title: Non-linear image blending improves visualization of head and neck primary squamous cell carcinoma compared to linear blending in dual-energy CT.
abstract: OBJECTIVE
  To compare non-linear and linear image-blending post-processing techniques in dual-energy CT (DECT) of primary head and neck squamous cell carcinoma (SCC) regarding subjective and objective image quality.
  
  
  METHODS
  Head and neck DECT studies from 69 patients (48 male, 21 female; mean age 62.3 years) were retrospectively evaluated. All tumour lesions were histologically confirmed SCC. Linearly blended 80/140 kVp images series with varying weighting factors of 0.3 (M_0.3), 0.6 and 0.8 were compared with non-linearly blended images. Attenuation of tumour lesion, various soft-tissue structures, the internal jugular vein, and image noise were measured, tumour signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Overall image quality, delineation of tumour lesion, image sharpness, and noise level were rated individually by three radiologists using five-point Likert scales. Interobserver agreement was calculated using intraclass correlation coefficient (ICC).
  
  
  RESULTS
  Enhancement of tumour lesions (non-linear, 137.5 ± 20.1 HU; M_0.3, 92.7 ± 14.4 HU; M_0.6, 110 ± 15.4 HU; M_0.8, 123 ± 18.2 HU), CNR (non-linear, 12 ± 8; M_0.3, 4 ± 4.7; M_0.6, 7.5 ± 5.5; M_0.8, 8 ± 5.5), subjective overall image quality and tumour delineation were significantly increased (all p < 0.001) with the non-linear blending technique compared to all investigated linear blending weighting factors. Overall interobserver agreement was substantial (ICC 0.70; 95% CI: 0.66-0.73).
  
  
  CONCLUSIONS
  Post-processing of DECT using a non-linear blending technique provides improved objective and subjective image quality of head and neck SCC compared to linearly blended images series.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany. Electronic address: janerikscholtz@gmail.com.
authors.forename: J-E
authors.initials: JE
authors.lastname: Scholtz
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Hüsers
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kaup
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Albrecht
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Schulz
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Frellesen
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Bodelle
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wagenblast
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: J M
authors.initials: JM
authors.lastname: Kerl
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: R W
authors.initials: RW
authors.lastname: Bauer
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Lehnert
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: T J
authors.initials: TJ
authors.lastname: Vogl
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
authors.forename: J L
authors.initials: JL
authors.lastname: Wichmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging*; D003287:Contrast Media; D005260:Female; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D007479:Iopamidol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol