漸變式驅動平衡類型平衡穩定態自由旋進磁振影像：特徵分析與臨床應用

Transition into Driven Equilibrium (TIDE) bSSFP MRI: Characteristics Analysis and Clinical Application

黃尹宬(Yin-Cheng Kris Huang)

指導教授 ： 郭德盛

共同指導教授 ： 阮春榮(Chun-Jung Juan)

國立臺灣大學/電機資訊學院/電機工程學研究所/博士(2014年)

https://doi.org/10.6342/NTU.2014.00466

摘要

漸變式驅動平衡方法為近十幾年來逐步發展的平衡穩定態自由旋進磁振影
像之變形。概念上，此版本的脈衝序列可分為兩部分：漸變式驅動平衡之磁化準
備時期以及隨後的固定傾角資料讀取時期。本論文作者於受試者實驗中發現：本
造影技術具有脂肪信號抑制的效果，前提為中央k 空間的資料來自暫態時期之影
像擷取。此外本技術呈現T2 權重影像對比。為分析這些影像特徵，我們採用程
式模擬及數學公式闡述，簡明呈現了在共振自旋與特定離共振自旋的時間演化行
為。我們另外募集了三十位健康受試者，測試漸變式驅動平衡技術作為超快速多
切面T2 權重腦部影像的可行性。為進行影像品質比較，我們亦採行了快速自旋
迴訊與快速梯度自旋迴訊兩種方法。我們也展示了幾位腦部病變患者的影像差異。
結果顯示：與其他兩種方法相比，漸變式驅動平衡方法大幅減少掃描時間與運動
假影干擾，但信噪比、灰質白質區分度、鐵質偵測等表現則較差。在如不自主運
動疾患等一些特殊臨床場合，漸變式驅動平衡技術有機會作為標準磁振造影方法
之外的替代方案。

關鍵字

磁振造影 ； 平衡穩定態自由旋進 ； 漸變式驅動平衡 ； 脂肪信號抑制 ； T2權重影像

並列摘要

Transition into Driven Equilibrium (TIDE) balanced steady-state free precession
(bSSFP) sequence is a variant of bSSFP MRI technique that has been developed over
the last decade. The pulse sequence can be conceptually divided into two parts: a
TIDE preparation and a repetitive constant flip angle readout. The authors of this
thesis independently discovered fat suppression phenomenon during volunteer studies
of TIDE bSSFP, when transient-phase data were sampled and registered at central
k-space. In addition, this imaging method also shows a T2-weighted contrast. To
analyze these specific properties, we used simulations and mathematical deduction to
demonstrate concisely the evolution behaviors of on-resonance spins as well as
certain off-resonance spins. We recruited thirty healthy volunteers to validate the
image quality for TIDE bSSFP for use as an ultrafast multisection T2-weighted image
of the brain. For image quality comparison, turbo spin echo (TSE) and turbo gradient
spin-echo (TGSE) were also used. We also exhibited the differences between
imaging methods on a few patients with brain pathologies. As a result, TIDE bSSFP
provides T2-weighted images with reduced scan times and reduced motion artifact
interference compared with TSE and turbo gradient spin-echo, with the trade-off of
reduced SNR as well as poorer gray-white matter differentiation and iron load
sensitivity. In certain situations like patients with involuntary motions, TIDE bSSFP
technique may serve as a supplement to standard MRI methods.

並列關鍵字

MRI ； bSSFP ； TIDE ； fat suppression ； T2 weighted image

參考文獻

Absil, J., V. Denolin and T. Metens (2006). "Fat attenuation using a dual steady-state balanced-SSFP sequence with periodically variable flip angles." Magn Reson Med 55(2): 343-351.

Bauer, C. M., H. Jara, R. Killiany and I. Alzheimer's Disease Neuroimaging (2010). "Whole brain quantitative T2 MRI across multiple scanners with dual echo FSE: applications to AD, MCI, and normal aging." Neuroimage 52(2): 508-514.

Bieri, O. and K. Scheffler (2013). "Fundamentals of balanced steady state free precession MRI." J Magn Reson Imaging 38(1): 2-11.

Carr, H. Y. (1958). "Steady-state free precession in nuclear magnetic resonance." Physical Review 112: 1693-1701.

Carr, H. Y. and E. M. Purcell (1954). "Effects of Diffusion on Free Precession in Nuclear Magnetic Resonance Experiments." Physical Review 94(3): 9.