Image reconstruction using small-voxel size improves image quality for positron emission tomography

Small-voxel reconstruction in positron emission tomography

Abstract

Background. PET/CT imaging is widely used in oncology and provides both metabolic and anatomic information. Because of the relatively poor spatial resolution of PET, the detection of small lesions is limited. The low spatial resolution introduces the partial-volume effect (PVE) which negatively affects images both qualitatively and quantitatively. The aim of our study was to investigate the effect of small-voxel (2 mm in-line pixel size) vs standard-voxel (4 mm in-line pixel size) reconstruction on lesion detection and image quality in a range of activity ratios.

Materials and methods. The NEMA body phantom and the Micro Hollow-Sphere phantom spheres were filled with a solution of [18F]fluorodeoxyglucose ([18F]FDG) in sphere-to-background ratios of 2:1, 3:1, 4:1 and 8:1. In all images reconstructed with 2 mm and 4 mm in-line pixel size the contrast recovery coefficient (CRC) and contrast-to-noise ratio (CNR) were evaluated.

Results. For smaller (≤ 13 mm) phantom spheres, significantly higher CRC and CNR using small-voxel reconstructions were found. CRC did not differ significantly for larger (≥ 17 mm) spheres using 2 mm and 4 mm in-line pixel size.

Conclusions. Small-voxel reconstruction appears to consistently improve precise small lesion localization, lesion contrast and image quality.