@article {1433657,
	title = {Normal thymus in adults: appearance on CT and associations with age, sex, BMI and smoking},
	journal = {Eur Radiol},
	volume = {26},
	number = {1},
	year = {2016},
	month = {2016 Jan},
	pages = {15-24},
	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{\textquoteright} 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.},
	keywords = {Adult, Age Factors, Aged, Body Mass Index, Cross-Sectional Studies, Female, Humans, Male, Middle Aged, Sex Characteristics, Smoking, Thymus Gland, Tomography, X-Ray Computed},
	issn = {1432-1084},
	doi = {10.1007/s00330-015-3796-y},
	author = {Araki, Tetsuro and Nishino, Mizuki and Gao, Wei and Dupuis, Jos{\'e}e and Hunninghake, Gary M and Murakami, Takamichi and Washko, George R and O{\textquoteright}Connor, George T and Hatabu, Hiroto}
}