Current Clinical Concerns in CT: Results : CT Scanner Hardware
Electron Beam CT (EBCT) vs. Multi-Detector Row CT (MDCT)
1. What are your thoughts about the use of the "new" electron beam CT equipment in terms of coronary, carotid, renal and peripheral CT angio when compared to the evolving multihead detector CT technology. GE is trying to sell EBA as a "better", "faster", "easier" alternative…especially for non-radiologists (e.g. cardiologists, vascular surgeons). Is EBA really a reasonable alternative?
| Answer: The electron beam is a good scanner for doing coronary artery calcification because of its speed. However, because of its limited resolution, I would not use it for CT angiography. |
2. I have seen advertisements for electron beam tomography. How does EBCT scanning compare with CT scanning for various diagnostic scans?
3. Could you tell me if it is really true that EBCT is the only FDA approved scanning technique at this point for Cardiac Scoring? I've also heard that multi-slice scanners have a greater percentage of error in scoring due to the fact that although the scan is gated, the scans are matched up in post processing vs. real time gating. Could you share your thoughts?
References
Kopp AF, Ohnesorge B, Becker C et al. Reproducibility and accuracy of coronary calcium measurements with multi-detector row versus Electron Beam CT. Radiology 2002; 225 (1): 113-119.
| Answer: For cardiac scoring they are both the same, but for anything else, go with MDCT. |
3. Could you tell me if it is really true that EBCT is the only FDA approved scanning technique at this point for Cardiac Scoring? I've also heard that multi-slice scanners have a greater percentage of error in scoring due to the fact that although the scan is gated, the scans are matched up in post processing vs. real time gating. Could you share your thoughts?
| Answer: To my knowledge, the FDA has not approved one scanner over the others. Both multidetector and EBCT have similar results for coronary calcification scoring. |
References
Kopp AF, Ohnesorge B, Becker C et al. Reproducibility and accuracy of coronary calcium measurements with multi-detector row versus Electron Beam CT. Radiology 2002; 225 (1): 113-119.
- Summary: EBCT and MDCT scanners were used to image a phantom which mimicked a beating heart, with a number of protocols and a variety of pulse rates. Acquisition times, reproducibility and accuracy of coronary artery calcium measurements were compared. The MDCT acquisition times were significantly shorter: "Our study showed that nonoverlapping sequential scanning is the most important contributor to the interexamination variability of Agatston and volumetric calcium scores, because of partial volume errors in plaque registration. We demonstrated that coupling retrospective gating with nearly isotropic volumetric imaging data by using spiral multi-detector row CT provided the best input data for quantification of CAC volume." By obtaining EKG-gated volume datasets with overlapping reconstructions (2.5 mm collimation, 1.0 mm increment), the mean interexamination variability was reduced from 35% to 4%.
Schoenhagen P, Halliburton SS, Stillman AE et al. Noninvasive imaging of coronary arteries: Current and future role of multi-detector row CT. Radiology 2004; 232(1): 7-17.
- Summary: The introduction of this article provides a nice overview of EBCT and MDCT, comparing technique, strengths and weaknesses. EBCT has better temporal resolution; however, the advantages of MDCT include higher signal-to-noise ratio, higher spatial resolution and faster scan time.
Hunold P, Vogt FA, Schmermund A et al. Radiation exposure during cardiac CT: Effective doses at multi-detector row CT and electron-beam CT. Radiology 2003; 226: 145-152.
- Summary: This study compared the effective dose from electron-beam CT, multi-detector row CT and catheter coronary angiography. A phantom was scanned with protocols for calcium scoring and coronary angiography. The MDCT unit was a 4 slice scanner, and the protocols were: calcium scoring 4 x 2.5 mm acquisition; CT angiography 4 x 1 mm acquisition. EBCT resulted in lower doses for both coronary artery calcium (CAC) scoring (1.0 to 1.3 mSv) and EBCT angiography (1.5 to 2 mSv) compared to MDCT (1.5 to 6.2 mSv for CAC; 6.7 to 13 mSv for MDCT angiography). In addition, the dose from 4 slice MDCT was higher than that from catheter coronary angiography (2.1 to 2.5 mSv).