Differences in tumor-to-normal organ SUV ratios measured with 68 Ga-DOTATATE PET compared with 177 Lu-DOTATATE SPECT in patients with neuroendocrine tumors.
Differences in tumor-to-normal organ SUV ratios measured with 68 Ga-DOTATATE PET compared with 177 Lu-DOTATATE SPECT in patients with neuroendocrine tumors.
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DOI：
10.1097/mnm.0000000000001592
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发表时间：
2022-08-01
影响因子：
1.5
通讯作者：
Dewaraja, Yuni K.
中科院分区：
文献类型：
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作者：
Wong, Ka Kit;Frey, Kirk A.;Niedbala, Jeremy;Kaza, Ravi K.;Worden, Francis P.;Fitzpatrick, Kellen J.;Dewaraja, Yuni K.
关键词：
我们的目标是定量比较接受肽受体放射性核素治疗（PRRT）的神经内分泌肿瘤（NET）患者在治疗前68Ga-DOTATATE PET和治疗后177Lu-DOTATATE SPECT上肿瘤和主要正常器官内的放射性示踪剂生物分布。接受标准177Lu-DOTATATE PRRT的患者可获得注射Ga-68 DOTATATE后约60分钟的PET/CT和第1周期后约4小时（SPECT1）和24小时（spec2）的研究177Lu-SPECT/CT成像。将基线CT或MRI上的病变手工轮廓应用于SPECT/CT和PET/CT的共注册，然后基于深度学习的CT自动分割器官。根据肿瘤的SUVmean和SUVpeak以及非肿瘤肝、脾和肾的SUVmean计算肿瘤与正常器官的比值（TNR）。还进行了球体幻影研究，以比较68Ga PET和177Lu SPECT上的SUV指标。24例进展性转移性NET患者的90个病灶可供分析。PET与SPECT SUV tnr的相关性为差/中度：PET与spec1 R2 =0.19, 0.21, 0.29；TNRnliver、TNRspleen、TNRkidney的PET与spectr2的R2分别为0.06、0.16、0.33。在所有患者中，PET测量的TNR平均值在两个时间点均显著低于SPECT （p < 0.001）。采用SUVmean计算肿瘤的TNR平均值和95%可信区间（CI）为PET: tnrliver =3.5 [CI: 3.0-3.9]， tnr脾=1.3 [CI, 1.2-1.5], TNRkidney=1.7 [CI: 1.6-1.9]；spec1: TNRnliver=10 [CI: 8.2-11.7]， tnr脾=2.9 [CI: 2.5-3.4], TNRkidney=2.8 [CI: 2.3-3.3]；spectr2: TNRnliver=16.9 [CI: 14-19.9], TNRspleen=3.6 [CI: 3-4.2], TNRkidney=3.6 [CI: 3.0-4.2]。使用肿瘤SUVpeak计算TNR也观察到同样的趋势。球体幻影的PET和SPECT结果的比较表明，这些差异不是由于成像方式。治疗组的肿瘤与正常器官摄取比存在差异，177Lu SPECT上的SUV TNR明显高于68Ga PET。我们假设这种现象是由于与正常器官相比，肿瘤中DOTATATE摄取和内化的时间差异。
Our goal is to quantitatively compare radiotracer bio-distributions within tumors and major normal organs on pre-therapy 68Ga-DOTATATE PET to post-therapy 177Lu-DOTATATE SPECT in patients receiving peptide receptor radionuclide therapy (PRRT) for their neuroendocrine tumor (NET). PET/CT at ~ 60 min post-injection of Ga-68 DOTATATE and research 177Lu-SPECT/CT imaging ~ at 4 h (SPECT1) and ~ 24 h (SPECT2) post-cycle#1 were available for patients who underwent standard 177Lu-DOTATATE PRRT. Manual contours of lesions on baseline CT or MRI were applied to co-registered SPECT/CT and PET/CT followed by deep learning-based CT auto-segmentation of organs. Tumor-to-normal organ ratios (TNR) were calculated from both SUVmean and SUVpeak for tumor, and SUVmean for non-tumoral liver (nliver), spleen and kidney. A sphere phantom study was also performed to compare SUV metrics on 68Ga PET to 177Lu SPECT. 90 lesions in 24 patients with progressive metastatic NET were available for analysis. The correlation between PET and SPECT SUV TNRs were poor/moderate: PET versus SPECT1 R2 =0.19, 0.21, 0.29; PET versus SPECT2 R2 =0.06, 0.16, 0.33 for TNRnliver,TNRspleen,TNRkidney, respectively. Across all patients, the average value of the TNR measured on PET was significantly lower than on SPECT at both time points (p < 0.001). Using SUVmean for tumor, average TNR values and 95% confidence intervals (CI) were PET: TNRnliver=3.5 [CI: 3.0–3.9], TNRspleen=1.3 [CI, 1.2–1.5], TNRkidney=1.7 [CI: 1.6–1.9]; SPECT1: TNRnliver=10 [CI: 8.2–11.7], TNRspleen=2.9 [CI: 2.5–3.4], TNRkidney=2.8 [CI: 2.3–3.3]; SPECT2: TNRnliver=16.9 [CI: 14–19.9], TNRspleen=3.6 [CI: 3–4.2], TNRkidney=3.6 [CI: 3.0–4.2]. The same trend was observed for TNR calculated using tumor SUVpeak. Comparison of PET and SPECT results in a sphere phantom demonstrated that these differences are not attributed to imaging modality. Differences in tumor-to-normal organ uptake ratios exist for the theranostic pair, with significantly higher SUV TNR on 177Lu SPECT compared with 68Ga PET. We postulate this phenomenon is due to temporal differences in DOTATATE uptake and internalization in tumor as compared to normal organs.