Lamina-Specific Functional MRI of Retinal and Choroidal Responses to Visual Stimuli

Shih, Yen‐Yu Ian; Garza, Bryan H. De La; Muir, Eric R.; Rogers, William E.; Kiel, Jeffrey W.; Duong, Timothy Q.

doi:10.1167/iovs.10-6438

Cited by 30 publications

(39 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The time courses and magnitudes of the measured responses are consistent with previous studies in the same species. 4,11,12 However, we also observed a weak flicker frequency dependence of the blood flow response time integral [ Fig. 7(f)], suggesting that the evoked response may be due, at least in part, to the increase in average luminance during stimulation.…”

Section: Resultsmentioning

confidence: 80%

“…Similar stimulus protocol and experimental designs have been used in the literature to evaluate visual stimulusevoked inner retinal hemodynamic changes. 4,11,12 Moreover, we observed no systemic physiological changes (such as blood pressure changes) synchronized with the stimulus that could account for the observed responses [ Fig. 4(c) and 4(d)].…”

Section: Resultsmentioning

confidence: 83%

“…Comparable stimulus protocols and experimental designs are frequently used in the literature to study functional hyperemia in the rat retina. 4,11,12 Uniform illumination of the retina was confirmed by imaging the retina onto a CCD camera connected to PC2. Repeated OCT volumes for angiography (128 ylocations × 256 axial scans per frame × 2 frames per y-location) or Doppler OCT (96 y-locations × 1024 axial scans per frame × 1 frame per y-location) were acquired during runs of 10 stimuli separated by 25 s. In one run, a stimulus frequency of 12 Hz was used, while in the other run, stimulus frequencies between 6 and 18 Hz were generated in a random order to test for frequency dependence of the response.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Multiparametric optical coherence tomography imaging of the inner retinal hemodynamic response to visual stimulation

Radhakrishnan

Srinivasan

2013

J. Biomed. Opt

View full text Add to dashboard Cite

Abstract. The hemodynamic response to neuronal activation is a well-studied phenomenon in the brain, due to the prevalence of functional magnetic resonance imaging. The retina represents an optically accessible platform for studying lamina-specific neurovascular coupling in the central nervous system; however, due to methodological limitations, this has been challenging to date. We demonstrate techniques for the imaging of visual stimulus-evoked hyperemia in the rat inner retina using Doppler optical coherence tomography (OCT) and OCT angiography. Volumetric imaging with three-dimensional motion correction, en face flow calculation, and normalization of dynamic signal to static signal are techniques that reduce spurious changes caused by motion. We anticipate that OCT imaging of retinal functional hyperemia may yield viable biomarkers in diseases, such as diabetic retinopathy, where the neurovascular unit may be impaired.

show abstract

Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 83%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Multiparametric optical coherence tomography imaging of the inner retinal hemodynamic response to visual stimulation

Radhakrishnan

Srinivasan

2013

J. Biomed. Opt

View full text Add to dashboard Cite

show abstract

“…These segmented data were then analyzed for either pixel area (retinal blood volume index area) or relative signal intensity (relative to dark values) (42).…”

Section: Discussionmentioning

confidence: 99%

Development of an MRI biomarker sensitive to tetrameric visual arrestin 1 and its reduction via light‐evoked translocation in vivo

Berkowitz¹,

Gorgis²,

Patel

et al. 2014

FASEB j.

View full text Add to dashboard Cite

Rod tetrameric arrestin 1 (tet-ARR1), stored in the outer nuclear layer/inner segments in the dark, modulates photoreceptor synaptic activity; light exposure stimulates a reduction via translocation to the outer segments for terminating G-protein coupled phototransduction signaling. Here, we test the hypothesis that intraretinal spin-lattice relaxation rate in the rotating frame (1/T1r), an endogenous MRI contrast mechanism, has high potential for evaluating rod tet-ARR1 and its reduction via translocation. Dark-and light-exposed mice (null for the ARR1 gene, overexpressing ARR1, diabetic, or wild type with or without treatment with Mn 2+ , a calcium channel probe) were studied using 1/T1r MRI. Immunohistochemistry and single-cell recordings of the retinas were also performed. In wild-type mice with or without treatment with Mn 2+ , 1/T1r of avascular outer retina (64% to 72% depth) was significantly (P < 0.05) greater in the dark than in the light; a significant (P < 0.05) but opposite pattern was noted in the inner retina (<50% depth). Light-evoked outer retina D1/T1r was absent in ARR1-null mice and supernormal in overexpressing mice. In diabetic mice, the outer retinal D1/T1r pattern suggested normal darkto-light tet-ARR1 translocation and chromophore content, conclusions confirmed ex vivo. Light-stimulated D1/ T1r in inner retina was linked to changes in blood volume. Our data support 1/T1r MRI for noninvasively assessing rod tet-ARR1 and its reduction via protein translocation, which can be combined with other metrics of retinal function in vivo.-Berkowitz, B. A., Gorgis, J., Patel, A., Baameur, F., Gurevich, V. V., Craft, C. M., Kefalov, V. J., Roberts, R. Development of an MRI biomarker sensitive to tetrameric visual arrestin 1 and its reduction via light-evoked translocation in vivo. FASEB J. 29, 554-564 (2015). www.fasebj.org

show abstract

“…Blood volume (BV) index was calculated as the change in transverse relaxivity (DR2*) between images obtained before and after MION administration (13). The retina was extracted from the 3D data and flattened to allow layer-specific kHz and the following parameters: repetition time msec/echo time msec, 26/4.3; field of view, 9 3 9 3 9 or 9 3 9 3 4.5 mm; zero-filling of 2. air because raw MR signal intensities were not comparable.…”

Section: Discussionmentioning

confidence: 99%

High-Resolution 3D MR Microangiography of the Rat Ocular Circulation

Shih

Muir

et al. 2012

Radiology

Self Cite

View full text Add to dashboard Cite

Purpose:To develop high-spatial-resolution magnetic resonance (MR) microangiography techniques to image the rat ocular circulation. Materials and Methods:Animal experiments were performed with institutional Animal Care Committee approval. MR microangiography (resolution, 84 3 84 3 84 µm or 42 3 42 3 84 µm) of the rat eye (eight rats) was performed by using a custom-made small circular surface coil with an 11.7-T MR unit before and after monocrystalline iron oxide nanoparticle (MION) injection. MR microangiography measurements were made during air, oxygen, and carbogen inhalation. From three-dimensional MR microangiography, the retina was virtually flattened to enable en face views of various retinal depths, including the retinal and choroidal vascular layers. Signal intensity changes within the retinal or choroidal arteries and veins associated with gas challenges were analyzed. Statistical analysis was performed by using paired t tests, with P , .05 considered to indicate a significant difference. Bonferroni correction was used to adjust for multiple comparisons. Results:The central retinal artery, long posterior ciliary arteries, and choroidal vasculature could be distinguished on MR microangiograms of the eye. With MR microangiography, retinal arteries and veins could be distinguished on the basis of blood oxygen level-dependent contrast. Carbogen inhalation-enhanced MR microangiography signal intensity in both the retina (P = .001) and choroid (P = .027) compared with oxygen inhalation. Carbogen inhalation showed significantly higher signal intensity changes in the retinal arteries (P = .001, compared with oxygen inhalation), but not in the veins (P = .549). With MION administration, MR microangiography depicted retinal arterial vasoconstriction when the animals were breathing oxygen (P = .02, compared with animals breathing air). Conclusion:MR microangiography of the eye allows depth-resolved imaging of small angiographic details of the ocular circulation. This approach may prove useful in studying microvascular pathologic findings and neurovascular dysfunction in the eye and retina.q RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup /suppl

show abstract

Lamina-Specific Functional MRI of Retinal and Choroidal Responses to Visual Stimuli

Cited by 30 publications

References 58 publications

Multiparametric optical coherence tomography imaging of the inner retinal hemodynamic response to visual stimulation

Multiparametric optical coherence tomography imaging of the inner retinal hemodynamic response to visual stimulation

Development of an MRI biomarker sensitive to tetrameric visual arrestin 1 and its reduction via light‐evoked translocation in vivo

High-Resolution 3D MR Microangiography of the Rat Ocular Circulation

Contact Info

Product

Resources

About