Normal Thymus in Adults: Appearance on CT and Associations with Age, Sex, BMI and Smoking

Overview

Journal Eur Radiol

Specialty Radiology

Date 2015 May 1

PMID 25925358

Citations 33

Authors

Tetsuro Araki

Mizuki Nishino

Wei Gao

Josee Dupuis

Gary M Hunninghake

Takamichi Murakami

George R Washko

George T OConnor

Hiroto Hatabu

Affiliations

Soon will be listed here.

Abstract

Objective: To investigate CT appearance and size of the thymus in association with participant characteristics.

Materials And Methods: 2540 supposedly healthy participants (mean age 58.9 years, 51 % female) were evaluated for the CT appearance of thymic glands with four-point scores (according to the ratio of fat and soft tissue), size and morphology. These were correlated with participants' age, sex, BMI and smoking history.

Results: Of 2540 participants, 1869 (74 %) showed complete fatty replacement of the thymus (Score 0), 463 (18 %) predominantly fatty attenuation (Score 1), 172 (7 %) half fatty and half soft-tissue attenuation (Score 2) and 36 (1 %) solid thymic gland with predominantly soft-tissue attenuation (Score 3). Female participants showed less fatty degeneration of the thymus with higher thymic scores within age 40-69 years (P < 0.001). Participants with lower thymic scores showed higher BMI (P < 0.001) and were more likely to be former smokers (P < 0.001) with higher pack-years (P = 0.04).

Conclusions: Visual assessment with four-point thymic scores revealed a sex difference in the fatty degeneration of the thymus with age. Women show significantly higher thymic scores, suggesting less fat content of the thymus, during age 40-69 years. Cigarette smoking and high BMI are associated with advanced fatty replacement of the thymus.

Key Points: 74% of participants (mean age 58.9 years) demonstrated complete fatty thymus. Women show less fatty thymus compared to men at ages 40-69 years. Smoking and high BMI are associated with advanced fatty degeneration in thymus.

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References

Gulvady A, Ciolino H, Cabrera R, Jolly C . Resveratrol inhibits the deleterious effects of diet-induced obesity on thymic function. J Nutr Biochem. 2013; 24(9):1625-33. DOI: 10.1016/j.jnutbio.2013.02.003. View

BARON R, Lee J, Sagel S, Peterson R . Computed tomography of the normal thymus. Radiology. 1982; 142(1):121-5. DOI: 10.1148/radiology.142.1.7053521. View

Araki T, Nishino M, Gao W, Dupuis J, Washko G, Hunninghake G . Anterior Mediastinal Masses in the Framingham Heart Study: Prevalence and CT Image Characteristics. Eur J Radiol Open. 2015; 2:26-31. PMC: 4332399. DOI: 10.1016/j.ejro.2014.12.003. View

Araki T, Sholl L, Gerbaudo V, Hatabu H, Nishino M . Imaging characteristics of pathologically proven thymic hyperplasia: identifying features that can differentiate true from lymphoid hyperplasia. AJR Am J Roentgenol. 2014; 202(3):471-8. PMC: 4020512. DOI: 10.2214/AJR.13.11210. View

Priola A, Priola S, Giaj-Levra M, Basso E, Veltri A, Fava C . Clinical implications and added costs of incidental findings in an early detection study of lung cancer by using low-dose spiral computed tomography. Clin Lung Cancer. 2012; 14(2):139-48. DOI: 10.1016/j.cllc.2012.05.005. View

Priola A, Priola S, Ciccone G, Evangelista A, Cataldi A, Gned D . Differentiation of rebound and lymphoid thymic hyperplasia from anterior mediastinal tumors with dual-echo chemical-shift MR imaging in adulthood: reliability of the chemical-shift ratio and signal intensity index. Radiology. 2014; 274(1):238-49. DOI: 10.1148/radiol.14132665. View

Suster S, Rosai J . Histology of the normal thymus. Am J Surg Pathol. 1990; 14(3):284-303. DOI: 10.1097/00000478-199003000-00010. View

MOORE A, Korobkin M, Olanow W, Heaston D, Ram P, Dunnick N . Age-related changes in the thymus gland: CT-pathologic correlation. AJR Am J Roentgenol. 1983; 141(2):241-6. DOI: 10.2214/ajr.141.2.241. View

Yang H, Youm Y, Vandanmagsar B, Rood J, Kumar K, Butler A . Obesity accelerates thymic aging. Blood. 2009; 114(18):3803-12. PMC: 2773495. DOI: 10.1182/blood-2009-03-213595. View

10.

Araki T, Sholl L, Gerbaudo V, Hatabu H, Nishino M . Thymic measurements in pathologically proven normal thymus and thymic hyperplasia: intraobserver and interobserver variabilities. Acad Radiol. 2014; 21(6):733-42. PMC: 4022310. DOI: 10.1016/j.acra.2014.02.006. View

11.

Mendis S . The contribution of the Framingham Heart Study to the prevention of cardiovascular disease: a global perspective. Prog Cardiovasc Dis. 2010; 53(1):10-4. DOI: 10.1016/j.pcad.2010.01.001. View

12.

Nishihara M . [CT of the thymus--I. CT image of the normal thymus]. Nihon Igaku Hoshasen Gakkai Zasshi. 1987; 47(6):799-803. View

13.

Jin G, Lynch D, Chawla A, Garg K, Tammemagi M, Sahin H . Interstitial lung abnormalities in a CT lung cancer screening population: prevalence and progression rate. Radiology. 2013; 268(2):563-71. PMC: 3721050. DOI: 10.1148/radiol.13120816. View

14.

Kundel H, Polansky M . Measurement of observer agreement. Radiology. 2003; 228(2):303-8. DOI: 10.1148/radiol.2282011860. View

15.

Tibbetts T, DeMayo F, Rich S, Conneely O, OMalley B . Progesterone receptors in the thymus are required for thymic involution during pregnancy and for normal fertility. Proc Natl Acad Sci U S A. 1999; 96(21):12021-6. PMC: 18405. DOI: 10.1073/pnas.96.21.12021. View

16.

Francis I, Glazer G, Bookstein F, Gross B . The thymus: reexamination of age-related changes in size and shape. AJR Am J Roentgenol. 1985; 145(2):249-54. DOI: 10.2214/ajr.145.2.249. View

17.

Simanovsky N, Hiller N, Loubashevsky N, Rozovsky K . Normal CT characteristics of the thymus in adults. Eur J Radiol. 2012; 81(11):3581-6. DOI: 10.1016/j.ejrad.2011.12.015. View

18.

Ackman J, Kovacina B, Carter B, Wu C, Sharma A, Shepard J . Sex difference in normal thymic appearance in adults 20-30 years of age. Radiology. 2013; 268(1):245-53. DOI: 10.1148/radiol.13121104. View

19.

Uh H, van der Wijk H, Houwing-Duistermaat J . Testing for genetic association taking into account phenotypic information of relatives. BMC Proc. 2009; 3 Suppl 7:S123. PMC: 2795896. DOI: 10.1186/1753-6561-3-s7-s123. View

20.

Sopori M . Effects of cigarette smoke on the immune system. Nat Rev Immunol. 2002; 2(5):372-7. DOI: 10.1038/nri803. View