对T(1)模糊不敏感的扩展ISIS序列。

Extended ISIS sequences insensitive to T(1) smearing.

作者信息

Ljungberg M, Starck G, Vikhoff-Baaz B, Alpsten M, Ekholm S, Forssell-Aronsson E

机构信息

Department of Radiation Physics, Göteborg University, Sahlgrenska University Hospital, Göteborg, Sweden.

出版信息

Magn Reson Med. 2000 Oct;44(4):546-55. doi: 10.1002/1522-2594(200010)44:4<546::aid-mrm8>3.0.co;2-7.

DOI:10.1002/1522-2594(200010)44:4<546::aid-mrm8>3.0.co;2-7

PMID:11025510

Abstract

Image selected in vivo spectroscopy (ISIS) is a volume selection method often used for in vivo (31)P MRS, since it is suitable for measurements of substances with short T(2). However, ISIS can suffer from significant signal contributions caused by T(1) smearing from regions outside the VOI. A computer model was developed to simulate this contamination. The simulation results for the ISIS experiment order implemented in our MR system (ISIS-0) were in agreement with results obtained from phantom measurements. A new extended ISIS experiment order (E-ISIS) was developed, consisting of four "optimal" ISIS experiment orders (ISIS-1 to ISIS-4) performed consecutively with dummy ISIS experiments in between. The simulation results show that contamination due to T(1) smearing is, effectively, eliminated with E-ISIS and is significantly lower than for ISIS-0 and ISIS-1. E-ISIS offers increased accuracy for quantitative and qualitative determination of substances studied using in vivo MRS. Hence, E-ISIS can be valuable for both clinical and research applications.

摘要

体内光谱成像选择法（ISIS）是一种常用于体内磷磁共振波谱（31P MRS）的容积选择方法，因为它适用于测量具有短T(2)的物质。然而，ISIS可能会受到感兴趣区（VOI）外区域T(1)模糊导致的显著信号干扰。为此开发了一个计算机模型来模拟这种干扰。在我们的磁共振系统中实施的ISIS实验序列（ISIS - 0）的模拟结果与体模测量结果一致。开发了一种新的扩展ISIS实验序列（E - ISIS），它由四个“最佳”ISIS实验序列（ISIS - 1至ISIS - 4）组成，中间穿插虚拟ISIS实验并连续进行。模拟结果表明，E - ISIS有效地消除了T(1)模糊造成的干扰，且显著低于ISIS - 0和ISIS - 1。E - ISIS提高了使用体内MRS研究物质的定量和定性测定的准确性。因此，E - ISIS在临床和研究应用中都具有重要价值。