Global scaling for semi-quantitative analysis in FP-CIT SPECT

Area of Science:

• Nuclear Medicine
• Neuroimaging
• Radiochemistry

Background:

• Semi-quantitative analysis of dopamine transporter (DAT) availability using 123I-ioflupane (FP-CIT) SPECT relies on uptake ratios relative to a reference region.
• Choosing an appropriate reference region is crucial for accurate DAT quantification and reducing statistical noise.

Purpose of the Study:

• To evaluate the whole brain as a reference region for semi-quantitative analysis of FP-CIT SPECT.
• To determine if using the whole brain as a reference region can minimize statistical noise in DAT availability estimation.

Main Methods:

• 150 FP-CIT SPECT scans were analyzed using Statistical Parametric Mapping (SPM) software.
• Specific binding ratios (SBR) were calculated comparing predefined regions of interest (e.g., putamen) to various reference regions (frontal lobe, occipital lobe, whole brain).
• The 75th percentile, mean, and median of voxel intensities were used to characterize tracer uptake in reference regions; Area Under the Curve (AUC) was the performance measure.

Main Results:

• The highest AUC (0.973) was achieved for putamen SBR when using the 75th percentile of the whole brain as the reference region.
• The lowest AUC (0.937) for putamen SBR was obtained using the mean of the frontal lobe as the reference region.
• The 75th percentile in the whole brain demonstrated superior performance in discriminating between neurodegenerative and non-neurodegenerative scans.

Conclusions:

• The 75th percentile of the whole brain is recommended as the optimal reference region for semi-quantitative FP-CIT SPECT analysis.
• This approach enhances the agreement between semi-quantitative analysis and expert visual evaluation.
• It provides a reliable method to support physicians, especially those with less experience, in interpreting SPECT images for DAT availability.