Digital Imaging of Umbelliferone Clearance: A Method for Repeated Measurements of Cerebral Cortical Blood Flow with High Temporal and Spatial Resolution

J Cereb Blood Flow Metab

Harland

Meldrum

et al. 1996

Self Cite

A method for the detection and tracking of propagated fluorescence transients as indicators of depolarizations in focal cerebral ischemia is described, together with initial results indicating the potential of the method. The cortex of the right cerebral hemisphere was exposed for nonrecovery experiments in five cats anesthetized with chloralose and subjected to permanent middle cerebral artery (MCA) occlusion. Fluorescence with 370-nm excitation (attributed to the degree of reduction of the NAD/H couple) was imaged with an intensified charge-coupled device camera and digitized. Sequences of images representing changes in gray level from a baseline image were examined, together with the time courses of mean gray levels in specified regions of interest. Spontaneous increases in fluorescence occurred, starting most commonly at the edge of areas of core ischemia; they propagated usually throughout the periinfarct zone and resolved to varying degrees and at varying rates, depending on proximity of the locus to the MCA input. When a fluorescence transient reached the anterior cerebral artery territory, its initial polarity reversed from an increase to a decrease in fluorescence. An initial increase in fluorescence in response to the arrival of a transient may characterize cortex that will become infarcted, if pathophysiological changes in the periinfarct zone are allowed to evolve naturally.

Section: Image Acquisitionmentioning

confidence: 64%

The Use of In Vivo Fluorescence Image Sequences to Indicate the Occurrence and Propagation of Transient Focal Depolarizations in Cerebral Ischemia

J Cereb Blood Flow Metab

Harland

Meldrum

et al. 1996

Self Cite

“…In four experiments, the lingual artery was cannulated retrogradely for intermittent delivery of 0.5 to 1.0 ml boluses of 0.125% umbelliferone for measurement of cerebral blood flow (Kirkpatrick et al, 1994).…”

Section: Anaesthesia and Surgical Preparationmentioning

confidence: 99%

“…The CBF umb method (Kirkpatrick et al, 1994) was used as a reference standard for evaluation of ICT as a measure of perfusion. First pass extraction of this dye into the cortical parenchyma after an intra-arterial bolus is sufficient to allow subsequent imaging of its elution from the cortical parenchyma (after clearance from the capillary circulation).…”

Section: Image Acquisition and Postprocessing (2): Umbelliferone Cleamentioning

confidence: 99%

“…In these experiments, in cats undergoing occlusion of the middle cerebral artery, we therefore evaluated the quantitative capacity of laser speckle imaging by comparing it with values for cortical perfusion obtained in the steady state in the same region of cortex using umbelliferone clearance (CBF umb ) (Kirkpatrick et al, 1994) as a reference method.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of Laser Speckle Flowmetry for Imaging Cortical Perfusion in Experimental Stroke Studies: Quantitation of Perfusion and Detection of Peri-Infarct Depolarisations

J Cereb Blood Flow Metab

Bezzina

Anderson

et al. 2005

Laser speckle imaging of the exposed cerebral cortex allows detailed examination of the time course and topography of perfusion under different experimental conditions. Here we examine the quantitative capacity of the method and its sensitivity for the detection of peri-infarct depolarisations (PIDs). In four cats anaesthetised with chloralose, the right hemisphere was exposed and the right middle cerebral artery was occluded. The brain was illuminated with a laser diode, the speckle pattern was imaged, and images of inverse speckle correlation time (ICT) were derived from the calculated speckle contrast images. We examined the relationship of ICT with perfusion, as imaged quantitively using umbelliferone clearance (CBF umb ). Values of ICT and CBF umb were compared and regression parameters were calculated for each experiment. In eight cats, cortical surface direct current (DC) potential was monitored at two locations and detection of PIDs by DC potential and ICT change was compared. ICT-and CBF umb -derived values of perfusion were closely correlated, with a high degree of significance (P < 0.0001). Overall, monitoring of DC potential detected 90% of PIDs, whereas ICT detected 56%. We conclude that (1) laser speckle imaging provides an index of perfusion that has a linear relationship with the clearance rate of umbelliferone within the range of levels of perfusion examined; (2) this relationship is relatively stable between experiments; and (3) the method's ability to detect blood flow changes associated with PIDs likely depends on the noise level of the speckle measurements.

“…The experimental system closely resembled that described previously 13,15 and comprises in summary (1) fluorescence excitation (75-W xenon source) at 370 nm delivered via 2 liquid light guides and oblique epi-illumination, (2) intensified charge-coupled device camera (Prostab), and (3) a frame-grabbing system (Synoptics Ltd) within a personal computer host, programmed with appropriate image-acquisition sequences. Sequences of between 20 and 130 images were acquired at a rate of 1 image every 12 seconds, before and after MCAO.…”

Section: Image Acquisitionmentioning

confidence: 99%

Factors Influencing the Frequency of Fluorescence Transients as Markers of Peri-Infarct Depolarizations in Focal Cerebral Ischemia

Smith

Whittington

et al. 2000

Stroke

Self Cite

Background and Purpose-Peri-infarct depolarizations (PIDs) that occur in ischemic boundary zones of the cerebral cortex of experimental animals have been shown to promote rather than simply to indicate the evolution of the lesion and are especially prominent in the rat. To study the influence of one factor, species, on PID incidence, we compared the frequency of PIDs in a primate species, the squirrel monkey, with that in the cat after middle cerebral artery occlusion. Plasma glucose was reviewed as a possible cause of interexperiment variability in the cat experiments. Methods-In open-skull experiments under chloralose anesthesia, changes in cortical fluorescence believed to indicate NADH/NAD ϩ redox state, as markers of PIDs, were recorded by serial imaging of the cortical surface in vivo for 4 hours after middle cerebral artery occlusion. Results-Fluorescence transients occurred in squirrel monkeys at a frequency (meanϮSD) of 0.7Ϯ0.8 hours Ϫ1 (nϭ5), which was not significantly less than in that observed in cats (1.3Ϯ1.6 hours Ϫ1 , nϭ8). Data from the cat experiments indicated a relationship between number of transients (dependent) and plasma glucose, with a striking increase in PID frequency in association with values of mean postocclusion plasma glucose Ͻ4.1 mmol/L (Mann-Whitney Uϭ15.0, Pϭ0.034); this observation agrees well with other published findings. Conclusions-Transient changes in fluorescence strongly suggestive of peri-infarct depolarizations, either transient or terminal, occur and propagate in the ischemic cerebral cortex of a nonhuman primate. The results also suggest that the relationship of frequency of peri-infarct depolarizations with plasma glucose requires further examination, to confirm the finding and to determine a safe lower limit for a target range for control of plasma glucose if insulin is used in the management of patients with cerebral ischemia. (Stroke. 2000;31:214-222.)