Performance evaluation of a multi-slice CT system with 16-slice detector and increased gantry rotation speed for isotropic submillimeter imaging of the heart.
BACKGROUND
4-slice CT scanners have shown limitations in clinical application for noninvasive coronary CT angiography (CTA). We evaluate advances in ECG-gated scanning of the heart and the coronary arteries with recently introduced 16-slice CT equipment (SOMATOM Sensation 16, Siemens, Forchheim, Germany).


METHODS
The technical principles of ECG-gated cardiac scanning, scan parameters, and detector design of the new scanner are presented. ECG-gated scan and image reconstruction techniques and ECG-controlled dose modulation ("ECG pulsing") for a reduction of the patient dose are described, key parameters for image quality and simulation results presented, and phantom studies and initial patient experience discussed. The impact of reduced gantry rotation time (0.42 s) on temporal resolution and initial estimations of the patient dose are presented.


RESULTS
Extensions of ECG-gated reconstruction algorithms used for 4-slice CT provide adequate image quality for up to 16 slices. For each detector collimation different slice widths are available for retrospective reconstruction with well-defined slice sensitivity profiles (SSPs). For coronary CTA the heart can be covered with 0.75 mm collimation within a 20-s breathhold. The best possible spatial resolution is 0.5 x 0.5 x 0.6 mm. For 0.42 s gantry rotation time, temporal resolution reaches its optimum (105 ms) at a heart rate of 81 bpm. Effective patient dose for coronary CTA is 4-5 mSv using ECG-pulsed acquisition.


CONCLUSIONS
The clinical performance of coronary CTA by means of spatial resolution, temporal resolution and scan time is substantially improved with the evaluated 16-slice CT scanner. Also, display of smaller coronary segments and instent visualization are substantially improved.
Flohr
Thomas
T
Siemens Medical Solutions, Computed Tomography, Forchheim, Germany. thomas.flohr@siemens.com
Küttner
Axel
A
Bruder
Herbert
H
Stierstorfer
Karl
K
Halliburton
Sandra S
SS
Schaller
Stefan
S
Ohnesorge
Bernd M
BM
D000465:Algorithms; D019985:Benchmarking; D003198:Computer Simulation; D003287:Contrast Media / Q000008:administration & dosage; D017023:Coronary Angiography / Q000295:instrumentation*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D003330:Coronary Vessel Anomalies / Q000000981:diagnostic imaging*; D004562:Electrocardiography / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation; D021621:Imaging, Three-Dimensional / Q000295:instrumentation; D008297:Male; D008432:Mathematical Computing; D008955:Models, Cardiovascular; D009203:Myocardial Infarction / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D011874:Radiometry; D012680:Sensitivity and Specificity; D012984:Software; D036542:Tomography, Spiral Computed / Q000295:instrumentation*
D003287:Contrast Media