title: Preliminary study on the differentiation between parapelvic cyst and hydronephrosis with non-calculous using only pre-contrast dual-energy spectral CT scans.
abstract: OBJECTIVE
  To investigate the value of using the quantitative parameters from only the pre-contrast dual-energy spectral CT imaging for distinguishing between parapelvic cyst and hydronephrosis with non-calculous (HNC).
  
  
  METHODS
  This retrospective study was approved by the institutional review board. 28 patients with parapelvic cyst and 24 patients with HNC who underwent standard pre-contrast and multiphase contrast-enhanced dual-energy spectral CT imaging were retrospectively identified. The parapelvic cyst and HNC were identified using the contrast-enhanced scans, and their CT number in the 70-keV monochromatic images, effective atomic number (Zeff), iodine concentration (IC) and water concentration in the pre-contrast images were measured. The slope of the spectral curve (λ) was calculated. The difference in the measurements between parapelvic cyst and HNC was statistically analyzed using SPSS®v. 19.0 (IBM Corp., New York, NY; formerly SPSS Inc., Chicago, IL) statistical software. Receiver-operating characteristic analysis was performed to assess the diagnostic performance.
  
  
  RESULTS
  The CT numbers in the 70-keV images, Zeffand IC values were statistically different between parapelvic cyst and HNC (all p < 0.05). The sensitivity, specificity and accuracy of these parameters for distinguishing between parapelvic cyst and HNC were 89.2%, 73.3% and 82.1%; 86.5%, 43.3% and 67.2%; 91.9%, 40.0% and 68.7%; and 64.9%, 73.3% and 83.6%, respectively, and the combined specificity was 92.9%. There was no statistical difference in λ between the two groups (p > 0.05).
  
  
  CONCLUSIONS
  The quantitative parameters obtained in the pre-contrast dual-energy spectral CT imaging may be used to differentiate between parapelvic cyst and HNC. Advances in knowledge: The pre-contrast dual-energy spectral CT scans may be used to screen parapelvic cysts for patients who are asymptomatic, thereby avoiding contrast-enhanced CT or CT urography examination for these patients to reduce ionizing radiation dose and contrast dose.
authors.affiliation: 1 College of Medical Technology, Shaanxi University of Traditional Chinese Medicine, Xianyang, Shaanxi, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Han
authors.affiliation: 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, Shaanxi, China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Ma
authors.affiliation: 1 College of Medical Technology, Shaanxi University of Traditional Chinese Medicine, Xianyang, Shaanxi, China.
authors.forename: Lequn
authors.initials: L
authors.lastname: Wei
authors.affiliation: 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, Shaanxi, China.
authors.forename: Chenglong
authors.initials: C
authors.lastname: Ren
authors.affiliation: 3 Department of Ultrasound, Xijing Hospital, Fourth Military Medical University of PLA, Xi'an, Shaanxi, China.
authors.forename: Jieli
authors.initials: J
authors.lastname: Zhou
authors.affiliation: 1 College of Medical Technology, Shaanxi University of Traditional Chinese Medicine, Xianyang, Shaanxi, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Shen
authors.affiliation: 2 Department of Radiology, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine, Xianyang, Shaanxi, China.
authors.forename: Taiping
authors.initials: T
authors.lastname: He
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging*; D007668:Kidney / Q000000981:diagnostic imaging; D052177:Kidney Diseases, Cystic / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014567:Urography; D055815:Young Adult
chemical_list: D003287:Contrast Media