Ponti Federico, Santoro Aurelia, Mercatelli Daniele, Gasperini Chiara, Conte Maria, Martucci Morena, Sangiorgi Luca, Franceschi Claudio, Bazzocchi Alberto
Diagnostic and Interventional Radiology, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Bologna, Italy.
Front Endocrinol (Lausanne). 2020 Jan 14;10:861. doi: 10.3389/fendo.2019.00861. eCollection 2019.
The aging process is characterized by the chronic inflammatory status called "inflammaging", which shares major molecular and cellular features with the metabolism-induced inflammation called "metaflammation." Metaflammation is mainly driven by overnutrition and nutrient excess, but other contributing factors are metabolic modifications related to the specific body composition (BC) changes occurring with age. The aging process is indeed characterized by an increase in body total fat mass and a concomitant decrease in lean mass and bone density, that are independent from general and physiological fluctuations in weight and body mass index (BMI). Body adiposity is also re-distributed with age, resulting in a general increase in trunk fat (mainly abdominal fat) and a reduction in appendicular fat (mainly subcutaneous fat). Moreover, the accumulation of fat infiltration in organs such as liver and muscles also increases in elderly, while subcutaneous fat mass tends to decrease. These specific variations in BC are considered risk factors for the major age-related diseases, such as cardiovascular diseases, type 2 diabetes, sarcopenia and osteoporosis, and can predispose to disabilities. Thus, the maintenance of a balance rate of fat, muscle and bone is crucial to preserve metabolic homeostasis and a health status, positively contributing to a successful aging. For this reason, a detailed assessment of BC in elderly is critical and could be an additional preventive personalized strategy for age-related diseases. Despite BMI and other clinical measures, such as waist circumference measurement, waist-hip ratio, underwater weighing and bioelectrical impedance, are widely used as a surrogate measure for body adiposity, they barely reflect the distribution of body fat. Because of the great advantages offered by imaging tools in research and clinics, the attention of clinicians is now moving to powerful imaging techniques such as computed tomography, magnetic resonance imaging, dual-energy X-ray absorptiometry and ultrasound to obtain a more accurate estimation of BC. The aim of this review is to present the state of the art of the imaging techniques that are currently available to measure BC and that can be applied to the study of BC changes in the elderly, outlining advantages and disadvantages of each technique.
衰老过程的特征是一种称为“炎症衰老”的慢性炎症状态，它与称为“代谢性炎症”的代谢诱导炎症具有主要的分子和细胞特征。代谢性炎症主要由营养过剩和营养素过量驱动，但其他促成因素是与年龄相关的特定身体成分（BC）变化相关的代谢改变。衰老过程确实以身体总脂肪量增加以及瘦体重和骨密度随之降低为特征，这与体重和体重指数（BMI）的一般生理波动无关。身体脂肪也会随着年龄的增长而重新分布，导致躯干脂肪（主要是腹部脂肪）普遍增加，而附属脂肪（主要是皮下脂肪）减少。此外，老年人肝脏和肌肉等器官中的脂肪浸润积累也会增加，而皮下脂肪量往往会减少。BC的这些特定变化被认为是与年龄相关的主要疾病的危险因素，如心血管疾病、2型糖尿病、肌肉减少症和骨质疏松症，并可能导致残疾。因此，维持脂肪、肌肉和骨骼的平衡比例对于维持代谢稳态和健康状况至关重要，对成功衰老有积极作用。出于这个原因，对老年人的BC进行详细评估至关重要，并且可能是预防与年龄相关疾病的额外个性化策略。尽管BMI和其他临床测量方法，如腰围测量、腰臀比、水下称重和生物电阻抗，被广泛用作身体肥胖的替代测量方法，但它们几乎不能反映身体脂肪的分布。由于成像工具在研究和临床中具有巨大优势，临床医生的注意力现在正转向强大的成像技术，如计算机断层扫描、磁共振成像、双能X线吸收法和超声，以获得更准确的BC估计。本综述的目的是介绍目前可用于测量BC并可应用于研究老年人BC变化的成像技术的现状，概述每种技术的优缺点。
