Purpose: To automatically analyze the time course of collateralization in a rat hindlimb ischemia model based on signal intensity distribution (SID).
Materials and methods: Time-of-flight magnetic resonance angiograms (TOF-MRA) were acquired in eight rats at 2, 7, and 21 days after unilateral femoral artery ligation. Analysis was performed on maximum intensity projections filtered with multiscale vessel enhancement filter. Differences in SID between ligated limb and a reference region were monitored over time and compared to manual collateral artery identification.
Results: The differences in SID correlated well with the number of collateral arteries found with manual quantification. The time courses of ultrasmall (diameter ≪0.5 mm) and small (diameter ≈0.5 mm) collateral artery development could be differentiated, revealing that maturation of the collaterals and enlargement of their feeding arteries occurred mainly after the first week postligation.
Conclusion: SID analysis performed on axial maximum intensity projections is easy to implement, fast, and objective and provides more insight in the time course of arteriogenesis than manual identification.
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