Pancreatic receptors: initial feasibility studies with a targeted contrast agent for MR imaging

Radiology. 1994 Nov;193(2):527-31. doi: 10.1148/radiology.193.2.7972773.


Purpose: To evaluate cholecystokinin (CCK) as a target-specific vector for magnetic resonance (MR) receptor imaging of rat pancreas.

Materials and methods: Monocrystalline iron oxide (MION) was labeled with CCK by noncovalent attachment. Receptor specificity of the conjugate was determined with competitive binding studies. Pharmacologic determinations were blood half-lives, biodistribution, time responses, dose responses, and limited toxicity.

Results: Specific cell binding of MION-20-CCK was saturable and inhibitable by a CCK antagonist. Blood half-life of MION-20-CCK was 20 minutes, which was shorter than that of unlabeled MION. Biodistribution studies showed a statistically significant decrease in relaxation times in pancreatic tissues from 42.7 msec +/- 2.0 to 33.8 msec +/- 1.4 (P < or = .05) but not in tumor after administration of MION-20-CCK. The half-life of MION-20-CCK in the pancreas was 3 weeks; no signs of toxicity were shown at the level tested.

Conclusion: Target-specific MR imaging of pancreatic receptors is feasible. Additional studies are necessary to perfect binding strategies, optimize preparations, and scale up synthesis for imaging in other species.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acute Disease
  • Animals
  • Cholecystokinin*
  • Contrast Media* / pharmacokinetics
  • Dose-Response Relationship, Drug
  • Ferrosoferric Oxide
  • Iron* / pharmacokinetics
  • Magnetic Resonance Imaging*
  • Male
  • Mammary Neoplasms, Experimental / diagnosis
  • Neoplasm Transplantation
  • Oxides* / pharmacokinetics
  • Pancreas / anatomy & histology*
  • Pancreas / metabolism
  • Pancreatitis / diagnosis
  • Rats
  • Rats, Inbred F344
  • Rats, Sprague-Dawley
  • Receptors, Cholecystokinin* / metabolism


  • Contrast Media
  • Oxides
  • Receptors, Cholecystokinin
  • Cholecystokinin
  • Iron
  • Ferrosoferric Oxide