title: The Value of Nonenhanced Single-Source Dual-Energy CT for Differentiating Metastases From Adenoma in Adrenal Glands.
abstract: OBJECTIVE
  To evaluate the value of the nonenhanced single-source dual-energy computed tomography (ssDECT) in differentiating metastases from adenomas in adrenal glands.
  
  
  METHODS
  This retrospective study was approved by our Institutional Review Board, and written informed consent was waived. One hundred twelve patients (66 men:46 women; mean age, 58 years) with 63 adrenal metastases (AMs) and 64 adrenal adenomas (AAs) underwent a plain dual-energy spectral CT imaging from August 2011 to December 2013 were included. The fat (water) density (DFa [Wa]) from the material decomposition (MD) images and CT number and effective atomic number (eff-Z) from the virtual monochromatic spectral (VMS) image sets were measured for the AMs and AAs. The spectral Hounsfield unit (HU) curve (CT number as a function of photon energy from 40 to 140 keV) was generated, and its slope (K) was calculated. The difference of these parameters between AMs and AAs was statistically compared by the Wilcoxon rank sum test. Receiver operating characteristic curve (ROC) curves were used to compare the diagnostic efficacies of these measures in the identification of AAs and AMs. The distribution of spectral HU curve was analyzed using the chi-square test in terms of its slope K: ascending (K > 0.1), straight (-0.1 ≤ K ≤ 0.1), and descending (K < -0.1).
  
  
  RESULTS
  1) The CT number (medium, range) of metastases (50.47, 29.93 HU at 40 keV and 29.00, 9.36 HU at 140 keV) was significantly higher than that of adenomas (-0.76, 33.04 to 13.73, 18.96 HU) at each energy level from 40 to 140 keV (P < .05). 2) The fat concentration of metastases (-177.37, 296.38 mg/mL) was statistically lower than that of adenomas (126.73, 328.07 mg/mL; P < .05). 3) The eff-Z of metastases (7.76, 0.23) was significantly higher than that of adenomas (7.42, 0.32; P < .05). 4) With CT number of VMS image at 40 keV of 21.78 HU as a threshold, the sensitivity and specificity for differentiating metastases from adenomas was 92.1% and 76.6%, respectively, and the area under the ROC curve was 0.90. 5) The spectral curve types included 3.2% (2 of 63) ascending, 20.6% (13 of 63) straight, and 76.2% (48 of 63) descending for the metastases, whereas the corresponding numbers were 60.9% (39 of 64), 21.9% (14 of 64), and 17.2% (11 of 64) for the adenomas. The difference was statistically significant (X(2) = 56.63; P < .05).
  
  
  CONCLUSIONS
  The nonenhanced ssDECT enables a multiparametric approach to provide an excellent sensitivity for identifying AMs from AAs.
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, No. 222 Zhongshan Road, Dalian, Liaoning 0086-116011, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Ju
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, No. 222 Zhongshan Road, Dalian, Liaoning 0086-116011, China. Electronic address: dmu_liuailian@126.com.
authors.forename: Ailian
authors.initials: A
authors.lastname: Liu
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, No. 222 Zhongshan Road, Dalian, Liaoning 0086-116011, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, No. 222 Zhongshan Road, Dalian, Liaoning 0086-116011, China.
authors.forename: Yijun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, No. 222 Zhongshan Road, Dalian, Liaoning 0086-116011, China.
authors.forename: Heqing
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, No. 222 Zhongshan Road, Dalian, Liaoning 0086-116011, China.
authors.forename: Meiyu
authors.initials: M
authors.lastname: Sun
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, No. 222 Zhongshan Road, Dalian, Liaoning 0086-116011, China.
authors.forename: Renwang
authors.initials: R
authors.lastname: Pu
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Dalian Medical University, No. 222 Zhongshan Road, Dalian, Liaoning 0086-116011, China.
authors.forename: Anliang
authors.initials: A
authors.lastname: Chen
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging*; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: Adrenal neoplasm; differential diagnosis; quantification; spectral imaging; x-ray computed tomography