Abstract

99mTc-DMSA is one of the most commonly used pediatric nuclear medicine imaging agents. Nevertheless, there are no pharmacokinetic (PK) models for 99mTc-DMSA in children, and currently available pediatric dose estimates for 99mTc-DMSA use pediatric S values with PK data derived from adults. Furthermore, the adult PK data were collected in the mid-70’s using quantification techniques and instrumentation available at the time. Using pediatric imaging data for DMSA, we have obtained kinetic parameters for DMSA that differ from those applicable to adults.MethodsWe obtained patient data from a retrospective re-evaluation of clinically collected pediatric SPECT images of 99mTc-DMSA in 54 pediatric patients from Boston’s Children Hospital (BCH), ranging in age from 1 to 16 years old. These were supplemented by prospective data from twenty-three pediatric patients (age range: 4 months to 6 years old).ResultsIn pediatric patients, the plateau phase in fractional kidney uptake occurs at a fractional uptake value closer to 0.3 than the value of 0.5 reported by the International Commission on Radiological Protection (ICRP) for adult patients. This leads to a 27% lower time-integrated activity coefficient in pediatric patients than in adults. Over the age range examined, no age dependency in uptake fraction at the clinical imaging time was observed. Female pediatric patients had a 17% higher fractional kidney uptake at the clinical imaging time than males (P < 0.001).ConclusionsPediatric 99mTc-DMSA kinetics differ from those reported for adults and should be considered in pediatric patient dosimetry. Alternatively, the differences obtained in this study could reflect improved quantification methods and the need to re-examine DMSA kinetics in adults.

Highlights

  • The activity administered to pediatric nuclear medicine patients is currently based on the joint, consensus guidelines from the Society of Nuclear Medicine and Molecular Imaging (SNMMI) and the European Association of Nuclear Medicine (EANM) [1,2,3]

  • Pediatric 99mTc-dimercaptosuccinic acid (DMSA) kinetics differ from those reported for adults and should be considered in pediatric patient dosimetry

  • There are no pharmacokinetic (PK) models for 99mTcDMSA in children and currently available pediatric dose estimates for 99mTc-DMSA use pediatric S values with PK data derived from adults using instrumentation and quantification techniques dating to the mid-70’s [4,5,6,7,8,9]

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Summary

Introduction

The activity administered to pediatric nuclear medicine patients is currently based on the joint, consensus guidelines from the Society of Nuclear Medicine and Molecular Imaging (SNMMI) and the European Association of Nuclear Medicine (EANM) [1,2,3]. These guidelines assure consistency across different institutions while promoting dose reduction; the recommended administered activities are based on a consensus approach rather than on a rigorous and quantitative approach. As part of an ongoing dose optimization effort [10, 11, 14, 15], we examine whether the current reference (ICRP 53 [4]) DMSA PK model is consistent with model parameters obtained by 99mTc-DMSA imaging quantification in children using current quantification techniques and imaging technologies

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