Abstract
Objective: To develop an automated diameter tracking method suitable for studies of isolated, perfused microvessels (< 100 μ m internal diameter (ID)). Methods: A diameter tracking method was implemented in conjunction with a standard PC workstation and video card. Within a user-defined window, the algorithm combined thresholding and iterative regression procedures to detect the average outer diameter (OD) of a vertically oriented microvessel. After an initial ID measurement by the user, the program continuously calculated ID based on the assumption of an incompressible vessel wall.
Results: The program, Vessel Track, was tested against a manual video caliper and two analog video dimension analyzers. Vessel Track was capable of accurately following arteriolar dimensions during extreme vasodilation and vasoconstriction. It provided more accurate, lower-noise recordings than either of the video dimension analyzers, particularly after strong vasoconstriction during which lumenal folds developed. Vessel Track also was capable of accurately measuring large-amplitude vasomotion in isolated lymphatic vessels at a tracking frequency of ∼ 30 times/s.
Conclusions: Vessel Track should be useful for automated diameter tracking of isolated arterioles, venules, and lymphatics. With suitable preparations, it provides fast, stable measurements of ID in microvessels even with irregular lumen geometry.
Microcirculation (2005) 12, 361–372. doi:10.1080/10739680590934772
The author is indebted to a number of colleagues for their valuable contributions: Erion Qamurani provided the coronary arteriole recordings, Anatoliy Gashev provided the rat mesenteric lymphatic recordings, and Travis Hein provided the pig retinal vessel recordings. Ed VanBavel and Christopher Quick contributed helpful suggestions regarding the general algorithm. Steve Griener, Wei Wang, and David Zawieja extensively tested preliminary versions of the software and offered many important suggestions for improvement. Supported by NIH grants HL-072989, HL-071796 and HL-075199. Interested academic users should contact the author ( [email protected]) for arrangements about obtaining the software.