Kamran M 1 , Deuerling-Zheng 2 , Mueller- Allissat B 2 , Grunwald IQ 1 , Byrne JV 1

Kamran M1, Deuerling-Zheng2, Mueller-Allissat B2, Grunwald IQ1, Byrne JV1

1. Oxford Neurovascular and Neuroradiology Research Unit, University of Oxford, 2. Siemens AG, Healthcare, Forchheim, Germany

Measurement of Cerebral Blood Volume using Dyna-CT: A Feasible

Method for Assessment of Vasospasm Severity Following Aneurysmal SAH

Background

Three dimensional volume

Angiograms CT-like soft tissue images

Image quality

• Contrast resolution• Spatial resolution• Temporal resolution

• Detector efficiency• Mechanical propertiesof C-arm gantry

Background


Angiograms CT-like soft tissue images

Image quality

• Contrast resolution• Spatial resolution• Temporal resolution

• Detector efficiency• Mechanical propertiesof C-arm gantry

Background

Cerebral vasospasm following aneurysmal SAH

An ideal technique for detection:

● Detect presence or absence of vasospasm before clinical deficits

● Be objective (reproducible)● Effective in the unconscious patient● Non-invasive

Background

Cerebral vasospasm following aneurysmal SAH

An ideal technique for detection:

● Detect presence of absence of vasospasm before clinical deficits

● Be objective (reproducible)● Effective in the unconscious patient● Non-invasive Diagnosis and assessment:

● Catheter angiography ● Transcranial Doppler Ultrasonography● CT or MR perfusion scans

CBV measurement using C-arm FDCT

Subtraction of the mask run from the contrast run

Normalisation of parenchyma with an input function from major vessels

CBV parametric maps

Time

Conc

entr

atio

n

Mask run Contrast run

8 seconds Steady state

C-arm FDCT


C-arm FDCT


MethodsDyna-CT

● CBV Scan parameters: Two 8-sec acquisitions (mask and contrast enhanced), approx. 400 projections each at 0.5° steps, fluoroscopic monitoring in between ● Post-processing for CBV estimation: co-registration, subtraction, normalisation with an input function ● Angiographic reconstructions: contrast enhanced run only, 512×512 matrix, smooth/sharp kernel

MR scan

● MR-PWI, MR-DWI, Time of Flight MRA, T1, and T2 weighted sequences● Perfusion scan: DSC, T2* weighted gradient echo planar sequence (20ml 0.5M Gadolinium based contrast material), TR~2000msec, TE 44msec, FOV 248×248mm, 256×256 matrix, voxel size 0.98×0.98×4mm, 15 slices, 50 time-points ● Perfusion analysis: block-circulant SVD algorithm, AIF chosen semi-automatically, motion correction

Example case 1A 60 year old lady presenting with ruptured anterior communicating artery aneurysm (5 × 7mm)

● Day 0: SAH, no loss of consciousness, Grade 1

● Day 1: Coil embolisation, Grade 1

● Day 3: Fluctuating LOC, numbness of the left arm

and leg, normal CT

● Day 4: Weakness of both legs,

neuro-ITU for supportive therapy MR-PWI and Dyna-CT scans

Angioplasty

Example case 1

MR-PWI MTT

Dyna-CT CBV MR-PWI CBV

MR-DWI

A 60 year old lady presenting with ruptured anterior communicating artery aneurysm (5 × 7mm)




and leg, normal CT



Angioplasty

Example case 1

MR-PWI MTT


MR-DWI





and leg, normal CT



Angioplasty

R L

Example case 1

MR-PWI MTT


MR-DWI





and leg, normal CT



Angioplasty

R L

Example case 2

A 41 year old man presenting with ruptured anterior communicating artery aneurysm (6×4.5mm)

● Day 0: SAH, Grade 1● Day 6: Reached hospital. CT scan ● Day 7: Dysphasia and right sided

hemiplegia; neuro-ITU for supportive therapy. Deficits recovered. CTA showed an Acom (6x4.5x5 mm) and a left MCA (3x3.5x3 mm) aneurysm.

● Day 7: Coil embolisation of both aneurysms. Vasospasm of ACA and MCA

● Day 8: Deteriorating LOC, dysphasia, and weakness of right side of the body.

CT, MR-PWI scan Dyna-CT CBV Angioplasty (Nimodipine)

Example case 2





● Day 8: Deteriorating LOC, dysphasia, and weakness of right side of the body


Example case 2







Example case 2







R L

ROIs analysis

Resultsa. Plot of identity

(Grey Matter ROIs)

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

0.8 1 1.2 1.4

Grey matter - C-arm system (relative CBV)

Gre

y m

atte

r - M

R-P

WI (

rela

tive

CB

V)

a. Plot of identity (White Matter ROIs)

0.8

0.9

1

1.1

1.2

1.3

1.4

0.8 1 1.2 1.4

White matter - C-arm system (relative CBV)

Whi

te m

atte

r - M

R-P

WI

(rel

ativ

e C

BV)

Grey matter

r = 0.84

95% limits of agreement =-0.21 to +0.23

Measurement bias = 0.03

White matter

r = 0.89


Measurement bias = -0.01

Results

b. Difference Plot (White Matter ROIs)

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.85 0.95 1.05 1.15 1.25 1.35

Mean of White matter

Diff

eren

ce (M

R-P

WI (

rela

tive

CB

V) -

C-a

rm s

yste

m

(rel

ativ

e C

BV)

)

Identity

Bias (-0.0050231997)

95% CI

95% Limits of agreement(-0.0715387122 to 0.0614923127)

95% CI

b. Difference Plot (Grey Matter ROIs)

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.8 1 1.2 1.4 1.6 1.8 2

Mean of Grey matter

Diff

eren

ce (

MR

-PW

I (re

lativ

e C

BV)

- C

-arm

sys

tem

(r

elat

ive

CB

V))

Identity

Bias (0.0108643749)

95% CI


95% CI

a. Plot of identity (Grey Matter ROIs)

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

0.8 1 1.2 1.4

Grey matter - C-arm system (relative CBV)

Gre

y m

atte

r - M

R-P

WI (

rela

tive

CB

V)

a. Plot of identity (White Matter ROIs)

0.8

0.9

1

1.1

1.2

1.3

1.4

0.8 1 1.2 1.4

White matter - C-arm system (relative CBV)

Whi

te m

atte

r - M

R-P

WI

(rel

ativ

e C

BV)

Grey matter

r = 0.84



White matter

r = 0.89


Measurement bias = -0.01

Results

b. Difference Plot (Both Grey and White Matter ROIs)

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.8 1 1.2 1.4 1.6 1.8 2

Mean of Overall

Diff

eren

ce (M

R-P

WI (

rela

tive

CB

V) -

C-a

rm s

yste

m

(rel

ativ

e C

BV)

)

Identity

Bias (0.0029205876)

95% CI


95% CI

a. Plot of identity (Both Grey and White Matter ROIs)

0.8

0.9

1

1.1

1.2

1.3

1.4

0.8 1 1.2 1.4

Overall - C-arm system (relative CBV)

Ove

rall

- MR

-PW

I (re

lativ

e C

BV)

Overall (GM+WM)

r = 0.87



Radiographic contrast:80ml of Niopam 370

Radiation dose:1.78 mSv

Scan time:~25 sec

Conclusion

Dyna-CT CBV agree with MR-PWI CBV

Improved spatial resolution, short scanning time, complete brain coverage

Exploits the same data to generate angiographic and soft tissue images (with reduced contrast and radiation dose)

Potentially useful tool that may help in time efficient triage of patients with brain ischaemia in optimized interventional environment

However,

Improvements in detector efficiency and gantry rotation speeds are warranted to exploit its soft tissue and perfusion imaging potential

Acknowledgements

Department of Neuroradiology, West Wing, JR Hospital, Oxford

The Rhodes Trust Siemens AG Healthcare, Forchheim Germany

Many Thanks !

Documents

Kamran M 1 , Deuerling-Zheng 2 , Mueller- Allissat B 2 , Grunwald IQ 1 , Byrne JV 1