Challenges in flap monitoring with indocyanine green angiography in experimental models

Non-invasive angiography with indocyanine green dye facilitates the assessment of flaps. Although ICG angiography has been successfully utilized in clinical settings for human beings, its application in experimental models exhibits certain limitations. This study aimed to address the encountered issues in angiography with different experimental models and introduce a novel modification to the ICG imaging of the McFarlane flap.

Rats were randomly divided into three groups: the first group received an epigastric flap (n = 4), the second group received a deep inferior epigastric perforator flap (n = 4), and the third group received a dorsal flap (n = 8). In the first group, sterile silicone background was placed under two flaps. In the second group, no background was used. In the third group, a sterile silicone or aluminum foil was placed under the flaps. Flap perfusions were assessed using fluorescent imaging after flap adaptations, at postoperative 30th minute and 3., 5. and 7. days. Necrosis calculations were performed using all images obtained from the digital camera and the fluorescent imaging. In the third group, the flow velocities were also calculated. All flaps were sent for histopathological examination.

Even with a silicone background, clear perfusion evaluation and determining the threshold value for predicting necrosis rates were challenging. Moreover, a portion of the flaps without background material survived as grafts. Using an aluminum foil background improved image quality by reducing reflection from interior organs.

The use of an aluminum foil background is beneficial in non-invasive angiography for assessing flap perfusions accurately and predicting necrosis in experimental animal models.