Max Planck Institute for Neurological Research, Gleueler Str 50, 50931 Cologne, Germany.
Stroke. 2012 Feb;43(2):378-85. doi: 10.1161/STROKEAHA.111.635458. Epub 2011 Dec 1.
Perfusion-weighted imaging maps are used to identify critical hypoperfusion in acute stroke. However, quantification of perfusion may depend on the choice of the arterial input function (AIF). Using quantitative positron emission tomography we evaluated the influence of the AIF location on maps of absolute and relative perfusion-weighted imaging to detect penumbral flow (PF; <20 mL/100 g/min on positron emission tomography(CBF)) in acute stroke.
In 22 patients with acute stroke the AIF was placed at 7 sites (M1, M2, M3 ipsi- and contralateral and internal carotid artery-M1 contralateral to the infarct). Comparative (15)O-water positron emission tomography and AIF-dependent perfusion-weighted imaging (cerebral blood flow, cerebral blood volume, mean transit time, and time to maximum) were performed. A receiver operating characteristic curve analysis described the threshold independent performance (area under the curve) of the perfusion-weighted maps for all 7 AIF locations and identified the best AIF-dependent absolute and relative thresholds to identify PF. These results were compared with AIF-independent time-to-peak maps.
Quantitative perfusion-weighted imaging maps of cerebral blood flow and time to maximum performed best. For PF detection, AIF placement did significantly influence absolute PF thresholds. However, AIF placement did not influence (1) the threshold independent performance; and (2) the relative PF thresholds. AIF placement in the proximal segment of the contralateral middle cerebral artery (cM1) was preferable for quantification.
AIF-based maps of cerebral blood flow and time to maximum were most accurate to detect the PF threshold. The AIF placement significantly altered absolute PF thresholds and showed best agreement with positron emission tomography for the cM1 segment. The performance of relative PF thresholds, however, was not AIF location-dependent and might be along with AIF-independent time-to-peak maps, more suitable than absolute PF thresholds in acute stroke if detailed postprocessing is not feasible.
灌注加权成像图用于识别急性中风中的临界低灌注。然而，灌注的定量可能取决于动脉输入函数（AIF）的选择。我们使用定量正电子发射断层扫描评估了 AIF 位置对绝对和相对灌注加权成像图的影响，以检测急性中风中的半影血流（PF；正电子发射断层扫描（CBF）<20 mL/100 g/min）。
在 22 名急性中风患者中，将 AIF 放置在 7 个部位（同侧和对侧 M1、M2、M3 以及颈内动脉-M1 对侧梗死）。进行比较（15）O-水正电子发射断层扫描和 AIF 依赖性灌注加权成像（脑血流、脑血容量、平均通过时间和达峰时间）。接收者操作特性曲线分析描述了所有 7 个 AIF 位置的灌注加权图的阈值独立性能（曲线下面积），并确定了最佳的 AIF 依赖性绝对和相对阈值以识别 PF。将这些结果与 AIF 独立的达峰时间图进行比较。
脑血流和达峰时间的定量灌注加权成像图表现最佳。对于 PF 检测，AIF 放置确实显著影响绝对 PF 阈值。然而，AIF 放置不影响（1）阈值独立性能；和（2）相对 PF 阈值。在对侧大脑中动脉（cM1）近端放置 AIF 更有利于定量。
基于 AIF 的脑血流和达峰时间图最能准确检测 PF 阈值。AIF 放置显著改变了绝对 PF 阈值，并与 cM1 段的正电子发射断层扫描具有最佳一致性。然而，相对 PF 阈值的性能不受 AIF 位置的影响，如果无法进行详细的后处理，则相对 PF 阈值可能与 AIF 独立的达峰时间图一起，在急性中风中比绝对 PF 阈值更合适。
