Expanding the Versatility of Cardiac PET/CT: Feasibility of Delayed Contrast Enhancement CT for Infarct Detection in a Porcine Model
Expanding the Versatility of Cardiac PET/CT: Feasibility of Delayed Contrast Enhancement CT for Infarct Detection in a Porcine Model
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DOI：
10.2967/jnumed.108.056218
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发表时间：
2009-02-01
影响因子：
9.3
通讯作者：
Bengel, Frank M.
中科院分区：
文献类型：
--
作者：
Holz, Andrew;Lautamaeki, Riikka;Bengel, Frank M.
最近有人建议，与MRI类似，CT可以通过延迟心肌对比增强在高分辨率下检测梗死。在心脏PET/CT中，这种检测梗死的能力可能会增加PET和CT研究成分的通用性和综合潜力。我们试图确定在PET/CT环境下延迟CT增强的可行性，并将其与PET定义的静息灌注进行比较，以测量梗死面积。方法：采用冠状动脉左前降支闭塞再灌注的方法诱导10头农场猪实验性心肌梗死。4-6周后，动物接受64层PET/CT检查。静息灌注用n -13-氨PET测定。然后，注射120ml造影剂，延迟1.5、5、10、15分钟后进行回顾性门控螺旋CT血管造影。两天后，6头猪再次接受对比增强CT，采用低辐射剂量方法（前瞻性门通和较厚的切片，用于临床钙评分），延迟时间相同。建立PET灌注和CT心肌增强的极坐标图以作进一步分析。结果：注射对比剂后5 ~ 10 min，梗死区CT Hounsfield单位（HUs）开始超过动脉血HUs，梗死心肌与远端心肌之比、梗死心肌与血液之比在10 ~ 15 min间稳定在1.9 ~ 1.2左右。高剂量和低剂量CT图像之间表现出良好的一致性（R = 0.87, P < 0.001）。在10min时，采用低剂量方法，CT梗死面积（远端有3.5 SDs的HU区域）为脑室的30% - 8%。PET灌注缺损面积（摄取面积<左心室最大值的60%）为左心室的31% +/- 8%（范围为17%-44%）。使用16节段心肌模型，我们发现区域氨潴留与造影剂增强之间存在良好的负相关关系（P = -0.93, P < 0.001）。结论：在我们的动物模型中，使用心脏PET/CT延迟CT增强可以准确且可重复性地测量梗死面积。在测量方面，低剂量、前瞻性门控采集与高剂量螺旋CT相当。这些结果为进一步的临床工作提供了理论基础，以探讨延迟ct增强是否可以提高心肌活力评估的准确性，替代灌注成像中的休息研究，或改善pet衍生分子信号的定位。
It has recently been suggested that, similar to MRI, CT can be used to detect infarcts at high resolution by delayed myocardial contrast enhancement. In cardiac PET/CT, this ability to detect infarcts may increase the versatility and integrative potential of PET and CT study components. We sought to determine the feasibility of delayed CT-enhancement in the PET/CT environment and compared it with PET-defined rest perfusion for the measurement of infarct size. Methods: Experimental myocardial infarction was induced in 10 young farm pigs by occlusion and reperfusion of the left anterior descending coronary artery. A er 4-6 wk, the animals underwent 64-slice PET/CT. Rest perfusion was measured by N-13-ammonia PET. Then, 120 mL of contrast were injected, and retrospectively gated helical CT was performed for angiography and after 1.5-, 5-, 10-, and 15-min delays. Two days later, 6 pigs again underwent contrast-enhanced CT, using a low-radiation-dose approach (prospective gating and thicker slices as used for clinical calcium scoring) and the same delay times. Polar maps of PET perfusion and CT myocardial enhancement were created for further analysis. Results: CT Hounsfield units (HUs) in the infarct area started to exceed those of arterial blood at 5-10 min after contrast injection, and the ratios of infarcted myocardium to remote myocardium and of infarcted myocardium to blood plateaued at around 1.9 and 1.2 between 10 and 15 min. Excellent agreement between high- and low-dose CT acquisitions (R = 0.87, P < 0.001) was demonstrated. At 10 min, CT infarct size (area with HU > 3.5 SDs from remote) was 30% 8% of the ventricle, using the low-dose approach. The PET perfusion defect size (area with uptake < 60% of the left ventricular maximum) was comparable at 31% +/- 8% of the left ventricle (range, 17%-44%). Using a 16-segment myocardial model, we showed an excellent inverse relationship between regional ammonia retention and contrast enhancement (P = -0.93, P < 0.001). Conclusion: In our animal model, infarct size can be measured accurately and reproducibly using cardiac PET/CT with delayed CT-enhancement. For measurement, a low-dose, prospectively gated acquisition was comparable to higher-dose spiral CT. These results provide a rationale for further clinical work to explore whether delayed CT-enhancement can improve the accuracy of myocardial viability assessment, substitute for rest studies in perfusion imaging, or improve localization of PET-derived molecular signals.