MRI Analysis of Chronological Changes in Free-flap Volume in Head and Neck Reconstruction by Volumetry

Objective: To evaluate changes in flap volumes for head and neck cancer patients by MRI.

Methods: MRI examinations of a total of 21 head and neck cancer patients (13 males and 8 females; average age, 67 years) were performed after surgery to monitor changes in flap volumes, including muscle and fat content, using volumetric analysis of T2-weighted images at 1, 3, 6, and 12 months after surgery.

Results: Fat-to-muscle ratios of all flaps at 1 month varied (muscle/fat ratio, 0.04-0.96). Flap volumes in all patients decreased at 12 months after surgery. The average final volumes of overall, muscle, and fat volumes reached 76.9% ± 5.2%, 37.1% ± 3.7%, and 85.5% ± 5.7%, respectively. The average fat volume slightly increased between 6 and 12 months, whereas compared with the fat volume, the average muscle volume significantly decreased (p<0.001).

Conclusions: The final overall flap volume in all patients decreased to approximately 25% of the original volume after surgery, which primarily resulted from muscle atrophy. Therefore fat-rich flaps may maintain flap volumes after surgery. MRI is a useful method to evaluate the size and shape of flaps of the head and neck.