Mri brain anatomy Dr Muhammad Bin Zulfiqar

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Anatomy of Brain by MRI
In this presentation we will discuss the cross sectional anatomy of brain. Then we will discuss the Most common diseases to be evaluated by brain imaging.
In my opinion this presentation is a road map for beginars.

Published in: Health & Medicine

Mri brain anatomy Dr Muhammad Bin Zulfiqar

  1. 1. MR IMAGING OF BRAIN Muhammad Bin Zulfiqar PGR II SIMS/SHL New Radiology Department
  2. 2. Basics of MR • MR sequences • MR signal characteristic
  3. 3. MRI----conventional sequences • SE sequence ( spin echo ) – T1-weighted,T1-WI TR: 200-800ms TE:15-30ms – T2-weighted,T2-WI TR:1500-2000ms TE:60-150ms – Proton Density,N(H) ) TR:1500-2500ms TE:15-30ms • IR sequence ( inversion recovery sequence ) TR ( short ) TE ( short ) TI ( short )
  4. 4. MR signal characteristics • SE sequences : – T1-WI: highest signal on fat tissue ,better for showing anatomical structures – T2-WI: highest signal in liquid, better for detecting lesions – N ( H ) Density(H): for characteristics of lesions • GRE sequence : flip angle , fast scan • IR sequence : separation between of fat and liquid
  5. 5. T2WI T1WI MR signal characteristics
  6. 6. Fat supression Liquid supression MR signal characteristics
  7. 7. THREE DIMENSIONAL BRAIN ANATOMY
  8. 8. Fig. 1.1 Post Contrast Axial MR Image of the brain 1 2 3 4 5 Post Contrast sagittal T1 Weighted M.R.I. Section at the level of Foramen Magnum Answers 1. Cisterna Magna 2. Cervical Cord 3. Nasopharynx 4. Mandible 5. Maxillary Sinus
  9. 9. Fig. 1.2 Post Contrast Axial MR Image of the brain 7 6 Post Contrast sagittal T1 Wtd M.R.I. Section at the level of medulla Answers 6. Medulla 7. Sigmoid Sinus
  10. 10. Fig. 1.3 Post Contrast Axial MR Image of the brain 15 8 9 10 11 12 13 14 16 17 Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Pons Answers 8. Cerebellar Hemisphere 9. Vermis 10. IV Ventricle 11. Pons 12. Basilar Artery 13. Internal Carotid Artery 14. Cavernous Sinus 15. Middle Cerebellar Peduncle 16. Internal Auditory Canal 17. Temporal Lobe
  11. 11. Fig. 1.4 Post Contrast Axial MR Image of the brain 18 19 20 21 22 Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Mid Brain Answers 18. Aqueduct of Sylvius 19. Midbrain 20. Orbits 21. Posterior Cerebral Artery 22. Middle Cerebral Artery
  12. 12. Fig. 1.5 Post Contrast Axial MR Image of the brain 23 24 25 26 27 Post Contrast sagittal T1 Wtd M.R.I. Section at the level of the III Ventricle Answers 23. Occipital Lobe 24. III Ventricle 25. Frontal Lobe 26. Temporal Lobe 27. Sylvian Fissure
  13. 13. Fig. 1.6 Post Contrast Axial MR Image of the brain 28 29 30 31 32 38 33 34 36 35 37 Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Thalamus Answers 28. Superior Sagittal Sinus 29. Occipital Lobe 30. Choroid Plexus within the occipital horn 31. Internal Cerebral Vein 32. Frontal Horn 33. Thalamus 34. Temporal Lobe 35. Internal Capsule 36. Putamen 37. Caudate Nucleus 38. Frontal Lobe
  14. 14. Fig. 1.7 Post Contrast Axial MR Image of the brain 39 40 41 Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Corpus Callosum Answers 39. Splenium of corpus callosum 40. Choroid plexus within the body of lateral ventricle 41. Genu of corpus callosum
  15. 15. Fig. 1.8 Post Contrast Axial MR Image of the brain 42 43 44 Post Contrast sagittal T1 Wtd M.R.I. Section at the level of Body of Corpus Callosum Answers 42. Parietal Lobe 43. Body of the Corpus Callosum 44. Frontal Lobe
  16. 16. Fig. 1.9 Post Contrast Axial MR Image of the brain 45 46 Post Contrast sagittal T1 Wtd M.R.I. Section above the Corpus Callosum Answers 45. Parietal Lobe 46. Frontal Lobe
  17. 17. Normal anatomical structure of head on MRI
  18. 18. T2WI
  19. 19. T1WI
  20. 20. Flair sequence
  21. 21. T2WI(coronal section )
  22. 22. T1WI ( sagittal section ) Corpus callosum; optic chiasm; pituitary gland; medulla oblongata
  23. 23. MRI diagnosis of brain vascular diseases • Intra cerebral Hemorrhage • Cerebral Infarction • Intracranial Aneurysm
  24. 24. Brain bleed (hemorrhage) • Causes : high blood pressure, vascular malformation and tumor • Stage : acute, sub acute, chronic
  25. 25. MRI appearances of hemorrhage at different stage • Acute hemorrhage MRI - iso-intensity on T1WI, slightly low or low intensity on T2WI( ideally MR was poor than CT for Acute hemorrhage ). • Sub acute hemorrhage MRI - iso- or high signal intensity on T1WI, iso- or slightly high signal intensity on T2WI. • Chronic hemorrhage MRI - high signal intensity both on T1WI/T2WI.
  26. 26. acute/subacute hemorrhage acute subacute T2WI T1WI
  27. 27. Chronic intracranial hemorrhage
  28. 28. MRI diagnosis of cerebral infarction
  29. 29. MR appearances of cerebral infarction • High signal intensity at Acute , subacute and chronic stage on T2WI because of increment of fluid at infarction. • Iso-intensity at acute stage , iso- or slightly low intensity at subacute stage, low intensity at chronic stage on T1WI. • Flair and DWI sequences are more sensitive for detecting acute infarction.
  30. 30. MR:44396 MR&CT appearances of acuteMR&CT appearances of acute cerebral infarctioncerebral infarction T2WI T1WI Flair
  31. 31. MR:44396 MR&CT appearances of acute cerebralMR&CT appearances of acute cerebral infarctioninfarction FlairT1WIT2WI
  32. 32. Acute infarction
  33. 33. Acute infarction
  34. 34. Acute infarction DWI
  35. 35. Subacute/chronic infarction—T2WI
  36. 36. T2WI--Coronal
  37. 37. Chronic infarction at brain stem and cerebellum—T2WI
  38. 38. Chronic infarction at brain stem and cerebellum—T1WI
  39. 39. MRI diagnosis of head trauma
  40. 40. The types of head trauma  Skull fracture  traumatic cerebral swelling  brain contusions  Intracranial bleed of trauma – Epidural hematoma – Subdural hematoma – Subarachnoid hemorrhage – Intracerebral hematoma
  41. 41. MR diagnosis of cranial trauma Epidural hematoma : ‫٭‬ direct violence on skull ‫٭‬skull fracture and deformation ‫٭‬direct laceration or tearing of meningeal arteries ‫٭‬ local hematoma ,not across cranial suture ‫٭‬shape of duple convex mirror
  42. 42. MR appearances ‫٭‬ shape of hematoma is biconvex ‫٭‬ signal intensity of hematoma varies greatly depending on times. ‫٭‬ at acute stage ( 0~2 days ), iso-intensity on T1WI , low intensity on T2WI. ‫٭‬at subacute stage ( 3~14 days ), becoming high signal intensity from rim to center on T1WI, still low signal intensity at 6~8 days and high signal intensity after 8 day on T2WI. ‫٭‬ at chronic stage (14 days later) , high signal intensity on both T1WI and T2WI for quite long times (may be several months)
  43. 43. Subacute hematoma at left frontal lobe
  44. 44. Subacute hematoma at left frontal lobe
  45. 45. Subdural hematoma ‫٭‬Location: supratentorial convexity. ‫٭‬ Caused by stretching and tearing of bridging veins. ‫٭‬ Hematoma is located between dura mater and arachnoid. Often quite large extent , across cranial suture. ‫٭‬ MR appearances : shape of hematoma semilunar , signal changes of hematoma similar to epidural hematoma at different stages.
  46. 46. Subacute Subdural Hematoma Axial T1-weighted magnetic resonance imaging demonstrates bilateral subacute subdural hematomas with increased signal intensity. Areas of intermediate intensity represent more acute hemorrhage into the subacute collections. T2-weighted magnetic resonance imaging in a patient with subdural hematoma shows blood products of differing ages.
  47. 47. Subacute subdural hematoma at left frontal-temporal area
  48. 48. Subacute subdural hematoma at left frontal-temporal area
  49. 49. MR Features of brain contusion ‫٭‬ Often involve the temporal and frontal lobe. • Temporal lobe lesions tend to lie just above the petrous bone or posterior to the greater sphenoid wing. • Frontal lobe lesions occur just above the cribriform plate, orbit, planum sphnoidale, and lesser sphenoid wing.
  50. 50. MR appearances ‫٭‬ MR is more sensitive than CT to find small contusion because of easy to find edema caused by contusion. ‫٭‬hemorrhagic foci appear petechia or multiple confluent regions with high signal intensity. ‫٭‬ easy to find contusion at brain stem.
  51. 51. Contusion and epidural hemorrhage at both temporal lobe and frontal lobe
  52. 52. Contusion and epidural hemorrhage at both temporal lobe and frontal lobe
  53. 53. Multiple contusions at both sides of frontal and temporal lobes
  54. 54. Multiple contusions at both sides of frontal and temporal lobes
  55. 55. INTRACRANIAL TUMORS ‫٭‬ primary (80%) :originating from cranial bone, cranial meninges, brain tissues, vessels, cranial nerves, pituitary gland, etc. glioma(50%) , meningioma(14%) , pituitary tumor (11%) , acoustic neuroma(7%) ‫٭‬secondary (20%) : metastasis , involved by tumor from near structures.
  56. 56. The types of intracranial tumors • Intraaxial brain tumors : 1.glioma( astrocytoma and oligodendroglioma) 2.ependymoma 3.medulloblastoma 4.hemangioblastoma 5.papilloma choroideum 6.metastases
  57. 57. The types of intracranial tumors • Extraaxial brain tumors 1.meningioma 2.craniopharyngioma 3.pituitary tumor 4.nerve sheath tumors-acoustic schwannoma 5.epidermorid cyst, dermoid cyst and hamartomas
  58. 58. Direct signs 1. tumor or occupying lesion. 2. abnormal density or signal. 3. enhancement in different degree on enhanced scan. CT and MRI Signs for diagnosis of intracranial tumors 、、
  59. 59. Indirect signs 1. shift of near structures 2. edema in brain tissue near tumor 3. Intratumoral bleed 4. Intratumoral calcification 5. bone changes
  60. 60. Astrocytoma lower grading of astrocytoma , grading I or II . • Often in adult (20~40 years ) -- more occult in cerebral hemisphere , grading II , solid • child– less seen , more in cerebellum , grading I, cyst
  61. 61. Astrocytoma MR : Isointensity on T1WI , unclear border , high or slightly high signal intensity on T2WI no or slight occupying effect , no or slight enhancement.
  62. 62. Grade I Astrocytoma T1WI T2WI
  63. 63. Grade II astrocytoma T2W Gd+ Gd+ MR:39547
  64. 64. Astrocytoma high grading ( grading III or IV) • Fast growing • Occur in any age
  65. 65. Imaging appearances of high grading astrocytoma • Obvious occupying effects ,infiltrating growing with unclear margin , growing across lobe and hemisphere. • Necrosis, cyst , bleed. • Obvious brain edema around tumor. • Obvious uneven or ring-like enhancement.
  66. 66. Grade IV astrocytoma MR:39985 T2W T1W Gd+
  67. 67. Grade IV astrocytoma MR:39985 T2W Gd+ T2W Gd+
  68. 68. MR : 53847 Grading IV astrocytoma
  69. 69. Brain metastasis • Old age • Single or multiple • Multiple appearances on CT or MR, but often shown in nodule • Heterogeneous density or signal, central necrosis with lower density or signal on T1WI. • Ring-like or even enhancement • Obviously finger-like peritumoral edema
  70. 70. Multiple metastases
  71. 71. Metastasis from lung cancer uncontrast contrast
  72. 72. Metastasis from lung cancer uncontrast contrast
  73. 73. Imaging of meningioma • Round or hemishere mass occur mostly in convexity of brain , especially sagittal sinus. • Mass with clear margin which was encysted with cerebral spinal fluid and/or vessels. • Iso- or slightly high density on plain CT and low signal on T1WI, iso- or slightly high signal on T2WI, which was enhanced obviously and evenly. • A broad thickened dural-based margin which was called “tail sign” . • Edema may be not or obvious. • Local bone changes including destruction, thin or thickness.
  74. 74. Right parietal meningioma Plain T1WI Contrast T1WI
  75. 75. T2WI AND contrast T1WI
  76. 76. Meningioma T2WI T1WI Gd-T1W
  77. 77. Acoustic schwannoma • Benign tumor, occur mostly at middle age people, approximately 7 ~8 of all primary intracranial neoplasms.﹪ ﹪ • Ovoid or tubular tumors may occur in the internal auditory canal and cerebellopontine angle cistern . • Tumor may be part of solid and cystic . • On Plain CT, solid part of tumor was iso-density ,and cystic part was low density. • Iso-intensity or low signal intensity were seen in solid or cystic part of tumor on T1WI, but high or very high signal intensity on T2WI,. • Obvious enhancement was seen on solid tumor. • Enlargement of internal auditory canal.
  78. 78. Left acoustic schwannoma
  79. 79. Left acoustic schwannoma T2WI T1WI Contrast T1WI
  80. 80. Left acoustic schwannoma

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