Initial direct comparison of 99mTc-TOC and 99mTc-TATE in identifying sites of disease in patients with proven GEP NETs.
The imaging of neuroendocrine tumors has become one of the most significant areas in nuclear oncology. In an attempt to provide high-quality imaging and possible sensitivity at a reduced cost, time, and radiation dose, several (99m)Tc agents have been proposed. The aim of this initial study was to compare the tumor uptake and biodistribution of 2 new 6-hydrazinopyridine-3-carboxylic acid (HYNIC)-derivatized Tyr(3)-octreotide analogs, (99m)Tc-[HYNIC,Tyr(3)]octreotide ((99m)Tc-TOC) and (99m)Tc-[HYNIC,Tyr(3),Thr(8)]octreotide ((99m)Tc-TATE), in patients with somatostatin receptor-expressing tumors.


METHODS
Each of 12 patients with proven gastrointestinal pancreatic neuroendocrine tumors received a mean activity of 520 MBq of (99m)Tc-TOC and (99m)Tc-TATE. Scintigraphy with both tracers was performed 3-4 h after their injection using standard whole-body and SPECT imaging. The images were reviewed subjectively by 2 readers, who reported tumor uptake lesion by lesion.


RESULTS
Both radiotracers demonstrated concordance between the results in 7 patients (58%). In total, 110 sites of disease were identified with (99m)Tc-TOC, compared with 115 with (99m)Tc-TATE. There was 1 case in which (99m)Tc-TOC identified sites of disease not seen on (99m)Tc-TATE imaging but 4 cases in which some sites of disease were seen with (99m)Tc-TATE and not (99m)Tc-TOC.


CONCLUSIONS
In this initial study, both tracers seem to show similar sites of tumor, with (99m)Tc-TATE having a slight edge in the total number of lesions seen, especially in lymph node metastases.
Department of Radiology and Diagnostic Imaging, Postgraduate Medical Centre and Central Clinical Hospital of Ministry of Internal Affairs and Administration, Warsaw, Poland. jaroslaw.cwikla@cskmswia.pl
Jaroslaw B
JB
Cwikla
Renata
R
Mikolajczak
Dariusz
D
Pawlak
John R
JR
Buscombe
Anna
A
Nasierowska-Guttmejer
Andrzej
A
Bator
Helmut R
HR
Maecke
Jerzy
J
Walecki
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007414:Intestinal Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000556:secondary; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000556:secondary; D015282:Octreotide / Q000031:analogs & derivatives*; D015609:Organotechnetium Compounds; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin / Q000096:biosynthesis; D015899:Tomography, Emission-Computed, Single-Photon; D051598:Whole Body Imaging
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D017481:Receptors, Somatostatin; C532019:technetium Tc 99m hydrazinonicotinyl-Tyr(3)-Thr(8)-octreotide; C410263:technetium Tc 99m hydrazinonicotinyl-Tyr(3)-octreotide; D015282:Octreotide