Division of Radiological Physics, Department of Medical Radiology, University of Basel Hospital, Basel, Switzerland.
Magn Reson Med. 2011 Aug;66(2):410-8. doi: 10.1002/mrm.22807. Epub 2011 Mar 9.
Fast quantitative MRI has become an important tool for biochemical characterization of tissue beyond conventional T1, T2, and T2*-weighted imaging. As a result, steady-state free precession (SSFP) techniques have attracted increased interest, and several methods have been developed for rapid quantification of relaxation times using steady-state free precession. In this work, a new and fast approach for T2 mapping is introduced based on partial RF spoiling of nonbalanced steady-state free precession. The new T2 mapping technique is evaluated and optimized from simulations, and in vivo results are presented for human brain at 1.5 T and for human articular cartilage at 3.0 T. The range of T2 for gray and white matter was from 60 msec (for the corpus callosum) to 100 msec (for cortical gray matter). For cartilage, spatial variation in T2 was observed between deep (34 msec) and superficial (48 msec) layers, as well as between tibial (33 msec), femoral, (54 msec) and patellar (43 msec) cartilage. Excellent correspondence between T2 values derived from partially spoiled SSFP scans and the ones found with a reference multicontrast spin-echo technique is observed, corroborating the accuracy of the new method for proper T2 mapping. Finally, the feasibility of a fast high-resolution quantitative partially spoiled SSFP T2 scan is demonstrated at 7.0 T for human patellar cartilage.
快速定量磁共振成像已成为组织生化特征分析的重要工具，超越了传统的 T1、T2 和 T2*加权成像。因此，稳态自由进动（SSFP）技术引起了越来越多的关注，并且已经开发出几种使用稳态自由进动快速定量弛豫时间的方法。在这项工作中，提出了一种新的基于非平衡稳态自由进动部分射频（RF）破坏的快速 T2 映射方法。新的 T2 映射技术通过模拟进行了评估和优化，并在 1.5T 下对人脑和 3.0T 下的人关节软骨进行了体内实验。灰质和白质的 T2 范围为 60 毫秒（胼胝体）至 100 毫秒（皮质灰质）。对于软骨，在深层（34 毫秒）和浅层（48 毫秒）之间以及胫骨（33 毫秒）、股骨（54 毫秒）和髌骨（43 毫秒）软骨之间观察到 T2 的空间变化。部分spoiled SSFP 扫描得出的 T2 值与参考多对比度自旋回波技术得出的值之间存在极好的一致性，这证实了该新方法用于正确 T2 映射的准确性。最后，在 7.0T 下演示了用于人髌骨软骨的快速高分辨率定量部分spoiled SSFP T2 扫描的可行性。
