Department of Radiology, New York University, New York, NY, USA.
J Neuroimaging. 2010 Jan;20(1):87-92. doi: 10.1111/j.1552-6569.2008.00331.x.
Double Inversion Recovery Magnetic Resonance Imaging (DIR) consists of two adiabatic non-selective inversion pulses applied before a Turbo Spin Echo (TSE) sequence, in order to suppress the signal from two tissues with different longitudinal relaxation times T(1) simultaneously. In the brain, DIR is used to selectively image the gray matter (GM) by nulling the signal from white matter (WM) and cerebrospinal fluid (CSF). The main limitation of the technique remains the intrinsic low SNR due to the specific preparation of the longitudinal magnetization. The recent availability of high field magnets operating at 7 T for human imaging offers the advantage of higher SNR. This study shows the feasibility of brain Double Inversion Recovery Magnetic Resonance Imaging (DIR-MRI) at 7 T in vivo in healthy volunteers.
The MRI experiments were performed on phantoms at 7 T and on four healthy volunteers at 7 and 3 T. For fat suppression, a chemical shift selective Fat Inversion Recovery (csFatIR) technique was used and compared to the standard fat saturation (FatSat).
The csFatIR method resulted to be significantly more efficient than the Fatsat at 7 T and slightly more efficient at 3 T, enabling a clear delineation of GM.
DIR is feasible at 7 T despite the problems associated with B(1) in-homogeneity.
双反转恢复磁共振成像（DIR）由两个绝热非选择性反转脉冲组成，在 Turbo 自旋回波（TSE）序列之前施加，以同时抑制具有不同纵向弛豫时间 T(1)的两种组织的信号。在大脑中，DIR 用于通过对来自白质（WM）和脑脊液（CSF）的信号进行零化来选择性地对灰质（GM）进行成像。该技术的主要限制仍然是由于纵向磁化的特定准备而导致的固有低 SNR。最近，7 T 高场磁体可用于人体成像，具有更高 SNR 的优势。本研究展示了在健康志愿者体内进行 7 T 磁共振成像（DIR-MRI）的可行性。
在 7 T 对体模和在 7 和 3 T 对四名健康志愿者进行了 MRI 实验。为了抑制脂肪信号，使用了化学位移选择性脂肪反转恢复（csFatIR）技术，并与标准的脂肪饱和（FatSat）进行了比较。
csFatIR 方法在 7 T 时比 FatSat 方法更有效，在 3 T 时略有效，能够清晰地描绘 GM。
尽管与 B(1)不均匀性相关的问题存在，但 DIR 在 7 T 时是可行的。
