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NEURO IMAGING

NEURO IMAGING. Dr. Francis Neuffer Department of Radiology USC-SOM 2013. GOALS AND OBJECTIVES. Review major imaging modalities of neuro imaging . CT, MR, Ultrasound , Angiography Understand the strengths of each modality .

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NEURO IMAGING

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  1. NEURO IMAGING Dr. Francis Neuffer Department of Radiology USC-SOM 2013

  2. GOALS AND OBJECTIVES • Reviewmajorimagingmodalities of neuroimaging. CT, MR, Ultrasound, Angiography • Understandthestrengths of eachmodality. • Reviewclassicdiseasestates of vascular, traumatic, infectious and neoplasticdiseases.

  3. NEURO IMAGING USING CT

  4. CT SCANNER COMPUTED TOMOGRAPHY

  5. DIGITAL SCOUT FILM SHOWING BEGINNING AND END OF CT SCAN. Multiple sectional images are obtained from a preliminary scout image showing the beginning and end of the scan.

  6. ANATOMY Selected images from CT scans posterior fossa level Basilar Artery Supracellar Cistern Temporal Horn lateral ventricle Pons 4th Ventricle Cerebellum

  7. ANATOMYInternal capsule level Anterior Horn Lateral ventricle Caudate Nucleus Internal capsule Lentiform nucleus Occipital Lobe

  8. ANATOMYThalamic level 3rd ventricle Atria Lateral Ventricle Sylvian fissure Thalamus Falx cerebri

  9. ANATOMYLateral ventricle level Frontal lobe Body lateral ventricle Parietal lobe Occipital lobe Falx cerebri

  10. ANATOMYSupraventricular level Gyrus Centrum Semiovale Sulcus Superior Sagittal Sinus

  11. NEURO IMAGING USING MR

  12. MAGNETIC RESONANCE Hydrogen protons align in magnetic field Radio frequency(RF) excitation and transmission No ionizing radiation

  13. MR SIGNAL • Determined by tissue responseto RF/magnetic field • 2. Tissues resonate a signal after the RF pulse • Examples: • How long a tissue resonates is a T2 characteristic • How quickly a tissue responds is a T1 characteristic

  14. T1 SCAN MR SIGNAL T2 SCAN SCANS ARE DESIGNED TO SHOW SPECIFIC TISSUE AND SPECIFIC PATHOLOGY

  15. VARIOUS MRI SEQUENCES Thetissuesignalvariesdependingonthetype of scanperformed. T1 T2 (CSF/edema) FLAIR (edema) Diffusion

  16. NEURO IMAGING USING VASCULAR & ULTRASOUND

  17. VASCULAR ANATOMY ARTERIAL CATHETER Anterior cerebral Middle cerebral Basilar artery ECA Carotid bulb ICA Vertebral artery CCA ECA ICA CCA MR Angiogram- venous injection Images can be obtained at MR by injecting gadolinium and imaging rapidly as the agent circulates through the arterial circuit.

  18. VASCULAR ANATOMY Images of vessels at the Circle of Willis ACA MCA

  19. VASCULAR DISTRIBUTIONS Anterior Cerebral Artery Middle Cerebral Artery Posterior Cerebral Artery The different vascular distributions of cerebral territories are represented on color coded CT diagrams

  20. NORMAL CEREBRAL ARTERIOGRAM NORMAL ULTRASOUND Flow is seen at the common carotid bifurcation on contrast X- ray arteriography and B-mode ultrasound.

  21. CAROTID ARTERY Color Doppler The vessel lumen can be imaged with ultrasound and the velocity of the flow can be measured. A stenotic lesion will show acceleration of flow through the narrowed lumen.

  22. WHO ARE THE PATIENTS ? • VASCULAR ISCHEMIA • TRAUMA • INFECTIOUS WORKUP • MALIGNANCY WORKUP

  23. CEREBROVASCULAR ISCHEMIA • Global Pressure, Hypoxia, Stenosis, Hypoglycemia • Affects borderland vascular territories Anterior, Middle, Posterior Cerebral arteries Watershed infarcts

  24. STENOSIS NORMAL

  25. VASCULAR DISTRIBUTIONS Anterior Cerebral Artery Middle Cerebral Artery Posterior Cerebral Artery The different vascular distributions of cerebral territories are represented on color coded CT diagrams

  26. FOCAL DEFICIT OF 24 HRS • ACUTE CVA • 85% ISCHEMIC • 15% HEMORRAGHIC • TREATMENT DIFFERENCE • ANTICOAGULATION FOR ISCHEMIC CVA

  27. CT OF ISCHEMIC STROKE EARLY • Often normal • Sulcal effacement asymmetry • Loss of grey / white differentiation The asymetry on the Rt. is due to ischemia and cellular edema effacing the normal sulci

  28. CT OF ISCHEMIC STROKE 1 DAY POST 2 DAY POST Note increase in edema

  29. LACUNAR INFARCT • Small vessel = lenticulostriate vessel lacunar infarct - basal ganglia

  30. INTRACEREBRAL HEMORHAGEHYPERTENSIVE EVENTS Acute Blood is dense on CT Charcot-Bouchard microaneurysms Pontine Hemorrhage Thalamic Hemorrhage

  31. CEREBRAL AMYLOID ANGIOPATHY (CAA) IS AN IMPORTANT CAUSE OF SPONTANEOUS CORTICAL- SUBCORTICAL INTRACRANIAL HEMORRHAGE (ICH) IN THE NORMOTENSIVE ELDERLY. Chao C P et al. Radiographics 2006;26:1517-1531

  32. Hemorragic infarction—delayed several days Withreperfusiononinfarctareathereishemorrhageintoinfarctzonewith local masseffect and midlineshift.

  33. Comparison of infarct zone and ischemic zoneto identify treatment candidates GOAL FOR IMAGING

  34. CT SCANNINGas initial sorting • Ischemia Hemorrhage • Hypertensive hemorrhage • Amyloid angiopathy • Hemorrhagic infarction • Subarachnoid hemorhage

  35. STROKE INTERVENTION Thrombolytic therapy to salvage ischemic brain at the border of the infarct zone (ischemic penumbra). Who benefits and how to select?

  36. Time constraints 3-6 hour window Risk of hemorrhagic conversion Thrombolytic therapy STROKE INTERVENTION Typically 3hrs sinceonsetisthelimitforinitiation of venousthrombolytictherapy. With arterial therapythewindow of action can be extended . Therisk of bleedingintotheinfarctzonewithreperfusionis a complicationthat can worsen prognosis.

  37. Lt Rt Note acute occlusion of Rt. MCA circulation and edema in Rt. hemisphere on CT. Comparison of the normal Lt. side is shown.

  38. catheter Catheter is advanced for thrombolysis of the MCA thrombus with improved perfusion on last injection of contrast.

  39. SUBARACHNOID HEMORHAGE Increased density Normal The supra sellar cisterniswhiteduetothebloodmixedwiththe CSF.

  40. SUBARACHNOID HEMORRHAGE Blood in the subarachnoid space Between the Pia & Arachnoid CT – acute blood, increased density Rupture of cerebral aneurysm “Worst Headache of Life” Location: basal cisterns, sylvian fissure, cortical sulci.

  41. CAROTID ANEURYSM Associated with Polycystic Renal disease And Marfans Syndrome Aneurysms are often at vascular branch points and show relative deficit of media there which contributes to vessel wall weakness

  42. CT SCANNINGas initial sorting • Ischemia Hemorrhage • Hypertensive hemorrhage • Amyloid angiopathy • Hemorrhagic infarction • Subarachnoid hemorhage

  43. CT OF THE BRAIN IS PREFERRED OVER MRI IN WHICH OF THE FOLLOWING SITUATIONS? Answer Now Chronic renal failure Suspected acute subarachnoid hemorrhage Suspected demyelinating disease Screening for metastatic neoplasm Suspected posterior fossa lesions

  44. CT vs. MR ?Abnormality on CT Questionable lesion on CT in a Rt. periventricular location.

  45. Compared to CT--MR scans with T1, T2, and diffusion weighted better show the acute evolving ischemic infarction T1 T2 Diffusion

  46. MR vs. CTIN EARLY CVA • MR LIMITATIONS • COMPLEX MR SIGNAL OF HEMORRHAGE • RELATED TO HEMAGLOBIN—Fe EFFECTS • UNSTABLE PATIENT-PATIENT MOTION • MORE A PROBLEM IN MR (LONGER SCAN TIME) • CT READILY VISUALIZES BLOOD PRODUCTS • ACCESS- CT IS AVAILABLE FOR ER PATIENTS

  47. WHO ARE THE PATIENTS? HEAD TRAUMA

  48. SUBDURAL HEMATOMA Venous bleeding from “bridging veins” which connect cerebral cortex to Dural sinuses Concave inner margin Older patient –atrophy enlarged subdural space unstable gait–falls Pediatric patient –shaken baby/child abuse small subdural space can lead to herniation

  49. SUBDURAL HEMATOMA (ACUTE) Over time thebloodbreaksdown and decreases in density.

  50. THE BONE MOST COMMONLY FRACTURED IN ASSOCIATION WITH AN EPIDURAL HEMATOMA IS: Answer Now Frontal Parietal Temporal Occipital Sphenodial

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