Abstract
Dosimetry of [18F]-MFBG in normal adults and extrapolation to pediatric patients - Comparison to measured dosimetry in neural crest tumor patients
The Journal of nuclear medicine (1978), Vol.66(Suppl 1), 251136
06/01/2025
Abstract
Introduction: [18F]-MFBG is being developed as a fluorinated alternative to [123I]-MIBG, widely utilized for imaging pediatric patients with neuroblastoma. Radiation dosimetry of [18F]-MFBG in healthy adults has not yet been reported. The purposes of this work were to: a) measure the biodistribution and radiation dosimetry of [18F]-MFBG in healthy adults; b) model the dosimetry in standard pediatric age groups; and c) compare the dosimetry estimates (measured and modeled) to published results from patients with neural crest tumors. Methods: As part of a Phase 1 trial (NCT# 04535193), sequential dynamic and serial static PET/CT imaging was acquired in five healthy volunteers (4 men aged 25 31; 1 female aged 41) following intravenous administration of 370 MBq of [18F]-MFBG. Dynamic imaging was performed for the first 30 minutes post-administration (22 cm axial field of view, centered over heart). Static PET/CT acquisitions were acquired at 35, 120, and 180 minutes post-administration, with the field of view covering vertex to mid-thigh. Images were reconstructed with corrections for uniformity (normalization), dead time, attenuation, scatter, decay, and random coincidence events. Iterative reconstruction was used with point spread function modeling (4 iterations, 12 subsets). Organs of interest were segmented on CT imaging manually or using MIM Prot g AI. Organ time-activity curve data were fit by exponential or bi-exponential regression, and pediatric time-integrated activity coefficients were determined by assuming (1) equivalent organ SUV-mean values compared to measured data and (2) organ masses derived from ICRP 89 phantoms. Dosimetry calculations were performed using OLINDA/EXM v2.2. The measured adult dosimetry results were compared to published dosimetry values for [18F]-MFBG in patients with neural crest tumors (neuroblastoma and pheochromocytoma). Results: [18F]MFBG cleared rapidly from the blood, with rapid uptake into normal organs. The critical organ (highest dose) was the urinary bladder wall (72 13 mGy), followed by the adrenals (18 13 mGy) and uterus (17 mGy, n=1). The mean measured effective dose (ED) (ICRP 103 tissue weighting factors) was 0.0202 mSv/MBq. For male/female patients, the extrapolated pediatric ED estimates were: 0.0246/0.0262 mSv/MBq (15 y.o.), 0.0389/0.0378 mSv/MBq (10 y.o.), 0.060/0.059 mSv/MBq (5 y.o.), 0.111/0.108 mSv/MBq (1 y.o.), and 0.273/0.274 mSv/MBq (newborn) (Figure). Mean measured ED was in reasonable agreement with the published values of 0.019-0.023 mSv/MBq from 12 neural crest tumor patients ages 5-64 (J Nucl Med 2018; 59:147 153; Eur J Nucl Med Molec Imag 2023; 50:1146 1157). Conclusions: [18F]-MFBG is a promising imaging agent for patients with neuroblastoma and other neural crest tumors. Measured dosimetry values in healthy adults were comparable to the aggregate published results from dosimetry measurements in pediatric and adult neural crest tumor patients, suggesting limited effect of tumor burden on dose-relevant biodistribution. Overall, dose estimates for [18F]-MFBG are similar to other 18F-labeled radiopharmaceuticals and should not represent a radiation safety concern for eventual clinical use of this agent.
Details
- Title: Subtitle
- Dosimetry of [18F]-MFBG in normal adults and extrapolation to pediatric patients - Comparison to measured dosimetry in neural crest tumor patients
- Creators
- Stephen GravesJagnat NarulaVikram AgarwalArnold Jacobson
- Resource Type
- Abstract
- Publication Details
- The Journal of nuclear medicine (1978), Vol.66(Suppl 1), 251136
- ISSN
- 0161-5505
- eISSN
- 1535-5667
- Publisher
- Society of Nuclear Medicine
- Language
- English
- Date published
- 06/01/2025
- Academic Unit
- Roy J. Carver Department of Biomedical Engineering; Radiology; Radiation Oncology
- Record Identifier
- 9984927087202771
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