Junik R, Drobik P, Małkowski B, Kobus-Błachnio K
Department of Endocrinology and Diabetology, Laboratory of Nuclear Medicine, Nicolaus Copernicus University in Torun, Collegium Medicum in Bydgoszcz, Poland.
Adv Med Sci. 2006;51:66-8.
PET is a successful modality to detect cancer and in recent years has demonstrated a great diagnostic value in large series of tumour types. PET combines high sensitivity and reasonable resolution, and offers the ability to perform whole body scans. 18F-deoxyglucose (FDG)-PET has also been used to diagnose tumours of neuroendocrine origin. Even if 18F-FDG has been successfully and widely employed in oncology, it has not demonstrated a significant uptake in well differentiated neuroendocrine tissues. Thus 18F-FDG is not a good tracer for neuroendocrine tumours, as FDG-PET imaging of number of GEP tumours revealed increased glucose metabolism only in less differentiated GEP tumours with high proliferative activity and in metastatising MTC associated with rapidly increasing CEA levels. In such a situation, additional 18F-FDG PET should be performed only if somatostatin receptor scintigraphy (alone or with 99mTc-DMSA) is negative. On the contrary, other positron emitter tracers seem to be more promising. 68Ga-DOTA-NOC (tetraazycyclododecanetetraacetic acid-[1-Nal3]-octreotide) has been used as a positron emitter tracer for the detection of NETs in preliminary studies. A serotonin precursor 5-hydroxytryptophan (5-HTP) labelled with 11C has shown an increased uptake in carcinoids. This uptake seems to be selective and some clinical evidence has demonstrated that it allows the detection of more lesions with PET than with CT or octreotide scintigraphy. Another radiopharmaceutical in the development for PET is 11C-L-DOPA, which seems to be useful in imaging endocrine pancreatic tumours.
正电子发射断层扫描（PET）是一种成功的癌症检测手段，近年来已在大量肿瘤类型中显示出巨大的诊断价值。PET兼具高灵敏度和合理的分辨率，还具备进行全身扫描的能力。18F-脱氧葡萄糖（FDG）-PET也已用于诊断神经内分泌起源的肿瘤。尽管18F-FDG已在肿瘤学中成功且广泛应用，但在分化良好的神经内分泌组织中并未显示出明显摄取。因此，18F-FDG并非神经内分泌肿瘤的良好示踪剂，因为对许多胃肠胰（GEP）肿瘤进行FDG-PET成像显示，仅在增殖活性高、分化程度低的GEP肿瘤以及癌胚抗原（CEA）水平快速升高的转移性甲状腺髓样癌（MTC）中葡萄糖代谢增加。在这种情况下，仅当生长抑素受体闪烁显像（单独或与99mTc-二巯基丁二酸[DMSA]联合）为阴性时，才应进行额外的18F-FDG PET检查。相反，其他正电子发射体示踪剂似乎更具前景。68Ga-多胺大环配体-奥曲肽（四氮杂环十二烷四乙酸-[1-萘基3]-奥曲肽）在初步研究中已被用作检测神经内分泌肿瘤（NETs）的正电子发射体示踪剂。用11C标记的血清素前体5-羟色氨酸（5-HTP）在类癌中显示摄取增加。这种摄取似乎具有选择性，一些临床证据表明，与CT或奥曲肽闪烁显像相比，PET利用它能检测到更多病灶。另一种正在研发用于PET的放射性药物是11C-L-多巴，它似乎对内分泌胰腺肿瘤成像有用。
