SHAPE Society

1. Fast CT Angiography on a
Fast Track to Your
Practice: Promises and
Limitations
S. Achenbach
Department of Radiology, Massachusetts General Hospital
Department of Cardiology, University of Erlangen

2. Coronary artery imaging:
- small diameters (~1-4 mm)
- complex anatomy
- rapid motion

3. CT Techniques
- High spatial resolution
- Good contrast
- Problem: temporal resolution

4. Electron Beam
Tomography (EBT)
50 - 100 ms image acquisition time
1.5 mm - 3.0 mm slice thickness

5. Electron Beam
Tomography (EBT)
CT coronary imaging feasible
Limitations: 1.5 -3.0 mm slice thickness
X-ray power
„e-Speed“: 1.5 mm slice thickness
50 ms temporal resolution

6. Multislice spiral CT
with retrospective ECG
gating
- Tube rotation: 420-500 ms
- Data acquisition in 4-16 slices
simultaneously
4 slice CT: ~1.3 mm slices
16 slice CT: ~0.75 mm slices

9. MSCT 4 Slice

10. EBT

11. MSCT 16 slice

12. MSCT 16 slice

13. MSCT 16 slice

14. MSCT 16 slice

15. MSCT 16 slice

16. n Sens. Spec. n.e.
Schmermund JACC 1998 28 82% 88% 12%
Reddy Radiology 1998 23 88% 79% 8%
Achenbach N Engl J Med 1998 125 92% 94% 25%
Ropers Z Kardiol 2000 118 90% 82% 24%
Achenbach Heart 2000 36 92% 91% 20%
Nieman Lancet 2001 31 81% 97% 27%
Achenbach Circulation 2001 64 91% 84% 32%
Knez Am J Cardiol 2001 42 78% 98% 6%
Kopp Eur Heart J 2002 102 86% 96% 16%
Becker JCAT 2003 28 78% 71% 11%
Nieman Heart 2002 53 82% 93% 30%
Nieman Circulation 2002 59 95% 86% 7%
Ropers Circulation 2003 77 93% 92% 12%

17. MSCT:
Heart Rate < 60/min
desirable:
oral ß-blockade to all
patients
EBT/MSCT:
Coronary calcium

18. LIMITATIONS:
Contrast, radiation
Sinus rhythm
Unevaluable arteries
Accuracy = 100%
Diagnostic tool with high
negative predictive value
(~95%) if image quality is
sufficient

19. CT to replace cardiac cath?
„A man with a hammer sees a
lot of things that need to be
hammered.“
(A radiologist/cardiologist
with a spiral CT ...)

20. Clinical Indications for MSCT?
... Not for screening
... Not in patients with typical symptoms
... Possibly in patients with relatively low
likelihood of signficant stenosis
(atypical symptoms, equivocal stress test ...)

21. > 20% „rule out“ coronary angiograms

22. 100 patients prior to valve surgery: All 36 patients with stenoses
identified by EBT. 54 patients: stenoses ruled out.

23. Anomalous coronary arteries

24. Bypass Grafts:
EBT 4-slice MSCT 16 slice MSCT

25. Nieman et al, Circulation 2002
STENT?

26. Detection of Plaque
4- slice MSCT
Schröder et al. JACC 2001

27. Detection of Plaque
16-slice MSCT

28. Detection of Plaque
Potential role in risk assessment?
- Accuracy / Quantification?
- Reproducibility?
- Progression over time?
- Prognostic value?

29. „Fast CT Coronary Angiography“:
- Technical issues
Heart rate, technology, protocols
- „Coronary Angiography“
Potential role to rule out stenoses
- „Plaque imaging“?
(Potential role for risk stratification)