Name: MRI Scanner Setup for Human Visual Functional Imaging
Uploaded: 2023-12-08T12:40:00
Description: Watch this Scientific Journal Video about MRI Scanner Setup for Human Visual Functional Imaging at JoVE.com

mri scanner setup for human visual functional imaging

दृष्टि विकारों के उन्नत मूल्यांकन के लिए दृश्य प्रांतस्था मानचित्रण को आगे बढ़ाना

Functional magnetic resonance imaging (fMRI) is a valuable method to assess changes in regional neurovascular function within the visual cortex in response to stimuli, as changes in regional blood flow correlate to the activation of brain regions1,2. High-resolution retinotopic blood oxygenation level-dependent (BOLD) signal measurements represent changes in deoxyhemoglobin, which are driven by localized changes in blood flow and blood oxygenation within the brain1,2. BOLD activity patterns collected from fMRI data can be used to functionally map the peripheral and central visual cortex, as well as detect changes in the retinotopic map in response to visual impairment and neurodegeneration3.
Most previous fMRI studies made use of narrow-view (around &#177;12&#176; of the central visual field) non-retinotopic stimuli or simple retinotopic stimuli with narrow-view visual stimuli, which provided limited functional parcellation of the retinotopic representation in the visual cortex and limited assessment to only the central visual field, excluding the periphery3. Consequently, narrow-view fMRI data has reported inconsistent BOLD percent changes in glaucoma patients4,5,6. There is therefore a need for improved fMRI approaches to assessing the peripheral and central visual field, particularly in the evaluation of diseases such as glaucoma.
Glaucoma is the leading cause of irreversible blindness, affecting 10% of people by the age of 807. Glaucoma is caused by the progressive, irreversible neurodegeneration of retinal ganglion cells, which are responsible for transmitting visual stimuli to the brain through the optic nerve. In primary open-angle glaucoma (POAG), the most common form of glaucoma, increased intraocular pressure causes thinning of the retinal nerve fiber layer (RNFL), leading to the loss of peripheral vision followed by peripheral and central blindess8,9,10,11. Histological evidence from animal studies suggests that glaucoma additionally results in progressive neurodegeneration of the optic nerve, optic tract, lateral geniculate nucleus, optic radiation, and visual cortex12,13. MRI technology offers a minimally invasive method of assessing both blood oxygenation and neurodegeneration in the visual cortex. In patients with glaucoma, MRI has found evidence of gray-matter atrophy in the visual pathway13,14,15,16 and abnormal white matter in the optic chiasm, optic tract, and optic radiation1,17,18.
To further explore the effects on visual processing, fMRI can be used to detect brain function in response to visual cues. The protocol herein describes a novel method to obtain a low-cost, wide-view retinotopic map using high-resolution retinotopy fMRI with wide-field (&#62;100&#176;) stimuli, as described by Zhou et al3. Visual stimuli of expanding rings and rotating wedges were used to elicit retinotopic mapping of the eccentricity and polar angle for fMRI. BOLD fMRI percent changes were analyzed as a function of eccentricity to evaluate brain function, corresponding to both central and peripheral vision. The BOLD fMRI percent change may be used to visualize activation throughout the visual cortex. These fMRI measures provide a reliable new method to evaluate neurodegenerative changes and their functional effects on the visual cortex found in eye diseases involving visual field defects, such as glaucoma.

लेखक स्पॉटलाइट: वाइड-व्यू एफएमआरआई मैपिंग के माध्यम से विजुअल कॉर्टेक्स रिसर्च में अंतर्दृष्टि 

वाइड-व्यू रेटिनोटोपिक उत्तेजना के साथ विजुअल कॉर्टेक्स के कार्यात्मक चुंबकीय अनुनाद इमेजिंग (एफएमआरआई)

This research focuses on providing a practical, cost-effective visual presentation system to evaluate changes in the visual cortex due to ophthalmic diseases. We provide a method to create a wide viewing angle, retina atopic map, using FMRI to assess the functional activity of the visual cortex. A current experimental challenge is that standard systems for presenting visual stimuli for FMRI only cover small area of the visual fields, and with the view partially obstructed by the head coil.This protocol provides method for wide view and unobstructed stimuli that balances cost, efficacy, and precision. Our protocol provides an affordable, moderately wide view of up to a hundred degrees of the visual field. Compared to other techniques, it avoids distortions, additional costs for projector lenses or fiber optic bundles, and other complexities, such as the need for contact lenses.Our findings can be used to expand the understanding of the visual cortex, enabling the mapping of peripheral and central regions via an affordable, wide view FMRI system. This could enhance the management of visual impairments in eye diseases such as glaucoma, which involves dysfunction of the visual system in the brain.

Watch this Scientific Journal Video about MRI Scanner Setup for Human Visual Functional Imaging at JoVE.com

MRI Scanner Setup for Human Visual Functional Imaging  

मानव दृश्य कार्यात्मक इमेजिंग के लिए एमआरआई स्कैनर सेटअप

कार्यात्मक चुंबकीय अनुनाद इमेजिंग के लिए मल्टी-चैनल रिसीवर हेड कॉइल से लैस 3T MRI स्कैनर का उपयोग करके शुरू करें। बिना किसी रुकावट के बड़े व्यूइंग एंगल को सुनिश्चित करने के लिए पीछे के आधे हिस्से का उपयोग करें। इसके बाद, 2.2 सेकंड के पुनरावृत्ति समय और 176 से 256 गुणा 208 मिलीमीटर के दृश्य क्षेत्र को इनपुट करके एक T1 भारित MPRAGE अनुक्रम स्थापित करें।1 बाय 1 बाय 1 मिलीमीटर का स्थानिक रिज़ॉल्यूशन प्रदान करें। प्रति पिक्सेल 190 हर्ट्ज की बैंडविड्थ। 13 डिग्री का फ्लिप कोण।और 3.1 मिनट की स्कैन अवधि। 2 सेकंड के पुनरावृत्ति समय के साथ एक ढाल गूंज ईपीआई अनुक्रम सेट करें, 30 मिलीसेकंड का गूंज समय, 220 से 220 मिलीमीटर के दृश्य क्षेत्र, 3 मिलीमीटर मोटाई के 29 स्लाइस के साथ 1.7 से 1.7 मिलीमीटर का इन-प्लेन रिज़ॉल्यूशन, और लगभग 1500 हर्ट्ज प्रति पिक्सेल की बैंडविड्थ। अब, सिर का तार और स्कैनर बोर के आयामों को मापें।फिर, एक साधारण पीवीसी पाइप फ्रेम बनाने के लिए पीवीसी कोहनी के साथ पीवीसी ट्यूबों को कनेक्ट करें, और नायलॉन शिकंजा के साथ, दर्पण को फ्रेम में रखने वाली प्लास्टिक रॉड के सिरों को संलग्न करें। ध्यान दें कि दर्पण प्लास्टिक के शिकंजे के साथ प्लास्टिक की छड़ से जुड़ा हुआ है। सुनिश्चित करें कि दर्पण को मैन्युअल रूप से इष्टतम कोण पर घुमाने के लिए शिकंजा पर्याप्त ढीले हैं।एक खंडित रियर प्रोजेक्शन स्क्रीन को एक फ्रेम में पेंच करने के बाद, स्क्रीन को स्कैनर के पीछे रखें, इसे देखने के क्षेत्र को अधिकतम करने के लिए हेड कॉइल के पीछे रखें।

Research

JoVE Journal

Neuroscience

MRI Scanner Setup for Human Visual Functional Imaging

Functional Magnetic Resonance Imaging (fMRI) of the Visual Cortex with Wide-View Retinotopic Stimulation

High-resolution retinotopic blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) with a wide-view presentation can be ...