title: National Electrical Manufacturers Association and Clinical Evaluation of a Novel Brain PET/CT Scanner.
abstract: The aim of this study was to determine the performance of a novel mobile human brain/small-animal PET/CT system. The scanner has a 35.7-cm-diameter bore and a 22-cm axial extent. The detector ring has 7 modules each with 3 × 4 cerium-doped lutetium yttrium orthosilicate crystal blocks, each consisting of 22 × 22 outer-layer and 21 × 21 inner-layer crystals, each layer 1-cm thick. Light is collected by 12 × 12 silicon photomultipliers. The integrated CT can be used for attenuation correction and anatomic localization. The scanner was designed as a low-cost device that nevertheless produces high-quality PET images with the unique capability of battery-powered propulsion, enabling use in many settings.
  
  
  METHODS
  Spatial resolution, sensitivity, and noise-equivalent counting rate were measured based on the National Electrical Manufacturers Association NU2-2012 procedures. Reconstruction was done with tight energy and timing cuts-400-650 keV and 7 ns-and loose cuts-350-700 keV and 10 ns. Additional image quality measurements were made from phantom, human, and animal studies. Performance was compared with a reference scanner with comparable imaging properties.
  
  
  RESULTS
  The full width at half maximum transverse resolution at a 1-cm (10-cm) radius was 3.2 mm (5.2-mm radial, 3.1-mm tangential), and the axial resolution was 3.5 mm (4.0 mm). A sensitivity of 7.5 and 11.7 kcps/MBq at the center for tight and loose cuts, respectively, increased to 8.8 and 13.9 kcps/MBq, respectively, at a 10-cm radial offset. The maximum noise-equivalent counting rate of 19.5 and 22.7 kcps for tight and loose cuts, respectively, was achieved for an activity concentration of 2.9 kBq/mL. Contrast recovery for 4:1 hot cylinder to warm background was 76% for the 25-mm-diameter cylinder but decreased with decreasing cylinder size. The quantitation agreed within 2% of the known activity distribution and concentration. Brain phantom and human scans have shown agreement in SUVs and image quality with the reference scanner.
  
  
  CONCLUSIONS
  We characterized the performance of the NeuroPET/CT and showed images from the first human studies. The study shows that this scanner achieves good performance when spatial resolution, sensitivity, counting rate, and image quality along with a low cost and unique mobile capabilities are considered.
authors.affiliation: The Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts.
authors.forename: Kira S
authors.initials: KS
authors.lastname: Grogg
authors.affiliation: Photo Diagnostic Systems, Inc., Boxborough, Massachusetts; and.
authors.forename: Terrence
authors.initials: T
authors.lastname: Toole
authors.affiliation: The Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts.
authors.forename: Jinsong
authors.initials: J
authors.lastname: Ouyang
authors.affiliation: The Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts.
authors.forename: Xuping
authors.initials: X
authors.lastname: Zhu
authors.affiliation: The Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts.
authors.forename: Marc D
authors.initials: MD
authors.lastname: Normandin
authors.affiliation: The Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts.
authors.forename: Quanzheng
authors.initials: Q
authors.lastname: Li
authors.affiliation: Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts.
authors.forename: Keith
authors.initials: K
authors.lastname: Johnson
authors.affiliation: The Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts.
authors.forename: Nathaniel M
authors.initials: NM
authors.lastname: Alpert
authors.affiliation: The Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts elfakhri.georges@mgh.harvard.edu.
authors.forename: Georges
authors.initials: G
authors.lastname: El Fakhri
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging*; D011211:Electric Power Supplies; D006801:Humans; D059906:Neuroimaging / Q000295:instrumentation; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D015203:Reproducibility of Results; D012449:Safety; D012542:Scattering, Radiation
keywords: NEMA standard; PET/CT; instrumentation