Watanabe M, Buch K, Fujita A, Christiansen C L, Jara H, Sakai O
1 Department of Radiology, Boston Medical Center, Boston University School of Medicine, Boston, MA, USA.
2 Department of Health Policy and Management, Boston University School of Public Health, Boston, MA, USA.
Dentomaxillofac Radiol. 2015;44(7):20150047. doi: 10.1259/dmfr.20150047. Epub 2015 May 14.
To investigate the location-specific tissue properties and age-related changes of the facial fat and facial muscles using quantitative MRI (qMRI) analysis of longitudinal magnetization (T1) and transverse magnetization (T2) values.
38 subjects (20 males and 18 females, 0.5-87 years old) were imaged with a mixed turbo-spin echo sequence at 1.5 T. T1 and T2 measurements were obtained within regions of interest in six facial fat regions including the buccal fat and subcutaneous cheek fat, four eyelid fat regions (lateral upper, medial upper, lateral lower and medial lower) and five facial muscles including the orbicularis oculi, orbicularis oris, buccinator, zygomaticus major and masseter muscles bilaterally.
Within the zygomaticus major muscle, age-associated T1 decreases in females and T1 increases in males were observed in later life with an increase in T2 values with age. The orbicularis oculi muscles showed lower T1 and higher T2 values compared to the masseter, orbicularis oris and buccinator muscles, which demonstrated small age-related changes. The dramatic age-related changes were also observed in the eyelid fat regions, particularly within the lower eyelid fat; negative correlations with age in T1 values (p<0.0001 for age) and prominent positive correlation in T2 values in male subjects (p<0.0001 for male×age). Age-related changes were not observed in T2 values within the subcutaneous cheek fat.
This study demonstrates proof of concept using T1 and T2 values to assess age-related changes of the facial soft tissues, demonstrating tissue-specific qMRI measurements and non-uniform ageing patterns within different regions of facial soft tissues.
通过对纵向磁化（T1）和横向磁化（T2）值进行定量磁共振成像（qMRI）分析，研究面部脂肪和面部肌肉的部位特异性组织特性以及与年龄相关的变化。
对38名受试者（20名男性和18名女性，年龄在0.5至87岁之间）采用1.5T的混合涡轮自旋回波序列进行成像。在六个面部脂肪区域（包括颊脂和皮下脸颊脂肪）、四个眼睑脂肪区域（上外侧、上内侧、下外侧和下内侧）以及五块面部肌肉（双侧眼轮匝肌、口轮匝肌、颊肌、颧大肌和咬肌）的感兴趣区域内获取T1和T2测量值。
在颧大肌中，观察到女性在晚年T1值随年龄下降，男性T1值随年龄增加，且T2值随年龄增加。与咬肌、口轮匝肌和颊肌相比，眼轮匝肌的T1值较低，T2值较高，而后三者随年龄的变化较小。在眼睑脂肪区域也观察到了与年龄相关的显著变化，特别是在下眼睑脂肪中；男性受试者T1值与年龄呈负相关（年龄相关p<0.0001），T2值与年龄呈显著正相关（男性×年龄相关p<0.0001）。皮下脸颊脂肪的T2值未观察到与年龄相关的变化。
本研究证明了使用T1和T2值评估面部软组织与年龄相关变化的概念，展示了组织特异性qMRI测量以及面部软组织不同区域的非均匀老化模式。
