PET/CT with ⁶⁸Ga-DOTA-somatostatin analogs has been tested for therapy monitoring in patients with neuroendocrine tumors (NETs). However, SUVs in tumors do not correlate with the net influx rate (K_i), as a representation of the somatostatin receptor expression. In this study, tumor-to-blood ratio (TBR) was evaluated as an alternative tool for semiquantitative assessment of ⁶⁸Ga-DOTATOC and ⁶⁸Ga-DOTATATE tumor uptake and as a therapy monitoring tool for patients with NETs. Methods: Twenty-two NET patients underwent a 45-min dynamic PET/CT scan after injection of ⁶⁸Ga-DOTATOC or ⁶⁸Ga-DOTATATE. K_i was determined using the Patlak method, and TBR was calculated for the 40- to 45-min interval. Results: A linear relation was found between K_i and TBR, with a square of Pearson correlation of 0.98 and 0.93 for ⁶⁸Ga-DOTATOC and ⁶⁸Ga-DOTATATE, respectively. Conclusion: A high correlation was found between K_i and TBR. Hence, TBR reflects somatostatin receptor density more accurately than SUV and is suggested as the preferred metric for semiquantitative assessment of ⁶⁸Ga-DOTATOC and ⁶⁸Ga-DOTATATE tumor uptake.

PET / CT和⁶⁸ Ga-DOTA-生长抑素类似物已经过测试，可用于神经内分泌肿瘤（NETs）患者的治疗监测。但是，肿瘤中的SUV与生长抑素受体表达的代表与净流入率（K _i）不相关。在这项研究中，肿瘤血比（TBR）被评估为半定量评估⁶⁸ Ga-DOTATOC和⁶⁸ Ga- DOTATATE肿瘤摄取的替代工具，以及作为NETs患者的治疗监测工具。方法：22名NET患者在注射⁶⁸ Ga-DOTATOC或⁶⁸ Ga- DOTATATE后进行了45分钟的动态PET / CT扫描。ķ_我使用Patlak方法确定TBR，并计算40至45分钟间隔的TBR。结果：发现K _i与TBR之间存在线性关系，对于⁶⁸ Ga-DOTATOC和⁶⁸ Ga- DOTATATE ，Pearson相关系数的平方分别为0.98和0.93 。结论： K _i与TBR之间存在高度相关性。因此，TBR比SUV更能准确地反映生长抑素受体的密度，并被建议作为半定量评估⁶⁸ Ga-DOTATOC和⁶⁸ Ga- DOTATATE肿瘤摄取的首选指标。