Departments of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States.
Eur J Radiol. 2013 Oct;82(10):1811-8. doi: 10.1016/j.ejrad.2013.05.021. Epub 2013 Jun 13.
To assess the effect of acquisition duration (T(acq)) and pre-enhancement set points (T₁) on computer tomography perfusion (CT(p)) parameter values in primary and metastatic tumors in the lung.
24 lung CT(p) datasets (10 primary; 14 metastatic), acquired using a two phase protocol spanning 125 s, in 12 patients with lung tumors, were analyzed by deconvolution modeling to yield tumor blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability (PS) values. CT(p) analyses were undertaken for the reference dataset (i.e., T₁=t₀) with varying T(acq) from 12 to 125 s. This was repeated for shifts in T₁ (±0.5 s, ±1.0 s, ±2.0 s relative to the reference at t₀). Resultant CTp values were plotted against T(acq); values at 30 s, 50 s, 65 s and 125 s were compared using linear mixed model.
All CT(p) parameter values were noticeably influenced by T(acq), with generally less marked changes beyond 50 s, and with no difference in behavior between primary and secondary tumors. Apart from BV, which attained a plateau at approximately 50s, the other three CT(p) parameters did not reach steady-state values within the available 125 s of data, with values at 30 s, 50 s and 65 s significantly different from 125 s (p<0.004). Shifts in T₁ also affected the CT(p) parameters values, with positive shifts having greater impact on CT(p) values than negative shifts.
CT(p) parameter values derived from deconvolution modeling can be markedly affected by T(acq), and pre-enhancement set-points. 50 s acquisition may be adequate for BV, but longer than 125 s is probably required for reliable characterization of the other three CT(p) parameters.
评估采集时间（T(acq)）和增强前设定点（T₁）对肺部原发性和转移性肿瘤计算机断层灌注（CT(p)）参数值的影响。
对 12 名患有肺部肿瘤的患者进行了 24 例肺部 CT(p)数据集（10 例原发性；14 例转移性）的分析，这些数据集是使用双相协议在 125 秒内采集的，采用去卷积建模来获得肿瘤血流（BF）、血容量（BV）、平均通过时间（MTT）和通透性（PS）值。对参考数据集（即 T₁=t₀）进行了 CT(p)分析，采集时间（T(acq)）从 12 秒到 125 秒不等。然后，将 T₁（相对于 t₀ 为±0.5 s、±1.0 s、±2.0 s）的偏移量重复进行了分析。将得到的 CTp 值与 T(acq)作图；使用线性混合模型比较 30 s、50 s、65 s 和 125 s 的值。
所有 CT(p)参数值均明显受到 T(acq)的影响，在 50 秒后变化较小，原发性和继发性肿瘤的行为无差异。除了 BV 在大约 50s 达到平台外，其他三个 CT(p)参数在可用的 125s 数据内没有达到稳态值，30s、50s 和 65s 的值与 125s 的值显著不同（p<0.004）。T₁的偏移也会影响 CT(p)参数值，正偏移比负偏移对 CT(p)值的影响更大。
来自去卷积建模的 CT(p)参数值可能会受到 T(acq)和增强前设定点的显著影响。50 s 的采集时间可能足以用于 BV，但对于其他三个 CT(p)参数的可靠特征描述，可能需要超过 125 s 的采集时间。
