,而周围平行放置的钆管的磁化率差异较大。垂直于B0的方向导致内部管位置之间的变化较小。空气等效磁化率为16.5 mM Ho(III)溶液。由于周围有钬溶液,几个后处理步骤变得具有挑战性。模拟结果表明,理论敏感性差异越大,低估程度越高。数学实现中的细节,例如,背景场去除会强烈影响结果。在某种程度上,模拟结果是出乎意料的,并提供了对重建技术局限性的认识,主要与室间敏感性差异较大的条件有关。
Notes on quantitative susceptibility mapping reconstruction accuracy under challenging conditions: Phantom measurements and simulations
Magnetic susceptibility can be assessed by quantitative susceptibility mapping (QSM), based on measured magnetic resonance imaging (MRI) phase data. The QSM reconstruction process is, however, mathematically challenging and still not fully robust. A signal-generating holmium [Ho(III)] aqueous solution with air-equivalent magnetic susceptibility was prepared, and used as a surrounding medium in a water phantom with tubes filled with a solution of gadolinium contrast agent at various concentrations. Extended analyses under controlled conditions were accomplished by simulations of the phantom construction. Without surrounding holmium solution, a gadolinium tube positioned centrally, parallel with B0, showed a susceptibility difference that agreed well with theoretical values, whereas a peripheral parallel tube position showed larger deviation. Orientation perpendicular to B0 resulted in less variation between the internal tube positions. Air-equivalent magnetic susceptibility corresponded to 16.5 mM Ho(III) solution. With surrounding holmium solution, several post-processing steps became challenging. Simulations indicated higher degree of underestimation when the theoretical susceptibility difference increased. Details in the mathematical implementation, for example, background field removal can strongly influence the result. Simulated results were, in part, unexpected, and provided awareness of limitations in the reconstruction technique, mainly related to conditions with large susceptibility differences between compartments.