• Document: Advanced MRI methods in diagnostics of spinal cord pathology
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Advanced MRI methods in diagnostics of spinal cord pathology Stanisław Kwieciński Department of Magnetic Resonance Diffusion Rat Injured Spinal Cord MR IMAGING LAB MRI /MRS IN BIOMEDICAL RESEARCH ON HUMANS AND ANIMAL MODELS IN VIVO Equipment: 4.7T/31cm MRI, 8.5T MR Microscope, Animal Lab, access to clinical 1.5T MRI Genomic Mouse Heart ƒ Diffusion Tensor Imaging & fMRI of spinal cord on humans and rats to develop methods of early diagnostics of injury. ƒ MRI of heart pathology on Transgenic mouse model. ƒ 31P MRS in human skeletal muscle physiology. ƒ MRI in pharmacy to monitor the disintegration Human spinal cord processes of drug tablets ƒ MRI in Dentistry in vitro on extracted teeth. ƒ MRI/MRS Physics and Technology: sequence design, software and hardware: gradient coils, RF-coils and probes Spinal Cord Imaging – why so important ? • Spinal cord injuries are main factor of permanent disability affecting population as a result of communication, work or sport accidents. • Outgrowth and regeneration of injured nerve fibers is possible • Early diagnosis of pathologies such as Alzheimer, Sclerosis Multiplex, tumors, venous malformations ... Major Nerve Pathways of a spinal cord www.paraplegic-online.com What MRI Physicist can offer ? To develop a non-invasive, quantitative method of EARLY COMPLETE DIAGNOSTICS of the spinal cord injuries , white matter diseases and other spinal cord pathologies in humans in vivo based on MR diffusion tensor imaging (DTI) and functional MRI (fMRI) Problems with Spinal Cord Imaging • Size and shape • Environment (various tissues, bones, CSF ) poor magnetic field homogeneity caused by susceptibility differences • Motional artefacts (breathing, swallowing, beating heart, pulsating CSF) Image from www.vilenski.org/science/humanbody Grey and White Matter in Spinal Cord Medium T1 (ms) T2 (ms) GM 1200 100 WM 1010 90 CSF 3120 160 Why Diffusion Imaging ? • Diffusion provides unique indicator of tissue microstructure (natural contrast !!!) • Diffusional parameters change immediately after injury • Diffusion attributes allow „fiber tracking“ Extracting information from Diffusion Imaging: • Images • Vector Maps • Quantitative Analysis (FA – Fractional Anisotropy ADC – Apparent Diffusion Coeficient...) Diffusion Tensor S∼ e-b⋅D  D xx D xy D xz    It fully describes Dαβ =  D yx D yy D yz  , molecular mobility D D zz  along each direction  zx D zy and correlation among Matrix these directions Quantitative analysis: FA = √{3[(λ1- 〈λ〉 )2 + (λ2- 〈λ〉 )2 + (λ3- 〈λ〉 )2]} / √{2[(λ12 + λ22 +λ32)]} ADC = 〈λ〉 Where 〈λ〉 = Trace/3 = (λ1 + λ2 + λ3)/3 λ1 , λ2 , λ3 : eigenvalues of a diffusion tensor We have started with RATS Sagital projection Axial projection T2 T2 4.7T Bruker, bore: 30 cm DTI DTI Testing neuroprotecive tADC Slice 1 WM drugs 0.0014 0.0012 Reference (normal) ADC [mm^2/s ] 0.001 0.0008 0.0006 Injured with drug 0.0004 ADC 0.0002 0 Injured without drug 1 24 48 168 time [h] We have continued with HUMANS Images from 1.5T clinical system T2 DTI ADC FA Cervical – Thoracic Spine FA and ADC

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