CT prosedures

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CT prosedures

• CT Colonography
• CT Urography
• CT Angiography
• CT Perfusion

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CT Colonography

• Why?
• Looking for cancer in the colon
• How?
• Air or CO2 gets pumped in the patients colon, the
  doctor feels the patients stomach and desides if
  a topogram should be made. By looking at this
  topogram he/she then desides if there is enough
  air in the colon to start scanning.
• Use Buscopan
• Scan both in supine and prone positioning.
• 120 kV/50 mAs
• No I.V contrast

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CT Colonography

• Comments
• Its important that the patient has gone trough a
  thorough preparation with taking laxidents and
  not eating.
• They should also take fecalie- tagging
• Equipment for pumping the air in could be the
  same as a convensionel x-ray examination of the
  colon.
• Equipment for using CO2 is very expensive.
• Always be aware that the patient can feel dizzy
  and sick after the exam. The preparation for the
  exam is hard for them!

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3D of colon after putting the CT images into
another computer hardware. This image can be
flipped and viewed in all angles.
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Image to the right is how the colon looks in
MSCT,in the middle the image shows how you can
look at the colon from inside using 3D computer
hardware, and to the left the image is also 3D,
but its subtracted so that you only see the wall
of the colon in grayscale. Both 3D images can be
flipped and viewed from all angles.
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CT scan of colon. The arrow shows a flebolitis
which can indicate colon cancer.
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CT Urography

• Why?
• Hematuri, kidney- and urotelcancer, difficult
  stone- exams.
• How?
• First one scan in prone positioning. This is to
  look for stones. By laying in prone position the
  stones are easyer to confirm. If the patient is
  laying in a suping position flebolitis could look
  like stones.
• I.V contrast- Omnipaque 300 mg/ml- after weight.
  Flow 3ml/s
• Second scan is done after 100 s to get the
  contrast in pharemcym-fase.
• After that you give the patient 250 ml of NaCl,
  which goes I.V over 10 minutes, and take the
  third scan. Then its possible to follow the
  ureter all the way from the kidneys to the
  bladder.
• First scan 120 kV/ 145 mAs
• Second/Third scan 120 kV/ 300 mAs

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CT Urography

• Comments
• ALARA
• Depending on the problem of the patient, you and
  the doctor should always think if this type of
  examination would come to the patients benefits.
• Studies has shown that CT gives more dose to
  patient than conventionel examitations of this
  type. But in some cases the CT Urography will
  give more answers to a problematic case.

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Image shows the uretertrackt and the bladder. The
CT image is transfered into 3D. Can be flipped
and viewed from all angles.
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MSCT scan of kidneys after I.V.CThe arrow
indicates an obstruction in the left kidney. The
delay after contrast is 100 s.
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CT Angiography

• Why?
• To look for occluded vessles in head, neck and
  body.
• How?
• Dipending on the examination you use 50 ml -100
  ml Omnipaque (or other) 350 mg/ml. Flow is 4
  ml/s.
• 120 kV and 300 mAs also depending on the
  examination.
• Bolus tracking.

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CT angiography of the head in sagittal view.
I.V.C used. In frontal you can se 2 occlusions in
the major vessles.
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Axial scan of CT angiography. This scan is over
the circle of willis, where all major arteries in
the brain meet.
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CT Perfusion

• Why?
• Brain infarction / thrombolysis
• When?
• After a standard brainscan, when theres no
  bleeding.
• Only done when the neurologist and the
  radiologist agree that its the best choise.
• Further scans?
• If the exam is positive, it can be descussed if
  CT angio of carotis and brain should be done.

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CT Perfusion

• How?
• Patient needs a large veneflone
• First take a regular scan of the brain
• Perfusion scan should be done over the circle of
  willis
• Orbita should NOT be in the scan
• CT brain 120 kV/ 380mAs
• CTperfusion 80kV / 270mAs
• I.V contrast 40 ml Omipaque 350 mg/ml
• Flow rate 7 ml/s
• NaCl 20 ml bolus.
• Repeated scans over one area.

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Images to the left show a brainscan where the
arrows point to a dark area. Image to the right
is the same as on the left, but it has been
convertet using a computer hardware
PERFUSION.The read area indicates low perfusion
in this part of the brain.
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Upper picture to the left shows a normal CT image
using perfusion protocoll. The other images show
different ways to use the computer hardware
PERFUSION.
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CT Perfusion

• Comments
• All patients that are submitted to the dep. of
  neurology with suspision of acute brain
  infarction, and has symphtoms less than 24 hours
  old, should get a cerebral CT as soon as they
  come to the hospital.
• CT perfusion should be done imidiatly after
  regular cerebral CT scan when theres no
  bleeding/ it has been less than 6 hours sinse the
  symphtoms started/ symphtoms point to a
  non-lacunar infarction/ the patient doesnt have
  kidneyfailure.
• If there is an area with decreased perfusion, CT
  angiography can be done to find the vessel that
  caused the infarction.
• The following day cerebral MRI can be done if
  theres still suspision of infarction that has
  not been resolved.

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Questions?