Cardiac CT and CT Angiography: Techniques Clinical Applications

3. Patient PreparationPrior to CT Ask patient to refrain from stimulants (i.e. coffee) on the day of the scan No solid food for 4 hours prior to the study Premedicate for asthma & allergic history Medrol 32mg po 12hrs and 2 hrs prior to study Patient should have good IV access (18G antecubital) Adequate EKG tracing � good contact Patient prep guidelines. Bullet 1 � Increase heart rate with coffee, the funny story from Wake Forest and the free cappuccino Bullet 3 � Motivation Bullet 4 � Decrease the chance of miscommunication Bullet 5 � Use the right basilic vein is preferredPatient prep guidelines. Bullet 1 � Increase heart rate with coffee, the funny story from Wake Forest and the free cappuccino Bullet 3 � Motivation Bullet 4 � Decrease the chance of miscommunication Bullet 5 � Use the right basilic vein is preferred

4. Patient Preparation - Heart Rate IV Beta Blockade (preferred) 2.5 � 30 mg Metoprolol Titrate to heart rate of 55-60 Monitor BP while giving metoprolol If asthmatic, consult physician No more than 10mg metoprolol Consider calcium channel blockers Diltiazem (bolus 0.25mg/kg) Oral Beta Blocker 50 � 100 mg Metoprolol 1 hour prior to examination Who will monitor the patient ?

5. Objective of the Contrast Injection Uniform enhancement of the left heart to greater than 300 HU Minimize streaking due to contrast in SVC and RV

6. Impact of Iodine Concentration

7. Contrast Injection Use high iodine density contrast ? 350 mgI/mL We use Optiray 350 (Mallinckrodt Inc.) 16 detector system (25-30 second scan) 100-150 cc contrast @ 4 cc/s 40 cc @ 4 cc/s 40 detector system (15-20 second scan) 100 cc contrast @ 5-5.5 cc/s 40 cc saline @ 5 cc/s 64 detector system (15 second scan) 75 cc contrast @ 5-5.5 cc/s 40 cc saline @ 5 cc/s Start scan 5 seconds after the contrast reaches the left heart Contrast volume = scan duration * injection rate Want sufficient contrast to enhance PDA at end of scan

8. Scan Start Position Native coronary arteries Begin above carina Tortuous aorta or prominent upper left heart border � begin scan 1-2cm higher Bypass Grafts Veins: top of arch LIMA: above clavicles

9. Scan Ending Position Need to image PDA Note overlap of heart & diaphragm Observe contour of heart Extend scan ~2cm below the caudal extent of the heart Position of heart will change with inspiratory effort

10. Center the Scan on the Heart Maximize spatial resolution for coronaries CT resolution is greatest in the center of scan field Set left-right position on AP scout view Move table up-down to center on aortic root and Left ventricle

13. Scan Parameters kVp Generally set at 120kVp For heavy patients (>200lbs) use 140kVp For patients with calcified arteries and stents also use 140kVp mAs Effective mAs = mA x (rotation time / pitch) Effective mAs in the range of 700-900 Increase for heavy patients to minimize noise Pitch Generally 0.2-0.3, but adjust for heart rate

14. EKG Gating Coronary CTA requires EKG gating to overcome cardiac motion Heart is most quiescent in mid-diastole and end-systole

20. Single Cycle vs. Multicycle

21. Temporal Window & Heart Rate

22. Image Quality & Heart Rate

23. Correction of Gating Errors

24. EKG Dose Modulation Best images obtained at mid-diastole RCA sometimes is best at end-systole Dose modulation can achieve dose reduction of 40-50% Use only with stable heart rate Limitations Cannot review coronary anatomy at end-systole Cannot correct for errors in gating

25. Image Reconstruction Reconstruction slice thickness 3mm for function 0.5-0.8mm for coronary arteries 1.0-1.2mm for photon limited scans Reconstruction kernel Sharper kernel: noisier image, but may be required to visualize coronary lumen with stents and calcified vessels

26. Slice thickness vs. noise A thicker slice from 0.8mm to 1.0mm decreases noise and makes the images less grainy.A thicker slice from 0.8mm to 1.0mm decreases noise and makes the images less grainy.

27. Reconstruction filter vs. noise Filters vs. noise: CA is the smoothest. CB gives you the higher standard deviation and noise. This filter is usually the best choice. Girth is size of the patient in diameter. Girth 0 = 32cm Girth 1 = 37cm Girth 2 = 42 cm 20 � 25 or below looks better visually with less noise for slice thickness and mAs. .Filters vs. noise: CA is the smoothest. CB gives you the higher standard deviation and noise. This filter is usually the best choice. Girth is size of the patient in diameter. Girth 0 = 32cm Girth 1 = 37cm Girth 2 = 42 cm 20 � 25 or below looks better visually with less noise for slice thickness and mAs. .

28. Reconstructions Choose appropriate filter Sharper filter for patients with heavy coronary calcium or stents Perform targeted reconstructions 3mm reconstruction of contiguous slices @ 10 phases for cardiac function analysis 0.8mm reconstruction of overlapping slices @ 40%, 70%, 75% and 80% for coronary anatomy. 1.0mm recons for heavy patients.

29. Clinical Application of Coronary CTA Indications Rendering & display modes Characterization of Plaque Grading of stenosis

30. Cardiac Indications The MDCT angiography of the chest for cardiac assessment (0146T-0149T) is indicated for the following signs or symptoms of disease: Emergency evaluation of acute chest pain Cardiac evaluation of a patient with chest pain syndrome (e.g. anginal equivalent, angina), who is not a candidate for cardiac catheterization Management of a symptomatic patient with known coronary artery disease (e.g., post-stent, post CABG) when the results of the MDCT may guide the decision for repeat invasive intervention Assessment of suspected congenital anomalies of coronary circulation

31. Rendering Modes MIP & slab MIP Surface Display Vessel tracking Curved MIP Globe view

32. Plaque Characterization Calcified vs. Soft Positive remodeling Irregularity Ulceration

33. Grading of Stenosis

34. Bland-Altman Analysis of Stenosis Grading

35. Impact of Calcified Vesselson detection of stenosis >50%

36. Impact of Coronary Calcium

37. Proximal versus Distal Segments

38. Non-coronary Assessment Valvular assessment Cardiac morphology Cardiac function EP planning