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