الفهرس 
Evolution of free flapsOnly 14 pages are availabe for public view
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Abstract
M
icrovascular free tissue transfer is a reliable method for reconstruction of complex surgical defects, with increased success rates that is likely attributable to technological advancements in magnification, suture material, surgical instruments and increasing surgical experience with microsurgery.
Free flap failure is disastrous to the patient and resource demanding to the society, warranting immediate re-exploration and restoration of adequate anastomosis patency still occurs in up to 28 % of patients even in the most experienced hands.
The postoperative free flap monitoring by clinical means is often subjective that may be dependent on room-light, temperature, and the experience of the observer. Many monitoring methods are based on relative measuring results and cannot be directly compared subjectively. Various methods of monitoring have been developed, laser Doppler, ultrasonic Doppler, microdialysis, near-infrared spectroscopy and dynamic CT have all been used
Dynamic contrast enhanced (DCE)-MRI is a technique that has been used extensively in the past to study the vascularity of tumors and its changes following therapeutic intervention. Recently, it has been proposed as non-invasive applicable tool to evaluate free flap perfusion.
The aim of our study is to further study the potential reliability of dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI) in monitoring the tissue perfusion of free flaps.
We conducted our study on 14 patients (eleven males and three females), with age ranged from 18 to 60 years, with various soft tissue defects of face, upper limb, lower limb and penile reconstruction, the most common cause of tissue defects was post tumor excision. They underwent coverage by various free flaps as: free fibula, free radial forearm flap, antrolateral thigh flap, free dorsalis pedis artery flap, free latissimus dorsi muscle flap, free tensor fascia lata flap and free rectus abdominus muscle flap.
Clinical evaluation of the flap by assessment of skin or muscle color, temperature, capillary refilling and pin prick tests (if needed) at 2 hours intervals for 72 hours postoperatively as the incidence of complications after 72 hours is much more less.
Dynamic contrast enhanced MRI (DCE-MRI) was done within the first 48 hours, and repeated at 2-3 weeks postoperative also throughout the follow up period if any compromise of arterial or venous supply occurs an additional MRI session is needed. Three different slice positions will be assessed: zone of anastomosis, central and distal parts and compared with reference tissue of the same composition, also different flap layers will be assessed. Within these slice positions; mean signal intensity curves over time were assessed for the free flap and for the reference tissue.
The results of our study showed that DCE-MRI is a valuable, reliable and non-invasive tool in assessment of free flap vascularity in different segments of the flaps as well as all tissue layers of the whole flap at different time intervals, correlating clinical findings in all patients. DCE-MRI can also visualize and assess perfusion of buried bone in cases of free fibula flap.
DCE-MRI can visualize the feeding vessel of free flap by which we could prove that delayed thrombosis was due to microemboli in micro vasculature of free flaps although feeding vessel is still patent and this can be further studied to detect the optimum timing of neovascularization of free flaps.
However, further studies with a higher number of patients are necessary to confirm the clinical effectiveness of these promising results as a new armamentarium in monitoring of tissue perfusion of free flaps.