a picture is worth 1000 words… but what do they mean? · mitigating potential bias ... •carotid...

A picture is worth 1000 words… but

what do they mean?

Imaging of the 3 Ps in Stroke An introduction of stroke diagnostics for

the non-neurologist

Sharon Jaspers Thunder Bay Regional Health Sciences Centre

Stroke Prevention Clinic Nurse Practitioner Northern Ontario School of Medicine

Assistant Professor

Objectives

• Describe the variety of imaging modalities required for stroke diagnostics

• Discuss the rationale for imaging modalities utilized in stroke diagnostics

Presenter Disclosure

Grants/Research Support: – Northern Ontario Academic Medicine Association (NOAMA) Clinical

Innovation Fund - Co-Investigator for:

• The Incidence of Carotid Artery Disease in Northwestern Ontario

• New Evidence Based Toolkit for Triaging TIA & Mild Non-Disabling Stroke in Northwestern

– DOC Utility Research Study- Research Support

– Navigate Trial - Co-Investigator

– Other: Writing Committee Member of the 2014 & 2017 Canadian

Stroke Best Practice Recommendations

Disclosure cont’

• m-health Solutions and Icentia Services have provided an in-kind contribution of ambulatory cardiac monitors and will be discussed in this simulation. The reason we are using these products, is because they are used in the Stroke Prevention at Thunder Bay Regional Health Sciences Centre.

Mitigating Potential Bias

• Discussion on ambulatory cardiac monitors will include the demonstrated products available at this workshop in addition to other options available in Northwestern Ontario.

Disclosure of Commercial Support

• This program has received product demos from m-health Solutions and Icentia Services to demonstrate options for ambulatory cardiac monitors and will be discussed in this program

Mitigating Potential Bias

• Discussion on ambulatory cardiac monitors will include the demonstrated products available at this workshop in addition to other options available in Northwestern Ontario

• Remainder of disclosures do not pertain to this presentation

What Diagnostic Test do you think is most valuable for diagnosing stroke?

1. CT head

2. MRI head

3. CTA head/neck

4. MRA head/neck

The Embrace Trial recommends

1. Prolonged cardiac monitoring to assess for presence of atrial fibrillation

2. Epley Maneouvre to reduce stroke risk

3. Sequential CT testing to determine stroke penumbra progress

4. Hugs for good health

Common Cause of Stroke is:

1. Atrial Fibrillation/Flutter

2. Carbon monoxide poisoning

3. Alzheimer's Disease

4. Omega 3 Fatty Acid Exposure

Our brains are incredibly complex

. ←

Image copyright of FRONTIER Frontotemporal Dementia Research Group, 2008

http://functionofarubberduck.files.wordpress.com/2012/10/brain-dominance1.png

…..unless you are Homer

Images from http://www.angelfire.com/oh5/pearly/homer/homer-brain.html

Imaging and the 3 Ps

• Parenchyma

• Pipes

• Pump

Parenchyma:The functional aspects of the Human Brain

• 100 billion nerve cells (neurons) – All in grey matter

– Highly organized into functional regions

• Prolonged processes of the neuron (axons) surrounded by myelin (insulation)

– White matter

https://www.google.ca/search?q=lobes+of+brain+and+function&safe=active&rlz=1C1GGRV_enCA756CA756&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjqj5aY2qXaAhVq5oMKHSaXBygQ_AUICigB&biw=1040&bih=878#imgrc=gxNEGcCrxQbDpM

Albers et al. Chest 2004; 126 (3 Suppl): 438S–512S.

Thom T, et al. Circulation 2006; 113(6): e85–e151.

Parenchyma Assessment: CT scan

• CT scans use computers and rotating X-ray machines to create images of slices, or cross-sections, of the brain.

• CT scans are a primary method to rule out hemorrhagic stroke or tumor. Ischemic stroke is not usually apparent until 6 – 12 hrs from symptom onset

• Often the first diagnostic test when a pt presents to the ED – determine if candidate for tPA

• In many cases, the involved area of the brain does not appear abnormal for the first several hours after the onset of ischemic stroke.

CT scan • Rapid, cheap, well tolerated,

• but poor visualization of brain stem and posterior fossa

• Xrays are absorbed by different degrees by different tissues

• The colour is the result of how much radiation is absorbed (attenuation)

air CSF White matter Old Blood Gray Matter Acute blood Bone Contrast

Edema Calcifications

Hypodense Hyperdense

http://www.radiologyassistant.nl/en/p483910a4b6f14/brain-ischemia-imaging-in-acute-stroke.html

Right side CT Head Left Side

CT • CT hemorrhage • CT brain stem infarct

http://www.google.ca/imgres?imgurl=http://www.pssjournal.com/content/figures/1754-9493-5-18-4.jpg&imgrefurl=http://www.pssjournal.com/content/5/1/18/figure/F4&usg=__NFNqd6Ho17sjdhdzzDvjvxgBhos=&h=320&w=310&sz=24&hl=en&start=26&zoom=1&tbnid=YfErDQ7qySeMMM:&tbnh=118&tbnw=114&ei=0kpTUNexDOeCyAGIi4HoAw&prev=/search%3Fq%3DcT%2Bbrain%2Bstem%2Binfarct%26start%3D20%26um%3D1%26hl%3Den%26safe%3Dactive%26sa%3DN%26rls%3Dcom.microsoft:en-us%26tbm%3Disch&um=1&itbs=1

Parenchymal Assessment: MRI

Corpus callosum

Lateral ventricle

Corona radiata

Anterior Cerebral artery

Middle Cerebral artery

Occipital lobe

Parietal lobe

Frontal lobe

radiology.med.sc.edu/neuro%20no%20audio.ppt

Parenchyma Assessment: MRI • Works by sending bursts of radio waves to

head (MAGNETS)

• Waves disrupt protons (water containing)

• Once waves stop, protons relax, realign and picture is produced

• T1-2/Flair/DWI variations of protons (tissue) relaxation times

• Can visualize in various modes. DWI (diffusion weighted imaging) lets you know if it is a fresh/acute stroke

• Not as precise for hemorrhage

• Called “intensity” vs “density”

• More sensitive for acute ischemia

• Can pick up ischemic stroke sooner than CT in hyper acute stage …..

• More expensive/time than CT

MRI axial FLAIR images of Brain show an infarct involving left frontal lobe anterior to sylvian fissure. Area of involvement corresponds to left MCA

http://www.neuroradiologycases.com/2012/09/ischemic-stroke-and-vascular.html

MRI : ACUTE ISCHEMIC STROKE

FLAIR (hyper intense) Acute infarcts are white due to edema

T2 (hyper intense) CSF is “white” White Matter is “black” Shows pathology better

Diffusion

(hyper intense) Shows acute infarct better Infarcts are white due to intracellular edema

radiology.med.sc.edu/neuro%20no%20audio.ppt

T1 (hypo intense)

CSF is “black” White matter is “white” Shows anatomy better

Parenchyma Assessment: MRI-Diffusion weighted image (DWI)

• is the MOST sensitive sequence

• Can be positive within minutes of stroke

• Produces a high intensity signal for 7 days, then settles

• Maximizes b/w 7 – 30 days (positive in early stage, then fades)

radiology.med.sc.edu/neuro%20no%20audio.ppt

MRI contraindications

• Metallic implants • Claustrophobia • Pacemakers • MR-incompatible prosthetic heart valves

• Patient Prep: Length, noise- ear plugs, no

jewelery,

Albers et al. Chest 2004; 126 (3 Suppl): 438S–512S.

Thom T, et al. Circulation 2006; 113(6): e85–e151.

Pipes Assessment: Vascular Imaging

• CTA

• MRA

• Carotid Doppler

• Cerebral angiography

• Purpose is to assess for atherosclerosis, thrombosis or aneurysm

Diagnostic Test Benefit Limitations

CTA -Assessing degree of stenosis of carotid arteries -visualizing vessel character -guides treatment -accuracy

-require adequate kidney function to tolerate dye -precautions when on metformin -

MRA -Assessing degree of stenosis -no dye involved that impacts kidneys

-neurosurgeons prefer CTA

Carotid Doppler -Assessing degree of stenosis with less invasive approach

-not as accurate

Cerebral Angiography

-precise, finite imaging Can be used singularly or in conjunction with other treatment eg: clot retrieval

--requires interventional radiologist/neurosurgeon -most invasive -more risks/inconvenience for patient

Pipes Assessment: Vascular Imaging

https://www.researchgate.net/figure/CT-angiogram-CTA-showing-stenosis-and-occlusion-A-Curved-multiplanar-reconstruction_fig3_233775898

3D CTA reconstruction of left MCA total occlusion

3D CTA reconstruction image of the carotid arteries showing a stent in right internal carotid and a 99% stenosis or blockage of the left ICA

http://www.google.ca/imgres?imgurl=http://www.radiologyinfo.org/photocat/popup/3dreccarotidctastnt.jpg&imgrefurl=http://www.radiologyinfo.org/en/photocat/gallery3.cfm%3Fimage%3D3dreccarotidctastnt.jpg%26pg%3Dangioct&usg=__

CTA

(on left ) right middle cerebral artery stenosis

(below) a)basilar artery stenosi

b) total left internal carotid occlusion c) left internal carotid stenosis

d)right internal carotid stenosis

http://jnnp.bmj.com/content/76/suppl_3/iii19/F9.large.jpg

Albers et al. Chest 2004; 126 (3 Suppl): 438S–512S.

Thom T, et al. Circulation 2006; 113(6): e85–e151.

PUMP • 20-30% of ischemic strokes are related to emboli

from heart, can cause significant strokes with major deficits –large vessels involved

• ie AF, PFO, ASD, myoxma, endocarditis, valve disease, recent MI, dilated cardiomyopathy, rheumatic stenosis,

ttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC2994107/

PUMP: Echocardiogram Test that uses sound waves to create a moving picture of heart, assessing valves/structures/presence of clots/thrombi TTE Trans-thoracic echo

• Transducer on chest wall

• Bubble study: saline solution (salt water) is injected into the body as the cardiologist watches the heart on an ultrasound (echocardiogram) monitor. If a PFO exists, tiny air bubbles will be seen moving from the right to left side of the heart.

TEE Trans-esophageal Echo

• Transducer/scope inserted in esophagus

• Better imaging in certain circumstances ie PFO

PUMP: Cardiac Rhythm Monitoring • Manual pulse rhythm gives clue for possible A-fib

• ECG

• Telemetry

• Holter 24 – 72 hours

• Loop Recorder x 2 weeks

• Focus is to rule out atrial fibrillation/flutter or paroxysmal A-Fib

• A-Fib most common cause of cardio-embolic stroke –why????

• Risk for A-Fib induced stroke increases with age – 1.5% risk at age 50 and 24% risk at age 80

Summary of 3 Ps

• Stroke Diagnostic Tests

1. Parenchyma (CT/MRI) • Help determine character of

lesion and pathology

2. Pipes (Carotid Doppler, CTA, MRA)

• Help to determine possible etiology of stroke

3. Pump (Echocardiogram, cardiac monitoring)

• Help to determine possible etiology of stroke

What Diagnostic Test do you think is most valuable for diagnosing stroke?

1. CT head

2. MRI head

3. CTA head/neck

4. MRA head/neck

The Embrace Trial recommends

1. Prolonged cardiac monitoring to assess for presence of atrial fibrillation

2. Epley Maneouvre to reduce stroke risk

3. Sequential CT testing to determine stroke penumbra progress

4. Hugs for good health

Common Cause of Stroke is:

1. Atrial Fibrillation/Flutter

2. Carbon monoxide poisoning

3. Alzheimer's Disease

4. Omega 3 Fatty Acid Exposure

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Questions & Discussion

jasperss@tbh.net