[123I]Mtr-TOCA, a radioiodinated and carbohydrated analogue of octreotide: Scintigraphic comparison with [111In]octreotide

Alexander Stahl, Günther Meisetschläger, Margret Schottelius, Kjerstin Bruus-Jensen, Ingo Wolf, Klemens Scheidhauer, Markus Schwaiger

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Purpose: Scintigraphy with maltotriose-[123I] Tyr 3-octreotate ([123I]Mtr-TOCA) is compared with [ 111In] DTPA-Phe1-octreotide ([111In]OC) to assess the differences in pharmacokinetics and imaging properties as well as to estimate the therapeutic potential of the corresponding [131I]Mtr- TOCA. Methods: Six patients with somatostatin receptor (sstr)-positive tumours were assessed using a dual-head gamma camera. After injection of 137±28 MBq [123I]Mtr-TOCA, dynamic data acquisition of the upper abdomen (30 min) was performed followed by whole-body scans at 0.5 h, 1 h, 3 h and 20 h as well as by SPECT imaging (tumour) at 2 h. [111In]OC scintigraphy was performed by acquiring whole-body scans (4 h, 24 h) and SPECT (24 h). Using a region of interest (ROI) method, tissue and tumour bound activity was assessed and dosimetry performed. Results: [123I]Mtr-TOCA shows rapid tumour uptake. Up to 4 h, tumour/organ (tu/org) ratios are stable and generally higher than with [111In]OC. From 3 h to 20 h, tu/org ratios increase for spleen, remain stable for liver and decrease significantly for all other tissues. In contrast, with [111In]OC, tu/org ratios decrease slightly between 4 h and 24 h for liver, spleen and kidney and increase for all other tissues. On [ 123I]Mtr-TOCA scintigraphy, a total of 27 lesions are detected, whereas 33 lesions are detected on [111In]OC scintigraphy (p=0.50). Effective patient absorbed dose is 1.9±0.9 mSv per 100 MBq [ 123I]Mtr-TOCA. Conclusion: Compared with [111In]OC, [ 123I]Mtr-TOCA enables faster imaging of sstr-positive tumours with a lower radiation burden to the patient. [123I]Mtr-TOCA and [ 111In] OC allow for tumour imaging with almost identical contrast and diagnostic yield. As regards peptide receptor radionuelide therapy, radioiodinated Mtr-TOCA is hampered by limited intratumoural activity retention.

Original languageEnglish
Pages (from-to)45-52
Number of pages8
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Volume33
Issue number1
DOIs
StatePublished - Jan 2006
Externally publishedYes

Keywords

  • Neuroendocrine tumour
  • Peptide receptor radionuclide therapy
  • Somatostatin analogue
  • Somatostatin receptor scintigraphy

Fingerprint

Dive into the research topics of '[123I]Mtr-TOCA, a radioiodinated and carbohydrated analogue of octreotide: Scintigraphic comparison with [111In]octreotide'. Together they form a unique fingerprint.

Cite this