Comparison of instruments for investigation of microcirculatory blood flow and red blood cell concentration.
The use of laser Doppler perfusion imaging (LDPI) and laser speckle perfusion imaging (LSPI) is well known in the noninvasive investigation of microcirculatory blood flow. This work compares the two techniques with the recently developed tissue viability (TiVi) imaging system, which is proposed as a useful tool to quantify red blood cell concentration in microcirculation. Three systems are evaluated with common skin tests such as the use of vasodilating and vasoconstricting drugs (methlynicotinate and clobetasol, respectively) and a reactive hyperaemia maneuver (using a sphygmomanometer). The devices investigated are the laser Doppler line scanner (LDLS), the laser speckle perfusion imager (FLPI)-both from Moor Instruments (Axminster, United Kingdom)-and the TiVi imaging system (WheelsBridge AB, Linkoping, Sweden). Both imaging and point scanning by the devices are used to quantify the provoked reactions. Perfusion images of vasodilatation and vasoconstriction are acquired with both LDLS and FLPI, while TiVi images are acquired with the TiVi imager. Time acquisitions of an averaged region of interest are acquired for temporal studies such as the reactive hyperaemia. In contrast to the change in perfusion over time with pressure, the TiVi imager shows a different response due its measurement of blood concentration rather than perfusion. The responses can be explained by physiological understanding. Although the three devices sample different compartments of tissue, and output essentially different variables, comparisons can be seen between the three systems. The LDLS system proves to be suited to measurement of perfusion in deeper vessels, while FLPI and TiVi showed sensitivity to more superficial nutritional supply. LDLS and FLPI are insensitive to the action of the vasoconstrictor, while TiVi shows the clear boundaries of the reaction. Assessment of the resolution, penetration depth, and acquisition rate of each instrument show complimentary features that should be taken into account when choosing a system for a particular clinical measurement.
O'Doherty
Jim
J
University of Limerick, Tissue Optics and Microcirculation Imaging Facility, Department of Physics, National Technology Park, County Limerick, Ireland.
McNamara
Paul
P
Clancy
Neil T
NT
Enfield
Joey G
JG
Leahy
Martin J
MJ
D000328:Adult; D000700:Analgesics / Q000494:pharmacology; D001783:Blood Flow Velocity / Q000187:drug effects; D004906:Erythrocyte Count; D004912:Erythrocytes / Q000187:drug effects / Q000502:physiology*; D006225:Hand / Q000098:blood supply; D006801:Humans; D006940:Hyperemia / Q000097:blood; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology*; D009539:Nicotinic Acids / Q000494:pharmacology; D055420:Perfusion Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012867:Skin / Q000098:blood supply*; D014022:Tissue Survival; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D000700:Analgesics; D009539:Nicotinic Acids; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C008473:methyl nicotinate