Improved PET/MRI accuracy by use of static transmission source in empirically derived hardware attenuation correction.
Improved PET/MRI accuracy by use of static transmission source in empirically derived hardware attenuation correction.
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DOI：
10.1186/s40658-021-00368-5
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发表时间：
2021-03-08
期刊：
影响因子：
4
通讯作者：
Théberge J
中科院分区：
文献类型：
--
作者：
Farag A;Thompson RT;Thiessen JD;Prato FS;Théberge J
通过集成正电子发射断层扫描（PET）和磁共振成像（MRI）系统测量放射性的准确量化仍然是一个挑战。这种挑战的一个方面是纠正硬件衰减，例如病人桌和射频（RF）谐振器。对于PET/MRI系统，计算机断层扫描（CT）通常用于生成硬件衰减校正（AC）图，通过使用双线性模型，将Hounsfield单位（HU）转换为PET能级511 keV的线性衰减系数（LAC）图。该模型不考虑光束硬化，也不考虑密度更高的材料，这可能导致不准确的修正。在本研究中，我们引入了一种基于传输（TX-based）的交流技术，采用静态锗-68 （Ge-68）传输源，使用PET/MRI系统本身生成硬件交流图，而无需PET或医用CT扫描仪。基于AC tx的地图是为一个均匀的圆柱体生成的，由丙烯酸制成作为验证器。随后，该技术被应用于患者台面和用于心血管PET/MRI成像的rf相控阵的后部。将所提出的基于tx和基于ct的硬件图用于重建一例心脏病患者的PET图像，并对结果进行了分析和比较。与文献报道的0.10698±0.00321 cm−1理论值相比，通过基于txd的方法得出的丙烯酸圆柱体LAC估计为0.10851±0.00380 cm−1。在用于心脏扫描的区域，PET光子计数与患者表相比减少了8.7±1.1%，而用于校正的基于ct的图则高估了4.3±1.3%。与基于ct的AC重建图像相比，基于tx的AC硬件图重建的体内图像显示4.1±0.9%的平均差异。使用基于tx的技术的丙烯酸圆柱体测量的LAC与文献中的结果一致，证实了该技术的有效性。采用基于x射线的技术改进了基于ct的模型对患者表光子计数的过高估计。因此，与心脏PET图像中基于ct的硬件AC相比，使用PET/MRI系统本身的基于tx的硬件AC是可能的，并且可以产生更准确的图像。
Accurate quantification of radioactivity, measured by an integrated positron emission tomography (PET) and magnetic resonance imaging (MRI) system, is still a challenge. One aspect of such a challenge is to correct for the hardware attenuation, such as the patient table and radio frequency (RF) resonators. For PET/MRI systems, computed tomography (CT) is commonly used to produce hardware attenuation correction (AC) maps, by converting Hounsfield units (HU) to a linear attenuation coefficients (LAC) map at the PET energy level 511 keV, using a bilinear model. The model does not address beam hardening, nor higher density materials, which can lead to inaccurate corrections. In this study, we introduce a transmission-based (TX-based) AC technique with a static Germanium-68 (Ge-68) transmission source to generate hardware AC maps using the PET/MRI system itself, without the need for PET or medical CT scanners. The AC TX-based maps were generated for a homogeneous cylinder, made of acrylic as a validator. The technique thereafter was applied to the patient table and posterior part of an RF-phased array used in cardiovascular PET/MRI imaging. The proposed TX-based, and the CT-based, hardware maps were used in reconstructing PET images of one cardiac patient, and the results were analysed and compared. The LAC derived by the TX-based method for the acrylic cylinder is estimated to be 0.10851 ± 0.00380 cm−1 compared to the 0.10698 ± 0.00321 cm−1 theoretical value reported in the literature. The PET photon counts were reduced by 8.7 ± 1.1% with the patient table, at the region used in cardiac scans, while the CT-based map, used for correction, over-estimated counts by 4.3 ± 1.3%. Reconstructed in vivo images using TX-based AC hardware maps have shown 4.1 ± 0.9% mean difference compared to those reconstructed images using CT-based AC. The LAC of the acrylic cylinder measurements using the TX-based technique was in agreement with those in the literature confirming the validity of the technique. The over-estimation of photon counts caused by the CT-based model used for the patient table was improved by the TX-based technique. Therefore, TX-based AC of hardware using the PET/MRI system itself is possible and can produce more accurate images when compared to the CT-based hardware AC in cardiac PET images.
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影响因子：
3.5
作者：
Bowen SL;Fuin N;Levine MA;Catana C
通讯作者：
Catana C
影响因子：
37.8
作者：
Cerqueira, MD;Weissman, NJ;Verani, MS
通讯作者：
Verani, MS
DOI：
10.1007/s00259-002-0796-3
发表时间：
2002-07-01
影响因子：
9.1
作者：
Burger, C;Goerres, G;von Schulthess, GK
通讯作者：
von Schulthess, GK
影响因子：
3.8
作者：
DEKEMP, RA;NAHMIAS, C
通讯作者：
NAHMIAS, C
影响因子：
3.8
作者：
Patrick, John C.;Thompson, R. Terry;Gaede, Stewart
通讯作者：
Gaede, Stewart