Carotid Artery Image-Derived Blood Time-Activity Curves on the NeuroEXPLORER: Initial Multitracer Validation Against
Tommaso Volpi1, Jean-Dominique Gallezot2, Shannan Henry2
1Yale University, New Haven, Connecticut tommaso.volpi@yale.edu.
Summary
Image-derived input functions (ID-BTAC) from carotid arteries show promise for PET kinetic modeling. Ultra-high-resolution scanners enable accurate early ID-BTAC extraction, minimizing bias for brain PET studies.
Area of Science:
- Nuclear Medicine
- Radiopharmaceutical Imaging
- Positron Emission Tomography (PET)
Background:
- Arterial blood sampling is the gold standard for obtaining whole-blood time-activity curves (BTAC) in PET kinetic modeling.
- Noninvasive image-derived input functions (ID-BTAC) from carotid arteries (CA) are desirable but limited by partial-volume effects in conventional PET scanners.
- Next-generation ultra-high-resolution PET scanners like NeuroEXPLORER may overcome these limitations.
Purpose of the Study:
- To evaluate the feasibility and accuracy of extracting ID-BTAC from the carotid arteries (common carotid and internal carotid) using the NeuroEXPLORER PET scanner.
- To assess the bias in ID-BTAC for early and late time points across various PET tracers.
- To determine the impact of ID-BTAC bias on kinetic parameter estimates (K1, Ki, VT).
Main Methods:
- Twelve individuals underwent PET scans with five tracers (18F-FDG, 18F-SynVesT-1, 18F-flubatine, 11C-LSN3172176, 11C-PHNO) on the NeuroEXPLORER.
- Arterial blood samples were used for gold-standard BTAC measurement.
- Common carotid and internal carotid ROIs were segmented, and their diameters were adjusted to evaluate partial-volume effects; ID-BTAC AUC bias and kinetic parameter bias were calculated.
Main Results:
- Early ID-BTAC AUC recovery showed minimal bias (CC: -8% ± 5%, IC: -3% ± 7%) for 1-2 mm ROI diameters.
- Late AUC recovery was accurate for 18F-FDG, 11C-PHNO, and 18F-SynVesT-1, but less so for 18F-flubatine and 11C-LSN3172176, correlating with higher late-time activity ratios.
- ID-BTAC biases resulted in small errors for K1 (CC: 5% ± 10%, IC: 3% ± 14%) but larger errors for Ki and VT (CC: -3% ± 20%, IC: -12% ± 25%).
Conclusions:
- A simple ID-BTAC extraction method using ultra-high-resolution PET scanners can accurately recover early BTACs, minimizing spill-out.
- Late BTAC recovery accuracy is tracer-dependent and influenced by background activity.
- Carotid artery ID-BTAC extraction with minimal bias is feasible, offering a noninvasive alternative for brain PET kinetic modeling.
