The concept of penumbra and salvageable brain tissue in acute - - PowerPoint PPT Presentation

The concept of penumbra and salvageable brain tissue in acute ischemia

Tatjana Stošić-Opinćal

Prof of Radiology and Neuroradiology General Hospital Euromedik, Belgrade, Serbia

XVth BCR 12-14th October, Budapest, Hungary

CBF<10ml/100gr/min depletion of energy metabolites CELLS Efflux of K+, Infflux Na+, Ca++, water Cytotoxic edema (from the first minutes) VESSELS Blood Brain barrier damage Vasogenic edema (after first 6-8 hours)

3-5 minutes 30 seconds

Modern imaging is able to identify the ischemic penumbra (CT,

Lopez AD et al. Lancet 2006; 367:1747-1757 Rothwell PM et al. Lancet 2005; 366:1773-1783 O'Brien JT et al. Lancet Neurol 2003; 2:89-98

Imaging of the penumbra

Radiographics, May-June2003.

Dense artery sign-the most early sign, 35-67% of acute stroke (common in MCA); disappears within a few days or after thrombolysis. BE CAREFUL: false positive cases (calcified atherosclerosis and high hematocrit levels)

2 days later At presentation Insular ribbon sign After 3h Disappearing BG sign After 24h

Regions with reduced blood flow can be showed immediately after the occlusion Penumbra - within the first 6 hours (sensitivity 100%)

CBV (ml/100g) CBF (ml/100g/min) MTT (sec)

Disadvantage: with every bolus injection only one segment could be evaluated

CBV CBF MTT OLIGEMIA Normal or elevated Moderately reduced Prolonged PENUMBRA Normal or mildly decreased Markedly reduced Prolonged (> 145%) INFARCT CORE Severely reduced (<2 ml/100g) Severely reduced Strong prolongation

• r not

measurable

Threshold values for CTP

CBV/MTT mismatch (penumbra) CBV<2ml/100gr = core infarct MTT>145% normal = penumbra

Wintermark et al, 2008

Definite thresholds are not still available High correlation between CTP and MRP (Schaefer et al, 2008)

Folow up 90 min after IV-thrombolysis

Yu, Y. et al. Defining Core and Penumbra in Ischemic Stroke: A Voxel- and Volume-Based Analysis of Whole Brain CT Perfusion. 2016.

Threshold values for CTP

Image processing for voxel-based analysis

delay time ≥ 3 s and rCBF ≤ 30% - optimal thresholds for penumbra and core

• mismatch=CBF/CBV

MTT CBV CBF

Courtesy B.Georgijevski-Brkic

F, 74 NIHSS 1=17 NIHSS 2= 9

F, 54 NIHSS 1=12 NIHSS 2=5

F, 55

F, 65

F, 72, wake up stroke

• *, SWI,

DWI/ADC PWI (rCBV, rCBF, MTT) MRA

Diffusion weighted imaging (DWI)

• core
• restricted diffusion

DWI

M 38 yrs with weakness of left leg, arm and face CT 1h, T2W i DWI 2h, CT 5 days after stroke

Measurements of tissue perfusion provide reliable estimates of the penumbra

Shows hemodynamic status within the first minutes of acute stroke Relative maps (MTT, CBV, CBF) show area of reduced perfusion in penumbra

M, 72

• Mismatched tissue represents “tissue-at-risk”

PWI > DWI Mismatch (penumbra) Thrombolysis

PWI = DWI MATCH (no tissue at risk) No thrombolysis

PWI < DWI Repefusion No thrombolysis

Detect Tissue at Risk with MRI – PD mismatch

NORMAL: CBF in GM 50-60 ml/100gr/min OLIGEMIA: CBF < 35 ml/100gr/min (50-60% of normal values) PENUMBRA : CBF < 20 ml/100gr/min (30-40%) IRREVERSIBILE CELL DEATH: CBF <10 ml/100gr/min (20%) PDM does not optimally define ischemic penumbra

Early DWI abnormality overestimates infarct core (include part of penumbra) PWI abnormality overestimates penumbra (including benign oligemia) The area of final infarction is normally smaller than the maximum perfusion deficit

Chen F, Ni YC. Magnetic resonance diffusion-perfusion mis-match in acute stroke. World J Radiol 2012; 4(3):63-74.

classical type (49%-70%) - target mismatch or positive mismatch

no target mismatch was the most common type in patients with diabetes

inverse or negative mismatch or “hidden mismatch”

(PWI < DWI) , small subcortical ischemic stroke

• single small artery occlusion or presence of small

subclinical infarct

total mismatch migraine or TIA

Hypoperfusion affecting >1 vascular territory

Floery AJNR 33 Sep 2012.

migraine PET

malignant mismatch poor outcome brain hemorrhage

Albers GW et al. Magnetic resonance imaging profiles predict clinical response to early reperfusion: The diffusion and perfusion imaging evaluation for understanding stroke evolution (DEFUSE) study. Ann Neurol. 2006;60:508–517. Davis SM, et al. Effects of alteplase beyond 3 h after stroke in the echoplanar imaging thrombolytic evaluation trial (EPITHET): A placebo-controlled randomised trial. Lancet Neurol. 2008;7:299–309.

M, 51 1h after onset

• f stroke,

hemiplegia l.sin.

DWI – b 1000

ADC

CBF

MTT

PDM is not yet perfectly matched with the ischemic penumbra Although MR is currently preferred imaging method for determining core and penumbra, CT perfusion is comparable and potentially more available Acute stroke patients with significant PD mismatch lesion volumes benefit from reperfusion therapies Little or no PDM and very large ischemic lesions may not benefit or may be harmed ( hemorrhage or reperfusion injury) following early reperfusion.

Thank You