Zhang Jin, Kim Sungheon
Center for Biomedical Imaging, Department of Radiology, New York University, School of Medicine, New York, USA.
Magn Reson Med. 2014 Aug;72(2):534-45. doi: 10.1002/mrm.24927. Epub 2013 Sep 4.
The aim of this study was to assess the uncertainty in estimation of MR tracer kinetic parameters and water exchange rates in T1-weighted dynamic contrast enhanced (DCE) MRI.
Simulated DCE-MRI data were used to assess four kinetic models; general kinetic model with a vascular compartment (GKM2), GKM2 combined with water exchange (SSM2), adiabatic approximation of the tissue homogeneity model (ATH), and ATH combined with water exchange (ATHX).
In GKM2 and SSM2, increase in transfer constant (K(trans)) led to underestimation of vascular volume fraction (vb), and increase in vb led to overestimation of K(trans). Such coupling between K(trans) and vb was not observed in ATH and ATHX. The precision of estimated intracellular water lifetime (τi) was substantially improved in both SSM2 and ATHX when K(trans) > 0.3 min(-1). K(trans) and vb from ATHX model had significantly smaller errors than those from ATH model (P < 0.05).
The results of this study demonstrated the feasibility of measuring τi from DCE-MRI data albeit low precision. While the inclusion of water exchange improved the accuracy of K(trans), vb, and the interstitial volume fraction estimation (ve), it lowered the precision of other kinetic model parameters within the conditions investigated in this study.
本研究旨在评估T1加权动态对比增强（DCE）磁共振成像中磁共振示踪剂动力学参数和水交换率估计的不确定性。
使用模拟的DCE-MRI数据评估四种动力学模型；具有血管腔室的一般动力学模型（GKM2）、结合水交换的GKM2（SSM2）、组织均匀性模型的绝热近似（ATH）以及结合水交换的ATH（ATHX）。
在GKM2和SSM2中，转运常数（K(trans)）增加导致血管容积分数（vb）估计值偏低，而vb增加导致K(trans)估计值偏高。在ATH和ATHX中未观察到K(trans)与vb之间的这种耦合。当K(trans)>0.3 min⁻¹时，SSM2和ATHX中估计的细胞内水寿命（τi）的精度均有显著提高。ATHX模型的K(trans)和vb的误差明显小于ATH模型（P<0.05）。
本研究结果证明了从DCE-MRI数据测量τi的可行性，尽管精度较低。虽然纳入水交换提高了K(trans)、vb和间质容积分数（ve）估计的准确性，但在本研究调查的条件下，它降低了其他动力学模型参数的精度。
