title: Performance Characteristics of the Whole-Body Discovery IQ PET/CT System.
abstract: The aim of this study was to assess the physical performance of a new PET/CT system, the Discovery IQ with 5-ring detector blocks.Methods:Performance was measured using the National Electrical Manufacturers Association NU2-2012 methodology. Image quality was extended by accounting for different acquisition parameters (lesion-to-background ratios [8:1, 4:1, and 2:1] and acquisition times) and reconstruction algorithms (VUE-point HD [VPHD], VPHD with point-spread-function modeling [VPHD-S], and Q.Clear). Tomographic reconstruction was also assessed using a Jaszczak phantom. Additionally, 30 patient lesions were analyzed to account for differences in lesion volume and SUV quantification between reconstruction algorithms.Results:Spatial resolution ranged from 4.2 mm at 1 cm to 8.5 mm at 20 cm. Sensitivity measured at the center and at 10 cm was 22.8 and 20.4 kps/kBq, respectively. The noise-equivalent counting rate peak was 124 kcps at 9.1 kBq/cm3The scatter fraction was 36.2%. The accuracy of correction for count losses and randoms was 3.9%. In the image quality test, contrast recovery for VPHD, VPHD-S, and Q.Clear ranged from 18%, 18%, and 13%, respectively (hot contrast; 10-mm sphere diameter; ratio, 2:1), to 68%, 67%, and 81%, respectively (cold contrast; 37-mm sphere diameter; ratio, 8:1). Background variability ranged from 3.4%, 3.0%, and 2.1%, respectively (ratio, 2:1), to 5.5%, 4.8%, and 3.7%, respectively (ratio, 8:1). On Q.Clear reconstruction, the decrease in the penalty term (β) increased the contrast recovery coefficients and background variability. With the Jaszczak phantom, image quality increased overall when a reconstruction algorithm modeling the point-spread function was used, and use of Q.Clear increased the signal-to-noise ratio. Lesions analyzed using VPHD-S and Q.Clear had an SUVmeanof 6.5 ± 3 and 7 ± 3, respectively (P< 0.01), and an SUVmaxof 11 ± 4.8 and 12 ± 4, respectively (P< 0.01). No significant difference in mean lesion volume was found between algorithms.Conclusion:Among the various Discovery bismuth germanium oxide-based PET/CT scanners, the IQ with 5-ring detector blocks has the highest overall performance, with improved sensitivity and counting rate performance. Q.Clear reconstruction improves the PET image quality, with higher recovery coefficients and lower background variability.
authors.affiliation: PET Unit, Nuclear Medicine Department, IDI, Hospital Universitari de Bellvitge, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain; and gabriel.reynes@idi.gencat.cat.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Reynés-Llompart
authors.affiliation: PET Unit, Nuclear Medicine Department, IDI, Hospital Universitari de Bellvitge, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain; and.
authors.forename: Cristina
authors.initials: C
authors.lastname: Gámez-Cenzano
authors.affiliation: PET Unit, Nuclear Medicine Department, IDI, Hospital Universitari de Bellvitge, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain; and.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Romero-Zayas
authors.affiliation: PET Unit, Nuclear Medicine Department, IDI, Hospital Universitari de Bellvitge, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain; and.
authors.forename: Laura
authors.initials: L
authors.lastname: Rodríguez-Bel
authors.affiliation: PET Unit, Nuclear Medicine Department, IDI, Hospital Universitari de Bellvitge, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain; and.
authors.forename: José L
authors.initials: JL
authors.lastname: Vercher-Conejero
authors.affiliation: Nuclear Medicine Department, Clínica Universidad de Navarra, Pamplona, Spain.
authors.forename: Josep M
authors.initials: JM
authors.lastname: Martí-Climent
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D009369:Neoplasms / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D000072078:Positron Emission Tomography Computed Tomography / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D051598:Whole Body Imaging / Q000295:instrumentation*
keywords: Discovery IQ; NEMA NU 2-2012; PET/CT; Q.Clear