Technical aspect for technologist

1. CT scan for STROKE and
updates(technical aspects)

2.  Nothing to Advertise
Disclosure

3. This presentation will cover
 What dose STROKE mean.
 Why CT for STROKE patients.
 Setup of a CT System.
 Get familiar with different kinds of routine STROKE
Head CT.
 State–of-art in CTA with both single and Dual
Energy technology.
 By the end of this presentation, you should be
familiar with STROKE scanning technique aspects.

4. *STROKE:
Is a common term meaning a neurological condition
due to lesions of brain caused by hemorrhage,
embolism, thrombosis , or ruptured aneurysm.

5. *STROKE types:
Most common stroke etiology:
1- Cerebral infarction -80%.*
2-Primary intracranial Hemorrhage- 15%.
3- Non-trumatic subarachnoid Hemorrhage- 5%.
*FOCUS: Cerebral infarction.

6.  Why CT scan for stroke patients?
The invention of computed tomography - of course, beside the
other vital imaging modalities - has played ultimate roles in
diagnostic medical imaging since the discovery of X-rays. In other
words, cross-sectional imaging has provided high level of
accurate imaging facilities with better visualization insight our
bodies’ anatomy and pathogenesis. However, no anymore
surgeries required. CT is fast, demandable, reliable and handy,
too.
- Today, CT is one of the un-ignorable imaging choices in majority of
CVA’s patients.
- Non-super-imposition, HR cross-sectional images of the brain,
accompanied with less artifacts.
- Shows smaller objects contrast and temporal resolution differences.
- Allows better visualization(SNR, SR)
All those Advantages have made CT the key stone as well as the
best choices for Stroke ER patients first imaging, who require to be
diagnosed properly and promptly. Definitely at the same time.

7. Setup of a CT System
CT system comprise several components
These basically include:
 The examination room, i.e. the gantry, with tube,
detector and patients’ table. IV CM Injector.
 The technical room, where tech manage his scans.
 The image processors for image reconstruction
software.

8.  Scanning unit (gantry)
A CT scanning system consists of an X-ray tube,
which functions as a transmitter, and data
acquisition unit detectors array, which function as a
X-Ray receiver.

9. Setup of a CT System
Scanning room
Technical room

10. Technical room
Inject IV Contras

11. CT Basics
 There are key concepts of stroke CT imaging:
CT head planes.
windowing and leveling.
Hounsfield Unit.
Stroke common terminology.
scanning technique.

12. CT head planes
1-Transvers (corpus callosum genu and splenium):
most often used.
2- Coronal MCP (brain stem):
used for skull base tumors, vascular anatomy, infundibulum, and
pituitary gland.
3-Sagittal MSP (midline)
brain lobe localization, pituitary, sella T and cranio-cervical junction..

13. coronal

14. Window width and level
It is process of using the calculated Hounsfield Unites(HU), to make interpretable CT
images.

15. Window width and level

16.  Named after inventing CT, designed by Godfrey N
Hounsfield.
 Ranges from -1000 to +1000.
 It’s attenuation(Brightness) of each pixel
in image matrix.
 Represent the relative scanned tissue density.
What’s a hounsfield Unit ?

17. What’s a Hounsfield Unit ?

18. CT Stroke common terminology
1.Hyperdense (White):
Abnormalities which is brighter than
surrounding tisues (white) on CT.
The solid arrow points to an area of right
frontal and parietal intraparenchymal
hemorrhage. The segmented arrow points to
blood in the posterior horn left lateral ventricle.
With mass effect…md line shift, edema
55 HU
40 HU
70 HU

19. What’s a hounsfield Unit ?

20. CT Stroke common terminology
2. Isodense (same density):
Abnormalities which have relatively same
density with the reference structures.
The solid arrow points to an Isodense area
in supracellar cistern, a normal structure,
which is filled with CSF. The dashed arrow
points to an area that is isodense to CSF.
This is cisterna magna, a normal structural
variant.
14 HU
12 HU

21. CT Stroke common terminology
3. Hypodense (Darker):
Abnormalities which have less dense than the
reference structures.
The solid arrow points to an area that is
hypodense relative to the adjacent gray
and white matter. infarction.
8 HU
40 HU

22. Type of stroke imaging in CT
 Non-Contrast:
● Scanning brain W/O IV CM, R/O different kinds hg, stroke, calcium containing
brain tumors SGC Astrocytoma, Oligodendroglioma 90% ca, as well as CVA.
 Contrast
 IV Contrast is given for better evaluate:
● Vascular Structure(CTA, AVM, Aneurysm)
● Brain perfusion(brain are supplied or perfused adequately)
● Tumors(low and high grads).
● Site of infection.
● Navigation Medtronic protocols(T resection, CSF management, Biopsy, DBS)
Relative contraindication to IV Iodinated material:
● Allergy to Iodine contrast, Acute Bronchial Asthma, elevated Serum createnine
to avoid CIN, as well as CAN.

24. Common indication for Head CT
 Cranio-facial truma.
 stroke patients.
 Evaluation of the headache.
 Evaluation of sinus cavities.
 Oncology patients.

25.  stroke patients.

27. CT stroke scanning technique
 Non- IV Contrast:
Identify your patients by adhering with IPSG, perform scan by utilizing
stroke protocol, patients supine, fix, instruct patients, protect other organ
from Scatterd radiations, scan Lateral tomogram, adjust SOM line(eyes and
beam hardening, too), precisely select slices from foramen magnum-vertex,
helical scan(SR & SNR) and Sequential for Navigation, use good parameters to
overcome bony skull, 3 planner reconstruction, PACS, inform Dr immediately
T/R report in ER/Critical patients.

28. CT stroke scanning technique
 Non-IV Contrast:
Identify your patients by adhering with IPSG, perform scan by utilizing stroke protocol,
patients supine, fix, instruct patients, protect un-exposed body, scan Lateral tomogram, adjust
SOM line(eyes and beam hardening, too), precisely select slices from foramen magnum-vertex, helical
medium scan(SR vs. SNR) and Sequential for Navigation, use good parameters to overcome bony
skull, 3 planner reconstruction, PACS, inform Dr immediately T/R report in ER/Critical patients.
 IV Contrast:
LOCM and viscosity, 1.85mgI/sec for CTA, and 1mgI/sec for routine, FR
≥5ml/s, 3ml/s for routine and CTA, respectively. Patent IV line(big size for CTA,
Multi-Hole), explain to the patient the warm feeling of IV CM, Dr. will explain
possibility side effect, obtain secured consent, normal RF, BHCG, neither
allergic to IV CM nor asthmatic, too. Stop metformin 48h, good hydration post
IV CM. 15min monitor allergic and asthmatic pt.

29. IV Contrast
Asthmatic and IV contrast Allergic patients Perpetrations:
 Normal patients
1)- Prednisolone(Hydrocortisone) 50mg/Oral 13/7/1 hrs. before IV contrast.
2)-Diphenhydramine (Antihistamine) 50 mg Oral 1 hr. before IV contrast.
 Emergency patients
 200mg IV of Hydrocortisone.
OR
 Dexamethasone 7.5 mg only.
NB: Use LOCM, Low flow rate warmed IV contrast have shown less adverse
reactions.

30. CT Dual Energy State-Of-Art new technology

31. CT Dual Energy of stroke imaging
Principle:
Iodine HU raised
70%
Bone HU raised
37.5%
X-Ray Spectra(Monoenergetic)
X 2
X 1/2

32. CT Dual Energy of stroke imaging
Principle: X-Ray Spectra(Monoenergetic)
Because many materials show different attenuation
at different mean energies.
The Iodine has large HU difference, Bone small HU
difference.

33. CT Dual Energy of stroke imaging
Dual Source Fast Kvp switching
single Source
Single Source Double
Detectors layer

34. CT Dual Energy of stroke imaging
Advantages
The most advantages of dual-energy CT in stroke neuroimaging are:
1)-Completely bone subtraction, comparing with traditional single source, especially base
of skull. Vasculature can be well assessed.
2)-superior image quality for CT angiography and minimization of streak artifacts due to
metals or dense bony structures.
3)- Use little amount of IV Contrast. As a result of low Kvp
4)-Low dose, VNC.
5)- Metallic artifact reduction technique.
6)- Differentiate between hemorrhage and iodinated contrast agents in brain parenchyma.

35. CT Dual Energy Stat-Of-Art new technology
CT Angiography of brain

36. Comparison of automated bone removal algorithm for dual-energy CT (A) and conventional bone
removal CT angiography (B). The dual-energy CT image is superior in quality and although larger
bone remnants are retained, the vasculature can be well assessed.
Dual Source conventional

38. Dual-energy acquisition with two different monoenergetic selections (A: 80 Kvp; B:
140 Kvp). The 140-kvp monoenergetic imaging shows decreased streak artifact and
enables better visualization of the surrounding brain parenchyma and vasculature
mapped out clearly.
CT Dual Energy of stroke imaging
Metal artifact reduction(Coils)
80Kvp
140Kvp

39. Stroke DE technology open an approach
renal function deteriorated patients.
80 Kvp –
High Contrast

40. Interesting DE case.

41. (A)Dual-energy CT, diffuse hyperdensity (arrows)
(B) Iodine overlay image the area of hyperdensity, most likely contrast staining.
(C) VNC image, no areas of hyperdensity are identified, suggesting there is no intracranial
hemorrhage.
(D) 24 hour follow-up near-complete washout—a property of water-soluble contrast—without
evidence of parenchymal edema to suggest hemorrhage……. Contrast staining
Has DE CT scan for stroke added a significant evaluation values in
compare with traditional CT? Intracerebral Hemorrhage vs. Iodine Staining?

42. Thank you