NEUROVASCULAR ANATOMY

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1 E. Michael Harned, M.D. Assistant Professor of Clinical Radiology ndiana University School of Medicine have nothing to disclose Neurovascular Magnetic Resonance Angiography And Magnetic Resonance Venography ACKNOWLEDGEMENTS 1. Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC: Bradley s Neurology in Clinical Practice, 6 th ed. Saunders 2. Anderson CM, Edelman RR, Turski PA: Clinical Magnetic Resonance Angiography. Raven Press For neurovascular imaging, MRA has largely been replaced by CTA due to its higher spatial resolution and relatively fewer artifacts. However, MRA may still be desired in certain situations: Patients with a contraindication to iodinated contrast administration: history of anaphylactoid reaction, severe asthma, renal insufficiency, multiple myeloma Lack of venous access Patients having an MR of the brain, neck, or cervical spine where it is desired to get vascular imaging done at the same time- killing 2 birds with 1 stone NEUROVASCULAR ANATOMY 1

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3 wpt!- t lo t\ ' " ' "..._. 4/17/2014 _,jll 1 e " ' " h,...ton MRA Time-Of-Flight (TOF) Relies on repeated saturation pulses to a slice or volume so that background tissue is suppressed and only new spins (flow) are able to generate signal May be performed as a 2D or 3D technique.,.. C'l lij liu 0 C:n«fniOB TECHNQUES 2D examines a single slice at a time and then stacks them 3D examines a slab and uses phase-encoding along the Z-axis 3D TOF allows better spatial resolution but is more susceptible to signal loss due to in-slab flow 0 h :,.,...'N il " O>'t EL SEV ER. NC - NETERMAGES.COM RF Pulse Z Gradient,,-,., ' ',,' ' \, \ CJ \._. SATURATON NCREASES WTH: Shorter TR Larger flip angle Y Gradient 0 Gradient r ' Multiple repetitions Longer T1 c 3

4 -----tu _tion 18 nd nflow of Magnetized Blood into 3D Slab Projected Plane Acquir d Slice a a/sine 4

5 Phase-Contrast Relies on bipolar gradient pulse which causes phase shift for flowing spins but no phase shift for stationary spins time Excellent background suppression No need for saturation band Also provides information on flow direction May be performed as a 2D or 3D technique Statiollary a p l aeaamulale pit... lobe and tiled wrap l t d arauad _..._ MJM.aamuladoa durln1111e LDM loije.,.._ r 3D Phase-Contrast allows better spatial resolution and provides flow direction information along all 3 axes Contrast-Enhanced MRA Really a form of 3D TOF MRA but uses gadolinium to increase intravascular signal and overcome problem of signal loss due to in-slab flow mages acquired quickly while a bolus of gadolinium is in the vessels of interest Different physics- uses elliptical-centric k-space filling: Central (most important) points of k-space are filled first, at time of greatest intravascular gadolinium concentration May acquire preinjection source images as mask for subtraction- Digital Subtraction MRA 5

6 ATHEROSCLEROTC STENOTC DSEASE WHY T MATTERS (all numbers approximate and for United States) 795,000 people suffer new or recurrent stroke each year 1 stroke every 40 seconds Stroke kills more than 137,000 people per year. 1 stroke death every 4 minutes #4 cause of death 1 in every 18 deaths Stroke death rates per year per 100,000 population: 41.7 for white males 41.1 for white females 67.7 for black males 57.0 for black females Americans pay about $73.7 billion per year for stroke-related medical costs and disability Likely Histories/ndications: WHAT THE RADOLOGST NEEDS FROM YOU 3D TOF MRA circle of Willis- source images Stroke, CVA, or TA Specific neurologic deficit- hemiparesis, aphasia, facial numbness, etc. Carotid bruit CA stenosis on carotid ultrasound 3D TOF MRA of the circle of Willis Contrast-enhanced MRA of the arteries of the neck (Often a good idea to do a 2D TOF MRA of the neck first in case there is a problem with the gadolinium bolus- There is no going back and doing this once contrast has been injected) Please send both sets of source images as well as rotating segmented MPs of right carotid, left carotid, and vertebrobasilar for circle of Willis and for neck 6

7 3D TOF MRA circle of Willis- MPs Contrast-enhanced MRA neck- source images Contrast-Enhanced MRA neck- MPs 2D TOF MRA neck- source images 2D TOF MRA neck- MPs Carotid stenosis%= (1 Nto) x 100 7

8 B Figure 1. A 58-year-old man with truncus bicaroticus as normal variant that is displayed both on MRA and DSA (a and b; arrow heads), and 90% diameter stenosis of the right CA diagnosed on MRA (c; bold arrow) and confirmed by DSA (d; bold arrow). Willinek W A et al. Stroke. 2005;36:38-43 Copyright American Heart Association, nc. All rights reserved. 8

9 Figure 2. Enlarged MP image from CE MRA (a) and DSA image (b) of the circle of Willis of a 44- year-old man: 50% stenosis in the M1 segment (arrow heads) of the right MCA was concordantly diagnosed on MRA and DSA. NON-ATHEROSCLEROTC STENOSS Willinek W A et al. Stroke. 2005;36:38-43 Likely Histories/ndications: Trauma Neck pain Specific neurologic deficit Drug abuse Protocol for evaluation same as for atherosclerotic stenosis 9

10 Figure 4. A 61-year-old man patient with subacute right MCA territory infarction. 75% stenosis of right CA was diagnosed on CE MRA (a; arrow), but DSA revealed a thrombus causing a 55% diameter stenosis (b; arrow). From: Cocaine-nduced Cerebral Vasoconstriction Detected in Humans With Magnetic Resonance Angiography JAMA. 1998;279(5): doi: /jama Moyamoya Disease Disease where vessels at the base of the brain become constricted- Most commonly distal internal carotid arteries but may also involve proximal middle and anterior cerebral arteries Collateral circulation develops around the blocked vessels, but the collateral vessels are small, weak, and prone to hemorrhage On angiography, the collateral vessels resemble a puff of smoke - Moyamoya in Japanese Patients present with TAs, strokes, headaches, and seizures Most common in women in their 20s and 30s Willinek W A et al. Stroke. 2005;36:38-43 Copyright American Heart Association, nc. All rights reserved. Figure Legend: Axial maximum intensity projection images at baseline (left) and20 minutes following intravenous cocaine (0.4 mg/kg) administration (right).cocaine induced a signal loss at distal segments of the middle cerebral arteries(upper arrowheads) and in the posterior cerebral arteries (lower arrowheads),indicative of vasoconstriction. A indicates anterior; P, posterior; L, left;and R, right. Scale bar = 1 cm. Copyright 2012 American Medical Date of download: 12/22/2013 Association. All rights reserved. Association with Down s syndrome, neurofibromatosis type 1, sickle cell disease, prior brain radiation Figure 3. A 45-year-old woman with Moyamoya disease. NTRACRANAL ANEURYSMS Willinek W A et al. Stroke. 2005;36:38-43 Copyright American Heart Association, nc. All rights reserved. 10

11 Likely Histories/ndications: Subarachnoid hemorrhage Headaches WHAT THE RADOLOGST NEEDS FROM YOU 3D TOF MRA of the circle of Willis No need for gadolinium 0 lrehijiiun ttl t:111 ( t W c 1nh :al n " on hrltttcq '" l :.l r Family history of intracranial aneurysms Autosomal dominant polycystic kidney disease No need to image the neck lll'lltttl ''f'rlm n 101 trr htll.u l'u'lrt N t,- ;, ii Ị 00. ELSEVER. NC - NETERMAGES.COM 11

12 VENOUS PATHOLOGY Likely Histories/ndications: Possible venous sinus thrombosis- pregnancy, oral contraceptives, cancer, other hypercoagulable states Cavernous sinus syndrome Hyperdense dural venous sinus or intracranial vein on CT Venous infarct on CT or MR 12

13 2D TOF MRV head- source images 2D TOF MRV head- MPs WHAT THE RADOLOGST NEEDS FROM YOU 2D TOF of the head No need for gadolinium No need to image the neck 13

14 Thanks! Questions? 14