Ct pulmonary angiogram

1. CT PULMONARY ANGIOGRAM Mr. M. Kartheeswaran Radiographer SRMC Chennai

2. 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.

3. Angiography is the visualization of blood vessel by injecting contrast media using invasive or non invasive technique. ANGIOGRAPHY

4. ANATOMY The pulmonary arteries carry blood from the heart to the lungs. They are the only arteries that carry deoxygenated blood.

5. 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.

6. INDICATION Pulmonary embolism Aortic dissection Aortic overloading Left ventricular stress Teratology of Fallot

7. CONTRAINDICATION Renal failure Severe diabetes Allergic to contrast reactions Pregnant patients

8. PREPERATION Enquire about pregnancy from females. Renal parameters are to be checked. Nil oral preparation for 4-6 hours Informed consent is to be got 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 catheterised with 18-20 guage venflon .

9. 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 Pressure 325 ppm

10. 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 Proper immobilization should be done

11. 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

12. 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

13. 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

14. 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 RECON OPTION 1500 – 700 mA 600 DYNAMIC PARAMETERS SPEED 39.37 mm/rot DETECTOR COVERAGE 40mm PITCH 0.984 : 1 ROTATING TIME 0.5 COVERAGE SPEED 78.74 mm/sec

15. It is a software, that allows real-time monitoring of IV Contrast enhancement in the area of interest. SMART PREP TECHNIQUE

16. SMART PREP PARAMETERS ROI Rt Atrium MONITORING DELAY 3.0 sec ENHANCEMENT THERSHOLD 150 HU DIAGNOSTIC DELAY 3.0 MONITORING ISD 1.0 sec MONITORING LOCATION Infero - Superior

17. 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

18. POST PROCESSING Volume rendering technique (VR) Maximum Intensity Projection (MIP)

19. Multi planar reconstruction (MPR)

20. MAIN AORTIC PULMONARY COLLATERAL ARTERIES

21. 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

22. 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.

23. THANK YOU…