Advances in cardiac imaging with 16-section CT systems.
OBJECTIVE
The authors present advances in electrocardiographically (ECG) gated cardiac spiral scanning with recently introduced 16-section computed tomographic (CT) equipment.


METHODS
The authors discuss the technical principles of ECG-gated cardiac scanning. They give an overview on system properties and on the detector design. They describe ECG-gated scan- and image-reconstruction techniques and ECG-controlled dose modulation ("ECG pulsing") for a reduction of the patient dose. They discuss key parameters for image quality and present simulation and phantom studies and they give preliminary values for the patient dose.


RESULTS
An extension of the adaptive cardiac volume reconstruction for ECG-gated spiral CT provides adequate image quality for up to 16 sections. With the smallest reconstructed section width (about 0.83 mm) and overlapping image reconstruction, cylindrical holes 0.6-0.7 mm in diameter can be resolved in a transverse resolution phantom independent of the heart rate. For coronary CT angiography, the influence of transverse resolution is most pronounced for coronary segments that are only slightly tilted relative to the scan plane. In this case, visualization of stents and plaques is considerably improved with 1.0-mm or smaller section width. For 0.42-second gantry rotation time, temporal resolution reaches its optimum (105 msec) at a heart rate of 81 beats per minute. Effective patient dose for the standard protocols recommended by the manufacturer ranges from 0.45 mSv (male) for ECG-triggered calcium scoring to 7.1 mSv (male) for high-resolution ECG-gated coronary CT angiography. With ECG pulsing, the dose is reduced by 30%-50% depending on the patient's heart rate.


CONCLUSIONS
Clinical experience will be needed to evaluate fully the potential of 16-section technology for cardiac imaging.
Flohr
Thomas G
TG
Siemens Medical Solutions, CTC CF, Siemensstrasse 1, D-91301 Forchheim, Germany.
Schoepf
U Joseph
UJ
Kuettner
Axel
A
Halliburton
Sandra
S
Bruder
Herbert
H
Suess
Christoph
C
Schmidt
Bernhard
B
Hofmann
Lars
L
Yucel
Edgar Kent
EK
Schaller
Stefan
S
Ohnesorge
Bernd M
BM
D016477:Artifacts; D003198:Computer Simulation; D003327:Coronary Disease / Q000000981:diagnostic imaging; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D036542:Tomography, Spiral Computed / Q000295:instrumentation