MRI findings of myocutaneous and fasciocutaneous flaps used for reconstruction of orbital exenteration defects

Purpose: To facilitate detection of tumor recurrence, the authors reviewed the MRI characteristics of myocutaneous and fasciocutaneous free flaps following orbital exenteration for treatment of orbital or maxillofacial tumors. Methods: The authors retrospectively reviewed the MRI characteristics, including T1 and T2 signal intensity, and enhancement pattern of 28 such flaps. Results: The study included 17 myocutaneous flaps and 11 fasciocutaneous flaps placed in 28 patients. For 23 flaps, additional imaging was performed after baseline imaging (range, 2-65 months after surgery). On precontrast T1 imaging, 15 of 17 myocutaneous flaps demonstrated a striated appearance similar to that of native muscle. Twenty-six of the 28 flaps in the series were T2 hyperintense. On baseline imaging, 26 flaps showed linear (n = 5), patchy (n = 10), or homogeneous (n = 11) enhancement. No flaps demonstrated mass-like enhancement. Five fasciocutaneous and 5 myocutaneous flaps showed decreased enhancement on follow-up imaging, while 4 myocutaneous flaps showed increased enhancement. Fourteen patients received postoperative radiation, 4 of which demonstrated increased enhancement, which subsequently decreased in 3 flaps. Fourteen of 23 followed flaps became smaller over time. Conclusions: On MRI, both myocutaneous and fasciocutaneous flaps placed after orbital exenteration generally demonstrate persistent non-mass-like enhancement and T2 hyperintensity, and both types of flaps may become smaller over time. Head and neck radiologists, ophthalmologic and plastic surgeons, and oncologists should be aware of the range of imaging features of these flaps to avoid misinterpreting the postoperative appearance as tumor recurrence.