Department of Nuclear Medicine, University Hospital Zürich, University of Zürich, Rämistrasse 100, CH-8091, Zürich, Switzerland.
Department of Nuclear Medicine, Città della Salute e della Scienza di Torino, University of Turin, Turin, Italy.
Eur Radiol. 2021 Oct;31(10):8011-8020. doi: 10.1007/s00330-021-07852-7. Epub 2021 Mar 25.
To compare block sequential regularized expectation maximization (BSREM) and ordered subset expectation maximization (OSEM) for the detection of in-transit metastasis (ITM) of malignant melanoma in digital [F]FDG PET/CT.
We retrospectively analyzed a cohort of 100 [F]FDG PET/CT scans of melanoma patients with ITM, performed between May 2017 and January 2020. PET images were reconstructed with both OSEM and BSREM algorithms. SUVmax, target-to-background ratio (TBR), and metabolic tumor volume (MTV) were recorded for each ITM. Differences in PET parameters were analyzed with the Wilcoxon signed-rank test. Differences in image quality for different reconstructions were tested using the Man-Whitney U test.
BSREM reconstruction led to the detection of 287 ITM (39% more than OSEM). PET parameters of ITM were significantly different between BSREM and OSEM reconstructions (p < 0.001). SUVmax and TBR were higher (76.5% and 77.7%, respectively) and MTV lower (49.5%) on BSREM. ITM missed with OSEM had significantly lower SUVmax (mean 2.03 vs. 3.84) and TBR (mean 1.18 vs. 2.22) and higher MTV (mean 2.92 vs. 1.01) on OSEM compared to BSREM (all p < 0.001).
BSREM detects significantly more ITM than OSEM, owing to higher SUVmax, higher TBR, and less blurring. BSREM is particularly helpful in small and less avid lesions, which are more often missed with OSEM.
• In melanoma patients, [F]FDG PET/CT helps to detect in-transit metastases (ITM), and their detection is improved by using BSREM instead of OSEM reconstruction. • BSREM is particularly useful in small lesions.
比较数字[F]FDG PET/CT 中顺次正则期望最大化（BSREM）和有序子集期望最大化（OSEM）在检测黑色素瘤转移（ITM）中的作用。
我们回顾性分析了 2017 年 5 月至 2020 年 1 月期间 100 例黑色素瘤患者 ITM 的[F]FDG PET/CT 扫描。使用 OSEM 和 BSREM 算法对 PET 图像进行重建。记录每个 ITM 的 SUVmax、靶标与背景比（TBR）和代谢肿瘤体积（MTV）。使用 Wilcoxon 符号秩检验分析 PET 参数的差异。使用曼-惠特尼 U 检验测试不同重建图像质量的差异。
BSREM 重建导致检测到 287 个 ITM（比 OSEM 多 39%）。BSREM 和 OSEM 重建的 ITM 的 PET 参数差异有统计学意义（p < 0.001）。BSREM 的 SUVmax 和 TBR 更高（分别为 76.5%和 77.7%），而 MTV 更低（49.5%）。OSEM 漏诊的 ITM 的 SUVmax（平均 2.03 与 3.84）和 TBR（平均 1.18 与 2.22）显著较低，而 MTV（平均 2.92 与 1.01）显著较高（所有 p < 0.001）。
BSREM 比 OSEM 检测到更多的 ITM，这归因于更高的 SUVmax、更高的 TBR 和更小的模糊度。BSREM 特别有助于小且活性较低的病变，而这些病变更容易被 OSEM 漏诊。
• 在黑色素瘤患者中，[F]FDG PET/CT 有助于检测 ITM，使用 BSREM 重建而不是 OSEM 重建可以提高其检测率。• BSREM 对小病变特别有用。
