A short ¹⁸F-FDG imaging window triple injection neuroimaging protocol for parametric mapping in PET

In parametric PET, kinetic parameters are extracted from dynamic PET images. It is not commonly used in clinical practice because of long scan times and the requirement for an arterial input function (AIF). To address these limitations, we designed an ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) triple injection dynamic PET protocol for brain imaging with a standard field of view PET scanner using a 24-min imaging window and an input function modeled using measurements from a region of interest placed over the left ventricle.

To test the protocol in 6 healthy participants, we examined the quality of voxel-based maps of kinetic parameters in the brain generated using the two-tissue compartment model and compared estimated parameter values with previously published values. We also utilized data from a 36-min validation imaging window to compare (1) the modeled AIF against the input function measured in the validation window; and (2) the net influx rate ( \(K_{i}\) $K_i$ ) computed using parameter estimates from the short imaging window against the net influx rate obtained using Patlak analysis in the validation window.

Compared to the AIF measured in the validation window, the input function estimated from the short imaging window achieved a mean area under the curve error of 9%. The voxel-wise Pearson’s correlation between \(K_{i}\) $K_i$ estimates from the short imaging window and the validation imaging window exceeded 0.95.

The proposed 24-min triple injection protocol enables parametric ¹⁸F-FDG neuroimaging with noninvasive estimation of the AIF from cardiac images using a standard field of view PET scanner.