Fan Audrey P, Bilgic Berkin, Gagnon Louis, Witzel Thomas, Bhat Himanshu, Rosen Bruce R, Adalsteinsson Elfar
Magnetic Resonance Imaging Group, Research Laboratory of Electronics, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA; Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.
Magn Reson Med. 2014 Jul;72(1):149-59. doi: 10.1002/mrm.24918. Epub 2013 Sep 4.
To demonstrate acquisition and processing methods for quantitative oxygenation venograms that map in vivo oxygen saturation (SvO2 ) along cerebral venous vasculature.
Regularized quantitative susceptibility mapping (QSM) is used to reconstruct susceptibility values and estimate SvO2 in veins. QSM with ℓ1 and ℓ2 regularization are compared in numerical simulations of vessel structures with known magnetic susceptibility. Dual-echo, flow-compensated phase images are collected in three healthy volunteers to create QSM images. Bright veins in the susceptibility maps are vectorized and used to form a three-dimensional vascular mesh, or venogram, along which to display SvO2 values from QSM.
Quantitative oxygenation venograms that map SvO2 along brain vessels of arbitrary orientation and geometry are shown in vivo. SvO2 values in major cerebral veins lie within the normal physiological range reported by (15) O positron emission tomography. SvO2 from QSM is consistent with previous MR susceptometry methods for vessel segments oriented parallel to the main magnetic field. In vessel simulations, ℓ1 regularization results in less than 10% SvO2 absolute error across all vessel tilt orientations and provides more accurate SvO2 estimation than ℓ2 regularization.
The proposed analysis of susceptibility images enables reliable mapping of quantitative SvO2 along venograms and may facilitate clinical use of venous oxygenation imaging.
展示定量氧合静脉造影的采集和处理方法，该方法可绘制沿脑静脉血管系统的体内氧饱和度（SvO2）图。
使用正则化定量磁化率成像（QSM）重建磁化率值并估计静脉中的SvO2。在具有已知磁化率的血管结构数值模拟中比较了具有ℓ1和ℓ2正则化的QSM。在三名健康志愿者中采集双回波、流动补偿相位图像以创建QSM图像。对磁化率图中的明亮静脉进行矢量化，并用于形成三维血管网格或静脉造影，沿着该网格显示来自QSM的SvO2值。
展示了在体内绘制沿任意方向和几何形状脑血管的SvO2的定量氧合静脉造影。大脑主要静脉中的SvO2值处于（15）O正电子发射断层扫描报告的正常生理范围内。来自QSM的SvO2与先前针对平行于主磁场定向的血管段的磁共振磁化率测量方法一致。在血管模拟中，ℓ1正则化在所有血管倾斜方向上导致的SvO2绝对误差小于10%，并且比ℓ2正则化提供更准确的SvO2估计。
所提出的磁化率图像分析能够可靠地绘制沿静脉造影的定量SvO2图，并可能促进静脉氧合成像的临床应用。
