Imaging retinal blood flow with laser speckle flowmetry

Srienc, Anja I.; Kurth‐Nelson, Zeb; Newman, Eric A.

doi:10.3389/fnene.2010.00128

Cited by 76 publications

(70 citation statements)

References 36 publications

(48 reference statements)

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“…2(f) and 3(f) are caused by major choroidal vessels. 22,23 To demonstrate further the complementary nature of these three modalities, a PAOM B-scan, 1D FA-SLO profile, and SD-OCT B-scan are compared in Fig. 4.…”

Section: Resultsmentioning

confidence: 99%

Integrating photoacoustic ophthalmoscopy with scanning laser ophthalmoscopy, optical coherence tomography, and fluorescein angiography for a multimodal retinal imaging platform

Song¹,

Wei²,

Liu³

et al. 2012

J. Biomed. Opt.

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Abstract. Photoacoustic ophthalmoscopy (PAOM) is a newly developed retinal imaging technology that holds promise for both fundamental investigation and clinical diagnosis of several blinding diseases. Hence, integrating PAOM with other existing ophthalmic imaging modalities is important to identify and verify the strengths of PAOM compared with the established technologies and to provide the foundation for more comprehensive multimodal imaging. To this end, we developed a retinal imaging platform integrating PAOM with scanning laser ophthalmoscopy (SLO), spectral-domain optical coherence tomography (SD-OCT), and fluorescein angiography (FA). In the system, all the imaging modalities shared the same optical scanning and delivery mechanisms, which enabled registered retinal imaging from all the modalities. High-resolution PAOM, SD-OCT, SLO, and FA images were acquired in both albino and pigmented rat eyes. The reported in vivo results demonstrate the capability of the integrated system to provide comprehensive anatomic imaging based on multiple optical contrasts.

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Section: Resultsmentioning

confidence: 99%

Integrating photoacoustic ophthalmoscopy with scanning laser ophthalmoscopy, optical coherence tomography, and fluorescein angiography for a multimodal retinal imaging platform

Song¹,

Wei²,

Liu³

et al. 2012

J. Biomed. Opt.

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“…The ex vivo retina and in vivo rat preparations have been described in detail previously (6,33). All methods were approved by the University of Minnesota's Institutional Animal Care and Use Committee.…”

Section: Methodsmentioning

confidence: 99%

“…Peak response was calculated as the mean of the three greatest responses. Blood velocity was measured by laser speckle flowmetry (33). Data were analyzed with custom MatLab routines.…”

Section: Methodsmentioning

confidence: 99%

Oxygen modulation of neurovascular coupling in the retina

Mishra

Hamid

Newman

2011

Proc. Natl. Acad. Sci. U.S.A.

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Neurovascular coupling is a process through which neuronal activity leads to local increases in blood flow in the central nervous system. In brain slices, 100% O 2 has been shown to alter neurovascular coupling, suppressing activity-dependent vasodilation. However, in vivo, hyperoxia reportedly has no effect on blood flow. Resolving these conflicting findings is important, given that hyperoxia is often used in the clinic in the treatment of both adults and neonates, and a reduction in neurovascular coupling could deprive active neurons of adequate nutrients. Here we address this issue by examining neurovascular coupling in both ex vivo and in vivo rat retina preparations. In the ex vivo retina, 100% O 2 reduced light-evoked arteriole vasodilations by 3.9-fold and increased vasoconstrictions by 2.6-fold. In vivo, however, hyperoxia had no effect on light-evoked arteriole dilations or blood velocity. Oxygen electrode measurements showed that 100% O 2 raised pO 2 in the ex vivo retina from 34 to 548 mm Hg, whereas hyperoxia has been reported to increase retinal pO 2 in vivo to only ∼53 mm Hg [Yu DY, Cringle SJ, Alder VA, Su EN (1994) Am J Physiol 267:H2498-H2507]. Replicating the hyperoxic in vivo pO 2 of 53 mm Hg in the ex vivo retina did not alter vasomotor responses, indicating that although O 2 can modulate neurovascular coupling when raised sufficiently high, the hyperoxia-induced rise in retinal pO 2 in vivo is not sufficient to produce a modulatory effect. Our findings demonstrate that hyperoxia does not alter neurovascular coupling in vivo, ensuring that active neurons receive an adequate supply of nutrients.functional hyperemia | glial cells | prostaglandins N euronal activity in the CNS induces local increases in blood flow (1, 2), a homeostatic response termed functional hyperemia. Neurovascular coupling, the process mediating this response, is thought to involve signaling from neurons to glial cells to blood vessels. Neuronal activity induces a rise in intracellular Ca 2+ in glial cell endfeet surrounding vessels, leading to the release of vasoactive arachidonic acid metabolites and resulting in vasomotor responses (2-6). Experiments in brain slices and in the ex vivo retina have revealed that glial activation can evoke both vasodilation and vasoconstriction. Evoked vasodilations are mediated by cyclooxygenase (COX) products (3, 5) and epoxyeicosatrienoic acids (EETs) (6-9), whereas vasoconstrictions are mediated by 20-hydroxyeicosatetraenoic acid (20-HETE) (4,6).A recent study demonstrated that neurovascular coupling is modulated by O 2 in brain slices (10). Both neuronal and glial cell stimulation elicited vasodilations in brain slices exposed to 20% O 2 . In contrast, vasoconstrictions were evoked in the presence of 100% O 2 . However, another recent study reported the opposite effect of O 2 in vivo (11). In that study, increasing systemic O 2 using hyperbaric hyperoxygenation had no effect on cortical functional hyperemia. Resolving these conflicting findings is critical, given that hyperoxia (breat...

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“…Beyond bench-side physiological research, there are direct implications for prognostic, diagnostic, and intraoperative imaging applications, as speckle imaging of microcirculatory flows is increasingly becoming applied for gauging local and systemic tissue health [8,9]. Consequently, laser speckle flowmetry studies are expanding in dermatological [10][11][12][13][14], ophthalmological [15][16][17], and neurosurgical settings [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

Kazmi

Balial

Dunn

2014

Biomed. Opt. Express

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Improved Laser Speckle Contrast Imaging (LSCI) blood flow analyses that incorporate inverse models of the underlying laser-tissue interaction have been used to develop more quantitative implementations of speckle flowmetry such as Multi-Exposure Speckle Imaging (MESI). In this paper, we determine the optimal camera exposure durations required for obtaining flow information with comparable accuracy with the prevailing MESI implementation utilized in recent in vivo rodent studies. A looping leave-one-out (LOO) algorithm was used to identify exposure subsets which were analyzed for accuracy against flows obtained from analysis with the original full exposure set over 9 animals comprising n = 314 regional flow measurements. From the 15 original exposures, 6 exposures were found using the LOO process to provide comparable accuracy, defined as being no more than 10% deviant, with the original flow measurements. The optimal subset of exposures provides a basis set of camera durations for speckle flowmetry studies of the microcirculation and confers a twofold faster acquisition rate and a 28% reduction in processing time without sacrificing accuracy. Additionally, the optimization process can be used to identify further reductions in the exposure subsets for tailoring imaging over less expansive flow distributions to enable even faster imaging.

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Imaging retinal blood flow with laser speckle flowmetry

Cited by 76 publications

References 36 publications

Integrating photoacoustic ophthalmoscopy with scanning laser ophthalmoscopy, optical coherence tomography, and fluorescein angiography for a multimodal retinal imaging platform

Integrating photoacoustic ophthalmoscopy with scanning laser ophthalmoscopy, optical coherence tomography, and fluorescein angiography for a multimodal retinal imaging platform

Oxygen modulation of neurovascular coupling in the retina

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

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