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What am i looking at
- 1. What Am I Looking At?
- 2. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 5. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 6. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 7. Bright signal on T1 Contrast Gadolinium Hemorrhage Methemoglobin Fat Lipoma Dermoid Protein Cysts of endodermal origin Minerals Immature calcification Copper Manganese
- 8. Hemorrhage
- 13. Fat
- 15. Intracranial cysts of endodermal origin
- 16. Intracranial cysts of endodermal origin Colloid cyst Rathke’s cleft cyst Neuroenteric cyst
- 17. Mineral Calcium Causes of intracranial calcification Manganese Chronic hepatic encephalopathy Copper Wilson disease
- 18. Intra- cranial calcification Physiologic Congenital Phakomatoses TS SW VHL Infection Congenital TORCH Acquired TB NCCGliosis Metabolic Hyper-parathyroidism Hypo-parathyroidism Fahr Tumor Intraaxial Oligodendroglioma Extra-axial Meningioma Craniophyrngioma Intraventricular Ependymoma Neurocytoma Vascular Atherosclerosis AVM Aneurysm Post-irradiation Mineralizing MA
- 20. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 21. T2 • Brain edema. • Encephalomalacia / gliosis. • Demyelination plaques (posterior fossa).
- 24. Low signal on T2 Contrast (Perfusion) Gadolinium Hemorrhage De-oxy hemoglobin Intracellular methemoglobin Protein Cysts of endodermal origin Minerals Calcification Iron
- 25. Black hole effect Intra-cystic nodule of low signal
- 26. Calcification
- 27. Acute intracerebral hematoma de-oxy hemoblobin
- 28. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 29. FLAIR • Brain edema. • Gliosis. • Demyelination plaques. • Subarachnoid hemorrhage.
- 31. Cytotoxic Vasogenic Interstitial Intra-cellular edema Extra-cellular edema Trans-ependymal CSF permeation Pathogenesis Na / k pump failure Disrupted BBB increased intraventricular pressure Causes Infarction. Infarction. Tumor. Infection. PRESS. Hydrocephalus Location Grey and white matter White matter Periventricular white matter T2 Loss of cortiomedullary differentiation Finger like Periventricular rim. Diffusion Restriction No restriction No restriction
- 34. MS
- 36. Gliosis • Neuro-epithelial cyst Vs Porencephalic cyst
- 37. Gliosis Lacunar infarct vs Virchow Robin space
- 38. Disadvantages of FLAIR • CSF flow artifact. • False negative FLAIR.
- 40. False negative FLAIR T1 T2 FLAIR
- 41. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 42. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 43. Detection of MS plaques • PD is the king under tentorium.
- 44. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 45. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 46. Gradient T2* WIS Sensitive to de-oxy hemoblobin and hemosiderin because of their susceptibility effects. • Cavernous malformations. • Amyloid angiopathy. • Post-radiation capillary telangiectasia.
- 49. Disadvantages of Gradient T2WIs • Blooming artifact.
- 50. Blooming artifact • Obscure adjacent smaller lesions
- 51. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 52. Brain image Skull is white CT Skull is not white CSF white T2 ADC Black T1 FLAIR DIFFUSION Grey Proton density Graident echo MRI
- 53. Diffusion Detection of Hyper-acute infarct Diffuse axonal injury Differentiation between Acute lacunar infarct chronic lacunar infarct Active demyelination plaque non active demyelination plaque Abscess metastasis Subdural empyema subdural effusion Lymphoma glioma Recurrent cholesteatoma Postoperative scarring tissue Ependymoma Medulloblastoma Arachnoid Epidermoid
- 54. Hyper-acute stroke • FLAIR / Diffusion mismatch
- 56. Acute vs chronic lacunar infarcts
- 58. Abscess vs metastasis • High viscosity of pus restricted diffusion
- 61. Recurrent cholesteatoma vs post-operative scarring tissue
- 62. Subdural empyema vs subdural effusion
- 64. Diffusion artifacts • T2 shine through effect. • Anisotropic diffusion.
- 65. T2 Shine through artifact
- 66. Restricted diffusion vs T2 shine through T2 DWI • B0 DWI • B500 DWI • B1000 ADC
- 68. Advanced MRI techniques • MR spectroscopy. • MR perfusion. • DTI • Tractography.
- 69. What is MRS? • It is an MRI technique whereby the echo that is obtained from the body is analyzed into its various radio-frequency components rather than making an image.
- 71. Suppression Techniques Water Metabolites CHESS = Chemical Shift Suppression. WEFT = Water Elimination Fourier Transform Tech. I.R Pulses to null water signal prior to spectroscopy •Water is 100,000 X than metabolites. •Fat is 10,000 X than metabolites. ………need suppression……….
- 72. Requirements • High Field. • 1.5 T & 3T. • High Homogeneity • Less than 0.2 p.p.m • Assessed by measuring the water peak width.
- 73. Metabolites • NAA: Neuronal marker. (2.0 ppm) – Neuronal marker – Any neuronal loss…….decrease NAA. • Choline: Cell membrane. (3.2 ppm) High cellularity & membrane turn- over…increase Choline. • Creatine: energy marker. (3.0 ppm)
- 74. Metabolites • Lactate: Cell death. (1.3 ppm) – Necrosis & hypoxia (anaerobic glycolysis) …increase Lactate. • Lipid: (1.3-1.5 ppm) – Necrosis • Myo-Inositol: (3.5 ppm) – Decreases in High grade malignancy
- 75. Single vs. Multi-Voxel Spectroscopy Single Voxel Multi Voxel •2X2X2 cm cube •Short TE (STEAM) •TE=30-35 msec •All Metabolites •Lesion = 60-80% •2X2X2 cm cube •2-3mm inner cubes •Long TE (PRESS) •TE=135-260 msec •Major Metabolites •Margin outline
- 76. MRS Infant Adult
- 77. MRS for 6 days
- 80. Multi-voxel allows comparison with normal tissue.
- 81. MRS of an abscess
- 82. MRS • Apart from Tumors, Necrosis and Infections ARE THERE ANY OTHER APPLICATIONS FOR MRS?
- 83. TLE
- 85. Canavan disease
- 86. MR perfusion MR perfusion Exogenous tracer technique Dynmaic susceptibility contrast imgaging (DSC) Dynamic contrast enhanced imaging (DCE) Endogeneous tracer technique Arterial spin labeled imaging
- 92. MR perfusion CBV color map Time signal intensity curve
- 93. MR perfusion Value Defined as Measured in Cerebral blood volume Volume of blood in a given region of brain tissue milliliters per 100 g of brain tissue Cerbral blood flow Volume of blood per unit time passing through a given region of brain tissue milliliter per minute per 100 g of brain tissue Mean transit time Average time it takes blood to pass through a given region of brain tissue Seconds
- 94. Stroke penumbra • Penumbra = perfusion / diffusion mismatch thrombolytic therapy
- 98. Post-radiation necrosis vs recurrent neoplasm
- 99. Diffusion tensor imaging • MRI technique that uses anisotropic diffusion to estimate the axonal (white matter) organization of the brain
- 104. Fiber tractography (FT) • is a 3D reconstruction technique to access neural tracts using data collected by DTI. Color coding of fiber tractography Red Commisural fibers Right left hemisphere Blue Projection fibers Cortex subcortical grey matter Green Association fibers Cortex cortex
- 105. Projection fibers Long projection fibers Cortico-spinal Cortico-bulbar Cortico-pontine Cortico-reticular Short projection fibers Thalamic radiation (thalamo-cortical) Anterior thalamic radiatation Anterior limb of internal capsule Superior thalamic radiation Posterior limb of internal capsule Posterior thalamic radiation Retrolental portion of internal capsule
- 106. Association fibers Long (inter-lobar) SLF ILF SFO IFO Cingulate Uncinate Fornix Short Intra-lobar (U shaped)
- 112. Cingulate fasciculus
- 113. Corpus callosum
- 114. Anisotropic diffusion directional dependence of diffusivisity • Diffusion of water molecules within white matter axons is more free along the axons than across the axons. • Because the myeline sheath act as barrier
- 115. Fractional anisotropy map (combines water mollecular diffusion with direction) White matter white free diffusion along specific direction anisotropy Grey matter dark free diffusion along all directions isotropy Demyelination plaque (white matter destruction) dark free diffusion along all direction isotropy
- 116. Fractional anisotropy map (combines water mollecular diffusion with direction) White matter white free diffusion along specific direction anisotropy Grey matter dark free diffusion along all directions isotropy Demyelination plaque (white matter destruction) dark free diffusion along all direction isotropy
- 117. ADC and FA values • FAWM = far normal appearing white matter • NAWM = near normal appearing white matter
- 118. Fractional anisotropy map (combines water mollecular diffusion with direction) • White matter white free diffusion along specific direction (anisotropy). • Grey matter dark free diffusion along all directions. (isotropy).
- 119. Tractography • Forceps minor • fronto-occipital fasciculus • Disruption of the white matter fibers at the site of the plaque.