Comparison of image quality and spatial resolution between F, Ga, and Cu phantom measurements using a digital Biograph Vision PET/CT.

BACKGROUND

PET nuclides can have a considerable influence on the spatial resolution and image quality of PET/CT scans, which can influence diagnostics in oncology, for example. The individual impact of the positron energy of F, Ga, and Cu on spatial resolution and image quality was compared for PET/CT scans acquired using a clinical, digital scanner.

METHODS

A Jaszczak phantom and a NEMA PET body phantom were filled with F-FDG, Ga-HCl, or Cu-HCl, and PET/CT scans were performed on a Siemens Biograph Vision. Acquired images were analyzed regarding spatial resolution and image quality (recovery coefficients (RC), coefficient of variation within the background, contrast recovery coefficient (CRC), contrast-noise ratio (CNR), and relative count error in the lung insert). Data were compared between scans with different nuclides.

RESULTS

We found that image quality was comparable between F-FDG and Cu-HCl PET/CT measurements featuring similar maximal endpoint energies of the positrons. In comparison, RC, CRC, and CNR were degraded in Ga-HCl data despite similar count rates. In particular, the two smallest spheres of 10 mm and 13 mm diameter revealed lower RC, CRC, and CNR values. The spatial resolution was similar between F-FDG and Cu-HCl but up to 18% and 23% worse compared with PET/CT images of the NEMA PET body phantom filled with Ga-HCl.

CONCLUSIONS

The positron energy of the PET nuclide influences the spatial resolution and image quality of a digital PET/CT scan. The image quality and spatial resolution of Ga-HCl PET/CT images were worse than those of F-FDG or Cu-HCl despite similar count rates.