2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography sensitivity to serum glucose: a survey and diagnostic applications.
OBJECTIVE
The positron emission tomography (PET) clinical utility of the sensitivity (gamma) of uptake (Q) to a change in plasma glucose concentration (C) is investigated.


METHODS
Gamma is obtained from data as [ln(Q (2)/Q (1))] / [ln(C(2)/C(1))], using previously published intrapatient studies varying C within a single patient and some interpatient ones. It can be theoretically related to the half-saturation constant in the Michaelis-Menten quantification of competitive uptake. One of its uses is making uptake corrections for desired vs. actual C using Q(2) = Q(1) (C(2)/C(1))(gamma).


RESULTS
Intrapatient studies proved to be preferable to interpatient ones, and a 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-PET survey with analyses for gamma yielded the following result: usually the gamma values of tumors and brain tissues were near -1, whereas those of other noncerebral tissues were near 0. Regarding correcting uptakes for C, instead of a universally assumed and applied gamma = -1, corrections should be for a single tissue using its known gamma. An advantageous use of gamma is predicting how C affects image contrast, including where glucose loading is sometimes preferable to fasting.


CONCLUSIONS
A potentially useful quantifier of uptake sensitivity to plasma glucose has been defined and values obtained. Correcting uptakes to some standard C requires special care. gamma can help PET clinicians select fasting or loading to achieve glucose levels for optimum contrast.
Thie
Joseph A
JA
Graduate School of Medicine, University of Tennessee, Knoxville, TN, USA. jathie@utk.edu
Smith
Gary T
GT
Hubner
Karl F
KF
D001786:Blood Glucose / Q000378:metabolism*; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D019788:Fluorodeoxyglucose F18; D006801:Humans; D049268:Positron-Emission Tomography / Q000379:methods* / Q000592:standards
D001786:Blood Glucose; D019788:Fluorodeoxyglucose F18