Transcript patient positioning

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
Angiography is the visualization of blood vessel by injecting
contrast media using invasive or non invasive technique.
ANATOMY
The 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
SCOUT
KvP
mAS
AP
120
10
LAT
120
10
PLAIN SCAN
SCAN MODE
Helical Full
SLIC THICKNESS
5mm
INTERVAL
5mm
SFOV
Large Body
KvP
120
mA
350
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
SMART PREP TECHNIQUE
 It is a software, that allows real-time monitoring of IV Contrast
enhancement in the area of interest.
SMART PREP PARAMETERS
ROI
Rt Atrium
MONITORING DELAY
3.0 sec
ENHANCEMENT THERSHOLD
150 HU
DIAGNOSTIC DELAY
3.0
MONITORING ISD
1.0 sec
SCANNING PROCEDURE
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.
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