Image quality evaluation for two different positron emitters in a preclinical pet scanner

• Autor(a) principal: Rodrigo Modesto Gadelha Gontijo
• Data de Publicação: 2020
• Outros Autores: Andréa Vidal Ferreira, Guilherme Cavalcante de Albuquerque Souza, Juliana Batista da Silva, Marcelo Mamede
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/57387
• topic: Image Quality; Preclinical PET scanner; Tomografia por Emissão de Pósitrons; Diagnóstico por Imagem

Positron emission tomography (PET) is widely used in preclinical trials, generating molecular images applied to biochemical, metabolic and functional investigation of organs and tissues. The positron emitters 11C and 18F are relevant for different diseases studies. However, they have different positron energies, ranges, and branching ratio. This could result in a distinct quality between the acquired PET images. Thus, the aim of this study was to evaluate differences in the image quality performance of the PET scanner (LabPET 4, GE) at Molecular Imaging Laboratory (LIM/CDTN) depending on the use of18F or 11C. The study followed the guidelines of the NEMA NU 4-2008 standards and the recommended specific phantom was used in experimental procedures. The NEMA image-quality (IQ) phantom consists of 3 different regions to analyze distinct characteristics: uniformity, recovery coefficients (RCs) and spill-over rations (SOR) in air and water. The IQ phantom was filled with two different aqueous solutions (18F-FDG and 11C-PK11195), both activities calibrated at the beginning of acquisition (3.7MBq). The IQ phantom was placed in the center of the field-of-view (FOV) and measured with the LIM/CDTN typical whole body imaging protocol. The images were reconstructed following the LIM/CDTN standard protocol: MLEM-3D algorithm, 20 iterations, no high-resolution mode, no attenuation or scatter corrections, no post-filtering. PMOD® software was used to perform images post-processing. Uniformity test revealed that 11C PET image roughness is about twice 18F PET image roughness. SOR tests indicated around 15% more counts in cold volumesin 11C PET image than in 18F PET image. The RCs for 11C were systematically lower and with higher percentage standard deviations than those for 18F. This study demonstrated and quantified the best performance of PET images with 18F when compared to 11C. This fact must be taken into account in laboratorial practice, especially when quantitative analyzes are performed.