Image-derived Input Function in brain [¹⁸F]FDG PET data: which alternatives to the carotid siphons?

Area of Science:

• Nuclear medicine
• Neuroimaging
• Radiochemistry

Background:

• Accurate quantification of brain [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography (PET) data relies on an input function.
• The image-derived input function (IDIF) is a noninvasive alternative to arterial sampling but faces challenges with segmentation and spillover when using internal carotid arteries (ICAs).

Purpose of the Study:

• To evaluate the feasibility of extracting IDIFs from common carotid arteries (CCAs) and the superior sagittal sinus (SSS) as alternatives to ICAs.
• To compare IDIFs from different vascular sites and assess their impact on fractional uptake rate (Kr) estimations in glioma patients.

Main Methods:

• Dynamic [¹⁸F]FDG PET/MR imaging was performed on a cohort of glioma patients.
• IDIFs were extracted from internal carotid arteries (ICAs), common carotid arteries (CCAs), and the superior sagittal sinus (SSS).
• Comparisons were made regarding IDIF peak amplitude, shape, and resulting Kr values (absolute, grey/white matter ratio, spatial patterns).

Main Results:

• The study assessed IDIFs from ICA, CCA, and SSS in glioma patients.
• Comparisons focused on IDIF characteristics and their influence on fractional uptake rate (Kr) estimations.
• CCA emerged as a promising alternative site for IDIF extraction.

Conclusions:

• Common carotid artery (CCA) extraction presents a feasible and potentially more accessible noninvasive method for obtaining image-derived input functions (IDIFs).
• This approach could enable fully noninvasive absolute PET quantification in clinical populations, particularly for brain imaging in glioma patients.
• Further validation of CCA as an IDIF source could enhance routine clinical PET data analysis.