Purpose

Physiological motion and partial volume effect (PVE) significantly degrade the quality of cardiac positron emission tomography (PET) images in the fast-beating hearts of rodents. Several Super-resolution (SR) techniques using a priori anatomical information have been proposed to correct motion and PVE in PET images. Ultrasound is ideally suited to capture real-time high-resolution cine images of rodent hearts. Here, we evaluated an ultrasound-based SR method using simultaneously acquired and co-registered PET-CT-Ultrafast Ultrasound Imaging (UUI) of the beating heart in closed-chest rodents.

Procedures

The method was tested with numerical and animal data (n = 2) acquired with the non-invasive hybrid imaging system PETRUS that acquires simultaneously PET, CT, and UUI.

Results

We showed that ultrasound-based SR drastically enhances the quality of PET images of the beating rodent heart. For the simulations, the deviations between expected and mean reconstructed values were 2 % after applying SR. For the experimental data, when using Ultrasound-based SR correction, contrast was improved by a factor of two, signal-to-noise ratio by 11 %, and spatial resolution by 56 % (~ 0.88 mm) with respect to static PET. As a consequence, the metabolic defect following an acute cardiac ischemia was delineated with much higher anatomical precision.

Conclusions

Our results provided a proof-of-concept that image quality of cardiac PET in fast-beating rodent hearts can be significantly improved by ultrasound-based SR, a portable low-cost technique. Improved PET imaging of the rodent heart may allow new explorations of physiological and pathological situations related with cardiac metabolism.

中文翻译：

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用于超分辨率临床前心脏 PET 的超快超声成像。

目的

生理运动和部分体积效应 (PVE) 显着降低了啮齿动物快速跳动心脏中心脏正电子发射断层扫描 (PET) 图像的质量。已经提出了几种使用先验解剖信息的超分辨率 (SR) 技术来校正 PET 图像中的运动和 PVE。超声波非常适合捕捉啮齿动物心脏的实时高分辨率电影图像。在这里，我们使用同时​​获得和共同配准的 PET-CT-Ultrafast 超声成像 (UUI) 评估了一种基于超声的 SR 方法，该方法对闭胸啮齿动物的跳动心脏进行了评估。

程序

该方法 使用通过同时采集 PET、CT 和 UUI 的非侵入性混合成像系统 PETRUS 采集的数值和动物数据 ( n = 2) 进行了测试。

结果

我们表明基于超声的 SR 大大提高了跳动的啮齿动物心脏的 PET 图像的质量。对于模拟，应用 SR 后预期和平均重建值之间的偏差为 2%。对于实验数据，当使用基于超声的 SR 校正时，相对于静态 PET，对比度提高了两倍，信噪比提高了 11%，空间分辨率提高了 56%（~0.88 毫米）。因此，以更高的解剖精度描绘了急性心脏缺血后的代谢缺陷。

结论

我们的结果提供了一个概念验证，即快速跳动的啮齿动物心脏中心脏 PET 的图像质量可以通过基于超声的 SR（一种便携式低成本技术）显着提高。改进的啮齿动物心脏 PET 成像可能允许对与心脏代谢相关的生理和病理情况进行新的探索。