Kunikowska Jolanta, Bajera Adam, Sawicka Magdalena, Czwarnowski Piotr, Pawłowicz Bożena, Aksamit Dariusz, Pawlak Dariusz, Królicki Leszek
Nuclear Medicine Department, Medical University of Warsaw, Poland.
Nucl Med Rev Cent East Eur. 2013;16(2):70-4. doi: 10.5603/NMR.2013.0038.
Neuroendocrine tumors (NETs) are a heterogeneous group of neoplasms derived from endocrine stem cells.These tumors are characterized by overexpression of somatostatin receptors (SSTR), which is utilized for imaging using SSTR analogs. Peptide receptor radionuclide therapy (PRRT) somatostatin analogs labeled with 90Y and 177Lu in neuroendocrine tumors (NETs) results in symptomatic improvement, prolonged survival,and enhanced quality of life. The post-therapeutic imaging leadsto possibility of biodistribution of therapy. The aim of our study was to describe different possibilities of post-therapeutic imaging in patients underwent tandem therapy 90Y/177Lu-DOTATATE with preliminary results of 90Y PET imaging.
Thirty patients (11 men, 19 women; the mean age 55 ± 10.9 y) with histological confirmation of metastatic neuroendocrine tumors (G1 and G2) were treated with tandem therapy 90Y/177Lu-DOTATATE. WHBA scan and SPECT acquisition of the abdomen were performed 24 hours post therapy injection, on the dual-head Varicam camera (ELSCINT) using 177Lu photopeak and 90Y bremsstrahlung. PET imaging of 90Y component was done on Siemens Biograph Truepoint PET/CT (window 511 keV ± 15%)4 hours after 90Y/177Lu-DOTATATE. Additionally phantom studies were performer to analyze the spatial resolution of different protocols.
Out of all the patients, median OS was 49.8 months and median EFS time 24.3 months. Spatial resolution achieved for 90Y, 177 Lu and PET imaging of 90Y component measured using the phantom of the torso filled up with water was 20 mm, 8 mm and 4-5 mm FWHM, respectively. Spatial resolution in human body in our study was about 30 mm for 90Y, 15 mm for 177Lu and 25-30 mm for PET imaging of 90Y component.
The theoretically best spatial resolution offers PET scanner, however it is important to keep in mind that 90Y-imaging PET is not used for diagnosis purposes (small activities)but rather to present new possibility of post-therapeutic imaging (substantially higher activities). For post-therapeutic imaging after intravenous radiopharmaceutical administration the best spatial resolution offers standard scintigraphic camera for 90Y/177Lu DOTATATE imaging, with using 177Lu photopeaks. The worst spatial resolution offers standard scintigraphic camera for 90Y/177Lu DOTATATE imaging, with using 90Y bremsstrahlung gammas.
神经内分泌肿瘤（NETs）是一组源自内分泌干细胞的异质性肿瘤。这些肿瘤的特征是生长抑素受体（SSTR）过表达，这被用于使用SSTR类似物进行成像。肽受体放射性核素治疗（PRRT）中，用90Y和177Lu标记的生长抑素类似物用于神经内分泌肿瘤（NETs），可改善症状、延长生存期并提高生活质量。治疗后的成像带来了治疗生物分布的可能性。我们研究的目的是描述接受90Y/177Lu-DOTATATE串联治疗的患者治疗后成像的不同可能性，并给出90Y PET成像的初步结果。
30例经组织学证实为转移性神经内分泌肿瘤（G1和G2）的患者（11例男性，19例女性；平均年龄55±10.9岁）接受了90Y/177Lu-DOTATATE串联治疗。治疗后注射24小时，使用177Lu光电峰和90Y轫致辐射，在双头Varicam相机（ELSCINT）上进行腹部的全身骨显像（WHBA）扫描和SPECT采集。在90Y/177Lu-DOTATATE注射4小时后，在西门子Biograph Truepoint PET/CT（窗宽511 keV±15%）上进行90Y成分的PET成像。此外，还进行了体模研究以分析不同方案的空间分辨率。
所有患者中，中位总生存期为49.8个月，中位无进展生存期为24.3个月。使用装满水的躯干体模测量的90Y、177Lu和90Y成分PET成像的空间分辨率，半高宽分别为20 mm、8 mm和4 - 5 mm。在我们的研究中，人体中90Y的空间分辨率约为30 mm，177Lu为15 mm，90Y成分PET成像为25 - 30 mm。
理论上PET扫描仪提供的空间分辨率最佳，但重要的是要记住，90Y成像PET并非用于诊断目的（活度小），而是为治疗后成像提供新的可能性（活度高得多）。对于静脉注射放射性药物后的治疗后成像，用于90Y/177Lu DOTATATE成像的最佳空间分辨率由使用177Lu光电峰的标准闪烁相机提供。用于90Y/177Lu DOTATATE成像的最差空间分辨率由使用90Y轫致辐射伽马的标准闪烁相机提供。
