title: Intra-individual comparison of PET/CT with different body weight-adapted FDG dosage regimens.
abstract: BACKGROUND
  18F-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/ computed tomography (CT) imaging demands guidelines to safeguard sufficient image quality at low radiation exposure. Various FDG dose regimes have been investigated; however, body weight-adapted dose regimens and related image quality (IQ) have not yet been compared in the same patient.
  
  
  OBJECTIVE
  To investigate the relationship between FDG dosage and image quality in PET/CT in the same patient and determine prerequisites for low dosage scanning.
  
  
  METHODS
  This study included 61 patients undergoing a clinically indicated PET/CT imaging study and follow-up with a normal (NDS, 5 MBq/kg body weight [BW]) and low dosage scanning protocol (LDS, 4 MBq/kg BW), respectively, using a Discovery VCT64 scanner. Two blinded and independent readers randomly assessed IQ of PET using a 5-point Likert scale and signal-to-noise ratio (SNR) of the liver.
  
  
  RESULTS
  Body mass index (BMI) was significantly lower at LDS (P = 0.021) and represented a significant predictor of SNR at both NDS (P < 0.001) and LDS (P = 0.005). NDS with a mean administered activity of 340 MBq resulted in significantly higher IQ (P < 0.001) and SNR as compared with LDS with a mean of 264 MBq (F-value = 23.5, P < 0.001, mixed model ANOVA adjusted for covariate BMI). Non-diagnostic IQ at LDS was associated with a BMI > 22 kg/m(2).
  
  
  CONCLUSIONS
  FDG dosage significantly predicts IQ and SNR in PET/CT imaging as demonstrated in the same patient with optimal IQ achieved at 5 MBq/kg BM. PET/CT imaging at 4 MBq/kg BW may only be recommended in patients with a BMI ≤ 22 kg/m(2) to maintain diagnostic IQ.
authors: Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland ; Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland.
authors: Jan H
authors: JH
authors: Geismar
authors: Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland ; Division of Neuroradiology, University Hospital Zurich, Zurich, Switzerland ; Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.
authors: Paul
authors: P
authors: Stolzmann
authors: Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.
authors: Bert-Ram
authors: BR
authors: Sah
authors: Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland ; Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.
authors: Irene A
authors: IA
authors: Burger
authors: Division of Biostatistics, Institute of Social- and Preventive Medicine, University of Zurich, Switzerland.
authors: Burkhardt
authors: B
authors: Seifert
authors: Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland ; GE Healthcare, Waukesha, Wisconsin, USA.
authors: Gaspar
authors: G
authors: Delso
authors: Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.
authors: Gustav K
authors: GK
authors: von Schulthess
authors: Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland ; Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.
authors: Patrick
authors: P
authors: Veit-Haibach
authors: Division of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.
authors: Lars
authors: L
authors: Husmann
keywords: 18F-fluorodeoxyglucose (18F-FDG); Medical oncology; computed tomography (CT); dosage; image enhancement; positron-emission tomography (PET); radiation protection