PURPOSE As an alternative to technetium-99m-macroaggregated albumin (99mTc-MAA), a scout dose of holmium-166 (166Ho) microspheres can be used prior to 166Ho-radioembolization. The use of identical particles for pre-treatment and treatment procedures may improve the predictive value of pre-treatment analysis of distribution. The aim of this study was to analyze the agreement between 166Ho-scout and 166Ho-therapeutic dose in comparison with the agreement between 99mTc-MAA and 166Ho-therapeutic dose. METHODS Two separate scout dose procedures were performed (99mTc-MAA and 166Ho-scout) before treatment in 53 patients. First, qualitative assessment was performed by two blinded nuclear medicine physicians who visually rated the agreement between the 99mTc-MAA, 166Ho-scout, and 166Ho-therapeutic dose SPECT-scans (i.e., all performed in the same patient) on a 5-point scale. Second, agreement was measured quantitatively by delineating lesions and normal liver on FDG-PET/CT. These volumes of interest (VOIs) were co-registered to the SPECT/CT images. The predicted absorbed doses (based on 99mTc-MAA and 166Ho-scout) were compared with the actual absorbed dose on post-treatment SPECT. RESULTS A total of 23 procedures (71 lesions, 22 patients) were included for analysis. In the qualitative analysis, 166Ho-scout was superior with a median score of 4 vs. 2.5 for 99mTc-MAA (p < 0.001). The quantitative analysis showed significantly narrower 95%-limits of agreement for 166Ho-scout in comparison with 99mTc-MAA when evaluating lesion absorbed dose (- 90.3 and 105.3 Gy vs. - 164.1 and 197.0 Gy, respectively). Evaluation of normal liver absorbed dose did not show difference in agreement between both scout doses and 166Ho-therapeutic dose (- 2.9 and 5.5 Gy vs - 3.6 and 4.1 Gy for 99mTc-MAA and 166Ho-scout, respectively). CONCLUSIONS In this study, 166Ho-scout was shown to have a superior predictive value for intrahepatic distribution in comparison with 99mTc-MAA.

中文翻译：

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与 99mTc-macro-aggregated 白蛋白相比，166Ho-scout 对肝转移患者进行 166Ho-微球放射栓塞术的预测价值更高。

目的 作为锝 99m 大聚集白蛋白 (99mTc-MAA) 的替代品，可在 166Ho 放射栓塞术之前使用侦察剂量的钬 166 (166Ho) 微球。对预处理和处理程序使用相同的粒子可以提高分布的预处理分析的预测值。本研究的目的是分析 166Ho-scout 和 166Ho-治疗剂量之间的一致性，以及 99mTc-MAA 和 166Ho-治疗剂量之间的一致性。方法 53 名患者在治疗前进行了两次单独的侦察剂量程序（99mTc-MAA 和 166Ho-侦察）。首先，由两名不知情的核医学医师进行定性评估，他们目测评估 99mTc-MAA、166Ho-scout 和 166Ho-治疗剂量 SPECT-扫描之间的一致性（即，均在同一患者身上进行），采用 5 分制。其次，通过在 FDG-PET/CT 上描绘病变和正常肝脏来定量测量一致性。这些感兴趣的体积 (VOI) 被共同注册到 SPECT/CT 图像。将预测的吸收剂量（基于 99mTc-MAA 和 166Ho-scout）与治疗后 SPECT 的实际吸收剂量进行比较。结果共纳入23个手术（71个病灶，22名患者）进行分析。在定性分析中，166Ho-scout 优于 99mTc-MAA 的中位得分为 4 分和 2.5 分（p < 0.001）。定量分析显示，在评估病灶吸收剂量（分别为 - 90.3 和 105.3 Gy 对比 - 164.1 和 197.0 Gy）时，与 99mTc-MAA 相比，166Ho-scout 的 95% 一致性限制明显更窄。正常肝脏吸收剂量的评估未显示侦察剂量和 166Ho 治疗剂量之间的一致性差异（99mTc-MAA 和 166Ho-侦察分别为 - 2.9 和 5.5 Gy 对比 - 3.6 和 4.1 Gy）。结论 在这项研究中，与 99mTc-MAA 相比，166Ho-scout 被证明对肝内分布具有更高的预测价值。