Assessment of facial autologous fat grafts using Dixon magnetic resonance imaging.

Background: Autologous fat grafting is a procedure that treats soft tissue defects by reallocating fat to improve a patient's physical appearance. Imaging methods may be used to evaluate and monitor the grafted fat after transplantation. The goal of imaging is to examine the signal and volume of the grafted fat after autologous fat grafting during the adipose tissue recovery. However, researchers have yet to examine the feasibility of using fat-only imaging to assess the autologous fat graft. Methods: In this prospective and observational study, 46 injected sides in 23 female patients (age 35±7.8 years) were included in the image evaluation. The patients underwent autologous fat grafting surgery with filtered and washed fat. A total of 16, 18, and 12 sides were scanned 7 days, 3 months, and 1 year after fat grafting, respectively. Fat-only images were obtained using Dixon imaging, and then the image quality and contrast of the T1W and T2W were rated to evaluate the application of this method when imaging the autologous fat. The signal and volume of the autologous fat graft were recorded to assess the retention during recovery of the autologous fat tissue. Results: Fat-only T1W magnetic resonance imaging (MRI) was used to identify and delineate grafted fat because this method had better image quality and image differentiation than did T2W MRI. The average signal contrast and retention rate measured 7 days postoperation (28.8%±4.7%; 94.1%±5.8%) was the highest and then decreased at 3 months (16.3%±2.1%; 48.7%±17.3%) and 1 year (3.3%±1.3%, 33.1%±12.9%) after surgery. There were statistically significant differences between the signal and volume retention measurements at each postoperative recovery phase. Conclusions: The T1W fat-only images produced by Dixon MRI is a feasible approach for identifying grafted fat and measure postoperative changes during clinical evaluation. We found a significant decrease in signal contrast and volume of the grafted fat from the surgery date to 3 months postoperation and from 3 months to 1-year postoperation.