Fluorodeoxyglucose positron emission tomography and somatostatin receptor scintigraphy for diagnosing and staging carcinoid tumours: correlations with the pathological indexes p53 and Ki-67

Abstract

We performed this study in order to evaluate the diagnostic accuracy of whole-body fluorodeoxyglucose positron emission tomography (FDG PET) imaging and somatostatin receptor scintigraphy (SRS) for localizing primary carcinoid tumours and evaluating the extent of the disease. A secondary aim was to correlate those findings with the histological characteristics of the lesions. FDG PET was performed in 17 patients and SRS in 16. All patients had pathologically proven carcinoids. All lesions were verified by histopathological analysis or by follow-up. Ki-67 and p53 expression were assessed as an indicator of the tumours' aggressiveness. FDG PET correctly identified 4/7 primary tumours and 8/11 metastatic spreads, as compared to six and 10 respectively, for SRS. Most tumours were typical carcinoids with low Ki-67 expression. No correlation was found between the histological features and the tracer's uptake. We conclude that SRS remains the modality of choice for evaluating patients with carcinoid tumours, regardless of their proliferative activity. FDG PET should be reserved to patients with negative results on SRS.

18F-Fluorodeoxyglucose Positron Emission Tomography Predicts Survival of Patients with Neuroendocrine Tumors

“…The assumption has been that due to the low proliferation rate and low metabolic activity generally seen in these tumors, FDG-PET would have a low sensitivity and not provide additional information to conventional CT and SRS (15,(19)(20)(21)(22). Studies on small groups of patients have confirmed this hypothesis, although FDG-PET tended to be positive for the low-differentiated NE tumors (14,19). The low diagnostic sensitivity of FDG-PET for NE tumors was confirmed in the present study in which we found an overall sensitivity of 58%.…”

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

“…Although some studies have shown a correlation between 18 F-FDG uptake and histology of NET as determined by Ki67 index, 10,11 others have failed to demonstrate such a relationship. 9 Data from PET somatostatin receptor ligand studies are limited. Dynamic PET studies have shown that while 68 Ga-DOTATOC uptake is most closely correlated with the pharmacokinetic K 1 parameter, 18 F-FDG uptake is most influenced by the V B (fractional blood volume) parameter.…”

Functional Imaging of Neuroendocrine Tumors: A Head-to-Head Comparison of Somatostatin Receptor Scintigraphy, 123I-MIBG Scintigraphy, and 18F-FDG PET

“…Therefore, most studies with functional imaging of neuroendocrine tumor patients are retrospective and have small populations. 123 I-MIBG scintigraphy and SRS have been compared only in retrospective studies (6,26), and most studies of 18 F-FDG PET in neuroendocrine tumor have included few patients (8,9). In a recent and larger study, 18 F-FDG PET seemed valuable for aggressive neuroendocrine tumors, but conclusions were based on only 6 patients, all having high-grade tumors (10).…”

“…However, 18 F-FDG PET has never been used on a routine basis for imaging of neuroendocrine tumors, and its diagnostic performance is unsettled. A few smaller studies on neuroendocrine tumor patients have indicated that 18 F-FDG PET might be of value for tumors with a high proliferation index, whereas the diagnostic sensitivity seems to be low for neuroendocrine tumors with a low proliferation index, slow growth rate, and low glucose consumption (8)(9)(10). However, the small sample size of the studies requires further investigation of the real sensitivity of 18 F-FDG PET for neuroendocrine tumor imaging in comparison with traditionally used functional imaging scans.…”