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

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 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 SCOUTKvPmAS AP LAT 12010

CONTRAST SCANRETRO RECON PARAMETERS SCAN MODE Helical FullTYPEStandard SLIC THICKNESS 5mmDFOV36 INTERVAL 5mmTHICKNESS0.625 SFOV Large BodyINTERVAL0.625 KvP 120 mA 600 DYNAMIC PARAMETERS DETECTOR COVERAGE 40mm PITCH : 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 PARAMETERS ROI Rt Atrium MONITORING DELAY 3.0 sec ENHANCEMENT THERSHOLD 150 HU DIAGNOSTIC DELAY 3.0 MONITORING 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