Encrypted login | home

Program Information

Preclinical Dosimetry of 51MnCl2 for Functional Beta Cell Mass Quantification PET Studies

S Graves

S Graves*, R Hernandez , H Valdovinos , P Ellison , T Barnhart , J Engle , W Cai , R Nickles , University of Wisconsin - Madison, Madison, WI


TH-AB-708-8 (Thursday, August 3, 2017) 7:30 AM - 9:30 AM Room: 708

Purpose: Recent preclinical radio-manganese PET studies have shown promise for the non-invasive quantification of functional pancreatic β-cell mass (fBCM). The purpose of this work was to assess the dosimetric feasibility of using ⁵¹MnCl₂ (t₁/₂=46m, β=97%) for clinical PET investigations of fBCM.

Methods: Non-anesthetized ICR mice (n=5) were administered an intravenous bolus of ⁵¹MnCl₂ (~4MBq). µPET/CT scans were acquired, mice were sacrificed, and tissue uptake of Mn was quantified by ex vivo gamma counting. Human dosimetry predictions were made using the OLINDA/EXM package (RADAR Software). Due to rapid tissue localization and slow clearance tracer kinetics, effective organ clearance half-lives were modeled as being equal to the radioactive half-life of ⁵¹Mn. It was assumed that the daughter isotope ⁵¹Cr (t₁/₂=27.7d) remained in the same tissue compartment as the parent isotope. Standard radiation weighting factors were used (γ=1, β=1).

Results: ⁵¹MnCl₂ was found to have a cumulative effective dose equivalent (EDE) of 0.0365 mSv/MBq and 0.0425 mSv/MBq for the standard 70kg adult male and female human, respectively. Approximately 1% of this dose was attributable to decay of the daughter isotope, but even this contribution was likely overestimated due to the biological clearance of ⁵¹Cr, which was not herein considered. For a clinical injection of 370MBq of ⁵¹MnCl₂, these values correspond to a cumulative EDE of 13.5mSv and 15.8mSv for an adult male and female human. These values are quite comparable to the average EDE of a clinical [¹⁸F]-FDG procedure of 14.1mSv (Mettler Jr. et al., Radiology, 2004). These results suggest that it would be possible to perform up to three ⁵¹Mn-PET studies in healthy or type-I diabetic volunteers without exceeding annual ICRP dose limits.

Conclusion: Human dosimetry predictions for ⁵¹MnCl₂ have been made using dynamic PET data in a murine animal model. These predictions indicate that ⁵¹MnCl₂ is suitable for use in humans.

Contact Email: