How to harmonize SUVs obtained by hybrid PET/CT scanners with and without point spread function correction

Area of Science:

• Nuclear Medicine Imaging
• Medical Physics
• Radiochemistry

Background:

• State-of-the-art point-spread function (PSF) corrections in PET/CT improve image quality but increase standardized uptake values (SUV) compared to OSEM reconstruction.
• The EANM recommends dual reconstructions for lesion detection and quantitative analysis, posing workflow challenges.
• Quantitative accuracy in PET/CT is crucial for treatment monitoring and clinical trials.

Purpose of the Study:

• To investigate an alternative methodology using a single reconstruction dataset with a post-reconstruction algorithm for SUV harmonization.
• To evaluate the effectiveness of a dedicated post-reconstruction algorithm (EQ-filter) in harmonizing quantitative values between different PET/CT scanners.
• To validate phantom and patient data to confirm the general applicability of the proposed methodology.

Main Methods:

• Data acquisition on Siemens Biograph mCT (lutetium oxyorthosilicate crystals, PSF, TOF) and GE Discovery STE (BGO crystals) PET/CT systems.
• Comparison of EANM double reconstruction method with a post-reconstruction EQ-filter algorithm for SUV harmonization.
• Phantom studies using NEMA IQ and Jaszczak phantoms with varying lesion-to-background ratios, followed by validation on seven oncologic patients with small lesion analysis (0.3-2.6 cm).

Main Results:

• PSF reconstruction resulted in SUV recovery deviations from 16% to 150% compared to OSEM.
• The EQ-filter and double-reconstruction methods reduced discrepancies to below 7%.
• Patient data analysis confirmed phantom findings, with the EQ-filter effectively harmonizing SUV values across scanners (p < 0.05).

Conclusions:

• The EQ-filter provides an effective method for harmonizing SUV values between different PET/CT scanners using a single reconstruction.
• This approach optimizes for maximum lesion detectability while ensuring quantitative accuracy, thereby avoiding the need for a second reconstruction.
• The EQ-filter offers a practical solution for standardized quantitative analysis in multi-center PET/CT studies.