RT Journal Article
SR Electronic
T1 Detection of unknown primary in patients with neuroendocrine tumors (NET) using Ga-68 somatostatin receptor (SR) PET/CT: Results in 129 patients
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1347
OP 1347
VO 52
IS supplement 1
A1 Vikas Prasad
A1 Daniel Kaemmerer
A1 U. Settmacher
A1 Dieter Hoersch
A1 Merten Hommann
A1 Richard Baum
YR 2011
UL http://jnm.snmjournals.org/content/52/supplement_1/1347.abstract
AB 1347 Objectives Despite advances in morphological imaging, in roughly 10% of the metastasized NET, the primary site of origin of the tumor remains unknown (CUP NET). New drugs are being developed targeting NET based upon their site of primary. The aim of this study was a) to investigate the diagnostic performance of Ga-68 SR PET/CT for the detection of the site of origin in patients with CUP NET and b) to analyze the causes for false negative results. Methods 129 patients with CUP NET were randomly selected from our NET database. Ga-68 SR PET/CT was performed (including diagnostic CT scan) in all patients. Additionally, FDG PET/CT, endoscopic ultrasonography (EUS)and MRI were performed whenever clinically indicated. Results SR PET/CT detected the primary in 58% of the patients studied. The most common site of origin was the pancreas (pNET) followed by small intestine (SI-NET). The primary tumors had significantly lower somatostatin receptor expression as compared to the metastases. There was a good correlation between SR PET/CT and EUS for pNET; however, EUS was more sensitive for lesions <5 mm in size. In poorly differentiated NET (Ki-67 >20%), the performance of SR PET/CT was significantly lower while FDG PET/CT was more useful in these patients. 13% of the primaries were multifocal. CT detected primary tumors of >1.5 cm in size in 25% of patients with pNET and in 23% of SI-NET patients. Conclusions SR-PET/CT is highly superior to In-111 pentetreotide scintigraphy(reported detection rate in CUP NET 39%) and CT alone. EUS has higher sensitivity for the detection of small pNET. The performance of SR PET/CT is low in NET with a proliferation rate of >20%