111In-pentetreotide scintigraphy of a 41-year-old man with
ectopicCushing's syndrome caused by a
neuroendocrine carcinoma of the
mesentery. Radiotracer accumulation in the left
thyroid in 10/2003 (arrow). The mesenterial neuroendocrine tumor became clearly visible in 4/2005 (arrow).
Octreotide scanning is reported to have a
sensitivity between 75% and 100% for detecting pancreatic neuroendocrine tumors.[4]
Instead of gamma-emitting 111In, certain octreotide derivatives such as
edotreotide (DOTATOC) or
DOTATATE are able to be linked by chelation to positron-emitting isotopes such as
gallium-68 and
copper-64 which in turn can be evaluated with more precise (compared with SPECT) scanning techniques such as
PET-CT. Thus, the octreotide scan is now being replaced in most centers with
gallium-68 DOTATATE and
copper-64 DOTATATE scans. Somatostatin receptor imaging can now be performed with positron emission tomography (PET) which offers higher resolution and more rapid imaging.[5]
Indications
An octreotide scan may be used to locate suspected primary neuroendocrine tumours (NET) or for follow-up or
staging after treatment.[6][7][8]
Approximately 200
megabecquerels (MBq) of indium-111 is injected
intravenously. Imaging takes place 24 hours after injection, but may also be carried out at 4 and 48 hours.[7][12]
Technetium-99m
The 99mTc product is supplied as a kit with two vials, one containing the
chelating agentethylenediaminediacetic acid (EDDA) and the other the HYNIC-Tyr3-octreotide chelator and somatostatin analog.[13] Approximately 400-700 MBq may be administered, with imaging at 2, 4, and occasionally 24 hours post administration.[14]99mTc based octreotide imaging shows slightly higher sensitivity than 111In.[2][15]
^Garai I, Barna S, Nagy G, Forgacs A (November 2019). "Limitations and pitfalls of 99mTc-EDDA/HYNIC-TOC (Tektrotyd) scintigraphy". Nuclear Medicine Review. Central & Eastern Europe (in German). 19 (2): 93–98.
doi:
10.1007/s00117-019-0574-x.
PMID27479887.
S2CID199443705.
^Kwekkeboom DJ, Krenning EP (April 2002). "Somatostatin receptor imaging". Seminars in Nuclear Medicine. 32 (2): 84–91.
doi:
10.1053/snuc.2002.31022.
PMID11965603.
^
abBombardieri E, Ambrosini V, Aktolun C, Baum RP, Bishof-Delaloye A, Del Vecchio S, et al. (July 2010). "111In-pentetreotide scintigraphy: procedure guidelines for tumour imaging". European Journal of Nuclear Medicine and Molecular Imaging. 37 (7): 1441–1448.
CiteSeerX10.1.1.609.1835.
doi:
10.1007/s00259-010-1473-6.
PMID20461371.
S2CID398563.