Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?
Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?
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DOI：
10.1088/0031-9155/61/16/6041
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发表时间：
2016-08-21
影响因子：
3.5
通讯作者：
Brace, Chris L.
中科院分区：
文献类型：
--
作者：
Wu, Po-hung;Brace, Chris L.
术中增强CT(CECT)已被用来评估热消融的治疗效果。我们假设在热消融的同时提供的造影剂可能会被困在消融区，并开始确定这种效应是否会影响消融的可视化。在微波消融正常猪肝脏的过程中，采集CECT图像：(A)正常血流灌注，无碘化造影剂；(B)正常血流灌注，碘化造影剂灌注；(C)无血流灌注，碘化造影剂残留。分析消融前、消融中和消融后CT衰减的变化，以评估对比是否被困在消融区内。用消融后对比噪声比(CNR)比较不同组间的可视化。计算消融边界和背景处的衰减梯度，以量化消融的显着性。在A组，消融过程中由于组织水的热膨胀和水汽化，衰减率降低。消融区难以显示(CNR=1.57+/-0.73，边界梯度=0.7+/-0.4HU mm(-1))，导致消融直径低于大体病理。B组消融后衰减增加，提示碘被困在消融区内。然而，由于正常灌注的肝脏增加得更多，B组的消融比A组更明显(CNR=2.04+/-0.84，边界梯度=6.3+/-1.1Hu mm(-1))，与大体病理相比，B组可以准确地估计消融区的大小。尽管消融区边界不是很明显(边界梯度=3.9+/-1.1HU mm(-1))，但C组的大量水汽化导致了显著的衰减变化。我们的结果表明，尽管碘化对比剂被困在消融区，但当对比剂在术中传递时，消融可见性最高。因此，CECT用于实时热消融监测是可行的。
Intra-procedural contrast-enhanced CT (CECT) has been proposed to evaluate treatment efficacy of thermal ablation. We hypothesized that contrast material delivered concurrently with thermal ablation may become trapped in the ablation zone, and set out to determine whether such an effect would impact ablation visualization. CECT images were acquired during microwave ablation in normal porcine liver with: (A) normal blood perfusion and no iodinated contrast, (B) normal perfusion and iodinated contrast infusion or (C) no blood perfusion and residual iodinated contrast. Changes in CT attenuation were analyzed from before, during and after ablation to evaluate whether contrast was trapped inside of the ablation zone. Visualization was compared between groups using post-ablation contrast-to-noise ratio (CNR). Attenuation gradients were calculated at the ablation boundary and background to quantitate ablation conspicuity. In Group A, attenuation decreased during ablation due to thermal expansion of tissue water and water vaporization. The ablation zone was difficult to visualize (CNR = 1.57 +/- 0.73, boundary gradient = 0.7 +/- 0.4 HU mm(-1)), leading to ablation diameter underestimation compared to gross pathology. Group B ablations saw attenuation increase, suggesting that iodine was trapped inside the ablation zone. However, because the normally perfused liver increased even more, Group B ablations were more visible than Group A (CNR = 2.04 +/- 0.84, boundary gradient = 6.3 +/- 1.1 HU mm(-1)) and allowed accurate estimation of the ablation zone dimensions compared to gross pathology. Substantial water vaporization led to substantial attenuation changes in Group C, though the ablation zone boundary was not highly visible (boundary gradient = 3.9 +/- 1.1 HU mm(-1)). Our results demonstrate that despite iodinated contrast being trapped in the ablation zone, ablation visibility was highest when contrast is delivered intra-procedurally. Therefore, CECT may be feasible for real-time thermal ablation monitoring.