Aging effects on human calf muscle properties assessed by MRI at 3 Tesla

Abstract

Purpose: To determine age-related changes in MR properties as T2 and T2* relaxation times, fat content, and magnetization transfer in the human calf, and comparison of these effects in different muscle groups. Materials and Methods:Studies were performed on 12 "younger" (mean, 31.2 Ϯ 6.1 years) and 11 "older" healthy adult individuals (mean, 66.1 Ϯ 7.8 years). The tibialis anterior muscle, the soleus muscle and the gastrocnemius muscle were examined at rest in a 3 Tesla whole-body MR unit. T2 and T2*, muscular fat content and magnetization transfer ratios (MTR) were determined. Results of the two age groups were compared, and differences between the muscle groups were investigated. Results:Increase of T2 and muscular fat was detected with age with significant difference between the age groups. The extent of fatty infiltration was much more variable for the "older" group. For both age groups, the tibialis anterior muscle showed the lowest fat content with 1.2 Ϯ 0.4% in the "young" group and 2.3 Ϯ 0.7% in the "older" group. A strong correlation between fat content and T2 was found, while the groups did not significantly differ regarding T2*. Decrease in the MTR could only be shown for the tibialis anterior muscle with age. Conclusion:Age-related changes in healthy human calf musculature were found. Further studies might show possible correlations of age-dependent changes with physical efficiency and susceptibility to diseases like type 2 diabetes. IN AN AGING SOCIETY, the quality of life for the elderly becomes more and more important. This includes physical activity, physical fitness, and health. It is known that senescence goes along with impairment in muscle function, reduction in bone density, and loss in joint mobility. For this reason, in the past years an increasing number of studies investigating the influence of aging on muscular functionality and metabolism have been performed; muscular atrophy and fiber composition are major research areas, because age-associated muscle atrophy is associated with muscular weakness and fatigability (1). It is known from histological studies that muscle volume decreases with age (2,3), with type II fibers more affected (4 -6).In contrast to histological studies, MR techniques have the advantage of noninvasive tissue characterization in vivo offering information about muscle structure, metabolism, and architecture in one examination. Different MR methods are available for determination of relaxation times and magnetization transfer, quantification of muscular lipids, and assessment of perfusion patterns and diffusion properties.To our knowledge there exists only one previous study focusing on muscle aging and transverse relaxation times (7), although measurement of T2 and T2* relaxation times has been reported to be useful in the assessment of muscle atrophy (8), the analysis of denervation effects (9,10), and the muscular metabolic state (11,12).Another useful parameter characterizing the composition of tissues is magnetization transfer contrast (MTC) (13,14). The MT imag...

The influence on sarcopenia of muscle quality and quantity derived from magnetic resonance imaging and neuromuscular properties

“…Skeletal muscle normally has a prominent MT effect because of the high concentration of protein bound to water (Dixon et al 1990). A lower MT ratio indicates reduced capacity of the macromolecular protons to exchange magnetization with free protons and therefore reflects decreased structural integrity and quality of macromolecules (i.e., protein) in muscle tissue (Michaelis et al 2008;Schwenzer et al 2009). For the MT protocol, the MT pre-saturation, off-resonance frequency scans were taken first, followed by a second scanning without pre-saturation of the same anatomical locations.…”

“…In pilot testing (results not shown), single slice analysis was found to be not significantly different than whole muscle volume MTR; therefore, to make relative comparisons to muscle CSA, the same slice ROI was used for MTR and CSA. The interaction of macromolecular protons and free protons of a specific tissue is quantitatively described by the magnetization transfer ratio (Schwenzer et al 2009;Sinclair et al 2010).…”

“…A lower MT ratio (MTR) reflects a decreased quantity and quality of the muscle protein content (McDaniel et al 1999;Schwenzer et al 2009;Sinclair et al 2010). To date, one study assessed MPQ in older subjects (~65 years) and found a decreased MTR, indicating reduced MPQ in old compared to young men in the tibialis anterior (Schwenzer et al 2009), although that study did not assess other structural or functional measures.…”

Imagerie et spectroscopie par résonance magnétique nucléaire du muscle strié squelettique

“…Des changements dans la composition des muscles striés squelettiques ont été systématiquement et régulièrement constatés chez les sujets âgés, même s'ils restent d'une amplitude limitée jusqu'à un âge très avancé. Le pourcentage du signal lipidique intramusculaire double généralement, de 2 à 4 %, entre la deuxième et la septième décennie (Schwenzer et al 2009a ;Alizai et al 2012 ;Csapo et al 2014 ;Morrow et al 2014 ;Azzabou et al 2015a). Pour l'essentiel, cette augmentation repré-sente un véritable accroissement de la teneur lipidique du muscle et elle ne reflète qu'accessoirement la perte de tissu contractile avec l'âge (Csapo et al 2014).…”

“…Cette méthode a été transférée chez l'homme sous le nom d'ISIS-CPMG. Elle a permis d'identifier des composantes T2 intra-et extracellulaires mais n'a jusqu'à présent pas mis en évidence cette composante de spins à T2 très court (Schwenzer et al 2009a ;Sinclair et al 2010 ;Sinclair et al 2012 ;Morrow et al 2014 ;Li et al 2014 ;Li et al 2015). La corrélation négative entre le contraste de transfert d'aimantation et l'âge dans une cohorte d'individus sains est par exemple, relativement déroutante .…”