This document summarizes the use of noninvasive MDCT imaging of the coronary arteries. It discusses the challenges of imaging small, rapidly moving coronary vessels. MDCT allows for successful coronary imaging with temporal resolution of 330-400ms, spatial resolution of 0.4-0.75mm, coverage of the heart in a single breath hold of 8-14 seconds. Sensitivity for detecting coronary stenosis is 80-86% for 4-16 slice MDCT and specificity is 90-97%. Potential clinical applications include decreasing invasive angiograms, improving risk assessment, detecting anomalies, and evaluating bypass grafts. Larger clinical trials are still needed to determine the impact on patient management.

1. Noninvasive MDCT-
based Imaging of the
Coronary Arteries
Udo Hoffmann, MD
Director of Cardiac CT Research
Assistant Professor of Radiology, Harvard Medical
School
Massachusetts General Hospital Boston, MA

2. Challenge of Coronary
Artery Imaging
Small Vessels with Complex
Anatomy in Rapid Motion
Cornerstone Invasive Selective
Coronary Angiography

3. Prerequisites forPrerequisites for
Successful Cardiac CTSuccessful Cardiac CT
II
• Temporal Resolution
• Spatial Resolution
• Volume Coverage

4. • 330- 400 ms gantry rotation (165- 200 ms)
temporal resolution (half scan reconstruction)
• 0.4 x 0.4 x 0.6 - 0.75 resolution
• single breath hold 8 - 14 sec
• 40 - 80 ml of contrast agent (4-5 ml/s)
• 500 - 950 mAs tube current (modulation)
• 7 – 24 mSv
64 Slice MDCT64 Slice MDCT
Protocol for CoronaryProtocol for Coronary
AngiographyAngiography

5. Prerequisites forPrerequisites for
Successful Cardiac CTSuccessful Cardiac CT
IIII
• Appropriate Breath Hold
exact instructions (mid inspiration)
exercise and observe heart rate
• Low heart rate, NSR (<65 bpm)
Beta Blocker PO/IV

6. Retrospective ECG
gating

7. Axial Source Images

8. Thin MIP 3D VRT Curved MPR
Post Processing

9. P A C S
Comprehensive Cardiac CT
Examination
betablocker i.v., sublingual Nitroglycerinebetablocker i.v., sublingual Nitroglycerine
O F F L I N E

10. Detection of significant
coronary artery stenosis

11. Systematic Review on
Diagnostic Accuracy of CT-
based Detection ofDetection of
significant CADsignificant CAD
• 30 studies
• 1849 patients
• 12913 coronary segments
• 13 EBCT - 847 patients
• 10 - 4/8 MDCT - 588 patients
• 7 - 16 MDCT - 414 patients
Hoffmann et al, JAMA 2005 submitted

12. Diagnostic Accuracy of EBCT, 4 -
and 16 - slice MDCT
Assessable
Segments
Pooled
Sensitivity
97.5% CI
Pooled
Specifici
ty
97.5% CI
All CT 83% 80.6%-85.3% 94%
93.2%-
94.6%
EBCT 83% 79.5%-87.0% 90%
89.0%-
91.8%
MSCT 83% 79.8%-85.7% 96%
95.1%-
96.5%
4- and 8-slice 82% 78.3%-85.2% 96%
95.0%-
96.6%
16-slice 86% 80.3%-91.4% 96%
94.4%-
97.1%
All
Segments
All CT 72% 69.5%-74.3% 84%
83.3%-
84.9%

13. RCA StenosisRCA Stenosis

14. n Sens. Spec. n.e.
Ropers ACC 2005 84 91% 93% 7%
Leschka Eur Heart J 2005 67 94% 97% --
Raff JACC 2005 70 86% 95% 12%
Diagnostic Accuracy of
64- slice MDCT

15. Maximum Intensity Projection RCA 3D VRT LCX and RCA

16. Occlusion 1st
diagonal
branch

19. Multiplanar Reconstruction

20. Limitations
TECHNICAL
-- Calcium
- Motion - Heart Rate
CONCEPTUAL
- Contrast, X-ray
- Sinus rhythm
- No intervention

21. - decrease number of purely diagnostic
invasive selective coronary angiograms
- complimentary to stress testing
- improve early triage of patients with acute
chest pain
Potential Clinical
Applications

22. Study Design
early risk stratification in the ED
decision to admit to hospital
MDCT
standard clinical care (blinded to MDCT)
discharge diagnosis

23. Test Raw Data Overall
Sensitivity 5/5 1 (0.49, 1)
Specificity 26/35 0.74 (0.57,0.88)
Accuracy 31/40 0.78 (0.62, 0.89)
PPV 5/14 0.38 (0.13, 0.65)
NPV 26/26 1 (0.87, 1)
DOR 286
Overall Diagnostic Accuracy
of MDCT (>50% stenosis) vs.
ACS outcome

24. Patient without ACSPatient without ACS
43 year old female, 3 hours of substernal chest pain
radiating to the back, negative initial Troponin and
CK-MB, ECG: sinus bradycardia

25. • Patient with crushing chest pain
• now relieved (Nitro)
• Borderline ST- Elevation
• No biomarker elevation
Patient with ACSPatient with ACS

27. LAD Occlusion

30. LCX Anomaly and Stenosis

32. Perfusion Defect

35. Potential Impact on
Decision Making
Pretest
Probability
Posttest
Probability
P-value
ACSACS 0.44±0.39 0.79±0.28 0.03
NoNo
ACSACS
0.28±0.21 0.05±0.07 0.0001
Decrease average LOS in patients without
ACS by 22 hours per patient

36. - decrease number of purely diagnostic
invasive selective coronary angiograms
- complimentary to stress testing
- improve early triage of patients with acute
chest pain
- detect coronary anomalies
Potential Clinical
Applications

37. Anomalous Right Coronary
Artery

38. - decrease number of purely diagnostic
invasive selective coronary angiograms
- complimentary to stress testing
- improve early triage of patients with acute
chest pain
- detect coronary anomalies
- determine bypass patency
Potential Clinical
Applications

39. • High sensitivity and specificity for arterial conduits
and venous grafts
• Limitations: distal Anastomosis in small vessels,
metallic clips
Martuscelli Circulation 2004
Bypass Graft Patency

40. - decrease number of purely diagnostic
invasive selective coronary angiograms
- complimentary to stress testing
- improve early triage of patients with acute
chest pain
- detect coronary anomalies
- determine bypass patency
- improve risk predicition/ change definition of
CAD
Potential Clinical
Applications

41. MPR of LAD in Cross SectionThin MIP
Detection of Plaque
Sensitivity 82%, Specificity 88%
Achenbach et al. Circulation 2004

42. r = 0.64, p < 0.001
Moselewski et al. AJC 2004
Plaque Area
Potential to detect and quantify coronary plaque

43. Plaque Composition
Potential to discriminate calcified and non- calcified
plaque
Leber et al JACC

44. SummarySummary
• Cardiac CT is a fast robust and highly
reproducible noninvasive test
• Lots of promise that it may change and
improve management of patients with
suspected or known CAD
But no data available yet
• Direct information on the presence and
extent of CAD (stenosis and plaque), LV
function and perfusion

45. MGH Cardiac CTA 2005MGH Cardiac CTA 2005
1. Core Lab for US Multi-center Trial on the
Detection of Coronary Artery Stenosis with
>1000 Patients
2. Cardiac CT for early triage in Patients with
Acute Chest Pain
3. Core Lab for Siemens Multi-center Trial IVUS
vs. MDCT
4. Non-Calcified Plaque (FHS) in Patients with
Family History of premature CAD
(Framingham)
5. Correction of Image Degradation in cardiac
CT

47. Thank you
Thank you