Incidental mediastinal masses detected at low-dose CT screening: prevalence and radiological characteristics

Ryo Miyazawa, Masaki Matsusako, Taiki Nozaki, Daiki Kobayashi, Fumitsugu Kojima, Toru Bando, Ukihide Tateishi

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Purpose: The primary and secondary aims were to investigate the prevalence of incidental mediastinal masses on low-dose chest CT examinations during health check-ups, and to review the radiological characteristics of prevascular mediastinal masses, respectively. Materials and methods: This retrospective study included 38,861 participants (mean age: 57.1 years; range: 21–99 years; men: 51.3%; never-smokers: 57.4%) who underwent low-dose chest CT examinations between January 2011 and December 2016. All images with incidental mediastinal masses were reviewed, and prevascular mediastinal masses were assessed for qualitative and quantitative imaging characteristics by two radiologists. Univariate and multivariate analyses were performed in clinical and CT features between some combinations of participants. Results: Overall, 653 participants (1.68%, 653 of 38,861) had incidental mediastinal masses; 578 in prevascular mediastinum, including 93 intrathymic cysts and 24 thymic epithelial tumors. Presence of mediastinal mass was not significantly associated with sex (p = 0.089) and smoking history (p = 0.098) but with age (p < 0.001). Significant differences were found between intrathymic cysts and thymic epithelial tumors in terms of shapes (p = 0.049), contours (p = 0.018), and CT values (p = 0.012). Conclusion: The prevalence of asymptomatic mediastinal masses on low-dose chest CT was 1.68%. CT values, shapes, and contours may effectively distinguish intrathymic cysts from thymic epithelial tumors.

Original languageEnglish
Pages (from-to)1150-1157
Number of pages8
JournalJapanese Journal of Radiology
Issue number12
Publication statusPublished - 2020 Dec
Externally publishedYes


  • Mass screening
  • Mediastinal neoplasms
  • Mediastinum
  • Thymoma
  • Thymus neoplasms

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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