Wildberger J E, Klotz E, Ditt H, Mahnken A H, Spüntrup E, Günther R W
Department of Diagnostic Radiology, University of Technology, Aachen, Germany.
Rofo. 2005 Jan;177(1):17-23. doi: 10.1055/s-2004-813875.
The purpose of our preliminary animal study was to evaluate the feasibility of a new subtraction technique for visualization of perfusion defects within the lung parenchyma in segmental and subsegmental pulmonary embolism (PE).
In three healthy pigs, PE were artificially induced by fresh human clot material. Within a single breath-hold, CT angiography (CTA) was performed on a 16-slice multi-slice CT scanner (SOMATOM Sensation 16; Siemens, Forchheim, Germany) before and after intravenous application of 80 mL of contrast-medium, followed by a saline chaser. Scan parameters were 120 kV and 100 mAs (eff.), using a collimation of 16 x 1.5 mm and a table speed/rot. of 36 mm (pitch: 1.5; rotation time: 0.5 s). A new 3D subtraction technique was developed, which is based on automated segmentation, non-linear spatial filtering and non-rigid registration. Data were analysed using a color-encoded "compound view" of parenchymal enhancement and CTA information displayed in axial, coronal and sagittal orientation.
Subtraction was technically feasible in all three data sets. The mean scan time for each series was 4.7 s, interscan delay was 14.7 s, respectively. Therefore, an average breath-hold of approximately 24 s was required for the overall scanning procedure. Downstream of occluded segmental and subsegmental arteries, perfusion defects were clearly assessable, showing lower or missing enhancement compared to normally perfused lung parenchyma. In all pigs, additional peripheral areas with triangular shaped perfusion defects were delineated, considered typical for PE.
Our initial results from the animal model studied show that perfusion imaging of PE is feasible within a single breath-hold. It allows a comprehensive assessment of perfusion deficits as the direct proof of a pulmonary embolus, can be combined with an indirect visual quantification of the density changes in the adjacent lung tissue.
我们初步动物研究的目的是评估一种新的减法技术在显示节段性和亚节段性肺栓塞（PE）肺实质内灌注缺损方面的可行性。
在三只健康猪中，用人新鲜血凝块材料人工诱导PE。在单次屏气期间，在静脉内注入80 mL造影剂前后，使用16层多层CT扫描仪（SOMATOM Sensation 16；西门子，德国福希海姆）进行CT血管造影（CTA），随后注入生理盐水冲洗。扫描参数为120 kV和100 mAs（有效），准直为16×1.5 mm，床速/旋转速度为36 mm（螺距：1.5；旋转时间：0.5 s）。开发了一种基于自动分割、非线性空间滤波和非刚性配准的新三维减法技术。使用在轴向、冠状和矢状方向显示的实质增强和CTA信息的彩色编码“复合视图”分析数据。
在所有三个数据集中，减法技术在技术上是可行的。每个系列的平均扫描时间为4.7 s，扫描间隔时间分别为14.7 s。因此，整个扫描过程平均需要约24 s的屏气。在闭塞的节段性和亚节段性动脉下游，灌注缺损清晰可评估，与正常灌注的肺实质相比，增强较低或缺失。在所有猪中，还勾勒出了三角形灌注缺损的额外周边区域，这被认为是PE的典型表现。
我们对动物模型的初步研究结果表明，在单次屏气内对PE进行灌注成像可行。它允许全面评估灌注缺陷作为肺栓塞的直接证据，并且可以与对相邻肺组织密度变化的间接视觉量化相结合。
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