Long-Term Serial Measurement of Muscle Volume in TRAM Flaps Using the Eclipse Treatment Planning System

Background: Muscle flaps used in reconstructive surgery are known to lose volume over time because of denervation and disuse atrophy. However, there is currently no agreement on a quantitative approach to evaluating volume changes. Here, long-term serial measurement of muscle volume in transverse rectus abdominis musculocutaneous (TRAM) flap breast reconstruction has been conducted using the Eclipse treatment planning system. Methods: This was a retrospective review of the medical records of patients who underwent unilateral immediate breast reconstruction using a pedicled TRAM flap between January of 2004 and December of 2007. Patients who completed three serial follow-up computed tomographic scans and did not have history of recurrence and/ or radiation therapy were included. Eclipse software was used for segmentation and three-dimensional reconstruction of the computed tomographic images; the volume of the pedicled rectus abdominis muscle was calculated, and the contralateral side served as the control. Results: Among 451 patients undergoing TRAM flap surgery during the study period, 35 met the inclusion requirements. Serial measurement of rectus abdominis muscle volume of the flap showed a mean volume ratio of 27.1 percent, 22.1 percent, and 19.8 percent at 15, 30, and 51 months, respectively. The extrapolated volume ratio finally converged at 19.4 percent. Contralateral muscle volume did not change significantly over time. Conclusions: The muscle of a TRAM flap loses more than 70 percent of its volume in the first 15 months, ultimately reducing to approximately 20 percent of its original size. Eclipse can be used retrospectively for volume measurement after a variety of reconstructive procedures using computed tomographic or magnetic resonance images.