Image reconstruction using small-voxel size improves small lesion detection for positron emission tomography

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Oncology

Background:

• Positron Emission Tomography/Computed Tomography (PET/CT) is vital in oncology for metabolic and anatomic imaging.
• Limited spatial resolution in PET hinders small lesion detection, causing partial-volume effect (PVE) that degrades image quality.
• Investigating reconstruction techniques is key to overcoming PET imaging limitations.

Purpose of the Study:

• To evaluate the impact of small-voxel (2 mm) versus standard-voxel (4 mm) reconstruction on lesion detection and image quality in PET/CT.
• To assess the influence of varying activity ratios on these reconstruction effects.
• To determine the optimal reconstruction parameters for improved diagnostic accuracy.

Main Methods:

• Utilized National Electrical Manufacturers Association (NEMA) and Micro Hollow-Sphere phantoms filled with [18F]fluorodeoxyglucose (FDG).
• Employed sphere-to-background activity ratios of 2:1, 3:1, 4:1, and 8:1.
• Assessed visual lesion delineation, contrast recovery coefficient (CRC), and contrast-to-noise ratio (CNR) for both 2 mm and 4 mm reconstructions.

Main Results:

• Small-voxel reconstruction significantly improved CRC, CNR, and visual delineation for smaller phantom spheres (≤ 13 mm).
• For larger spheres (≥ 17 mm), CRC was comparable, but CNR was lower with small-voxel reconstruction, without impacting visual delineation.
• The findings highlight the benefit of small-voxel reconstruction for small lesion characterization.

Conclusions:

• Small-voxel reconstruction consistently enhances the precise delineation of small lesions in PET/CT imaging.
• This technique improves lesion contrast and overall image quality, aiding oncologic diagnosis.
• Optimized reconstruction parameters are crucial for maximizing the diagnostic performance of PET/CT.