title: Current generation time-of-flight (18)F-FDG PET/CT provides higher SUVs for normal adrenal glands, while maintaining an accurate characterization of benign and malignant glands.
abstract: OBJECTIVE
  Modern PET/CT scanners have significantly improved detectors and fast time-of-flight (TOF) performance and this may improve clinical performance. The aim of this study was to analyze the impact of a current generation TOF PET/CT scanner on standardized uptake values (SUV), lesion-background contrast and characterization of the adrenal glands in patients with suspected lung cancer, in comparison with literature data and commonly used SUV cut-off levels.
  
  
  METHODS
  We included 149 adrenal glands from 88 patients with suspected lung cancer, who underwent (18)F-FDG PET/CT. We measured the SUVmax in the adrenal gland and compared this with liver SUVmean to calculate the adrenal-to-liver ratio (AL ratio). Results were compared with literature derived with older scanners, with SUVmax values of 1.0 and 1.8 for normal glands [1, 2]. Final diagnosis was based on histological proof or follow-up imaging. We proposed cut-off values for optimal separation of benign from malignant glands.
  
  
  RESULTS
  In 127 benign and 22 malignant adrenal glands, SUVmax values were 2.3 ± 0.7 (mean ± SD) and 7.8 ± 3.2 respectively (p < 0.01). Corresponding AL ratios were 1.0 ± 0.3 and 3.5 ± 1.4 respectively (p < 0.01). With a SUVmax cut-off value of 3.7, 96% sensitivity and 96% specificity was reached. An AL ratio cut-off value of 1.8 resulted in 91% sensitivity and 97% specificity. The ability of both SUVmax and AL ratio to separate benign from malignant glands was similar (AUC 0.989 vs. 0.993, p = 0.22).
  
  
  CONCLUSIONS
  Compared with literature based on the previous generation of PET scanners, current generation TOF (18)F-FDG PET/CT imaging provides higher SUVs for benign adrenal glands, while it maintains a highly accurate distinction between benign and malignant glands. Clinical implementation of current generation TOF PET/CT requires not only the use of higher cut-off levels but also visual adaptation by PET readers.
authors.affiliation: Department of Nuclear Medicine, Isala, Dokter van Heesweg 2, 8025 AB, Zwolle, The Netherlands. d.koopman@isala.nl.|MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands. d.koopman@isala.nl.
authors.forename: Daniëlle
authors.initials: D
authors.lastname: Koopman
authors.affiliation: Department of Medical Physics, Isala, Zwolle, The Netherlands.
authors.forename: Jorn A
authors.initials: JA
authors.lastname: van Dalen
authors.affiliation: Department of Pulmonology, Isala, Zwolle, The Netherlands.
authors.forename: Jos A
authors.initials: JA
authors.lastname: Stigt
authors.affiliation: MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
authors.forename: Cornelis H
authors.initials: CH
authors.lastname: Slump
authors.affiliation: Department of Nuclear Medicine, Isala, Dokter van Heesweg 2, 8025 AB, Zwolle, The Netherlands.
authors.forename: Siert
authors.initials: S
authors.lastname: Knollema
authors.affiliation: Department of Nuclear Medicine, Isala, Dokter van Heesweg 2, 8025 AB, Zwolle, The Netherlands.
authors.forename: Pieter L
authors.initials: PL
authors.lastname: Jager
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D000311:Adrenal Glands / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D000368:Aged; D001692:Biological Transport; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008297:Male; D064847:Multimodal Imaging; D009929:Organ Size; D049268:Positron-Emission Tomography; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG; Adrenal glands; Lung cancer; PET/CT