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Coronary
calcifications
1.
I am trying to fine tune the consistency of coronary calcium scoring
on the 16 slice Siemens. It varies with the kV and mAs automatically
despite not using care dosing. This is altering our follow up scores.
I saw your protocol for the Plus4 volume zoom. What do you use/recommend
for the Sensation 16? Siemens recommends sequential study, but I feel
that negates the advantage of spiral resolution/precision.
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Answer:
David Bradley from Siemens, who is well versed on the coronary
scoring software writes:"The system can not vary the
kV and mAs automatically without care dose…it is not possible!
The current protocols for Calcium Scoring on the Sensation 16
can utilize either the Spiral technique or the Sequential technique.
While the Sequential technique offers the lowest dose to the
patient (often a prerequisite for "early detection procedures"),
the reproducibility of this technique can be low. With ECG pulsing,
it is possible to cut normal dose to the patient with a Spiral
acquisition by about 50% and still have the benefits of a spiral
scan, which can offer a better reproducibility, ultimately.
There are protocols for both the Sequential and Spiral techniques
that are stored with the scanner. The user should choose the
protocol that best suits his/her requirements. "
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2.
A patient here asked the difference between 5 dimensional heart scans
and our CT Calcium scoring scan. I haven't heard of 5-D scans. Any
info on this?
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Answer:
We are doing a 4D CT which is gated cardiac CT that is displayed
with the heart contracting. We used InSpace 4D for this. As
for 5D CT, that is news to me. I am not sure what 5D even means.
If you find out, let me know.
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3.
Do we need to use a beta blocker performing in each calcium scoring
exam? Could you advise any beta blocking agent and dosage that routinely
used?
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Answer:
As calcium scoring is used more as an early detection method,
most folks would not advocate using a beta blocker regimen for
those studies. If you have a Siemens scanner, you have the ability
to use ECG pulsing which allows you to use the spiral protocol
at much lower dose-50% of those systems without ECG Pulsing.
By using the spiral approach, your temporal resolution can be
improved and so too can your reproducibility of those scans.
Per David Bradley, Siemens Medical Solutions.
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4.
For Calcium Scoring: when do you like to use prospective gating (axial
acquisition protocol) and when you choose retrospective gating (spiral
MSCT)? We have MX 8000 Philips.
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Answer:
We are only doing retrospective gating. It is easier and more
reproducible and gives you a better chance at success with the
coronary arteries by being able to select intervals in the cardiac
cycle. It is also lower radiation dose; try it.
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References
Schoepf UJ, Becker CR, Ohnesorge BM and Yucel EK. CT of coronary artery
disease. Radiology 2004; 232 (1): 18-37.
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Summary:
This recent review covers MDCT acquisition protocols for coronary
artery calcification and coronary artery angiography, as well as
radiation dose. For angiography, image display (2D and 3D) and clinical
applications are discussed and demonstrated.
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.
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