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Introduction to Neuroimaging Aaron S. Field, MD, PhD Neuroradiology University of Wisconsin–Madison BRAIN Updated 3/12/07.

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Presentation on theme: "Introduction to Neuroimaging Aaron S. Field, MD, PhD Neuroradiology University of Wisconsin–Madison BRAIN Updated 3/12/07."— Presentation transcript:

1 Introduction to Neuroimaging Aaron S. Field, MD, PhD Neuroradiology University of Wisconsin–Madison BRAIN Updated 3/12/07

2 Brain Imaging: “The Big 10” InfarctionInfarction HemorrhageHemorrhage InfectionInfection TumorTumor TraumaTrauma DementiaDementia MSMS EpilepsyEpilepsy Cranial neuropathyCranial neuropathy Orbits / Ophtho dxOrbits / Ophtho dx

3 Acute Ischemic Stroke Imaging  Confirm diagnosis  Triage for therapy (risk / prognosis)  Rule out hemorrhage  Assess damage: location, pattern, extent  Is there salvageable brain (“penumbra”)?  Follow outcome  Vessel patency, ultimate infarct size, hemorrhagic transformation

4 CT Signs in Early MCA Ischemia Hyperdense MCA Insular Ribbon Lentiform Nucleus

5 Pathophysiology of Ischemic Injury: Duration and Degree of  CBF Normal neuronal function Reversible injury (penumbra) Infarction CBF ml / 100g / min Time (hrs) 1 2

6 MRI in Stroke Intervention “The 4 P’s” Pipes  Perfusion  Parenchyma MRA Perfusion MR Diffusion MR “Penumbra” Rowley AJNR 22(4); , 2001

7 MCA Infarct MCA

8 PCA Infarct PCA

9 ACA Infarct ACA

10 Brain Imaging: “The Big 10” InfarctionInfarction HemorrhageHemorrhage InfectionInfection TumorTumor TraumaTrauma DementiaDementia MSMS EpilepsyEpilepsy Cranial neuropathyCranial neuropathy Orbits / Ophtho dxOrbits / Ophtho dx

11 Cerebral Hemorrhage TraumaTrauma Ruptured aneurysmRuptured aneurysm HypertensiveHypertensive Hemorrhagic transformation of ischemic infarction (esp. venous)Hemorrhagic transformation of ischemic infarction (esp. venous) Venous infarctionVenous infarction TumorTumor Vascular malformationsVascular malformations Angioinvasive infectionAngioinvasive infection Amyloid angiopathyAmyloid angiopathy

12 Acute intraparenchymal hematoma Cerebral Hemorrhage

13 Hemorrhagic melanoma metastases Cerebral Hemorrhage

14 Acute subarachnoid hemorrhage (and intraventricular) Cerebral Hemorrhage

15 Subdural vs. Epidural Hematoma

16 Acute subdural hematoma Cerebral Hemorrhage

17 Acute epidural hematoma Cerebral Hemorrhage

18 Subdural: Follows inner layer of dura “Rounds the bend” to follow falx or tentorium “Rounds the bend” to follow falx or tentorium Not affected by sutures of skull Not affected by sutures of skull Tendency for crescentic shapes Tendency for crescentic shapes More mass effect than expected for their size More mass effect than expected for their size Typical source of SDH: cortical vein Typical source of SDH: cortical vein Epidural: Follows outer layer of dura (periosteum) Crosses falx or tentorium Crosses falx or tentorium Limited by sutures of skull (typically) Limited by sutures of skull (typically) Tendency for lentiform shapes Tendency for lentiform shapes Typical source of EDH: Typical source of EDH: skull fracture with arterial or sinus laceration skull fracture with arterial or sinus laceration Subdural vs. Epidural Hematoma *

19 Mixed acute/chronic subdural hematoma Cerebral Hemorrhage

20 Hematocrit level! Cerebral Hemorrhage

21 MRI of Hemorrhage MR appearance of hematomas depends on image type. Magnetic properties change over time (Hgb breakdown products), allowing approximate dating T1 T2 T2* T1 T2 T2*

22 Brain Imaging: “The Big 10” InfarctionInfarction HemorrhageHemorrhage InfectionInfection TumorTumor TraumaTrauma DementiaDementia MSMS EpilepsyEpilepsy Cranial neuropathyCranial neuropathy Orbits / Ophtho dxOrbits / Ophtho dx

23 Infection MeningitisMeningitis EncephalitisEncephalitis Cerebritis and parenchymal abscessCerebritis and parenchymal abscess Empyema (subdural/epidural)Empyema (subdural/epidural)

24 Leptomeningitis: pia-arachnoid Meningitis Pachymeningitis: dura Most common imaging findings in meningitis: NONE !!

25 Herpes Encephalitis

26 Cerebritis w/ Bacterial Abscess T1 + Gd T2 Diffusion T1 + Gd T2 Diffusion

27 Cerebritis w/ Subdural Empyema T1 + Gd T2 FLAIR Diffusion T1 + Gd T2 FLAIR Diffusion

28 Brain Imaging: “The Big 10” InfarctionInfarction HemorrhageHemorrhage InfectionInfection TumorTumor TraumaTrauma DementiaDementia MSMS EpilepsyEpilepsy Cranial neuropathyCranial neuropathy Orbits / Ophtho dxOrbits / Ophtho dx

29 Brain Tumor Imaging Diagnosis Location: Intra- / Extra-axial, Supra- / Infra-tentorial, Grey / white matter, etc. Location: Intra- / Extra-axial, Supra- / Infra-tentorial, Grey / white matter, etc. Single or multiple? Single or multiple? Tumor or tumor-like alternatives? Tumor or tumor-like alternatives? Histology: Type and grade? Histology: Type and grade? Treatment Planning Surgery, radiation, chemo tx Surgery, radiation, chemo tx Functional MRI for eloquent brain mapping Functional MRI for eloquent brain mapping 3D scans to guide surgery, radiation 3D scans to guide surgery, radiation Follow-up Stable vs. recurrence / progression Stable vs. recurrence / progression Complications Complications

30 T1 + Gd T2 T1 + Gd T2 Intra- or Extra-axial?

31

32 Tumor vs. Other Masses Arachnoid Cyst Abscess Hematoma “Tumefactive” MS GBM

33 Tumor vs. Stroke Cytotoxic Edema Vasogenic Edema Cellular swelling Gray-white margin lost Leaky capillaries Gray matter is spared

34 T1 T1 + Gd T2 T2 FLAIR Tumor? Stroke? Encephalitis?

35 3D Imaging for XRT or Surgical Guidance

36 Brain Imaging: “The Big 10” InfarctionInfarction HemorrhageHemorrhage InfectionInfection TumorTumor TraumaTrauma DementiaDementia MSMS EpilepsyEpilepsy Cranial neuropathyCranial neuropathy Orbits / Ophtho dxOrbits / Ophtho dx

37 Fractures: CT not MRI !

38 Traumatic Brain Swelling Cerebellopontine angle Pontine Cerebellomedullary (Cisterna Magna) Know your basal cisterns!

39 Traumatic Brain Swelling Know your basal cisterns! Quadrigeminal Interpeduncular Suprasellar Ambient

40 Effacement of basal cisterns Traumatic brain swelling with downward herniation Traumatic Brain Swelling

41 Traumatic brain swelling

42 Extra-axial Hemorrhage Subdural Epidural Subarachnoid

43 Intra-axial Hemorrhage Hemorrhagic contusions

44 Intra-axial Hemorrhage Hemorrhagic contusions Mechanism Direct contact with skull Shear-strain deformation Lesion locations Commonly located along inferior, lateral, and anterior frontal and temporal lobes Often above bony prominences (petrous pyramid, sphenoid wing, orbital roof) Appearance of cortical contusions Overlying cortex, by definition, always involved (vs. DAI) “Salt and pepper” appearance due to intermixed hemorrhage and edema Non-hemorrhagic contusions often not initially seen on CT scans Lesions often more visible days after injury as edema and hemorrhage increase Acute lesions much more conspicuous on T2 or T2-FLAIR MRI

45 Diffuse Axonal (Shear) Injury (DAI) Intra-axial Hemorrhage

46 Diffuse Axonal (Shear) Injury (DAI) T2: Reveals non-hemorrhagic lesions occult on CT

47 Diffuse Axonal (Shear) Injury (DAI) T2*: Increased sensitivity to hemorrhage

48 Diffuse Axonal (Shear) Injury (DAI) Tissues w/ differing elastic properties shear against each other, tearing axons Caused by rapid deceleration/rotation of head Locations: Cerebral hemispheres near gray-white junction Basal ganglia Corpus callosum, especially splenium Dorsal brainstem High morbitity & mortality – common cause of post-traumatic vegetative state Initial CT often normal despite poor GCS Lesions often non-hemorrhagic and seen only on MRI

49 Brain Imaging: “The Big 10” InfarctionInfarction HemorrhageHemorrhage InfectionInfection TumorTumor TraumaTrauma DementiaDementia MSMS EpilepsyEpilepsy Cranial neuropathyCranial neuropathy Orbits / Ophtho dxOrbits / Ophtho dx

50 Dementia Primary role of imaging is to exclude treatable causes, e.g.:Primary role of imaging is to exclude treatable causes, e.g.:  Hydrocephalus  Subdural hematoma  Neoplasm

51 Dementia Irreversible dementias (imaging non-specific): Alzheimer’s diseaseAlzheimer’s disease Multi-infarct dementiaMulti-infarct dementia Dementias associated with Parkinson’s disease and similar disordersDementias associated with Parkinson’s disease and similar disorders AIDS dementia complexAIDS dementia complex

52 Alzheimer’s: Temporal-Parietal Lobe Atrophy (Late)

53 Brain Imaging: “The Big 10” InfarctionInfarction HemorrhageHemorrhage InfectionInfection TumorTumor TraumaTrauma DementiaDementia MSMS EpilepsyEpilepsy Cranial neuropathyCranial neuropathy Orbits / Ophtho dxOrbits / Ophtho dx

54 Multiple Sclerosis (MS) Imaging MRI is the imaging study of choiceMRI is the imaging study of choice Help establish “dissemination of lesions in time and space”Help establish “dissemination of lesions in time and space” Estimate disease burdenEstimate disease burden Identify acute (inflammatory) vs. chronic lesions (enhancement = active inflammation)Identify acute (inflammatory) vs. chronic lesions (enhancement = active inflammation)

55 MS

56 Tumefactive MS

57 Brain Imaging: “The Big 10” InfarctionInfarction HemorrhageHemorrhage InfectionInfection TumorTumor TraumaTrauma DementiaDementia MSMS EpilepsyEpilepsy Cranial neuropathyCranial neuropathy Orbits / Ophtho dxOrbits / Ophtho dx

58 Seizure Imaging MRI is the imaging study of choice MRI is the imaging study of choice Identify and localize offending lesion Identify and localize offending lesion New onset vs. chronic epilepsy New onset vs. chronic epilepsy Younger vs. older patients Younger vs. older patients Search may be guided by EEG / clinical sx Search may be guided by EEG / clinical sx Preoperative planning Preoperative planning e.g. language lateralization before temporal lobectomy e.g. language lateralization before temporal lobectomy

59 Congenital anomalies: Polymicrogyria

60 Congenital anomalies: Schizencephaly

61 Mesial Temporal Sclerosis Most common pathology found in medically refractory epilepsy patients Rare under age 10 or with new seizures Pathogenesis unknown - Post ictal / kindling? Pathology: Hippocampal atrophy / gliosis

62 Mesial Temporal Sclerosis FLAIR T1 T2 Atrophy Loss gray-white ↑T2 / FLAIR

63 Brain Imaging: “The Big 10” InfarctionInfarction HemorrhageHemorrhage InfectionInfection TumorTumor TraumaTrauma DementiaDementia MSMS EpilepsyEpilepsy Cranial neuropathyCranial neuropathy Orbits / Ophtho dxOrbits / Ophtho dx

64 Cranial Nerve Imaging FIESTA CN-5 CN-8 CN-7

65 Vestibular Schwannoma

66 Intracochlear Schwannoma

67 30 y/o F with 6wk h/o blurred visionCraniopharyngioma

68 Introduction to Neuroimaging Aaron S. Field, MD, PhD Neuroradiology University of Wisconsin–Madison BRAIN


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