Muellauer J, Willimayer R, Goertzen A L, Wanek T, Langer O, Birkfellner W, Kuntner C
Claudia Kuntner, Biomedical Systems, Health & Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, Austria, Tel. +43/505 50 34 71, Fax +43/505 50 34 73, E-mail:
Nuklearmedizin. 2013 Dec 13;52(6):250-61. doi: 10.3413/Nukmed-0578-13-04.
The partial volume effect (PVE) significantly affects quantitative accuracy in PET. In this study we used a micro-hollow sphere phantom filled with 18F, 11C or 68Ga to evaluate different partial volume correction methods (PVC). Additionally, phantom data were applied on rat brain scans to evaluate PVC methods on in vivo datasets.
The four spheres (7.81, 6.17, 5.02, 3.90 mm inner diameter) and the background region were filled to give sphere-to-background (sph/bg) activity ratios of 20 : 1, 10 : 1, 5 : 1 and 2 : 1. Two different acquisition and reconstruction protocols and three radionuclides were evaluated using a small animal PET scanner. From the obtained images the recovery coefficients (RC) and contrast recovery coefficients (CRC) for the different sph/bg ratios were calculated. Three methods for PVC were evaluated: a RC based, a CRC based and a volume of interest (VOI) based method. The most suitable PVC methods were applied to in vivo rat brain data.
RCs were shown to be dependent on the radionuclide used, with the highest values for 18F, followed by 11C and 68Ga. The calculated mean CRCs were generally lower than the corresponding mean RCs. Application of the different PVC methods to rat brain data led to a strong increase in time-activity curves for the smallest brain region (entorhinal cortex), whereas the lowest increase was obtained for the largest brain region (cerebellum).
This study was able to show the importance and impact of PVE and the limitations of several PVC methods when performing quantitative measurements in small structures.
部分容积效应（PVE）显著影响正电子发射断层扫描（PET）的定量准确性。在本研究中，我们使用填充有18F、11C或68Ga的微空心球模体来评估不同的部分容积校正方法（PVC）。此外，将模体数据应用于大鼠脑部扫描，以评估体内数据集的PVC方法。
四个球体（内径分别为7.81、6.17、5.02、3.90 mm）和背景区域填充后，使球体与背景（sph/bg）的活度比分别为20∶1、10∶1、5∶1和2∶1。使用小动物PET扫描仪评估两种不同的采集和重建方案以及三种放射性核素。从获得的图像中计算不同sph/bg比的恢复系数（RC）和对比恢复系数（CRC）。评估了三种PVC方法：基于RC的方法、基于CRC的方法和基于感兴趣体积（VOI）的方法。将最合适的PVC方法应用于大鼠脑内数据。
结果表明，RCs取决于所使用的放射性核素，18F的值最高，其次是11C和68Ga。计算得到的平均CRCs通常低于相应的平均RCs。将不同的PVC方法应用于大鼠脑数据，导致最小脑区（内嗅皮质）的时间-活度曲线大幅增加，而最大脑区（小脑）的增加最小。
本研究能够证明PVE在对小结构进行定量测量时的重要性和影响，以及几种PVC方法的局限性。
