Abstract：
OBJECTIVE: Centiloid (CL) scales play an important role in semiquantitative analyses of amyloid-β (Aβ) PET. CLs are derived from the standardized uptake value ratio (SUVR), which needs Aβ positron emission tomography (PET) normalization processing. There are two methods to collect the T1-weighted imaging (T1WI) for normalization: (i) anatomical standardization using simultaneously acquired T1WI (PET/MRI), usually adapted to PET images from PET/MRI scanners, and (ii) T1WI from a separate examination (PET + MRI), usually adapted to PET images from PET/CT scanners. This study aimed to elucidate the correlations and differences in CLs between when using the above two T1WI collection methods.
METHODS: Among patients who underwent Aβ PET/MRI (using 11C-Pittuberg compound B (11C-PiB) or 18F-flutemetamol (18F-FMM)) at our institution from 2015 to 2023, we selected 49 patients who also underwent other additional MRI examinations, including T1WI for anatomic standardization within 3 years. Thirty-one of them underwent 11C-PiB PET/MRI, and 18 participants underwent 18F-FMM PET/MRI. Twenty-five of them, additional MRI acquisition parameters were identical to simultaneous MRI during PET, and 24 participants were different. After normalization using PET/MRI or PET + MRI method each, SUVR was measured using the Global Alzheimer\'s Association Initiative Network cerebral cortical and striatum Volume of Interest templates (VOI) and whole cerebellum VOI. Subsequently, CLs were calculated using the previously established equations for each Aβ PET tracer.
RESULTS: Between PET/MRI and PET + MRI methods, CLs correlated linearly in 11C-PiB PET (y = 1.00x - 0.11, R2 = 0.999), 18F-FMM PET (y = 0.97x - 0.12, 0.997), identical additional MRI acquisition (y = 1.00x + 0.33, 0.999), different acquisition (y = 0.98x - 0.43, 0.997), and entire study group (y = 1.00x - 0.24, 0.999). Wilcoxon signed-rank test revealed no significant differences: 11C-PiB (p = 0.49), 18F-FMM (0.08), and whole PET (0.46). However, significant differences were identified in identical acquisition (p = 0.04) and different acquisition (p = 0.02). Bland-Altman analysis documented only a small bias between PET/MRI and PET + MRI in 11C-PiB PET, 18F-FMM PET, identical additional MRI acquisition, different acquisition, and whole PET (- 0.05, 0.67, - 0.30, 0.78, and 0.21, respectively).
CONCLUSIONS: Anatomical standardizations using PET/MRI and using PET + MRI can lead to almost equivalent CL. The CL values obtained using PET/MRI or PET + MRI normalization methods are consistent and comparable in clinical studies.
METHODS: Among patients who underwent Aβ PET/MRI (using 11C-Pittuberg compound B (11C-PiB) or 18F-flutemetamol (18F-FMM)) at our institution from 2015 to 2023, we selected 49 patients who also underwent other additional MRI examinations, including T1WI for anatomic standardization within 3 years. Thirty-one of them underwent 11C-PiB PET/MRI, and 18 participants underwent 18F-FMM PET/MRI. Twenty-five of them, additional MRI acquisition parameters were identical to simultaneous MRI during PET, and 24 participants were different. After normalization using PET/MRI or PET + MRI method each, SUVR was measured using the Global Alzheimer\'s Association Initiative Network cerebral cortical and striatum Volume of Interest templates (VOI) and whole cerebellum VOI. Subsequently, CLs were calculated using the previously established equations for each Aβ PET tracer.
RESULTS: Between PET/MRI and PET + MRI methods, CLs correlated linearly in 11C-PiB PET (y = 1.00x - 0.11, R2 = 0.999), 18F-FMM PET (y = 0.97x - 0.12, 0.997), identical additional MRI acquisition (y = 1.00x + 0.33, 0.999), different acquisition (y = 0.98x - 0.43, 0.997), and entire study group (y = 1.00x - 0.24, 0.999). Wilcoxon signed-rank test revealed no significant differences: 11C-PiB (p = 0.49), 18F-FMM (0.08), and whole PET (0.46). However, significant differences were identified in identical acquisition (p = 0.04) and different acquisition (p = 0.02). Bland-Altman analysis documented only a small bias between PET/MRI and PET + MRI in 11C-PiB PET, 18F-FMM PET, identical additional MRI acquisition, different acquisition, and whole PET (- 0.05, 0.67, - 0.30, 0.78, and 0.21, respectively).
CONCLUSIONS: Anatomical standardizations using PET/MRI and using PET + MRI can lead to almost equivalent CL. The CL values obtained using PET/MRI or PET + MRI normalization methods are consistent and comparable in clinical studies.
摘要：
目的：Centiloid（CL）量表在淀粉样蛋白-β（Aβ）PET的半定量分析中起重要作用。CLs来自标准化摄取值比率(SUVR)，需要Aβ正电子发射断层扫描(PET)归一化处理。有两种方法可以收集T1加权成像（T1WI）进行归一化：（i）使用同时采集的T1WI（PET/MRI）进行解剖学标准化，通常适用于PET/MRI扫描仪的PET图像，和（ii）来自单独检查（PET+MRI）的T1WI，通常适用于PET/CT扫描仪的PET图像。本研究旨在阐明使用上述两种T1WI收集方法时CLs的相关性和差异。
方法：在2015年至2023年在我们机构接受AβPET/MRI（使用11C-Pittuberg化合物B（11C-PiB）或18F-氟美他莫（18F-FMM））的患者中，我们选择了49名同时接受其他MRI检查的患者，包括T1WI，用于3年内的解剖标准化。其中31例接受了11C-PiBPET/MRI检查,18例患者接受18F-FMMPET/MRI检查。其中25个,额外的MRI采集参数与PET期间的同步MRI相同,24名参与者有所不同。分别使用PET/MRI或PET+MRI方法进行归一化后，使用全球阿尔茨海默病协会倡议网络大脑皮层和纹状体兴趣体积模板（VOI）和整个小脑VOI测量SUVR。随后，使用先前建立的每个AβPET示踪剂的方程式计算CL。
结果：在PET/MRI和PET+MRI方法之间，CLs在11C-PiBPET中呈线性关系（y=1.00x-0.11，R2=0.999），18F-FMMPET（y=0.97x-0.12，0.997），相同的额外MRI采集(y=1.00x+0.33,0.999),不同的采集(y=0.98x-0.43，0.997)，和整个研究组（y=1.00x-0.24，0.999）。Wilcoxon符号秩检验显示没有显着差异：11C-PiB（p=0.49），18F-FMM(0.08),和整个PET（0.46）。然而,在相同采集(p=0.04)和不同采集(p=0.02)中发现显著差异.Bland-Altman分析仅记录了11C-PiBPET中PET/MRI和PET+MRI之间的小偏差，18F-FMMPET,相同的额外MRI采集，不同的收购，和整个PET（分别为-0.05、0.67、-0.30、0.78和0.21）。
结论：使用PET/MRI和使用PET+MRI的解剖学标准化可导致几乎相等的CL。使用PET/MRI或PET+MRI归一化方法获得的CL值在临床研究中是一致且相当的。
方法：在2015年至2023年在我们机构接受AβPET/MRI（使用11C-Pittuberg化合物B（11C-PiB）或18F-氟美他莫（18F-FMM））的患者中，我们选择了49名同时接受其他MRI检查的患者，包括T1WI，用于3年内的解剖标准化。其中31例接受了11C-PiBPET/MRI检查,18例患者接受18F-FMMPET/MRI检查。其中25个,额外的MRI采集参数与PET期间的同步MRI相同,24名参与者有所不同。分别使用PET/MRI或PET+MRI方法进行归一化后，使用全球阿尔茨海默病协会倡议网络大脑皮层和纹状体兴趣体积模板（VOI）和整个小脑VOI测量SUVR。随后，使用先前建立的每个AβPET示踪剂的方程式计算CL。
结果：在PET/MRI和PET+MRI方法之间，CLs在11C-PiBPET中呈线性关系（y=1.00x-0.11，R2=0.999），18F-FMMPET（y=0.97x-0.12，0.997），相同的额外MRI采集(y=1.00x+0.33,0.999),不同的采集(y=0.98x-0.43，0.997)，和整个研究组（y=1.00x-0.24，0.999）。Wilcoxon符号秩检验显示没有显着差异：11C-PiB（p=0.49），18F-FMM(0.08),和整个PET（0.46）。然而,在相同采集(p=0.04)和不同采集(p=0.02)中发现显著差异.Bland-Altman分析仅记录了11C-PiBPET中PET/MRI和PET+MRI之间的小偏差，18F-FMMPET,相同的额外MRI采集，不同的收购，和整个PET（分别为-0.05、0.67、-0.30、0.78和0.21）。
结论：使用PET/MRI和使用PET+MRI的解剖学标准化可导致几乎相等的CL。使用PET/MRI或PET+MRI归一化方法获得的CL值在临床研究中是一致且相当的。
