Intended learning outcome The student should learn at the end of this lecture procedures of CT pulmonary angiography.
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Intended learning outcome
• The student should learn at the end of this lecture procedures of CT pulmonary angiography.
INTRODUCTION
CTPA was introduced in the 1990s as an alternative to
ventilation/perfusion scanning, which relies on radionuclide
imaging of the blood vessels of the lung. It is regarded as a highly
sensitive and specific test for pulmonary
embolism.
Angiography is the visualization of blood vessel by injecting
contrast media using invasive or non invasive technique.
ANGIOGRAPHY
ANATOMYThe pulmonary arteries carry blood from the heart to the lungs.
They are the only arteries that carry deoxygenated blood.
ANATOMY
Pulmonary artery begins at the base of the right ventricle.
It is short and wide approximately 5 cm (2 inches) in length
and 3 cm (1.2 inches) in diameter.
It then branches into two pulmonary arteries (left and right),
which deliver de-oxygenated blood to the corresponding lung.
INDICATION
Pulmonary embolism
Aortic dissection
Aortic overloading
Left ventricular stress
CONTRAINDICATION
Renal failure
Severe diabetes
Allergic to contrast reactions
Pregnant patients
PREPERATION
Enquire about pregnancy from females.
Renal parameters are to be checked.
Nil oral preparation for 4-6 hours
Informed consent from patient
All metal objects are to be removed from the region of interest
Patient is changed into hospital’s cotton apron.
Enquire about allergic history
A prominent vein in patients upper limb is catheterized with
18-20 gauge .
CONTRAST DOSAGE
1.2ml /kg (body weight) of non-ionic iodinated contrast
medium is injected intravenously into the patient using a
pressure injector.
Rate of injection being 4-5 ml /sec
PATIENT POSITIONING
Patient is positioned feet first with the help of laser localizers
at the level of sternal notch with coronal beam at mid-axillary
line
Head first position can be also performed
Proper immobilization should be done
PATIENT POSITIONING
Proper breath hold instructions should be given
Ensure the patient connected IV lines, are long enough to
allow full travel of the couch without being pulled or entangled
while undergoing a CT
PATIENT POSITIONING
Test dose of about 2 – 5 ml of contrast is injected and patient
is observed for any reaction associated
Patency should be checked before starting the scan
SCAN PARAMETERS
PLAIN SCAN
SCAN MODE Helical Full
SLIC THICKNESS 5mm
INTERVAL 5mm
SFOV Large Body
KvP 120
mA 350
SCOUT KvP mAS
AP 120 10
LAT 120 10
CONTRAST SCAN RETRO RECON PARAMETERS
SCAN MODE Helical Full TYPE Standard
SLIC THICKNESS 5mm DFOV 36
INTERVAL 5mm THICKNESS 0.625
SFOV Large Body INTERVAL 0.625
KvP 120
mA 600
DYNAMIC PARAMETERS
DETECTOR COVERAGE 40mm
PITCH 0.984 : 1
ROTATING TIME 0.5
It is a software, that allows real-time monitoring of IV Contrast
enhancement in the area of interest.
SMART PREP TECHNIQUE
SMART PREP PARAMETERSROI Rt Atrium
MONITORING DELAY 3.0 secENHANCEMENT THERSHOLD 150 HU
DIAGNOSTIC DELAY 3.0MONITORING ISD 1.0 sec
The caudal-cranial direction is used because most emboli
are located in the lower lobes and, if the patient breathes
during image acquisition, there is more coverage of the
lower lobes compared with the upper lobes.
SCANNING PROCEDURE
POST PROCESSING
Volume rendering technique (VR) Maximum Intensity Projection (MIP)
Multi planar reconstruction (MPR)
MAIN AORTIC PULMONARY COLLATERAL ARTERIES
ADVANTAGES AND DISADVANTAGES Less time consuming
Non-invasive nature
Almost all radiology departments have CT scan
Less complication than conventional (elevated pulmonary
artery pressures)
Lesser volume of contrast needed
Simple post procedure care
Can be done in out patient basis
CONCLUSION
Conventional pulmonary angiography has long been considered
the gold standard in the diagnosis of Pulmonary pathologies
and historically it is the technique against which all other
modalities have been measured.
This position has now been seriously challenged by helical CT
Pulmonary Angiography and now it is set to replace it as the
new gold standard.
Text Book
• David Sutton’s Radiology• Clark’s Radiographic positioning and
techniques
Assignment
• Two students will be selected for assignment.
Question
• Define smart preparation parameters in pulmonary angiogram?
• Thank You
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