title: National Electrical Manufacturers Association NU-4 performance evaluation of the PET component of the NanoPET/CT preclinical PET/CT scanner.
abstract: The NanoPET/CT represents the latest generation of commercial preclinical PET/CT systems. This article presents a performance evaluation of the PET component of the system according to the National Electrical Manufacturers Association (NEMA) NU-4 2008 standard.
  
  
  METHODS
  The NanoPET/CT consists of 12 lutetium yttrium orthosilicate:cerium modular detectors forming 1 ring, with 9.5-cm axial coverage and a 16-cm animal port. Each detector crystal is 1.12 × 1.12 × 13 mm, and 1 module contains 81 × 39 of these crystals. An optical light guide transmits the scintillation light to the flat-panel multianode position-sensitive photomultiplier tubes. Analog-to-digital converter cards and a field-programmable gate array-based data-collecting card provide the readout. Spatial resolution, sensitivity, counting rate capabilities, and image quality were evaluated in accordance with the NEMA NU-4 standard. Energy and temporal resolution measurements and a mouse imaging study were performed in addition to the standard.
  
  
  RESULTS
  Energy resolution was 19% at 511 keV. The spatial resolution, measured as full width at half maximum on single-slice rebinning/filtered backprojection-reconstructed images, approached 1 mm on the axis and remained below 2.5 mm in the central 5-cm transaxial region both in the axial center and at one-quarter field of view. The maximum absolute sensitivity for a point source at the center of the field of view was 7.7%. The maximum noise equivalent counting rates were 430 kcps at 36 MBq and 130 kcps at 27 MBq for the mouse- and rat-sized phantoms, respectively. The uniformity and recovery coefficients were measured with the image-quality phantom, giving good-quality images. In a mouse study with an (18)F-labeled thyroid-specific tracer, the 2 lobes of the thyroid were clearly distinguishable, despite the small size of this organ. The flexible readout system allowed experiments to be performed in an efficient manner, and the system remained stable throughout.
  
  
  CONCLUSIONS
  The large number of detector crystals, arranged with a fine pitch, results in excellent spatial resolution, which is the best reported for currently available commercial systems. The absolute sensitivity is high over the field of view. Combined with the excellent image quality, these features make the NanoPET/CT a powerful tool for preclinical research.
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK. istvan.szanda@kcl.ac.uk
authors.forename: Istvan
authors.initials: I
authors.lastname: Szanda
authors.forename: Jane
authors.initials: J
authors.lastname: Mackewn
authors.forename: Gergely
authors.initials: G
authors.lastname: Patay
authors.forename: Peter
authors.initials: P
authors.lastname: Major
authors.forename: Kavitha
authors.initials: K
authors.lastname: Sunassee
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Mullen
authors.forename: Gabor
authors.initials: G
authors.lastname: Nemeth
authors.forename: York
authors.initials: Y
authors.lastname: Haemisch
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Blower
authors.forename: Paul K
authors.initials: PK
authors.lastname: Marsden
mesh_terms: D000818:Animals; D005260:Female; D051379:Mice; D064847:Multimodal Imaging / Q000295:instrumentation* / Q000592:standards; D036103:Nanotechnology / Q000295:instrumentation* / Q000592:standards; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography; D051381:Rats; D012015:Reference Standards; D012542:Scattering, Radiation; D012952:Societies / Q000592:standards*; D013997:Time Factors; D014057:Tomography, X-Ray Computed