ADVANCES IN IMAGING OF ISCHAEMIC STROKE IMAGING

Vipul GuptaNeurointerventional Surgery(Interventional Neuroradiology)Artemis Hospital, Gurgaon

Advances in Stroke imaging …

Acute stroke imaging – clinical approach Vessel wall imaging Neurointerventional suite imaging TCD – integration in clinical practice

MR CLEAN TrialNetherlands, 2015

ESCAPE TrialCanadian, 2015

EXTEND-IA TrialAustralian, 2015

SWIFT PRIME TrialUSA, 2015

REVASCAT TrialSpanish, 2015

AHA/ ASA guideline 2015:Patients should receive endovascular therapy with a stent retriever if they meet all the following criteria (Class I; Level of Evidence A). (New recommendation):

prestroke mRS score 0 to 1 acute ischemic stroke receiving intravenous r-tPA within 4.5 hours of onset causative occlusion of the internal carotid artery or proximal MCA (M1) age ≥18 years NIHSS score of ≥6 ASPECTS of ≥ 6 treatment can be initiated (groin puncture) within 6 hours of symptom onset

Advanced Imaging:

CTA used to detect MVO

CT Perfusion:

SWIFT Prime – Criterion changed (71 with perfusion; 125 without)

possibility that patients who may have responded to therapy were excluded.

Site of occlusion should be documented:

studies not designed to validate the utility of the advanced imaging selection criteria

Imaging approaches for case selection

NCCT (ASPECTS)- NIHSS NCCT & CTA, CTA-SI NCCT, CTA & CTP MRI-DWI, (MRA, PWI)

What information is needed?• Bleed• Infarct core – is critical 70-100 ml• Major vessel occlusion• Tissue at risk- penumbra

Time, imaging interpretation, unstable patients

Imaging… Hemorrhage # NCCT- excluding hemorrhage is necessary and sufficient for IV –tPA # MR- quite good, expert interpretation Major vessel occlusion # CTA better & quicker than MRA for MVO # Can be obtained without slowing IV thrombolysis. Core # Most accurate - DWI. # NCCT – least # CT A- SI- better than NCCT # CT perfusion- CBF, CBV, MTT – better Penumbra # MVO with small core (CTA-SI or DWI)- penumbra is usually there # CT perfusion # MR perfusion???

NCCT & CTA, CTA-SI….Benefits of CTA: Presence of proximal occlusion Core on CTA source images Collateral circulation assessment Arch anatomy - facilitate DSA Other - unstable aortic thrombus, arterial dissections

Hemorrhage, major vessel occlusion- very good Infarct core- good Penumbra- small core with MVO, collaterals (Calgary group)- reasonable Issue- interpretation

Left terminal ICA with Bovine arch Type 2 and type 3 arches

Extra stiff wire for exchange

Penumbra 3 Max and 4 MaxDAC 0.044 to cross loop

Contralateral approachPenumbra 3Max through PCOM/ Solumbra

•68/M, DM, HTN, CAD, underwent PTCA to LAD•Admitted for surgery of aortic stenosis.•Double anti-platelets was stopped•Patient developed acute onset right side weakness with aphasia.

IV- tPA given, no improvement

Futile recanalization….

ASPECTS scoring (tricky)

Good collaterals by the Miteff method (OR, 3.341; 95% CI, 1.203–5.099; P .014) was the independent predictor of good outcome amongst various collateral grading scales.

Arterial Collateral status – penumbra, retention of penumbra

Miteff system. A, Contrast opacification all sylvian branches. B, Some vessels can be seen at the Sylvian fissure. C, distal cortical filling alone

Multiphase CTA

Better able to predict outcomes than single phase and perfusion CT

CT, CTA, CTP….

CT perfusion imaging

MTTCBF CBVQuantitative CTP mismatch classification using relCBF and Tmax is similar to perfusion-diffusion MRI. Stroke. 2012 Oct;43(10):2648-53. Epub 2012 Aug 2.

Incremental improvement in interobserver reliability was demonstrated for NCCT, CTA-SI, and CTP-CBV, respectively. (Stroke. 2013;44(1):234-6) 25.

Left hemiplegia, left UL and LL 0/5 5:14AM

6:22AM

8:07 AM

Patient made gradual recoveryLeft LL 4/5 and UL 3/5 - 30 day follow up mRS at 90 days- 0

Patient presented with in 2 hours

Futile IV tpa

• 60 years old female.

• h/o hypertension and hypothyroidism

• Acute onset left hemiparesis and left facial weakness

• CT Brain , CTP and CTA done 6 1/2 hours after ictus.

CT, CTA, CTP Hemorrhage, major vessel occlusion- very good Infarct core- CBV, good ? Better than SI Penumbra- CBF & MTT vs CBV Over all sensitivity and specificity – 80-90% Interpretation – convenient in emergency, technical

issues are there

MRIAdvBest for core – DWINo radiation or contrast Can do MRA and perfusionimaging

But•Time…..time…..time…..•Shifting, checking for CI, MRA and perfusion time•Sick restless patients •MRA- not good enough•Key- should not be delaying IV tPA•Having one protocol for all acute stroke patients•Every 30 min delay – 10% decrease possibility of good outcome (IMS-II)

Hand PJ, Wardlaw JM, Rowat AM, et al. Magnetic resonance brain imaging in patients with acute stroke: feasibility and patient related difficulties. J Neurol Neurosurg Psychiatry 2005;76:1525–27

Goyal M AJNR 33 August 2012

Every 30-min delay in angiographic reperfusion reduced the relative likelihood of a good clinical outcome by 12% in adjusted analysis.

Conclusion

• Improving door to puncture time may be the key

SNIS – 2015 …• Target Door to puncture < 60 min Door to recanalization <90 min

• Small steps make a big difference!!!

Thrombus imaging•Length•Type•Fragmentation

Vessel wall imaging •MR vessel wall imaging is a powerful tool for extracranial (eg, carotid) plaque characterization, enabling the determination of stroke risk from carotid plaque rupture •The Multi-Ethnic Study of Atherosclerosis carotid MR imaging study first reported associations of carotid plaque features with future events. It showed that the remodeling index and lipid core presence measuredon MR imaging added a risk for a new event beyond traditional risk factors in individuals without a history of cardiovascular disease.

ICAD

DynaCT stents

syngo® Neuro PBV IRNeuro Parenchymal Blood Volume

1. DynaCT – Mask Acquisition

2. Steady State Contrast Injection

3. DynaCT – Fill Acquisition

Segmentation of Bone and Air

–

Subtracted Image

remove

Detection of Arterial Input normalize

Smoothing

0

10

5

mL/100gPBV Map

Case study 1:

65 male with vascular risk factors

Diagnosed with asymptomatic carotid stenosis

Underwent VMR testing

Why? Meta-analysis - odds ratio of 3.86 (95% CI, 1.99–7.48) for stroke risk

Technique:

Breath hold at end of inspiration for 30 seconds

Uncooperative patients – re breath

Always compare with the opposite side

Formula – MFV (end) – MFV (start)/ MFV ( start) x 100/ seconds of breath holding

< 0.6 is impaired

Vasomotor reserve testing

Criterion for MES

3 db higher than background

Unidirectional (spatial > 7.5 mm and temporal > 30 ms)

MCA positive slope

ACA negative slope

Case study 2

60 male with left sided minor strokeStarted on dual antiplateletHad a further event

Planned for MES testing

Study 3 61 year male patient

presented in ER with c/o severe headache a/w nausea since one day.

NCCT Head shows SAH

Pulsatility index •ICP•Distal spasm

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Dr Vipul Gupta

Thank you ….