In the article “Quantification of Task-Specific Glucose Metabolism with Constant Infusion of 18F-FDG” by Hahn et al. (J Nucl Med. 2016;57:1933–1940), the task-specific glucose metabolism as defined in Equations 6 and 7 represents an oversimplification. Considering that the slopes of the baseline and task regressors are different, the model was refined as follows:
Task-specific changes in metabolism are proportional to changes in the slope of the time–activity curve, hence, changing baseline metabolism by βtask × regressortaskEq. 6from which follows that task-specific metabolism is proportional toEq. 7
For the quantification with the Patlak plot, the task regressor was then reconstructed as a linear function with the same slope as defined in the GLM analysis. This assumes that task-related glucose metabolism is constant throughout the task.
As a consequence, the task-specific values in CMRGlu and percentage signal changes are higher by a factor of approximately 4, as shown in the table below. Since this factor slightly varies across subjects and regions, the statistics were adapted but the interpretations remained stable. The authors regret the error.
- © 2018 by the Society of Nuclear Medicine and Molecular Imaging.