title: Comparison of Ga-68 DOTA-TATE and Ga-68 DOTA-LAN PET/CT imaging in the same patient group with neuroendocrine tumours: preliminary results.
abstract: BACKGROUND
  Recent studies have suggested that PET imaging with Ga-68-labelled DOTA-somatostatin analogues such as octreotide and octreotate is useful in diagnosing neuroendocrine tumours (NETs) and has superior value over both computed tomography and planar and SPECT somatostatin receptor scintigraphy.
  
  
  OBJECTIVE
  The aim of the present study was to evaluate the role of Ga-68 DOTA-lanreotide (Ga-68-DOTA-LAN) in patients with somatostatin receptor (sst)-expressing tumours and to compare the results of Ga-68 DOTA-D-Phe1-Tyr3-octreotate (Ga-68-DOTA-TATE) in the same patient population.
  
  
  METHODS
  Twelve patients with NETs who were referred to our department for somatostatin receptor scintigraphy were included in the study. There were four patients with well-differentiated neuroendocrine tumour (WDNET) grade 1, two patients with WDNET grade 2, and three patients with poorly differentiated neuroendocrine carcinoma (PDNEC) grade 3. There was also one patient with medullary thyroid cancer, one patient with meningioma and one patient with MEN-1. All patients underwent two consecutive PET imaging studies with Ga-68-DOTA-TATE and Ga-68 DOTA-LAN. All images were evaluated visually, and maximum standardized uptake value was calculated for quantitative evaluation.
  
  
  RESULTS
  On visual examination of maximum intensity projection images, GA-68 DOTA-LAN was seen to have high background activity and high bone marrow uptake. Both tracers defined 67 lesions. Ga-68 DOTA-TATE images revealed 63 (94%) clearly defined lesions, missing four lesions. In contrast, Ga-68 DOTA-LAN images defined only 23 (44%) lesions, missing 44 (56%) lesions. Thirty-two bone lesions were detected on Ga-68-DOTA-TATE images. Among them, only 11 (34%) were positive on Ga-68 DOTA-LAN images, whereas 21 (66%) were negative. When we evaluated liver, mediastinum and gastrointestinal tract lesions, Ga-68 DOTA-LAN was seen to be positive for 12 (34%) lesions and negative for 23 (66%) lesions.
  
  
  CONCLUSIONS
  Although the results are preliminary, the image quality obtained by Ga-68-DOTA-TATE seems to be superior to that obtained by Ga-68 DOTA-LAN. With its significantly higher lesion uptake and higher ability to detect lesions, Ga-68-DOTA-TATE seems to be a better radioligand compared with Ga-68-DOTA-LAN for the diagnosis of NETs.
authors.affiliation: Department of Nuclear Medicine, Cerrahpasa Medical Faculty, Istanbul University, Turkey.
authors.forename: Emre
authors.initials: E
authors.lastname: Demirci
authors.forename: Meltem
authors.initials: M
authors.lastname: Ocak
authors.forename: Levent
authors.initials: L
authors.lastname: Kabasakal
authors.forename: Ahmet
authors.initials: A
authors.lastname: Araman
authors.forename: Yildiz
authors.initials: Y
authors.lastname: Ozsoy
authors.forename: Bedii
authors.initials: B
authors.lastname: Kanmaz
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006573:Heterocyclic Compounds, 1-Ring; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000378:metabolism; D009942:Organometallic Compounds; D010456:Peptides, Cyclic; D049268:Positron-Emission Tomography / Q000379:methods*; D017481:Receptors, Somatostatin / Q000378:metabolism; D013004:Somatostatin / Q000031:analogs & derivatives*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D006573:Heterocyclic Compounds, 1-Ring; D009942:Organometallic Compounds; D010456:Peptides, Cyclic; D017481:Receptors, Somatostatin; C558148:gallium 68-DOTA-lanreotide; D013004:Somatostatin; C513399:gallium Ga 68 dotatate