Comparison of gallium-68 somatostatin receptor and 18F-fluorodeoxyglucose positron emission tomography in the diagnosis of neuroendocrine tumours: A systematic review and meta-analysis

Abstract

Objective: A meta-analysis was performed to compare the diagnostic performance of gallium-68 (¹⁸Ga) somatostatin receptor positron emission tomography (⁶⁸Ga-SSTR PET) and fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) PET in patients with neuroendocrine tumours (NET) and whether the two imaging modalities can be mutually substituted in clinical work.

Methods: We performed electronic literature searches of the MEDLINE, PubMed, Embase and Cochrane Library databases for English-language articles from the earliest available date of indexing through 30 July 2019. We calculated the pooled sensitivity, specificity and diagnostic odds ratios (DOR) with 95% confidence intervals (95% CI) of ⁶⁸Ga-SSTR PET and ¹⁸F-FDG PET in NET. We drew a summary receiver operator characteristic (SROC) curve and calculated the area under the curve (AUC) to measure the accuracy of ⁶⁸Ga-SSTR PET and ¹⁸F-FDG PET in patients or lesions with NET.

Results: Thirty studies comprising 3401 patients and 5793 lesions with NET were included in this meta-analysis. The pooled sensitivity, sensitivity, DOR and AUC for ⁶⁸Ga-SSTR PET or PET/computed tomography (CT) in the diagnosis of NET, based on lesion patient, were 0.92(0.89-0.95), 0.91(0.83-0.95),119(51-282) and 0.96(0.94-0.98), and based on lesion, were 0.95(0.86-0.98), 0.93(0.83-0.97), 229(43-1205) and 0.98(0.96-0.99), respectively. The pooled sensitivity, sensitivity, DOR and AUC for ¹⁸F-FDG PET or PET/CT in NET were 0.70(0.41-0.89), 0.97(0.70-1.00), 67(7-612) and 0.94(0.92-0.96), respectively, when analyzed on a per-patient basis.The pooled sensitivities of ⁶⁸Ga-SSTR PET/CT were 0.923 (95% CI: 0.884-0.952), 0.902 (0.862-0.934) and 0.578 (0.482-0.669) in the G1(ki67,≤2%), G2(ki67,>3%,≤20% and G3(ki67,>20%) groups based on patients with NET, respectively. The pooled sensitivities of ¹⁸F-FDG PET/CT were 0.378 (0.319-0.440), 0.554 (0.492-0.615) and 0.712 (0.633-0.783) in the G1, G2 and G3 groups based on patients with NET, respectively.

Conclusion: The ⁶⁸Ga-SSTR PET has highly sensitive and had a greater diagnostic value than ¹⁸F-FDG PET for patients with NET. Fluorine-18-FDG PET, however, had significant specificity than ⁶⁸Ga-SSTR PET. The ⁶⁸Ga-SSTR has high sensitivity in G1/G2 NET, while ¹⁸F-FDG has a low positive rate. In G3 NET, however, the opposite is true. Therefore, the ⁶⁸Ga-SSTR PET and ¹⁸F-FDG PET modalities are complementary rather than substitutive in clinical practice.