【 文献重点摘要 】
 

Background: The present study evaluated volumetric changes in the aging midface. Both young and old living subjects were studied using high-resolution magnetic resonance imaging (MRI) to investigate the distribution and volume of the muscle and subcutaneous components of the midface.

Methods: MRI with a customized radiofrequency coil was performed in 20 healthy Caucasian female volunteers equally divided between young (16 to 30 years) and old (>59 years) age groups. Sagittal oblique images were obtained at 1-mm intervals through the midface, perpendicular to the nasolabial fold. Quantitative analyses of the cheek fat pad overlying the levator labii superioris and zygomaticus major muscles were performed separately.

Results: For both mimetic muscles, there were no significant differences between young and old subjects in muscle length, thickness, or volume from muscle origin to nasolabial fold. In addition, there were no significant differences between age groups in fatty infiltration of the muscles. The volumes of the medial and lateral aspects of the cheek fat pad were significantly greater in old than in young subjects (p < 0.05). In young subjects the greatest distribution of fat pad volume was found in the middle third of the cheek mass. There was a significant reduction in that portion of the fat pad distributed in the upper third and a further reduction in the lower third (p < 0.01). In old subjects, because of the increased distribution of fat in the upper third of the cheek fat pad, there was no significant difference in volume between the upper and middle thirds of the cheek fat pad. The percentage increase in fat in the upper third relative to the remainder of the midface was significantly greater in old compared with young subjects (p < 0.01). In contrast, the volume of the lower third of the midface was not significantly different between young and old subjects.

Conclusions: The present study indicates that ptosis alone does not account for the changes observed in the aging midface. Selective hypertrophy of the upper portion of the cheek fat pad was also observed. The mimetic muscles, on the other hand, showed no significant differences with aging. To attain maximum precision in facial rejuvenation, these data suggest that after suspension of the ptotic cheek fat pad, each patient should be evaluated for excess bulk in the upper portion of the cheek fat pad. If excess bulk is present, patients may benefit further from selective reduction directed to the upper portion of the cheek fat pad, remaining superficial to the mimetic muscles of the face.

背景：本研究评估了衰老的面中部的体积变化。使用高分辨率磁共振成像(MRI)对年轻和老年活体受试者进行研究，以研究面中部肌肉和皮下成分的分布和体积。

方法：20名健康高加索女性志愿者，按年龄分为青年组(16~30岁)和老年组(>59岁)，采用定制射频线圈进行MRI检查。矢状面斜位图像通过面中部，垂直于鼻唇皱褶，间隔1 mm。分别对上唇提肌和颧大肌上方的颊脂垫进行定量分析。

结果：在两种模拟肌肉中，青年和老年受试者从肌肉起源到鼻唇皱褶的肌肉长度、厚度或体积均无显著差异。此外，在肌肉脂肪浸润方面，各年龄组之间没有显著差异。老年组面颊脂肪垫内侧和外侧体积明显大于青年组(p<0.05)。在年轻受试者中，脂肪垫体积最大的分布在面颊质量的中间1/3。脂肪垫分布在上1/3处明显减少，在下1/3处进一步减少(p<0.0 1)。在老年人中，由于面颊脂肪垫上1/3处脂肪分布增多，上1/3和中1/3面颊脂肪垫体积无明显差异。与年轻受试者相比，老年受试者面中部上1/3脂肪增加的百分比明显大于年轻受试者(p<0.01)。相比之下，年轻和老年受试者的面中下三分之一的体积没有显著差异。

结论：本研究表明，单单上睑下垂并不能解释老化的面中部所观察到的变化。此外，还观察到面颊脂肪垫上部选择性肥大。另一方面，模仿肌肉则没有表现出随年龄增长的显著差异。为了达到面部年轻化的最大精确度，这些数据建议，在悬吊上睑脂肪垫后，每个患者都应该评估面颊脂肪垫上部是否有过大的体积。如果存在过大的肿块，患者可以进一步受益于选择性复位至面颊脂肪垫的上部，保持面部模拟肌肉的浅层。