Abstract
BackgroundA kinetic model analysis was recently proposed to estimate the 18F-fluorodeoxyglucose (18F-FDG) integrated activity in an arbitrary tissue that uses tracer uptake and release rate constants. The aim of the current theoretical paper was to estimate 18F-FDG integrated activity using one standardized uptake value (SUV).MethodsA further kinetic model analysis allowed us to derive an analytical solution for integrated activity determination, involving both irreversible and reversible trapping. It only uses SUV, which is uncorrected for 18F physical decay (SUVuncorr, in g.mL−1) and is assessed about its peak value. Measurement uncertainty of the estimate was also assessed.ResultsIn a tissue (volume V, in mL) that irreversibly traps 18F-FDG, the total number of disintegrations can be estimated as: ÃC = 162 * 105 * SUVuncorr * V * ID / W (ID, injected dose, in MBq; W, patient’s weight, in kg), where SUVuncorr is a mean over V and is assessed between 55 and 110 min after tracer injection. The relative uncertainty ranges between 18% and 30% (the higher the uptake, the lower the uncertainty). Comparison with the previous Zanotti-Fregonara’s model applied to foetus showed less than 16% difference. Furthermore, calculated integrated activity estimates were found in good agreement with Mejia’s results for healthy brain, lung and liver that show various degrees of tracer trapping reversibility and various fractions of free tracer in blood and interstitial volume.ConclusionEstimation of integrated activity in an arbitrary tissue using one SUV value is possible, with measurement uncertainty related to required assumptions. A formula allows quick estimation that does not underestimate integrated activity so that it could be helpful in circumstances such as accidental exposure, or for epidemiologic purposes such as in patients having undergone several examinations.
Highlights
A kinetic model analysis was recently proposed to estimate the 18F-fluorodeoxyglucose (18F-FDG) integrated activity in an arbitrary tissue that uses tracer uptake and release rate constants
An estimate of integrated activity occurring in a tissue volume (V, in mL) can be computed from either Equation 8 or 9, and using AUCNIF / λCpN(tpeak) = 269 min, as
This estimation requires the following: (a) the use of a population-based input function [15], which is involved in the [AUCNIF / λCpN(tpeak)] ratio (Equations 8 and 9) and (b) the use of standardized uptake value (SUV), which is uncorrected for 18F physical decay and is assessed about its peak value
Summary
A kinetic model analysis was recently proposed to estimate the 18F-fluorodeoxyglucose (18F-FDG) integrated activity in an arbitrary tissue that uses tracer uptake and release rate constants. In all nuclear medicine procedures, it is important to assess the absorbed dose deposited from internally distributed radionuclides This assessment requires combination of integrated activity in source regions and of the so-called S values that relate mean. A kinetic model analysis was recently proposed to calculate the integrated activity in an arbitrary tissue for 18F-FDG PET imaging, and its efficacy was demonstrated in the brain [9]. An analytical solution derived from a kinetic model analysis was established, involving a population-based input function This analytical solution allows determination of integrated activity that only uses SUV uncorrected for 18F physical decay (SUVuncorr) and assessed about its peak. This work assesses the measurement uncertainty of the integrated activity estimation that is related to required assumptions
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