title: 99mTc-depreotide tumour uptake in patients with non-Hodgkin's lymphoma.
abstract: BACKGROUND
  99mTc-depreotide (NeoTect) is a synthetic somatostatin analogue, which binds to somatostatin receptor (SSTR) subtypes 2, 3 and 5. Imaging patients with non-Hodgkin's lymphoma (NHL) using the somatostatin analogue In-pentetreotide (Octreoscan) has demonstrated the feasibility of identifying lymphoma sites with this class of peptide radiopharmaceutical. SSTR peptides can be labelled with beta emitters and, if sufficient tumour uptake relative to normal organs can be demonstrated, therapeutic applications can be considered.
  
  
  METHODS
  In this prospective Institutional Review Board (IRB)-approved study, patients with NHL and a recent computed tomography (CT) examination were eligible. Whole-body and selected single-photon emission computed tomography (SPECT) imaging was performed 1 h after intravenous injection of 99mTc-depreotide. Images were compared with CT scan findings. The radioactivity concentration of 99mTc-depreotide in abdominal/pelvic tumour sites, together with normal organs, was determined and expressed as the percentage of injected activity per gram of tissue (%IA x g).
  
  
  RESULTS
  Paired CT and 99mTc-depreotide images for three patients with indolent and six with aggressive NHL revealed abnormal 99mTc-depreotide uptake corresponding to the tumour seen on CT in seven of these patients. In three of the patients, all known tumour sites were detected on 99mTc-depreotide images. The mean %IA x g for nine abdominal/pelvic tumour foci from four patients was found to be 0.004% (range, 0.001-0.007%). The mean tumour to bone marrow activity concentration ratio in these four patients was found to be 0.94 (range, 0.33-1.40), whereas the tumour to kidney ratio was 0.53 (range, 0.16-0.80).
  
  
  CONCLUSIONS
  Levels of 99mTc-depreotide in tumour suggest at least the possibility of potential therapy with beta emitter-labelled SSTR peptides; however, depreotide itself appears not to be a suitable candidate as a targeting agent due to the relatively high bone marrow concentration.
authors.affiliation: Iowa City Veterans Administration Hospital, Diagnostic Imaging and Radioisotope Therapy Service, Iowa City, IA 52246, USA. david-bushnell@uiowa.edu
authors.forename: David L
authors.initials: DL
authors.lastname: Bushnell
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Menda
authors.forename: Mark T
authors.initials: MT
authors.lastname: Madsen
authors.forename: Brian K
authors.initials: BK
authors.lastname: Link
authors.forename: Daniel
authors.initials: D
authors.lastname: Kahn
authors.forename: Scott M
authors.initials: SM
authors.lastname: Truhlar
authors.forename: Malik
authors.initials: M
authors.lastname: Juweid
authors.forename: Mary
authors.initials: M
authors.lastname: Shannon
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Murguia
mesh_terms: D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000000981:diagnostic imaging* / Q000378:metabolism*; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics*; D011859:Radiography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000493:pharmacokinetics*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
chemical_list: D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D013004:Somatostatin; C444119:technetium Tc 99m depreotide