title: Accessory spleen versus lymph node: Value of iodine quantification with dual-energy computed tomography.
abstract: OBJECTIVE
  To evaluate whether iodine quantification with Dual-Energy Computed Tomography (DECT) improves the differentiation of accessory spleens (AS) from lymph nodes (LN) compared to CT number measurements.
  
  
  METHODS
  Abdominal DECT images of 75 patients with either AS (n=35) or LN (n=48) (benign entity) were retrospectively evaluated. Hounsfield Units (HU) and iodine concentrations of AS, LN and the main spleen were measured. Receiver operating characteristics (ROC) were performed to calculate an optimal threshold for distinguishing AS from LN. Sensitivity, specificity, and accuracy were calculated for distinguishing AS from LN by iodine concentration measurements.
  
  
  RESULTS
  Mean CT numbers and iodine concentrations were higher for AS (148±29 HU and 48.2±11×100μg/cc) than LN (83±19 HU and 31.5±6.2×100μg/cc, respectively, P<0.001 each). Mean CT numbers were lower for AS compared to the main spleen (161±29HU, P<0.01), whereas mean iodine concentrations (47.7±10×100μg/cc) were not significantly different (P=0.095). An iodine concentration greater than 38×100μg/cc suggested AS with a sensitivity, specificity and accuracy of 91%, 85%, and 88%, respectively (Area under ROC curve 0.941).
  
  
  CONCLUSIONS
  Iodine measurements might contribute to the differentiation of AS from LN. Iodine concentrations similar to that of the main spleen may help to confirm the diagnosis of AS.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Ave., Box 0628, M-372, San Francisco, CA 94143-0628, USA; Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, 8091 Zurich, Switzerland. Electronic address: Sebastian.winklhofer@usz.ch.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Winklhofer
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Ave., Box 0628, M-372, San Francisco, CA 94143-0628, USA; Department of Radiology, China Medical University Hospital, No. 2, Yuh-Der Rd., Taichung 40447, Taiwan, Republic of China; Department of Biomedical Imaging and Radiological science, China Medical University, No. 91, Syueshih Rd., Taichung 40402, Taiwan, Republic of China. Electronic address: d7466@mail.cmuh.org.tw.
authors.forename: Wei-Ching
authors.initials: WC
authors.lastname: Lin
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Ave., Box 0628, M-372, San Francisco, CA 94143-0628, USA. Electronic address: Jack.Lambert@ucsf.edu.
authors.forename: Jack W
authors.initials: JW
authors.lastname: Lambert
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California San Francisco, 505 Parnassus Ave., Box 0628, M-372, San Francisco, CA 94143-0628, USA. Electronic address: Benjamin.Yeh@ucsf.edu.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Yeh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000493:pharmacokinetics; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007455:Iodine / Q000493:pharmacokinetics; D007472:Iohexol / Q000493:pharmacokinetics*; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013154:Spleen / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
chemical_list: D003287:Contrast Media; D007472:Iohexol; D007455:Iodine
keywords: Dual-energy computed tomography; Iodine; Lymph nodes; Lymphoid tissue; Spleen; Splenosis