[Optimizing temporal resolution in CT with retrospective ECG gating].
OBJECTIVE
Spiral CT of the heart using the established ways of ECG synchronization is hampered by the relatively long acquisition times of 250 to 500 ms. This only allows to acquire diastolic images in patients with moderate heart rates. In this work, algorithms for time-optimized retrospective cardiac gating are presented, and their potential to improve temporal resolution is investigated.


METHODS
These algorithms use data from multiple gantry rotations for image reconstruction, which is possible for multi-scans at fixed slice positions as well as for overlapping spiral scans. Temporal resolution was quantified using computer simulations and compared to experimental data from pigs.


RESULTS
Using a conventional sub-second CT scanner, considerably higher temporal resolutions are possible with spiral scanning. A temporal resolution of 170 ms already provides systolic images with little motion artifacts. Higher temporal resolutions of up to 70 ms are demonstrated for multi-scans, which allows to depict ventricle wall movement over the complete cardiac cycle.


CONCLUSIONS
The method of time-optimized retrospective cardiac gating broadens the spectrum of conventional spiral-CT for cardiac imaging. It can be directly transferred to multi-slice scanners. Here it can be used clinically because of reduced scan time. Potential applications are the determination of functional cardiac parameters like ejection fraction and the detection of disorders of ventricle wall movement.
Boese
J M
JM
Abteilung Onkologische Diagnostik und Therapie, Deutsches Krebsforschungszentrum Heidelberg. j.boese@dkfz.de
Bahner
M L
ML
Albers
J
J
van Kaick
G
G
D000465:Algorithms; D000818:Animals; D003971:Diastole / Q000502:physiology; D004562:Electrocardiography / Q000295:instrumentation*; D006331:Heart Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D009200:Myocardial Contraction / Q000502:physiology; D013552:Swine; D013599:Systole / Q000502:physiology; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*; D016277:Ventricular Function, Left / Q000502:physiology