title: Tumor volumes measured from static and dynamic 18F-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography scan: comparison of different methods using magnetic resonance imaging as the criterion standard.
abstract: OBJECTIVE
  The objective of this study was to compare the accuracy of calculating the primary tumor volumes using a gradient-based method and fixed threshold methods on the standardized uptake value (SUV) maps and the net influx of FDG (Ki) maps from positron emission tomography-computed tomography (PET-CT) images.
  
  
  METHODS
  Newly diagnosed patients with head and neck cancer were recruited, and dynamic PET-CT scan and T2-weighted magnetic resonance imaging were performed. The maps of Ki and SUV were calculated from PET-CT images. The tumor volumes were calculated using a gradient-based method and a fixed threshold method at 40% of maximal SUV or maximal Ki. Four kinds of volumes, VOLKi-Gra (from the Ki maps using the gradient-based method), VOLKi-40% (from the Ki maps using the threshold of 40% maximal Ki), VOLSUV-Gra (from the SUV maps using the gradient-based method), and VOLSUV-40% (from the SUV maps using the threshold of 40% maximal SUV), were acquired and compared with VOLMRI (the volumes acquired on T2-weighted images) using the Pearson correlation, paired t test, and similarity analysis.
  
  
  RESULTS
  Eighteen patients were studied, of which 4 had poorly defined tumors (PDT). The positron emission tomography-derived volumes were as follows: VOLSUV-40%, 2.1 to 41.2 cm (mean [SD], 12.3 [10.6]); VOLSUV-Gra, 2.2 to 28.1 cm (mean [SD], 13.2 [8.4]); VOLKi-Gra, 2.4 to 17.0 cm (mean [SD], 9.5 [4.6]); and VOLKi-40%, 2.7 to 20.3 cm (mean [SD], 12.0 [6.0]). The VOLMRI ranged from 2.9 to 18.1 cm (mean [SD], 9.1 [3.9]). The VOLKi-Gra significantly correlated with VOLMRI with the highest correlation coefficient (PDT included, R = 0.673, P = 0.002; PDT excluded, R = 0.841, P < 0.001) and presented no difference from VOLMRI (P = 0.672 or 0.561, respectively, PDT included and excluded). The difference between VOLKi-Gra and VOLMRI was also the smallest.
  
  
  CONCLUSIONS
  The tumor volumes delineated on the Ki maps using the gradient-based method are more accurate than those on the SUV maps and using the fixed threshold methods.
authors.affiliation: From the *Department of Radiology, Guangzhou Panyu Central Hospital; †Medical Imaging Center, The First Affiliated Hospital of Jinan University, Guangzhou; ‡Department of Radiology, Peking University Shenzhen Hospital, Shenzhen; §Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong Special Administrative Region, China; ∥Department of Radiation Sciences, Radiation Physics, Umeå University, Umeå, Sweden; ¶Department of Radiology, Hospital of Stomatology, Guanghua School of Stomatology; #Department of Radiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China; and **Shenzhen University, Shenzhen, China.
authors.forename: Hanwei
authors.initials: H
authors.lastname: Chen
authors.forename: Jinzhao
authors.initials: J
authors.lastname: Jiang
authors.forename: Junling
authors.initials: J
authors.lastname: Gao
authors.forename: Dan
authors.initials: D
authors.lastname: Liu
authors.forename: Jan
authors.initials: J
authors.lastname: Axelsson
authors.forename: Minyi
authors.initials: M
authors.lastname: Cui
authors.forename: Nan-Jie
authors.initials: NJ
authors.lastname: Gong
authors.forename: Shi-Ting
authors.initials: ST
authors.lastname: Feng
authors.forename: Liangping
authors.initials: L
authors.lastname: Luo
authors.forename: Bingsheng
authors.initials: B
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D005260:Female; D019788:Fluorodeoxyglucose F18; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007479:Iopamidol; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D007479:Iopamidol