Quantitative regression analysis of the cutaneous vascular territories in a rat model.

Background: The rat skin flap model has been widely used in experimental flap survival studies; however, most of these have been qualitative studies. The purpose of this study was to investigate the quantitative relationship between the diameter of a cutaneous artery and the area of skin that it supplies, and also to explore the factors that influence this relationship.

Methods: Thirty rats were injected with lead oxide and gelatin and then radiographed. Computer imaging of the diameter and the area of blood supply of the cutaneous artery were made to investigate the mathematical relationship between the arterial diameter and its perfusion area. Angiograms were assembled using Adobe Photoshop and analyzed with Scion Image and SPSS software.

Results: The blood vessels had an average diameter of 0.53 ± 0.12 mm, perimeter of 18.74 ± 4.84 cm, vascular density of 391.31 ± 76.58 gray value/pixel cm, vascular territory of 22.32 ± 10.04 cm(2) and supplying volume of 4.88 ± 3.02 cm(3). There was a positive correlation between the diameter and the perimeter of the vascular territory, and the area and volume of the vascular territory. The linear regression equation was y = 32.44x + 1.23 [y: nutrition region perimeter (cm), x: cutaneous artery diameter (mm)], y = 72.70x-15.93 [y: supplying area (cm(2)), x: cutaneous artery diameter (mm)] and y = 20.36x-5.83 [y: supplying volume (cm(3)), x: cutaneous artery diameter (mm)], respectively.

Conclusions: Based on this data, it is postulated that the size of reliable skin flaps can be calculated by the diameter and the distribution patterns of the cutaneous artery. With the same diameter, the area of the flap supplied by branch-style artery is larger than the one supplied by the axial artery.