CT Angiography: Patient Preparation, Acquisition, Contrast Medium, and Postprocessing Techniques

1. CTANGIOGRAPHY Dr. DevadasAcharya Prof. and H.O.D Department of Radio-Diagnosis Yenepoya Medical College YENEPOYAUNIVERSITY www.yenepoya.edu.in

2. CT IMAGE OF THE BLOOD VESSEL OPACIFIED BY CONTRAST

3. REQUIREMENTS FOR CTA • PATIENT PREPARATION • ACQUSITION PARAMETERS • CONTRAST MEDIUM ADMINISTRATION • POSTPROCESSING TECHNIQUES

4. Patient Preparation

5. INFORMED CONSENT

6. PATIENT PREPARATION • Blood Urea 15-40 mg/dl • CREAT.- 0.6 –1.2 mg/dl • IODINE ALLERGY • Pregnancy? • eGFR >45 ml/min/1.73 m2 (Ideally >60) • NPO – 4-5 Hours

7. High Risk Patients • Hypersensitivity towards iodine • Diabetes Mellitus • Asthma • Dehydration • Chronic/Acute renal disease

8. GAUGE SUITABLE FOR CTA CANULA SELECTION • 22G • Paediatric • Peripheral Smaller veins • Slow Flow rate <3ml/sec • 18G • CT Angiography • High Flow rate 4-5ml/sec • ` • 20G • Routine CECT/Angio • Flow rate 3-4ml/sec

10. TRI-IODINATED CONTRAST MEDIA

11. 300 vs. 370 Iodine • 300mg/ml • Routine: • Cerebral Angio • Peripheral Angio • Pulmonary Angio • 370mg/ml • Selective Visceral Angio • Coronary Angio • Paediatric Angiocardiography

12. How to Calculate Total Volume of Contrast Ideally volume of CM Adapted to concentration and Patient’s weight 1.7–2.0 ml/kg of 300 mgI/ml CM OR 1.4–1.6 ml/kg of 370 mgI/ml C

13. CreatinineGuidlines • If the creatinine is ≤ 1.5 and the GFR is >60mL/min/1.73m2 – go ahead and administer contrast. • If the creatinine is >1.5 in a diabetic, >2.0 in a non-diabetic, or GFR is <30 mL/min/1.73m2, radiologist must discuss with the clinician.

14. Visipaque It is the only iso-osmolar contrast agent, with an osmolality of 290 mOsm/kg H2O: The same as blood Used in Creatinine level upto 2.4 mg/dl

15. ACQUSITION PARAMETERS

16. PARAMETERS • Usually routine CT precedes a CTA exam • The routine exam is used as a reference scan helping to determine the scanning range in CTA.

17. SLICE THICKNESS SPATIAL RESOLUTION SLICE THICKNESS

18. CEREBRAL CTA ABDOMINAL CTA THORACIC CTA 1MM (LOWER mA) 3MM 3MM SLICE THICKNESS

19. PITCH SPATIAL RESOLUTION SPIRAL PITCH 0.984 : 1

20. kVp, mA, TIME • SIMILAR TO NON- CTA EXAM OF THE SAME BODY PART RECONSTRUCTION INTERVAL 0.625

21. CONTRAST ADMINISTRATION

22. POWER INJECTOR POWER INJECTORS

23. POWER INJECTOR PARAMETERS VOLUME OF CONTRAST-ml RATE ml/sec TIME OF INJECTION – sec SCAN DELAY TIME - sec

24. Pushes contrast in tubing and peripheral veins into central veins (20 – 30 cc) Reduced streak artifacts from veins and right heart SALINE CHASER Dual Injector

25. Scan Timing

26. Timing Bolus • Select target location from scout topogram • Inject small test-bolus; 15 – 20 mL contrast • Acquire low-dose scan at specified location • ROI in target structure • Measure time-attenuation curve • Contrast material arrival time in aortic root Scan Timing

27. Bolus Triggering • Select trigger location • Acquire reference image • •Place ROI in vascular structure of interest • Inject contrast bolus • Monitor attenuation in ROI • Start scan when desired threshold reached Scan Timing

28. Post Processing

29. CTA - MPR

30. CTA – Maximum Intensity Projection (MIP)

31. CTA – Shaded Surface Display

32. CTA – Volume Rendering

33. CT Renal Angio

34. CT Renal Angio

35. CT Peripheral Angio

36. CT Peripheral Angio

37. CT Aortography

38. CT Aortography

39. CT Cerebral Angio

40. ContrastReactions

44. Thank You…