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INTRODUCTION TO NEURO MR Dr. Francis Neuffer USC School of Medicine Department of Radiology.

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Presentation on theme: "INTRODUCTION TO NEURO MR Dr. Francis Neuffer USC School of Medicine Department of Radiology."— Presentation transcript:

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2 INTRODUCTION TO NEURO MR Dr. Francis Neuffer USC School of Medicine Department of Radiology

3 MR IMAGING Based on behavior of protons exposed to a magnetic field and a radio wave T1, T2, FLAIR, Diffusion, Gadolinium enhanced, and Angiography are specific types of Neuro imaging sequences.

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6 RF

7 MR INTERPRETATION Symmetry Identify normal structures – Ventricles – Grey matter structures – White matter tracts – Language – Intensity/ Signal – Description of tissue signal on various different scanning sequences ie. – T1 T2 Flair Diffusion Gadolinium

8 MAGNETIC RESONANCE IMAGING Limitations 1. ICU patients and Claustrophobia 2. Metal artifact 1. RF Energy – pacemaker override 2. Magnetic field - aneurysm clips - ocular metal -missile effect 3. Nephrogenic Systemic Fibrosis- gadolinium toxicity in renal failure

9 Child Dies in MRI Machine The Associated Press Monday, July 30, 2001: 2:42 p.m. EDT A child undergoing an MRI exam received a fatal head wound when the machine’s powerful magnet pulled a metal oxygen canister inside.

10 GADOLINEUM TOXICITY

11 MAGNETIC RESONANCE IMAGING Advantages 1.Multiple signal sources 2.No iodine toxicity/allergy issues 3.No ionizing radiation issues

12 MR HAS ADVANTAGE OF MULTI PLANAR IMAGING

13 MRI INDICATIONS Ischemia Tumor Infection Dating blood products Congenital abnormalities

14 MRI INTERPRETATION Pulse Sequences- − T1 weighted-- (Fat, Melanin, Hemosiderin, Methemoglobin= bright) − T2 weighted-- (Water, Oxyhemoglobin, Hemosiderin= bright) − FLAIR-- (Pathology bright, CSF dark) − Diffusion Weighted- recent infarction bright

15 T1 SCANT2 SCAN MR SIGNAL Tissues resonate a signal based on their intrinsic T2 time. Tissues recover their magnetization based on intrinsic T1 time.

16 T1 SCAN T2 SCAN Anatomic structures Fat = bright Water = hypo intense Water weighted sequence Water = bright Fat = relatively hypo intense Good for identifying pathology

17 MRI FINDINGS OF ACUTE ISCHEMIC STROKE T1 (hypo intense) FLAIR (hyper intense) T2 (hyper intense) FLAIR SCANS ARE T2 SCANS WITH THE FREE WATER SIGNAL NULLED.

18 MRI FINDINGS OF ACUTE STROKE T1 (hypo intense ) FLAIR (hyper intense) T2 (hyper intense) Diffusion (hyper intense)

19 DIFFUSION IMAGING DIFFUSION IMAGING SEPARATES INFARCTION ON ACUTE OR CHRONIC BASIS THE ACUTE INFARCT HAS A DIFFERENT DIFFUSION SIGNAL DUE TO INTRACELLULAR EDEMA

20 DIFFUSION IMAGING Increased sensitivity for early changes of edema – Becomes abnormal within 30 mins. – Ischemia Cellular Dysfunction Increased Intracellular Space Restricted Diffusion of Water Increased signal Distinguish b/w old and new stroke New stroke = bright on DWI (diffusion weighted image) Old stroke (encephalomalacia) = low SI on DWI

21 MRI ACUTE STROKE T1 T2 Diffusion PCA DISTRIBUTION

22 MRI OLD - VS- NEW ISCHEMIC INFARCT T1T2DIFFUSION

23 4 th ventricle Pons Temporal lobe Occipital lobe Temporal lobe Basillar artery Middle Cerebellar peduncle ANATOMY

24 Supracellar cistern Middle Cerebral artery Cerebral peduncle Aqueduct Of Sylvius Temporal Horn lateral venticle Optic chiasm

25 Putamen Globus pallidus Caudate head Thalamus ALIC PLIC ALIC Middle Cerebral artery Corpus callosum External capsule ANATOMY

26 Corpus callosum Lateral ventricle Corona radiata Anterior Cerebral artery Middle Cerebral artery Occipital lobe Parietal lobe Frontal lobe

27 ANATOMY Centrum Semiovale

28 ENHANCED SCANS BLOOD/BRAIN BARRIER DISRUPTION IDENTIFY PATHOLOGY ARTERIOGRAM EFFECTS GADOLINEUM IMAGING MR CONTRAST

29 CT WITH CONTRAST ENHANCEMENT ENHANCING RING LESION NON ENHANCED

30 T2 T1- SCAN – WITHOUT GADOLINEUM T1 – SCAN WITH GADOLINEUM T2- SCAN MR

31 NORMAL ABNORMAL PITUITARY ADENOMA

32 T1 SAGITTAL MR WITHOUT GADOLINEUMWITH GADOLINEUM

33 ACOUSTIC NEUROMA WITH GADOLINEUMWITHOUT GADOLINEUM

34 VASCULAR ANATOMY CCA ICA ECA Cavernous Carotid CCA ICA Vertebral artery Basilar artery Middle cerebral Carotid bulb Anterior cerebral ECA MR ARTERIOGRAM

35 VASCULAR ANATOMY Cavernous carotid MCA BA ACA Basilar artery Anterior cerebral MCA Cavernous carotid ECA ICA Vertebral TIME OF FLIGHT MRA TOF-MRA

36 VASCULAR ANATOMY MCA ACoA ACA ICA PCoA Basilar Artery Circle of Willis PCA

37 VASCULAR DISTRIBUTIONS MCA ACA PCA

38 STROKE Ischemic – Large artery atherosclerosis Higher mortality – Cardioembolism Recurrence – Small vessel ischemia Occlusion of small end arteries Predilection for BG, IC, Pons, Corona Radiata Hemorrhagic

39 IMAGING OF STROKE CT – Better identification of acute hemorrhage – Availability – Decrease expense – Decrease time – Less contraindications MRI – More sensitive to early changes of stroke ie. edema

40 CT FINDINGS SAH

41 STROKE INTERVENTION THROMBOLYTIC THERAPY TO SALVAGE ISCHEMIC BRAIN AT THE BORDER OF THE INFARCT ZONE WHO BENEFITS AND HOW SELECT?

42 TIME CONSTRAINTS 3-6 HOUR WINDOW RISK OF HEMORRAGIC CONVERSION WITH THROMBOLYTIC THERAPY STROKE INTERVENTION

43 RT LT

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47 MR PERFUSION Gadolineum Injection

48 CT PERFUSION Iodine Injection

49 COMPARISON OF INFARCT ZONE AND ISCHEMIC ZONE TO IDENTIFY TREATMENT CANDIDATES GOAL FOR IMAGING

50 MRI FINDINGS OF ACUTE STROKE T1 (hypointense ) FLAIR (hyperintense) T2 (hyperintense) Diffusion (hyperintense)


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