title: Histogram Analysis of Apparent Diffusion Coefficients for Occult Tonsil Cancer in Patients with Cervical Nodal Metastasis from an Unknown Primary Site at Presentation.
abstract: OBJECTIVE
  To explore the added value of histogram analysis of apparent diffusion coefficient (ADC) values over magnetic resonance (MR) imaging and fluorine 18 ((18)F) fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) for the detection of occult palatine tonsil squamous cell carcinoma (SCC) in patients with cervical nodal metastasis from a cancer of an unknown primary site.
  
  
  METHODS
  The institutional review board approved this retrospective study, and the requirement for informed consent was waived. Differences in the bimodal histogram parameters of the ADC values were assessed among occult palatine tonsil SCC (n = 19), overt palatine tonsil SCC (n = 20), and normal palatine tonsils (n = 20). One-way analysis of variance was used to analyze differences among the three groups. Receiver operating characteristic curve analysis was used to determine the best differentiating parameters. The increased sensitivity of histogram analysis over MR imaging and (18)F-FDG PET/CT for the detection of occult palatine tonsil SCC was evaluated as added value.
  
  
  RESULTS
  Histogram analysis showed statistically significant differences in the mean, standard deviation, and 50th and 90th percentile ADC values among the three groups (P < .0045). Occult palatine tonsil SCC had a significantly higher standard deviation for the overall curves, mean and standard deviation of the higher curves, and 90th percentile ADC value, compared with normal palatine tonsils (P < .0167). Receiver operating characteristic curve analysis showed that the standard deviation of the overall curve best delineated occult palatine tonsil SCC from normal palatine tonsils, with a sensitivity of 78.9% (15 of 19 patients) and a specificity of 60% (12 of 20 patients). The added value of ADC histogram analysis was 52.6% over MR imaging alone and 15.8% over combined conventional MR imaging and (18)F-FDG PET/CT.
  
  
  CONCLUSIONS
  Adding ADC histogram analysis to conventional MR imaging can improve the detection sensitivity for occult palatine tonsil SCC in patients with a cervical nodal metastasis originating from a cancer of an unknown primary site.
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: Jeong Hyun
authors.initials: JH
authors.lastname: Lee
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: Hye Ok
authors.initials: HO
authors.lastname: Kim
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: Dae Yoon
authors.initials: DY
authors.lastname: Kim
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: Ra Gyoung
authors.initials: RG
authors.lastname: Yoon
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: So Hyun
authors.initials: SH
authors.lastname: Cho
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: Myeong Ju
authors.initials: MJ
authors.lastname: Koh
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: Namkug
authors.initials: N
authors.lastname: Kim
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: Sang Yoon
authors.initials: SY
authors.lastname: Kim
authors.affiliation: From the Department of Radiology and Research Institute of Radiology (Y.J.C., J.H.L., D.Y.K., R.G.Y., S.H.C., M.J.K., N.K., J.H.B.), Department of Nuclear Medicine (H.O.K.), Department of Convergence Medicine (N.K.), and Department of Otolaryngology (S.Y.K.), University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-Gu, Seoul 138-736, South Korea.
authors.forename: Jung Hwan
authors.initials: JH
authors.lastname: Baek
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009382:Neoplasms, Unknown Primary / Q000175:diagnosis*; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods; D014067:Tonsillar Neoplasms / Q000175:diagnosis* / Q000601:surgery; D014068:Tonsillectomy
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18