Perfusional radionuclide evaluation of cutaneous flaps with previous detachment from the subjacent muscle: Study on rats

Aim: To evaluate the blood perfusion in a previously surgically detached area, in a rat model, using human albumin microspheres labeled with technetium-99m (microspheres-99mTc). Materials and Methods: Forty-eight Wistar rats arranged on four groups were used. The cutaneous tegument of the left flank was detached and after 0, 6, 14 and 28 days (Groups 1, 2, 3 and 4, respectively) it blood perfusion and the dermal and sub-dermal vessels were evaluated. The rats were anesthetized with pentobarbital and the left carotid artery was catheterized to allow the injection of the microspheres-99mTc into the left ventricle and its uniform distribution to all teguments. An experimental flap with 2 X 2 cm was done on the left inferior abdominal region of each rat without detaching the skin flap from the abdominal muscle. A 2 X 2 cm square was drown on the right abdominal side (control). After this procedure the rats were injected with 37 MBq and 150.000 particles of microspheres-99mTc through the catheter. Two fragments per quadrant of the experimental flaps were isolated after 15 minutes. The mass of the gamma counting fragments was evaluated and after it each fragment was counted on a gamma counter (Siemens) during one minute. After this procedure, it was calculated the index of gamma counting by the average of the net gamma counting/mg of the experimental flap divided by the net gamma counting/mg of the control skin of the 4 quadrants of the abdominal region (EF/C). The second fragment of each quadrant was used to the vessel counting. Non-parametric statistical analysis was done and the significance was taken as 5%. Results: The EF/C index of the group at day 0 was smaller than the other 3 groups (P<0.0001) that did not differ among them. The indexes of the G3 showed a tendency of increased perfusion of the experimental flap compared to the contra-lateral control. The analysis of the vessel counting did not show any difference between the 4 groups. Conclusion: Blood perfusion of the cutaneous tegument previously detached at 7, 14 and 28 days was detected with no difference on the number of dermal and sub-dermal vessels. The radioisotopical evaluation of the skin perfusion with microspheres-99mTc showed the physiological phenomena of reperfusion of the skin flap through the muscle vessels without increasing the number of dermal and sub-dermal vessels