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Bio-imaging - mccabe
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- 1(5) Importance of imaging in neuroscienceIn vivo assessment of pathology, longitudinal assessment of disease and intervention, translation of biomarkers to clinic, assessmend of physiologcal, functional, molecular and cellular process (multimodal techniques), reduced numbers of animals used.
- 2How to decide what technnique to use?What is being measured (BF/structure), spatial resolution required (um or mm), temporal resolution (ms-mins), Sensitivity (nM-mM), field of view (eg whole or just striatum etc)
- 3CT exampleBBB breakdown after ischaemia by using an iodine based contrast agent
- 4PET example 1use 18F-FDG - monitor glucose metabolism - the product 2-deoxyglucose-6-phosphate trapped in cells = amplify signal (Zimmer et al 2014)
- 5PET example 211C labelled DASB - radioligand for 5HTT transporter whos signal can be attenuated by blockade with WF-516 and fluvoxamine (5HT reuptake inhibitory)
- 6Laser speckle contrast imaging exampleEffects of administering a drug to facilitate blood flow after stroke to monitor action on CBF
- 7Benefits of MRINon-invasive, longitudinal assessment, accesability of the brain, good WM/GM contrast, distinguish between tissues based on physiological and biochemical properties, stroke diagnosis especially acute, dynamic technique
- 8Image resolutionResolution of a voxel = divide field of view by matrix size and x slice thickness.
- 9SIgnal to noise ratioSignal within image divided by the S.D of background noise
- 10Increasing SNRHigher field strength, specifc surface coils and larger voxels (decrease res)
- 11Issues for small animal MRIGetting high enough res - 1mm not good for a 0.5ml brain, physiological noise (eg movement artefacts), anaesthesia
- 12T2 (transverse signal) - dark signal =WM
- 13T2 - bright signalGM, CSF, oxyhaemoglobin, oedema, lesions
- 14T2 examplevasogenic oedema within 3-4 hours of stroke - hyperintense signal - infarct quanitification - CORRECT for brain swelling
- 15T2 imaging example 2Image MS lesions - Ge et al 2006 - hyperintense
- 16High resolution T2Volumetry - segmentation - Yang et al 2011 - AD tg4510 mouse - ventricular dilatation and cerebral cortex atrophy.
- 17T1 weighted - dark signalGM, CSF, oedema, lesions
- 18T1 imaging - bright signalWM, fat blood and gad
- 19T1 exampleGad - BBB breakdown eg in stroke - hyperintense signal
- 20T1 example 2Contrast agents to see cortical vasculature - Howles et al (2010) - high conc of Gd-DTPA - susceptability induced loss of signal - see vessels even though less than limits of resolution
- 21DWICytotoxic oedema - Baskerville et al (2016) - male and female using thresholding
- 22PWI two main methodsContrast agent and arterial spin
- 23PWI exampleImage the penumbra - low flow = hypointense signal
- 24DTI exampleWM lesions in ms, WM integrity changes in epilepsy (Ie altered FA values due to altered WM)
- 25Tractography exampleBudde et al 2011 - controlled cortical impact - tracts originating in external capsule and corpus callosum propogate into lesioned corted - (see decreased FA due to axonal degeneration and demylination)
- 26Cell tracking - contrast agents for labellingSuperparamagnetic - SPIO (50-200nm), Ultrasmall SPIO (35nm), Micron sized iron oxide (0.96-5.8nm) - hypointense signal on T2/T2*. Paramagnetic contrast agents - based on metals like manganese and gadolinium = hyperintense T1 - dipole-dipole interactions between nearby water protons affect relaxation times of proton spins.
- 27Cell tracking example antibodiesVCAM1 (vascular cell adhesion molecule) - highlight activated endothelium in MS (EAE mouse). Serres et al 2011 - hypointese bound to MPIO
- 28Stem cell tracking exampleHoehn et al 2002 - Stem cells + iron oxide - non-ischaemic hemisphere - track to damage via cc
- 29Cell tracking in the eyeLabel OECs with IOs - inject intravitreally = hypointense
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- Fichas sobre Bio-imaging - mccabe, creado por em-lee-o el 03/05/2016.
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