1. CRT 2010 Imaging Requirements and Interpretation in Acute Stroke
Allan L. Brook, M.D.
Director, Interventional Neuroradiology
Montefiore Medical Center
Associate Professor of Clinical
Radiology and Neurosurgery
Albert Einstein College of Medicine

2. Allan L. Brook, MD DISCLOSURES
I have no real or apparent conflicts of interest to report.

3. Stroke Facts
Stroke is a leading cause of death and disability worldwide with far reaching consequences for society
Burden of stroke is high and is likely to increase in future decades as a result of demographic and epidemiological transitions in populations
Feigin et al., Lancet Neurology 2003; 2: 43–53

4. Origins

5. Imaging of Acute Stroke Overview
Practical
Theory CT
CTA/CTP
MRI
MRA
DWI & perfusion imaging
DSA
What are the goals of imaging?
Complimentary modalities ….not exclusive

6. Imaging Goals To exclude pathology that needs acute intervention
Localize
Acute hemorrhage
Tumor
Infection
Herniation syndromes

7. Importance of Early Ischemic Changes(EIC) on CT
Can predict both functional outcome and the risk of cerebral hemorrhage
AJNR: 22, September 2001

8. Dense MCA Sign Clot vs calcium Predictor of large vessel occlusion
Srinivasan et al October 2006 RadioGraphics, 26, S75-S9

9. Basics: CT of Acute Stroke
Evaluating earliest subtle findings
to severe & chronic changes
Posterior putamen
Loss of gw distinction
Srinivasan et al October 2006 RadioGraphics, 26, S75-S9

10. Spectrum Dense MCA sign- M1 or distal M2
Subtle loss of grey white distinction in basal ganglia, perisylvian, or cortical edema

11. CTA

12. False Positive
52-year-old man with a history of patent foramen ovale presented with diplopia, a left facial droop, and mild left-side weakness
Small infarct in the medial right thalamus on MRI
CTA helps
exclude clot

13. MCA Territory & Safety for Revascularization?
Less than 1/3rd
Greater than 1/3rd
Gadda et al., Eur Radiol (2005) 15: 2387–2395

14. 33% vs 50% ??? MCA territory regions according to ASPECTS
Alberta Stroke Program Early CT Score
MCA territory is allotted 10 points, each territory corresponding to a region
One point is subtracted for any infarcted area
A score of 10 points means no ischemic areas
0 points that the whole MCA territory is affected
A sharp increase in dependence and death occurs with an ASPECTS of 7 or less
AJNR: 22, September 2001

15. MRI & Acute Stroke Imaging Exclude Mimics & Hem!
T1W, T2W
FLAIR
DWI
FFE
Gd enhancement
Perfusion
Slow flow
Cortical edema
AJR:179, July 2002

16. Enhancement MRI Stroke
Hyperacute
Acute
Subacute and chronic
Intravascular-hours
Meningeal-1-3days
Parenchymal->3days
MRA

17. DWI Has Revolutionized Imaging of Acute Stroke
Is The Gold Standard … seen in black and white
DWI
ADC

18. MRI with diffusion weighted imaging
Isolated weakness right index finger
JS Kim, Neurology, 2002

19. Where is the stroke?

20. Natural history ~ 7Hour F/U Small DWI lesion in deep MCA terrirtory with extensive area of prolonged time to peak (ie, mismatch) M1 occlusion
1 -Hour
7-Hour F/U
Neurology thelancet Vol 5 September 2006

21. The Crux Recanalization does not always produce good clinical outcome
Imaging can be achieved in reasonable time
Patient selection by imaging will hopefully identify those who will benefit from early reperfusion
Limit risk by proper stratification

22. The DEFUSE Study Identified a “target mismatch” profile based on MRI
Patients had a robust clinical response after early reperfusion
Stroke. 2007;38:
AnnNeurol.2006;60:508 –517

23. Mismatch/Penumbra Core Irreversibly injured tissue
Penumbra At risk, but salvageable, if reperfusion occurs
Benign Oligemia Decreased flow but not at risk of infarction
mL/100g/min
Neurology thelancet Vol 5 September 2006

24. c/o Kristine Blackham MD
Zones of Ischemia
Imaging-Guided Acute Ischemic Stroke Therapy: From "Time Is Brain" to "Physiology Is Brain"
R.G. Gonzáleza AJNR 27:
c/o Kristine Blackham MD

25. Imaging Modalities used to Identify The Ischemic Penumbra and Core
CTPerfusion
CT-Xe
MR-DWI/PWI
MR-Spectroscopy
PET- 15O2
SPECT-TC-HMPAO
CBF, CBV, MTT, TTP
CBF
CBF, CBV, MTT, TTP, ADC
NAA, Lactate
CBF, CBV, MTT,CMRO2, OEF
Positron emission tomography (PET) has bee particularly instrumental in these developments and continues to be the gold standard in stroke imaging
CTP & MRP Correlation with PET is far from perfect!!!!!!!

27. When Exact time is unknown Can we utilize imaging to triage?
38-year-old man who was found with a severe left hemiparesis
Pt wakes up with deficit
Gonzalez AJNR 27 Apr 2006

28. NeuroImaging Goals
Findings from a physical examination and patient history cannot always help determine diagnosis (accurate time and anatomic localization)
Decipher & triage quickly which patients have the option of medical or interventional recanalization

29. Comparison of CT and MR Perfusion
Whole head
Conspicuous lacunar infarcts on diffusion
Use TTP primarily
Relative values only CT
Ostensibly better quantification
Closer to ER
Limited FOV by detector thickness
Distal, posterior fossa or watershed infarcts
Radiation!
Both can function well utilize what is available and best in your institute!

30. Conclusion
Diagnostic imaging in acute stroke is a prerequisite for successful acute stroke therapy (IV & IA)
The severity of the early ischemic edema has prognostic relevance for hemorrhagic complications after thrombolysis

31. Conclusion
Structural, vascular, and physiological imaging of acute stroke continue to be studied in clinical trials
It is likely that both CT and MRI-based techniques will be more widely applied in future, & should be regarded as complementary rather than competing
This is the Genesis in Acute Stroke Therapy not the end!

32. Thank You