2. Department Workflow
1.
2.
3.
EMS alerts facility to prepare for arrival of potential stroke victim.
1.1. Is patient inside the time window for t-PA? (3 hours from onset of
symptoms).
Facility alerts necessary personnel (We utilized pagers)
2.1. CT Department
2.2. Emergency Department personnel
2.3. Respiratory Therapy (if needed)
EMS transports patient directly to CT department
3.1. Emergency department personnel are waiting in CT with appropriate
life sustaining equipment, monitor, and stretcher.
3.2. If respiratory therapy is needed, they would be waiting in CT with a
ventilator.
3. Department Workflow
4.
5.
Patient is put on monitor and transferred to CT table.
4.1. Observations are made by the CT Technologist of patient
regarding facial droop, fixed gaze, slurred speech, numbness
etc…
4.2. Vital signs are documented by attending nurse.
Head w/o contrast is performed and evaluated by CT personnel for
hemorrhage.
5.1. If there is no hemorrhage CT perfusion can be performed.
(Technologists need to be trained to identify brain bleed)
5.2. Head w/o contrast is sent to radiologist or off site reading
service for immediate interpretation.
5.3. 25 minute result time is required
4. Department Workflow
6.
7.
8.
9.
10.
11.
CT brain perfusion is performed according to department protocol
6.1. CT brain perfusion series sets are sent to VITREA for mapping.
CT Head and Neck is performed.
7.1. Post processing including coronal, sagittal, and 360 degree rotational
MIPS are performed (of each internal carotid artery).
7.2. Post Processing of Brain (Coronal, Sagittal, and Axial MIP’s)
Patient is transported back to Emergency Department.
CT Perfusion mapping results and CTA head and neck are sent to radiologist or
off site reading service for interpretation.
If stroke is identified in Head w/o contrast, either t-PA is administered or
MERCI procedure is performed in Special Procedures. (as per facility
policy)
Standard for resulting of all studies was 45 minutes from door time to final
resulting.
5. Scan Parameters
Scan mode
DualScano ( 0 and 90 degrees)
kV
120
mA
50
Range
240.0
Scan Angle
0
CE
Off
Direction
OUT
Scan Mode
Dynamic
Thickness
4 Rows (8.0x 4)
kV
80
mA
150 – 200
Rotation Time
1.0 sec
Scan Time
50 sec
SureExp
Off
CE
On
SureIQ
CBP
Image Thickness
8.0
Recon Interval
1.0
8. Positioning
• Position as you would for a normal
Head CT.
• Immobilize as necessary
• Once you have obtained a SCANO
image position your DYNAMIC slice
marker as image demonstrates
• Stay in line with the base of skull
and approximately 1cm Superior to
the Sella Turcica. (This will image
the necessary vascular structures
(see Picture next slide).
10. Positioning / Scanning Notes
• Notice that the area imaged includes from the Supra Sellar region through
the superior portion of the Circle of Willis. This includes all the necessary
vascular structures pertinent to the diagnosis of stroke and the ability for
mapping to occur with success.
• We have used 80 kV as low contrast resolution isn’t as important due to
the fact that we are only interested in contrasted areas of the vascular
structures. It also serves to reduce patient dose. Reduced mA also serves
this same purpose and anywhere between 100-200 mA has been proven to
be sufficient.
11. Positioning / Scanning Notes
• Inject 50ml of 370 Contrast at a rate of 4-6ml/sec. followed by 50 ml Saline Flush
• 18g or 20g IV (Right Arm Preferred)
• Since it takes approximately 15-22 secs for contrast to reach the basilar artery,
you can do one of two things, you can build a delay into the protocol itself and
start your time at the same time you start contrast, or you can start the contrast
injection and wait to start your scan manually without any delay built in. This
helps to reduce dose to the patient where no useful imaging is being performed.
While non-contrasted images are important for the mapping, it is unnecessary to
radiate a patient for 10-15 secs without need. Venous flow begins to drop off at
approximately 35-45 secs.
12. Positioning / Scanning Notes
While actively scanning you will see contrast begin to perfuse the brain, there will be 2 distinct
phases, Arterial and Venous. These phases are important for mapping in terms of CBF, CBV, MTT, and
TTP.
CBF – Cerebral Blood Flow
Flow rate of volume of blood through cerebral vasculature.
(ml/100gm/min)
CBV – Cerebral Blood Volume
Volume of flowing blood. (ml/100gm)
MTT – Mean Transit Time
Time required for blood to pass through tissue. (sec)
TTP – Time to Peak
Sensitive measure of decrease in flow
These maps will be used to demonstrate the vascular flow pattern to further identify a stroke and the
level of severity, including penumbra. (Refer to the VITREA Brain Perfusion manual I have included for
additional information and instructions on mapping.)
