Timing on 16-slice scanner and implications for 64-slice cardiac CT: do you start scanning immediately after breath hold?
OBJECTIVE
Slow heart rate and small changes in heart rate are factors for improving image quality on spiral cardiac computed tomography (CT). The purpose of this study is to investigate whether it is possible to improve non-enhanced cardiac CT quality by delaying the data-acquisition window after breath hold.


METHODS
Electrocardiograph files (n = 240) for 16-slice non-enhanced cardiac CT scans were analyzed. Mean heart rates and maximal changes in heart rates between adjacent cardiac cycles were compared between phase 1 (defined as cardiac cycles 1-5), phase 2 (cardiac cycles 2-6), ... , and phase 6 (cardiac cycles 6-10).


RESULTS
Heart rates gradually increased by phases, but were limited to a range of 66.8-68.0 beats/min. Maximal changes in heart rates were 2.5 beats/min (phase 1) at the highest and 1.3 beats/min (phases 5 and 6) at the lowest (t-test; P < .01). Maximal changes in heart rates for more than five beats/min occurred in 24, eight, and eight patients on phases 1, 5, and 6, respectively (chi-square test; P < .01).


CONCLUSIONS
The delayed scan (four or five cardiac cycles after breath hold) has the potential to improve the quality of non-enhanced cardiac CT.
Horiguchi
Jun
J
Department of Clinical Radiology, Hiroshima University Hospital, Minami-ku, Hiroshima 734-8551, Japan. horiguch@hiroshima-u.ac.jp
Shen
Yun
Y
Hirai
Nobuhiko
N
Yamamoto
Hideya
H
Akiyama
Yuji
Y
Ishifuro
Minoru
M
Kakizawa
Hideaki
H
Hieda
Masashi
M
Tachikake
Toshihiro
T
Matsuura
Noriaki
N
Ito
Katsuhide
K
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000000981:diagnostic imaging / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D001239:Inhalation; D008297:Male; D008875:Middle Aged; D012107:Research Design; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*