Multi-Slice CT for Coronary Calcium Scoring and Coronary ...


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Multi-Slice CT for Coronary Calcium Scoring and Coronary ...

  1. 1. Multi-Slice CT for Coronary Calcium Scoring and Coronary Angiography John D. Symanski, M.D., F.A.C.C The Sanger Clinic, PA and Carolinas Medical Center No Disclosures
  2. 4. Objectives <ul><li>Show lots of pretty pictures </li></ul><ul><li>Overview fundamental principles of MSCT technology </li></ul><ul><li>Review strengths and limitations of MSCT </li></ul><ul><li>Raise awareness of current indications and clinical scenarios for which to consider CT angiography </li></ul>
  3. 5. Case Presentation <ul><li>64-year-old female with stage 1 CLL </li></ul><ul><li>Dyslipidemia (untreated); No HTN, diabetes, or tobacco use </li></ul><ul><li>Negative stress echo previously </li></ul><ul><li>Atypical chest pain </li></ul><ul><li>Stress echo: septal hypokinesis at rest, LVEF: 50% </li></ul><ul><li>Referred for calcium scoring and CTA </li></ul>
  4. 11. CT Angiogram Interpretation <ul><li>Calcium Volume Score: ZERO </li></ul><ul><li>CT angiography: </li></ul><ul><ul><li>Left Main, Circumflex, and Right coronary arteries: normal </li></ul></ul><ul><ul><li>LAD: eccentric, soft plaque adjacent to origin of first diagonal (~60% stenosis) </li></ul></ul><ul><li>Correlation recommended </li></ul>
  5. 14. Summary Cardiovascular Imaging - State of the Art <ul><li>Multi-slice CT (MSCT) not likely to replace conventional angiography </li></ul><ul><li>Post-processing of images for MSCT angiography time & labor intensive </li></ul><ul><li>Major strength of CTA is its high negative predictive value </li></ul><ul><li>CMR to become the preferred cardiac imaging modality in the future </li></ul>
  6. 15. Which Test for Which Patient? <ul><li>All modalities are improving </li></ul><ul><li>No single modality fits all applications and all patients </li></ul><ul><li>Choice of initial test depends on the specific clinical question in individual patient </li></ul>
  7. 16. Cardiac Magnetic Resonance
  8. 17. Viability Assessment CMR Delayed Hyper-Enhancement
  9. 18. Hazards of MRI Magnet-Seeking Projectiles
  10. 19. First whole-body CT cross-section through a human thorax, generated by Ledley et al in 1974 ( Science 1974;186:207)
  11. 21. The Examination
  12. 22. Current Generation Scanners <ul><li>Spatial resolution 0.4 mm - conventional coronary angiography 0.15-0.25 mm </li></ul><ul><li>Temporal resolution (shutter speed) improved to 166 msec with faster gantry rotation (330 msec) – conventional angiography 6 msec </li></ul><ul><li>Up to 64 slices in one rotation </li></ul>
  13. 23. 4 to 64 Slice Scans Five Heart Beats 10 mm detector Pitch ~0.25 3 cm in 5 sec 20 mm detector Pitch ~0.25 6.2 cm in 5 sec 40 mm detector Pitch ~0.25 12.5 cm in 5 sec
  14. 24. 64-Slice CT Scanner <ul><li>More coverage (volume) with each heart beat </li></ul><ul><li>Entire heart imaged in 5-15 seconds </li></ul><ul><li>Less contrast required </li></ul><ul><li>No increase in rotation speed, but with overlapping slices, can use segments from different heart beats to improve temporal resolution </li></ul>
  15. 25. 3-D Volume Rendered Image
  16. 26. Maximum Intensity Projection Soft Plaque in Proximal LAD
  17. 27. Curved Planar Image
  18. 31. Quantification of Obstructive and Nonobstructive Coronary Lesions by 64-Slice Computed Tomography <ul><li>59 patients with stable angina subjected to CTA before catheter-based angio </li></ul><ul><li>Diagnostic image quality in 55 of 59 </li></ul><ul><li>Sensitivity for detection of stenosis <50%, >50%, and >75%: (79%, 73%, and 80%, respectively) </li></ul><ul><li>Excellent accuracy with proximal lesions </li></ul>Leber AW et al. J Am Coll Cardiol . July 5, 2005;46:147-54
  19. 32. Diagnostic Accuracy of Noninvasive Coronary Angiography Using 64-Slice Spiral Computed Tomography <ul><li>70 patients undergoing invasive cath </li></ul><ul><li>Of 1,065 segments, 935 evaluated (88%) </li></ul><ul><li>Quantitative assessment in 773 of 935 segments by MSCT and QCA </li></ul><ul><li>Sensitivity, specificity, (+) PV, (-) PV: </li></ul><ul><ul><li>By segment- (86%, 95%, 66%, and 98%) </li></ul></ul><ul><ul><li>By artery- (91%, 92%, 80%, and 97%) </li></ul></ul><ul><ul><li>By patient- (95%, 90%, 93%, and 93%) </li></ul></ul>Raff GL et al. J Am Coll Cardiol . Aug 2, 2005;46:552-7.
  20. 33. Coronary Calcium Scoring <ul><li>Initial ACC/AHA guidelines “may be useful in selected patients”… </li></ul><ul><li>Added prognostic power to conventional risk stratification tools (Framingham) </li></ul><ul><li>Revised guidelines (and reimbursement for service) likely forthcoming </li></ul>
  21. 35. Hn x-factor (Agatston Scoring) 130-199 1 200-299 2 300-399 3 >400 4 Area = 15 mm 2 Peak CT = 450 Score = 15 x 4 = 60 Area = 8 mm 2 Peak CT = 290 Score = 8 x 2 = 16 Total Score = S Calcium Volume Scoring
  22. 36. The Calcium Scale <ul><li>The calcium scale is a linear scale with 4 calcium score categories: </li></ul><ul><ul><li>0 none </li></ul></ul><ul><ul><li> 1–99 mild </li></ul></ul><ul><ul><li>100–400 moderate </li></ul></ul><ul><ul><li>>400 severe </li></ul></ul><ul><li>*Calcium score correlates directly with risk of events and likelihood of obstructive CAD* </li></ul>
  23. 37. Ethnic Differences in Coronary Calcification The Multi-Ethnic Study of Atherosclerosis (MESA) Bild DE et al. Circulation . 2005;111:1313-1320. 6814 men and women aged 45-84 years
  24. 38. Five-Year Mortality Rates in Framingham Risk Subsets by Coronary Calcium Score Shaw et al. Radiology 2003; 228:826-833 * * * *p<0.001
  25. 39. <ul><li>MI in 41 pts during 3.2 + 0.7 years </li></ul><ul><li>LDL levels similar in MI and non-MI pts </li></ul><ul><li>Relative risk of MI in presence of CAC progression was 17.2-fold higher (P<0.0001) </li></ul>Progression of Coronary Artery Calcium and Risk of First MI 495 Asymptomatic Patients Started on Statin Therapy Raggi P et al. Arterioscler Thromb Vasc Biol . 2004;24:1272-77.
  26. 40. Coronary Disease Progression ? Role for CTA >60% stenosis (+) stress/imaging Calcified Plaque Detected by CT
  27. 41. Soft Plaque Visualization
  28. 42. CTA Limitations <ul><li>Rapid (>80 bpm) and irregular HR </li></ul><ul><li>High calcium scores (>800-1000) </li></ul><ul><li>Stents </li></ul><ul><li>Contrast requirements (Cr > 2.0 mg/dl) </li></ul><ul><li>Small vessels (<1.5 mm) and collaterals </li></ul><ul><li>Obese and uncooperative patients </li></ul><ul><li>RADIATION EXPOSURE </li></ul>
  29. 48. Effective Dose of Selected Radiologic Examinations <ul><li>PA/Lateral CXR 0.04-0.06 mSv </li></ul><ul><li>Head CT 1-2 mSv </li></ul><ul><li>Chest CT 5-7 mSv </li></ul><ul><li>Abd/Pelvis CT 8-11 mSv </li></ul><ul><li>Diagnostic Cor Angiogram 3-5 mSv </li></ul><ul><li>MSCT angiography 9.3-11.3 mSv </li></ul>Morin et al. Circulation 2003;107:917-22. *Average annual background radiation in U.S ~ 3.6 mSv
  30. 49. Radiation Risks <ul><li>Exact quantification of harmful effects of radiation difficult to ascertain </li></ul><ul><li>For a child under age 15, the risk of cancer death from a single CT scan is approximately 1 in 500 </li></ul><ul><li>For a 45 year old adult, the risk of death from cancer from a single CT exam is about 1 in 1,250 </li></ul>Brenner et al. Radiology, 231(2):440-445.
  31. 50. Clinical Indications for MSCT <ul><li>Calcium Scoring (CS) - risk stratification in the intermediate risk patient </li></ul><ul><li>Non-invasive coronary angiography (CTA) in the symptomatic low-risk patient or asymptomatic intermediate-risk patient </li></ul><ul><li>* A negative test (normal CTA) has a 98% chance of revealing normal coronary arteries on invasive angiography * </li></ul>
  32. 51. Test Selection According to Pretest Probability of CAD
  33. 52. Association for the Eradication of Heart Attacks ( )
  34. 53. When to Consider MSCT <ul><li>Equivocal stress test or persistent symptoms despite negative stress test </li></ul><ul><li>Prior to non-coronary cardiac surgery (valve or congenital repair) </li></ul><ul><li>Patients with difficult access or on therapeutic warfarin </li></ul><ul><li>Suspected coronary anomalies </li></ul>
  35. 54. Lt Main CFX RCA LAD
  36. 55. <ul><li>Idiopathic dilated cardiomyopathy </li></ul><ul><li>Cardiac transplant evaluation </li></ul><ul><li>Patients to undergo electrophysiologic intervention (AF ablation, BiV pacing) </li></ul><ul><li>Selected patients pre- and post-bypass surgery (aortic pathology, graft patency) </li></ul>When to Consider MSCT (continued)
  37. 56. Mikaelian BJ et al. Circulation . 2005;112:e35-e36.
  38. 57. Pulmonary Vein Stenosis Vasamreddy et al. Heart Rhythm (2004) 1, 78-81 .
  39. 59. Aortic Coarctation Visualized by 16-Row Detector MSCT Fr ö hlich, G et al. Circulation . 2005;112:e81.
  40. 60. Pericardial Calcification Multi-Slice CT Scanning Superior to MRI Hoffmann et al. Circulation 108 (7): 48e Figure IG1
  41. 61. Nikolaou et al. Cardiology Clinics . 21;(2003):639-655. Future Indications
  42. 62. The Great Promise of MSCT The “Triple Rule-Out”
  43. 63. <ul><li>“ an appropriate imaging study is one in which the expected incremental information together with clinical judgment exceed the expected negative consequences* by a sufficiently wide margin that the procedure is generally considered acceptable care and a reasonable approach for the indication.” </li></ul>Appropriateness Criteria * include risks of the procedure and the downstream impact of poor test performance such as delay in diagnosis (false -) or inappropriate diagnosis (false +)