F18-FDG PET in Neuroendocrine Tumors

Somatostatin receptor scintigraphy (e.g., octreoscan) is more sensitive than both ¹²³I-MIBG scintigraphy and ¹⁸F-FDG PET for neuroendocrine tumors. However, ¹⁸F-FDG PET is more sensitive for detection of aggressive tumors, with a sensitivity of around 90%, compared to ~70% and ~45% for somatostatin receptor and ¹²³I-MIBG scintigraphy for tumors with proliferation index above 15%.

In these aggressive tumors, somatostatin receptor and ¹²³I-MIBG scintigraphy can underestimate the extent of disease dissemination and lead to suboptimal treatment for these patients (aggressive disease is treated with systemic chemotherapy, while less aggressive disease is treated with somatostatin analogs or α-interferon).

In the example above, FDG-PET shows uptake in several areas not seen on octreoscan. One example is an enlarged retroperitoneal lymph node that is not hot on octreoscan, but light s up on FDG-PET (black arrows).

References

Binderup T, Knigge U, Loft A, Mortensen J, Pfeifer A, Federspiel B, Hansen CP, Højgaard L, Kjaer A. Functional imaging of neuroendocrine tumors: a head-to-head comparison of somatostatin receptor scintigraphy, 123I-MIBG scintigraphy, and 18F-FDG PET. J Nucl Med. 2010 May;51(5):704-12.