K-t GRAPPA-accelerated 4D flow MRI of liver hemodynamics: influence of different acceleration factors on qualitative and quantitative assessment of blood flow
K-t GRAPPA-accelerated 4D flow MRI of liver hemodynamics: influence of different acceleration factors on qualitative and quantitative assessment of blood flow
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DOI：
10.1007/s10334-014-0456-1
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发表时间：
2014-08
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通讯作者：
Z. Stankovic;J. Fink;J. Collins;Edouard Semaan;M. Russe;J. Carr;M. Markl;M. Langer;B. Jung
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作者：
Z. Stankovic;J. Fink;J. Collins;Edouard Semaan;M. Russe;J. Carr;M. Markl;M. Langer;B. Jung
材料与方法16名健康志愿者在3 T加速条件下（R = 3、R= 5、R = 8），用GRAPPA加速4D血流成像技术对16例健康志愿者肝脏血管系统进行了k-t并行成像（2.0 × 2.5 × 2.4 mm 3，TR = 82 ms），R = 5（TR = 41 ms）; GRAPPAR= 2用作参考标准。定性流动分析包括三维流线和时间分辨颗粒痕迹的分级。定量评估评估了速度、净流量和壁面剪切应力（WSS）。结果与标准GRAPPAR= 2（21- 71%）相比，所有加速因子实现了显著的扫描时间节省（p< 0.001）。与标准GRAPAR = 2相比，k-tGRAPAR = 3 andR= 5之间的速度和净流量的量化提供了类似的结果。在标准GRAPPAR= 2和k-t GRAPPAR= 8之间观察到显著增加的泄漏伪影和噪声（p< 0.001），肝动脉系统中峰值速度和WSS的显著低估高达31%（p<0.05）。对于k-t GRAPPAR= 5，门静脉系统所有血管的WSS被显著低估高达13%，而在两个静脉中，对于具有较高时间分辨率的相同加速度，观察到显著较高的值结论4D Flow MRI的k-t加速技术用于肝脏血流动力学评价是可行的，加速因子R = 3和R = 5导致扫描时间减少至少40%，与GRAPPAR= 2相比，肝脏血流动力学的定量相似。
ObjectiveWe sought to evaluate the feasibility of k-t parallel imaging for accelerated 4D flow MRI in the hepatic vascular system by investigating the impact of different acceleration factors.Materials and methodsk-t GRAPPA accelerated 4D flow MRI of the liver vasculature was evaluated in 16 healthy volunteers at 3T with acceleration factorsR= 3,R= 5, andR= 8 (2.0 × 2.5 × 2.4 mm3, TR = 82 ms), andR= 5 (TR = 41 ms); GRAPPAR= 2 was used as the reference standard. Qualitative flow analysis included grading of 3D streamlines and time-resolved particle traces. Quantitative evaluation assessed velocities, net flow, and wall shear stress (WSS).ResultsSignificant scan time savings were realized for all acceleration factors compared to standard GRAPPAR= 2 (21–71 %) (p< 0.001). Quantification of velocities and net flow offered similar results between k-t GRAPPAR= 3 andR= 5 compared to standard GRAPPAR= 2. Significantly increased leakage artifacts and noise were seen between standard GRAPPAR= 2 and k-t GRAPPAR= 8 (p< 0.001) with significant underestimation of peak velocities and WSS of up to 31 % in the hepatic arterial system (p<0.05). WSS was significantly underestimated up to 13 % in all vessels of the portal venous system for k-t GRAPPAR= 5, while significantly higher values were observed for the same acceleration with higher temporal resolution in two veins (p< 0.05).Conclusionk-t acceleration of 4D flow MRI is feasible for liver hemodynamic assessment with acceleration factorsR= 3 andR= 5 resulting in a scan time reduction of at least 40 % with similar quantitation of liver hemodynamics compared with GRAPPAR= 2.