Human Radiation Dosimetry for Orally and Intravenously Administered ¹⁸F-FDG

Abstract

Intravenous access is difficult in some patients referred for 18 F-FDG PET imaging. Extravasation at the injection site and accumulation in central catheters can lead to limited tumor 18 F-FDG uptake, erroneous quantitation, and significant image artifacts. In this study, we compared the human biodistribution and dosimetry for 18 F-FDG after oral and intravenous administrations sequentially in the same subjects to ascertain the dosimetry and potential suitability of orally administered 18 F-FDG as an alternative to intravenous administration. We also compared our detailed intravenous 18 F-FDG dosimetry with older dosimetry data. Methods: Nine healthy volunteers (6 male and 3 female; aged 19-32 y) underwent PET/CT imaging after oral and intravenous administration of 18 F-FDG. Identical preparation and imaging protocols (except administration route) were used for oral and intravenous studies. During each imaging session, 9 whole-body PET scans were obtained at 5, 10, 20, 30, 40, 50, 60, 120, and 240 min after 18 F-FDG administration (370 ± 16 MBq). Source organ contours drawn using CT were overlaid onto registered PET images to extract time-activity curves. Time-integrated activity coefficients derived from time-activity curves were given as input to OLINDA/EXM for dose calculations. Results: Blood uptake after orally administered 18 F-FDG peaked at 45-50 min after ingestion. The oral-to-intravenous ratios of 18 F-FDG uptake for major organs at 45 min were 1.07 ± 0.24 for blood, 0.94 ± 0.39 for heart wall, 0.47 ± 0.12 for brain, 1.25 ± 0.18 for liver, and 0.84 ± 0.24 for kidneys. The highest organ-absorbed doses (μGy/MBq) after oral 18 F-FDG administration were observed for urinary bladder (75.9 ± 17.2), stomach (48.4 ± 14.3), and brain (29.4 ± 5.1), and the effective dose was significantly higher (20%) than after intravenous administration (P 5 0.002). Conclusion: 18 F-FDG has excellent bioavailability after oral administration, but peak organ activities occur later than after intravenous injection. These data suggest PET at 2 h after oral 18 F-FDG administration should yield images that are comparable in biodistribution to conventional clinical images acquired 1 h after injection. Oral 18 F-FDG is a palatable alternative to intravenous 18 F-FDG when venous access is problematic.

Biodistribution and radiation dosimetry of multiple tracers on total-body positron emission tomography/computed tomography

“…In the study by Yu et al , vitamin C was given 30 min after starting the dynamic PET acquisition ( 23 ). Radiation doses of [ 18 F]F-FDG and [ 68 Ga]Ga-FAPI-04 were comparable (2.52E−02±1.04E−02 mSv/MBq and 2.23E−02±7.29E−03 mSv/MBq), the effective dose of [ 18 F]F-FDG was close to that reported in the literature ( 24 ). The corresponding dose of [ 68 Ga]Ga-FAPI-04 was higher than that reported by Giesel et al (1.64E−02 mSv/MBq) ( 5 ).…”

Amyloid pathology induces dysfunction of systemic neurotransmission in aged APPswe/PS2 mice

“…According to the Radioactive Drug Research Committee guidelines in the United States, the effective dose for the whole body should not exceed 30 or 50 mSv/year (FDA 21 CFR 361.1). Previous studies have reported that the whole-body effect dose of PET scans used in the present study was 0.015-0.021 mSv/MBq (mean 0.018 mSv/MBq, Van Laere et al, 2010;Kessler et al, 2014;Sabri et al, 2015;Srinivasan et al, 2020). For an injected dose of 370 MBq, the whole-body was 6.68 mSv/each and 33.4 mSv/five study.…”

Estimation of the Internal Dose Imparted by 18F-Fluorodeoxyglucose to Tissues by Using Fricke Dosimetry in a Phantom and Positron Emission Tomography

“…The activity of 18 F-FDG (0-60 MBq) in the present Fricke dosimeter was chosen, first in relation to the clinical observation of the level of accumulated activity of 18 F-FDG in different tissues. Typically, a patient is injected with 400 MBq FDG (33), and 18 F-FDG time-activity curves for selected source organs are plotted as activity concentration normalized to administered activity (34). Secondly, this activity was chosen to fit in the range of the maximum detection efficiency of the small animal PET scanner (LabPET8 TM ) at the CIMS, with a linear range from noise equivalent count rate to 60 MBq (35).…”