Wagatsuma Kei, Sakata Muneyuki, Miwa Kenta, Hamano Yumi, Kawakami Hirofumi, Kamitaka Yuto, Yamao Tensho, Miyaji Noriaki, Ishibashi Kenji, Tago Tetsuro, Toyohara Jun, Ishii Kenji
School of Allied Health Sciences, Kitasato University, 1-15-1 Kitazato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan.
Research Team for Neuroimaging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, 35-2, Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan.
EJNMMI Phys. 2024 Apr 22;11(1):37. doi: 10.1186/s40658-024-00641-3.
Bayesian penalised likelihood (BPL) reconstruction, which incorporates point-spread-function (PSF) correction, provides higher signal-to-noise ratios and more accurate quantitation than conventional ordered subset expectation maximization (OSEM) reconstruction. However, applying PSF correction to brain PET imaging is controversial due to Gibbs artefacts that manifest as unpredicted cortical uptake enhancement. The present study aimed to validate whether BPL without PSF would be useful for amyloid PET imaging.
Images were acquired from Hoffman 3D brain and cylindrical phantoms for phantom study and 71 patients administered with [F]flutemetamol in clinical study using a Discovery MI. All images were reconstructed using OSEM, BPL with PSF correction, and BPL without PSF correction. Count profile, %contrast, recovery coefficients (RCs), and image noise were calculated from the images acquired from the phantoms. Amyloid β deposition in patients was visually assessed by two physicians and quantified based on the standardised uptake value ratio (SUVR).
The overestimated radioactivity in profile curves was eliminated using BPL without PSF correction. The %contrast and image noise decreased with increasing β values in phantom images. Image quality and RCs were better using BPL with, than without PSF correction or OSEM. An optimal β value of 600 was determined for BPL without PSF correction. Visual evaluation almost agreed perfectly (κ = 0.91-0.97), without depending on reconstruction methods. Composite SUVRs did not significantly differ between reconstruction methods.
Gibbs artefacts disappeared from phantom images using the BPL without PSF correction. Visual and quantitative evaluation of [F]flutemetamol imaging was independent of the reconstruction method. The BPL without PSF correction could be the standard reconstruction method for amyloid PET imaging, despite being qualitatively inferior to BPL with PSF correction for [F]flutemetamol amyloid PET imaging.
贝叶斯惩罚似然（BPL）重建结合了点扩散函数（PSF）校正，与传统的有序子集期望最大化（OSEM）重建相比，能提供更高的信噪比和更准确的定量分析。然而，由于吉布斯伪影表现为未预测到的皮质摄取增强，将PSF校正应用于脑PET成像存在争议。本研究旨在验证无PSF的BPL是否对淀粉样蛋白PET成像有用。
在体模研究中，从霍夫曼3D脑模型和圆柱形体模获取图像；在临床研究中，使用Discovery MI对71例接受[F]氟代脱氧葡萄糖的患者进行成像。所有图像均使用OSEM、带PSF校正的BPL和无PSF校正的BPL进行重建。从体模获取的图像中计算计数轮廓、对比度百分比、恢复系数（RC）和图像噪声。由两名医生对患者的淀粉样β沉积进行视觉评估，并基于标准化摄取值比（SUVR）进行定量分析。
使用无PSF校正的BPL消除了轮廓曲线中放射性高估的情况。在体模图像中，对比度百分比和图像噪声随β值增加而降低。使用带PSF校正的BPL比无PSF校正或OSEM时图像质量和RC更好。确定了无PSF校正的BPL的最佳β值为600。视觉评估几乎完全一致（κ = 0.91 - 0.97），且不依赖于重建方法。不同重建方法之间的复合SUVR无显著差异。
使用无PSF校正的BPL时，吉布斯伪影在体模图像中消失。[F]氟代脱氧葡萄糖成像的视觉和定量评估与重建方法无关。尽管在[F]氟代脱氧葡萄糖淀粉样蛋白PET成像中，无PSF校正的BPL在质量上不如带PSF校正的BPL，但无PSF校正的BPL可能是淀粉样蛋白PET成像的标准重建方法。
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