Dr sridhar role of CT and CT perfusion in evaluation of stro

Role of CT in Acute Stroke
Dr. PG Sridhar
Sr. Consultant


Epidemiology
• Third most common cause of death
world wide
• Age adjusted prevalence rate of
stroke in India  250350/100,000*
• Age adjusted prevalence rate of
stroke in Bangalore 
262/100,000**
• Estimated
*Neurologystroke
Asia 2006;related
11 : 1 – 4 death
1.2 %
of the total 2004;23:261–268
deaths*
**Neuroepidemiology


Stroke
• Infarction 85%
–
–
–
–

Cerebral atherothrombosis 30-40%

Cardiogenic embolism 20-25%
Penetrating artery disease (lacune) 20%
Other unusual causes 5%

• Hemorrhage 15%
• In India, ratio of cerebral infarct to
hemorrhage is estimated to be 2.21*
*Neurology Asia 2006; 11 : 1 – 4


“Time is Brain”


“Time is Brain”
National Institute of
Neurological Diseases and
Stroke trial (NINDS)

3Hrs

(N Engl J Med 1995;333:1581-7.)

European Cooperative Acute
Stroke Study III (ECASS III)
(Stroke. 2009;40:2262-2263 )

4.5 Hrs


Goals of Acute Stroke

Imaging
• Parenchyma: Assess early signs of acute stroke and rule
out
hemorrhage
• Pipes: Assess extracranial and intracranial circulation for
evidence
of intravascular thrombus
• Perfusion :
Assess cerebral blood volume, cerebral
blood flow, and
mean transit time
• Penumbra :
Assess tissue at risk of dying if ischemia
continues without
recanalization of
intravascular thrombus

Rowley HA. AJNR 2001;22:599–601.


• Non contrast CT
• CT perfusion
• CT angiogram
• Other emerging imaging
techniques


Unenhanced CT
• R/o hemorrhage.
• Insular ribbon sign

• obscuration of the lentiform
nucleus
• Cerebral swelling
• Dense vessel sign (MCA or MCA dot
sign)


Intracranial Hemorrhage


obscuration of the lentiform
nucleus

May be seen on CT images within 2 hours after the onset of a Stroke


Insular Ribbon Sign

73Y/F, 2 1⁄2 hours after the onset of left hemiparesis


66Y/M, Left hemiparesis
history of a visit to a chiropractitioner


Stroke Window


24 Hrs

Follow Up

1 Week


Stroke window

width
centre
Sensitiv
ity
Specific
ity

Std. soft
tissue
window

Stroke
window

80
20

8
32

57%

71%

100%

100%

Lev et al. Radiology 1999; 213: 150-155


Lev et al. Radiology 1999; 213:
150-155
small attenuation difference
between normal and acutely
edematous brain tissue can be
accentuated by using variable,
nonstandard window width and
center level settings.


Alberta Stroke Program Early CT
Score
(ASPECTS)


ASPECT SCORE
An ASPECTS score less than or
equal to 7 predicts worse
functional outcome at 3 months
as well as symptomatic
haemorrhage.

Dense Basilar and PCA
85Y/F, Change in mental status



41Y/F, right sided
weakness


4 Day F/UP MRI & MRA


False Positive Dense
vessel sign
• increased hematocrit
• wall calcifications
• Polycythemia
• arterial dolichoectasia


CT PERFUSION


CT PERFUSION
• Cerebral blood volume (CBV): the
volume of blood per unit of brain tissue
• Cerebral blood flow (CBF): the volume
of blood flow per unit of brain tissue per
minute

• Mean transit time (MTT): defined as the
time difference between the arterial
inflow and venous outflow
• Time to peak (TTP): The time from the
beginning of contrast material injection
to the maximum concentration of