Limited value of fluorine-18 fluorodeoxyglucose positron emission tomography for the imaging of neuroendocrine tumours

Abstract

Scintigraphy using [111In-DTPA-d-Phe1]-pentetreotide or pentavalent technetium-99m-dimercaptosuccinic acid [99mTc(V)-DMSA] has been shown to localize well-differentiated and slowly growing neuroendocrine tumours, whereas increased fluorodeoxyglucose (FDG) uptake is associated with malignancy. The aim of this study was to compare the value of fluorine-18 FDG positron emission tomography (PET) with that of somatostatin receptor scintigraphy (SS-R) and dual-radionuclide scintigraphy [SS-R and 99mTc(V)-DMSA = DNS] in detecting malignant neuroendocrine tumours. Fifteen patients with metastasizing gastroenteropancreatic tumours (GEP tumours; n = 7), medullary thyroid carcinomas (MTCs; n = 8) and elevated tumour markers [GEP tumours: 5-hydroxyindoleacetic acid, insulin; MTCs: calcitonin, carcinoembryonic antigen (CEA)] were studied. Prior to PET, all patients with GEP tumours underwent SS-R. DNS was performed in all patients with MTC. Patients had been fasting for at least 12 h and normal glucose plasma levels were confirmed. Sixty minutes after intravenous administration of 18F-FDG (mean: 374 MBq) whole-body PET and regional scans were performed. In addition, the resected tissues were prepared for immunocytochemistry examination (cell cycle-associated Ki-67 antigen). In two patients with less-differentiated GEP tumours associated with high proliferative activity and increased FDG uptake, SS-R failed to detect any lesion. In comparison, in four patients with well-differentiated GEP tumours showing low proliferative activity, SS-R localized four primary tumours, 22 lymph node metastases and 18 malignant liver lesions, whereas 18F-FDG PET demonstrated normal distribution. In one patient with a metastasizing carcinoid (medium proliferative activity) SS-R localized multiple metastases, whereas PET demonstrated low FDG uptake in all known metastases. In patients with recurrent MTC and rapidly increasing CEA levels DNS detected only three lesions in two patients, whereas PET demonstrated one pulmonary, three osseous, 20 mediastinal, ten locoregional, and four liver metastases in seven patients. Twenty-nine malignant lesions were confirmed by follow-up and nine lymph node metastases could be surgically removed. In conclusion, PET imaging of gastroenteropancreatic tumours revealed increased glucose metabolism only in less-differentiated GEP tumours with high proliferative activity and metastasizing MTC associated with rapidly increasing CEA levels. Therefore, additional 18F-FDG PET should be performed only if SS-R or DNS is negative.

Secretive and proliferative tumor profile helps to select the best imaging technique to identify postoperative persistent or relapsing medullary thyroid cancer

“…For MIBG, 99mTc-dimercaptosuccinic acid and SRS, a proportion of patients ranging between 30-80% had unidentified lesions despite the biological evidence of postoperative disease persistence (Clarke 1988, Udelsman et al 1989, Hoefnagel et al 1991, Celentano et al 1995, Anthony et al 1996, Baudin et al 1996, Adams et al 1998a, Berna et al 1998, Arslan et al 2001. FDG-PET seems to be more informative than CIT and other functional techniques, especially in detecting postoperative persistent or relapsing MTC lesions (Musholt et al 1997, Adams et al 1998b, Diehl et al 2001, Szakall et al 2002, de Groot et al 2004). However, the detection rate of postoperatively persistent or recurrent MTC remains low for all the imaging modalities investigated.…”

6-[ 18 F]Fluorodopamine Positron Emission Tomographic (PET) Scanning for Diagnostic Localization of Pheochromocytoma

“…In general, however, rapidly metabolizing cells take up 18 Ffluorodeoxyglucose, so this agent cannot detect pheochromocytoma specifically. 16 One might expect that a sympathomimetic amine, such as 11 C-hydroxyephedrine, would have greater specificity than 18 F-fluorodeoxyglucose, because of the requirement for visualization of uptake by the plasma membrane and intracellular vesicular monoamine transporters. 11 C-Hydroxyephedrine PET scanning can detect pheochromocytoma rapidly (in 2 to 5 minutes) and clearly in most but not all patients, visualizing more lesions with better contrast than by using 131 I-metaiodobenzylguanidine.…”

Functional imaging of neuroendocrine tumors with combined PET/CT using 68Ga‐DOTATATE (DOTA‐DPhe1,Tyr3‐octreotate) and 18F‐FDG

“…18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography (PET) is of limited value in well-differentiated NETs as these tumors often have near-normal glucose turnover. 8 As both 18 F-FDG and 68 Ga-DOTATATE exploit distinct tumor characteristics it is possible that they may be complementary for tumor staging. Higher-grade NETs may show higher metabolic turnover and lose expression of SSRs.…”

“…To date, however, only a few small series have correlated FDG and/or somatostatin receptor scintigraphy (SSRS) with tumor grade. [8][9][10][11] Aim The purpose of this study was to compare the performance of 68 Ga-DOTATATE and 18 F-FDG in confirmed NET and correlate uptake with tumor grade on histology.…”