Differences between the image-derived input functions of the descending aorta and carotid artery in brain pharmacokinetic parametric analysis.

Objectives: This study aimed to quantitatively reveal the difference between the descending aorta IDIF (IDIFa) and carotid artery IDIF (IDIFc) in the task of brain pharmacokinetic parametric analysis.

Methods: 18F-FDG dynamic PET data from 50 patients collected by UIH uEXPLORER PET/CT were used to extract the IDIFa and IDIFc; the Patlak graphical model (PGM) and irreversible 2-tissue compartmental model (2TCM) were applied for brain pharmacokinetic parametric analysis. The Patlak Ki and Vt images yielded by the two types of IDIFs are compared using relative error (RE), while the parameters K1∼k3 and fv were analyzed via paired t-tests to determine the significance of the differences.

Results: : IDIFa and IDIFc had significant differences in peak value (p = 0.0009) and curve integral value (p = 0.0012). Based on PGM, 0-15% REs were found between the Ki and Vt images yielded by IDIFa and IDIFc; based on 2TCM, significant differences were found in brainstem's K1 (p = 0.0009), left cerebellum's k3 (p = 0.0009) and all selected regions' fv and Ki (p < 0.05). Fitting residuals of IDIFa are lower than that of IDIFc without significant differences (p > 0.05).

Conclusions: : IDIFa and IDIFc have different curves characteristics and different brain pharmacokinetic parametric analysis results based on PGM and 2TCM. One should be prudential when using IDIFa to conduct brain dynamic PET parametric analysis.

Advances in knowledge: This study quantitatively compares carotid artery and descending aorta IDIFs in the term of brain pharmacokinetic analysis, providing an important reference for nuclear clinicians.