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Fact
Sheet :Technological Difference
Between EBCT And Multislice CT
The
insurmountable speed barrier to mechanical CT scanners
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Electron
Beam CT
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Multi-slice
CT or Spiral CT
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Weightless
electron beam source
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Uses
heavy mechanical Xray source
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More than
1000 published studies
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Limited
published studies
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Widely
used for cardiac
scanning
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Widely
used for non-cardiac scanning
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FDA
approved for cardiac scanning
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Not
FDA approved cardiac scanning
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No
post processing of images
Not
operator dependent
Standardized protocol Consistent results
across different laboratories
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Post
processing of images needed
Subjective
and operator dependent
Protocols under development
Limited experience
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No
post processing of images
Not
operator dependent
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Post
processing of images needed
Subjective
and operator dependent
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Better
temporal resolution
Actual
scan speed up to 50 ms/slice
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Better
spatial resolution
Actual
scan speed up to
330-500 ms/slice; virtual scan speed of 250ms/slice
achieved by acquiring data from half slice and extrapolating data
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No
motion artifact; reproducible
5-10
% interscan variability in calcium score
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More
motion artifacts; poor reproducibility
35
% interscan variability in calcium score 6
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5%
false negative
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30%
false negative
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Low radiation
Prospective
triggering; radiation is applied only 10% of cardiac cycle, no
discarding of acquired data
EBCT Coronary calcium scan radiation dose : 0.7- 1.0 mSv
Electron Beam angiogram radiation dose: Morin3: 1.1 mSv3;
Hunold4: 1.5-2.0mSv
Safer for women; Lower breast
tissue radiation dose : Only 20% of entry
dose
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5-10
times higher radiation 1,2
Retrospective
triggering (Radiation is applied continuously; partial data acquisition
on each scan; 90% of acquired data is subsequently discarded);
MSCT Coronary calcium scan radiation dose: 5.2-6.4
mSv
MSCT angiogram radiation dose:
Morin3: 9.3-11.3mSv; Hunold4: 8.1-13mSv
Effective radiation dose
another 25% higher in women5;
Breast
tissue receives highest radiation dose
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Calcium
scores correlated with histopathology and IVUS studies
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No
autopsy or IVUS corretation data for calcium scores obtained with MSCT
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95%
success rate for CTangiography
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30%
success rate for CT angiography
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Comparison
of Coronary Artery Calcium Scan Results
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EBCT
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Mechanical
(Multi-slice CT / Spiral CT)
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Sensitivity
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High
( 98%)
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Low
for moderate-low score (ave. 74%)
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Specificity
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High
( 99 %)
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Low
for moderate-low score (ave. 70%)
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Reproducibility
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High
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Moderate-low
(variation average >100 points)
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Negative
Predictive Value
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Very
high
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Moderate
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Comparison
of Contrast-enhanced CT Angiogram
Results
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EBCT
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Mechanical
(Multi-Slice CT / Spiral CT)
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Sensitivity
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High
( 86-95 %)
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Low
for moderate-low score (ave. 68 %)
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Specificity
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High
( 91-95 % )
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Low
for moderate-low score (ave. 83%)
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Standardized
protocol
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Yes
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Under
development
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Published
clinical papers
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>
50
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<
8
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FDA
approved
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Yes
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No
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Success
rate in visualizing all three major epicardial arteries
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95%.
HR can range up to 130/min
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30%.
Beta blocker required to
slow heart rate to <60/min
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Correlation
between EBA and Coronary Angiograhy
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Author,
Year
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No
of Patients
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Sensitivity
(%)
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Specificity
(%)
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Moshage,Radiology
95
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20
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74
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100
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Nakanishi,
1997
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37
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74
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94
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Reddy,
Radiology 1998
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23
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88
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79
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Rensing,Circulation
98
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37
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77
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94
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Achenbach,NEJM
1998
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125
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92
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94
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Schmermund,JACC
98
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28
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83
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91
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Budoff,
AJC 1999
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52
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87
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91
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Moshage,
2000
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118
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90
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82
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Achenbach,Heart
2000
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36
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92
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91
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Ropers,
Z Kardiol 2000
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118
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90
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82
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Lu
, Invest Rad 2002
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107
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91
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94
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AVERAGE
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701
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87
%
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91
%
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Correlation
between MSCT Angiography and Coronary Angiograhy
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Author,
Year
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No
of patients
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Sensitivity
(%)
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Specificity
(%)
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Knez,
2000
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44
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58
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91
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Hong,
2000
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25
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80
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76
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Becker,JACC
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44
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58
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83
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Achenbach,
2001
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64
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85 |
76
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Giesler,
2001
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83
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56
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86
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Giesler, 2002 |
100 |
49 |
89 |
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Nieman, 2002 |
53 |
61 |
93 |
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Nieman, 2002 |
78 |
63 |
94 |
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Kuettner, 2003 |
66 |
37 |
99 |
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AVERAGE
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513 |
59 %
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89
%
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Comments:
The
Multi Slice CT is capable of performing coronary calcium scanning and CT
angiography, but there are limitations which have been well documented.
There are systematic differences between calcium scores obtained with
MSCT and those obtained with EBCT. 4 The scanning speed of MSCT
is 10 times slower than EBCT. This
gap in scan speed is physically insurmountable due to the centrifugal force
generated by the rotating Xray tube.
Increasing the number of slices acquired per scan from 4 to 16 does not
solve the problem because the scan speed is the same.
Slower scan speeds results in more motion artifacts and inaccuracies.
Serial scanning with MSCT to monitor progression of atherosclerosis is
meaningless due to its high inter-test variability.
3 Coronary calcium scanning by Multi Slice CT will miss 30% of
heart patients as compared to 5% by EBCT. Consideration should be given to the
higher radiation dose associated with retrospective gating. To date EBCT is the
only modality approved by the Food and Drug Administration for coronary calcium
scanning and Electron Beam Angiography.
Currently,
the American Heart Association is making a statement that MSCT is not yet ready
for clinical use, until more validation work is done and radiation doses are
reduced.
References:
-
Knollman et all
CTA of the coronary arteries:comparison of radiation exposure with EBCT and
multi-slice detector CT. Radiology 2000;217:364-5
-
Becker C et at. Assessment of the
effective dose for routine protocols in conventional CT, electron beam CT and
coronary angiograpy. Rofo Fortschr Geb Rontgenstr Neuen Bildgeb Verfahr 1999;
170:99-104
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Morin RL et all Radiation
dose in computed tomography of the heart. Circulation 2003;107:917-22
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Hunold
P et al Radiation expoosure during cardiac CT:effective doses at multi-detector
row CT and electron beam CT. Radiology 2003;226:145-52
-
International Commission on Radiological Protection.
Recommendation of the ICRP. ICRP Publication 60, Oxford, UK:Pergammon Press,
1990
-
Achenbach S et al Detection of
coronary artery stenoses by contrast enhanced, retrospectively
electrocardiographically gated, multislice computed tomography.
Circulation 2001;103:2535-8
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