Does Q.Clear Processing Change PET Ratios? Quantitative Evidence Using BTXBrain-DAT.

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Neuroimaging

Background:

• Bayesian penalized likelihood (BPL) reconstruction algorithms, such as Q.Clear, are used to enhance PET image quality.
• The impact of BPL on quantitative metrics in dopamine transporter (DAT) PET imaging is not fully understood.
• Accurate quantification is crucial for clinical studies and diagnosis.

Purpose of the Study:

• To investigate the effect of Q.Clear (BPL) reconstruction on quantitative metrics in F-18 FP-CIT DAT PET imaging.
• To compare specific binding ratios (SBRs), asymmetry indices, and interregional ratios between conventional OSEM and Q.Clear reconstructions.
• To assess the impact on visual interpretation and reproducibility.

Main Methods:

• Retrospective analysis of 170 paired F-18 FP-CIT PET datasets.
• Reconstruction using conventional 3D-OSEM and Q.Clear.
• Quantification performed with BTXBrain-DAT software for SBRs, asymmetry indices, and interregional ratios.
• Statistical testing, Bland-Altman analysis, and visual reads by nuclear medicine physicians.

Main Results:

• Q.Clear significantly altered all quantitative metrics (p < 0.001), affecting SBRs in all 57 regions.
• Striatal and caudate asymmetry indices differed significantly (p < 0.0001), while putamen index was stable.
• Interregional ratios showed significant differences, but Bland-Altman analysis indicated relative stability for ratios compared to asymmetry indices.
• Visual interpretation was unaffected by reconstruction method.

Conclusions:

• Q.Clear reconstruction substantially influences F-18 FP-CIT PET quantitative analysis, including ratios and asymmetry indices.
• Visual interpretation of DAT PET scans is not affected by Q.Clear processing.
• Caution is advised when using Q.Clear for quantitative analysis, especially in low-uptake regions or multicenter studies.