title: Effect of a Noise-Optimized Second-Generation Monoenergetic Algorithm on Image Noise and Conspicuity of Hypervascular Liver Tumors: An In Vitro and In Vivo Study.
abstract: OBJECTIVE
  The purpose of this study is to investigate whether the reduction in noise using a second-generation monoenergetic algorithm can improve the conspicuity of hypervascular liver tumors on dual-energy CT (DECT) images of the liver.
  
  
  METHODS
  An anthropomorphic liver phantom in three body sizes and iodine-containing inserts simulating hypervascular lesions was imaged with DECT and single-energy CT at various energy levels (80-140 kV). In addition, a retrospective clinical study was performed in 31 patients with 66 hypervascular liver tumors who underwent DECT during the late hepatic arterial phase. Datasets at energy levels ranging from 40 to 80 keV were reconstructed using first- and second-generation monoenergetic algorithms. Noise, tumor-to-liver contrast-to-noise ratio (CNR), and CNR with a noise constraint (CNRNC) set with a maximum noise increase of 50% were calculated and compared among the different reconstructed datasets.
  
  
  RESULTS
  The maximum CNR for the second-generation monoenergetic algorithm, which was attained at 40 keV in both phantom and clinical datasets, was statistically significantly higher than the maximum CNR for the first-generation monoenergetic algorithm (p < 0.001) or single-energy CT acquisitions across a wide range of kilovoltage values. With the second-generation monoenergetic algorithm, the optimal CNRNC occurred at 55 keV, corresponding to lower energy levels compared with first-generation algorithm (predominantly at 70 keV). Patient body size did not substantially affect the selection of the optimal energy level to attain maximal CNR and CNRNC using the second-generation monoenergetic algorithm.
  
  
  CONCLUSIONS
  A noise-optimized second-generation monoenergetic algorithm significantly improves the conspicuity of hypervascular liver tumors.
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, Erwin Rd, Durham, NC 27710.
authors.forename: Daniele
authors.initials: D
authors.lastname: Marin
authors.affiliation: 2 Siemens Medical Solutions USA, Malvern, PA.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Ramirez-Giraldo
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, Erwin Rd, Durham, NC 27710.
authors.forename: Sonia
authors.initials: S
authors.lastname: Gupta
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, Erwin Rd, Durham, NC 27710.
authors.forename: Wanyi
authors.initials: W
authors.lastname: Fu
authors.affiliation: 3 Duke University Eye Center, Duke University Medical Center, Durham, NC.
authors.forename: Sandra S
authors.initials: SS
authors.lastname: Stinnett
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, Erwin Rd, Durham, NC 27710.
authors.forename: Achille
authors.initials: A
authors.lastname: Mileto
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, Erwin Rd, Durham, NC 27710.
authors.forename: Davide
authors.initials: D
authors.lastname: Bellini
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, Erwin Rd, Durham, NC 27710.
authors.forename: Bhavik
authors.initials: B
authors.lastname: Patel
authors.affiliation: 4 Carl E. Ravin Advanced Imaging Laboratories (RAI Laboratories), Duke University Medical Center, Durham, NC.
authors.forename: Ehsan
authors.initials: E
authors.lastname: Samei
authors.affiliation: 1 Department of Radiology, Duke University Medical Center, Erwin Rd, Durham, NC 27710.
authors.forename: Rendon C
authors.initials: RC
authors.lastname: Nelson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002277:Carcinoma / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D015900:Radiography, Dual-Energy Scanned Projection; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: MDCT; dual-energy CT; hypervascular liver tumors; monoenergetic reconstruction algorithm; noise