title: Normal CT characteristics of the thymus in adults.
abstract: BACKGROUND
  The thymus changes with age. Its shape and the proportion of solid tissue and fat vary between individuals, yet there is no comprehensive work describing the size and morphology of the normal thymus on CT. As a result, many adults with some preserved soft tissue in the thymus may undergo extensive work-up to exclude mediastinal tumor. Our aim was to quantify CT characteristics of the normal thymus in an adult population.
  
  
  METHODS
  CT chest scans of 194 trauma patients aged 14-78 years (mean 52.6 years), were retrospectively reviewed. The density, volume, shape and predominant side of the thymus were recorded for 56 patients in whom some solid tissue was preserved. Statistical analysis of these characteristics according to the patient age and gender was performed.
  
  
  RESULTS
  Thymic density and volume decreased progressively with age. No solid tissue component was seen in the thymus in patients older than 54 years. In the majority of patients, the thymus had an arrowhead shape, with middle position. However, great variability in thymic shape and border were noted. There was a highly significant relationship between density and patient age (p<0.0001).
  
  
  CONCLUSIONS
  We hope that our work will help in the definition of normal thymic CT parameters in adults, help to prevent unnecessary and expensive imaging procedures, and reduce patient exposure to ionizing radiation.
authors.affiliation: Department of Medical Imaging, Hadassah-Hebrew University Medical Center, Jerusalem, Israel. natalias@hadassah.org.il
authors.forename: Natalia
authors.initials: N
authors.lastname: Simanovsky
authors.forename: Nurith
authors.initials: N
authors.lastname: Hiller
authors.forename: Natali
authors.initials: N
authors.lastname: Loubashevsky
authors.forename: Katya
authors.initials: K
authors.lastname: Rozovsky
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007557:Israel; D008297:Male; D008875:Middle Aged; D013902:Radiography, Thoracic / Q000379:methods* / Q000592:standards; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013950:Thymus Gland / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards; D055815:Young Adult