Background and objective.

Improving the tolerance of myocutaneous flaps to ischemia is clinically relevant and therefore it has been the subject of numerous investigations, using a wide variety of measuring methods and animal models. Edema formation is key in the pathophysiology process of the ischemia-reperfusion injury and an accurate method for its evaluation has not yet been described. Fast "T2 gradient-spin-echo (T2-GraSE)" has been recently validated to quantify myocardial edema after sustaining ischemia-reperfusion injury. Although this technique has been used for the evaluation of skeletal muscle integrity, it has ever been validated against actual muscle water content for edema detection.

Our objective was to obtain an in vivo validation of a sequence for fast and accurate skeletal muscle T2-mapping that can be easily integrated in research protocols for the better study of ischemia-reperfusion injury.

Methods.

Eighteen myocutaneous flaps based on the rectus abdominis muscle were harvested in 9 pigs. The flaps were elevated, utilizing the superior epigastric vessels as the pedicle. On each animal, one of the flaps sustained 6 hours of normothermic ischemia and the other one was used as control. Pigs were sacrificed at diferent moments after reperfusion, and muscle tissue extracted for quantification of myocardial water content. Five animals were sacrificed after basal resonance and used as non surgical control.

Results.

Sequences were obtained for mapping in 30 minutes. Both histological measures and T2 measurements showed higher water content in the injured flap The T2-mapping sequences showed good correlations with muscular water content. Our data demonstrate good correlation between muscular water content and T2-mapping using the gradient-spin-echo (GraSE) technique.

Conclusions.

The introduction of MRI in ischemia / reperfusion injury research give us a useful tool in order to characterize the bimodal edema pattern after the ischemic insult and to proper evaluate conditioning therapies.

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