Harrington Kate A, Kennedy David S, Tang Bobby, Hickie Conor, Phelan Emma, Torreggiani William, Halpenny Darragh
1 Radiology Department, Adelaide and Meath Hospital , Tallaght, Dublin , Ireland.
2 Radiology Department, Memorial Sloan Kettering Cancer Center , New York, NY , USA.
Br J Radiol. 2018 Sep;91(1089):20170609. doi: 10.1259/bjr.20170609. Epub 2018 Mar 7.
To determine a relationship between increased body mass index (BMI) and fatty involution of the thymus in subjects aged between 20 and 30 years.
CT images of 94 patients aged between 20 and 30 years were reviewed. Quantitative thymic mean attenuation was recorded and qualitative thymic attenuation was assigned to 1 of 4 possible grades. BMI and subcutaneous fat thickness were documented. Correlations between thymic attenuation, and BMI and subcutaneous fat thickness were assessed using linear regression models. Differences in thymic attenuation in overweight vs normal weight patients were assessed using t-test and Pearson Χ analysis.
Low mean thymic attenuation values were associated with higher patient BMI (p = 0.024). Normal weight patients had a mean quantitative thymic attenuation of 15.5 Hounsfield unit and overweight patients had a mean quantitative thymic attenuation of -16.4 Hounsfield unit (p = 0.0218). There was a significant association between increasing subcutaneous fat thickness and reduced mean quantitative thymic attenuation (p < 0.0001). There was also a significant difference in subcutaneous fat thickness when comparing qualitatively assessed thymic Grade 0 with grades 2 and 3 (p = 0.027 and 0.001 respectively); and Grade 1 with Grade 3 (p = 0.001).
In patients between 20 and 30 years old, the degree of thymic fatty infiltration is related to BMI. Advances in knowledge: Multidetector CT can assess fatty involution of the thymus gland. This retrospective study demonstrates a relationship between BMI and thymus gland fatty involution. Subjects with increased subcutaneous fat have decreased mean thymus gland attenuation.
确定20至30岁人群体重指数（BMI）增加与胸腺脂肪退化之间的关系。
回顾了94例年龄在20至30岁之间患者的CT图像。记录胸腺平均衰减的定量数据，并将胸腺衰减的定性数据分为4个可能等级中的1级。记录BMI和皮下脂肪厚度。使用线性回归模型评估胸腺衰减与BMI和皮下脂肪厚度之间的相关性。使用t检验和Pearson Χ分析评估超重患者与正常体重患者胸腺衰减的差异。
胸腺平均衰减值低与患者较高的BMI相关（p = 0.024）。正常体重患者的胸腺平均定量衰减为15.5亨氏单位[1]，超重患者的胸腺平均定量衰减为-16.4亨氏单位（p = 0.0218）。皮下脂肪厚度增加与平均定量胸腺衰减降低之间存在显著相关性（p < 0.0001）。在定性评估的胸腺0级与2级和3级进行比较时，皮下脂肪厚度也存在显著差异（分别为p = 0.027和0.001）；1级与3级比较时（p = 0.001）。
在20至30岁的患者中，胸腺脂肪浸润程度与BMI相关。知识进展：多排CT可评估胸腺的脂肪退化。这项回顾性研究证明了BMI与胸腺脂肪退化之间的关系。皮下脂肪增加的受试者胸腺平均衰减降低。
[1]亨氏单位（Hounsfield unit）是CT图像中用于表示组织密度的单位。
