Image quality of high-resolution CT with 16-channel multidetector-row CT: comparison between helical scan and conventional step-shoot scan.
OBJECTIVE
The aim of this study was to evaluate the image quality of high-resolution CT (HRCT) reconstructed from volumetric data with 16-channel multidetector-row CT (MDCT).


METHODS
Eleven autopsy lungs that were diagnosed histopathologically were scanned by 16-channel MDCT with the step-and-shoot scan mode and three helical scan modes. Each helical mode had each size of focal spot, pitch, and time of gantry rotation. HRCT images were reconstructed from the volumetric data with each helical mode and axial sequence data. Two observers evaluated the image quality and noted the most appropriate diagnosis for each imaging.


RESULTS
Visualization of abnormal structures with one helical mode was equal to those with axial mode, whereas those with the other two helical modes were inferior to those with axial mode (Wilcoxon signed rank test; p<0.0001). There was no significant difference in diagnostic efficacy between modes.


CONCLUSIONS
The image quality of HRCT with appropriate helical mode is equal to that with axial mode and diagnostic efficacy is equal among all modes. These results may indicate that sufficient HRCT images can be obtained by only one helical scan without the addition of conventional axial scans.
Sumikawa
Hiromitsu
H
Department of Radiology, Osaka University Graduate School of Medicine, Suita 565-0825, Japan.
Johkoh
Takeshi
T
Koyama
Mitsuhiro
M
Kozuka
Takenori
T
Ikemoto
Minako
M
Inoue
Atsuo
A
Murai
Sachiko
S
Tsubamoto
Mitsuko
M
Honda
Osamu
O
Tomiyama
Noriyuki
N
Hamada
Seiki
S
Nakamura
Hironobu
H
Narita
Hiroaki
H
D002102:Cadaver; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008171:Lung Diseases / Q000000981:diagnostic imaging; D015588:Observer Variation; D036542:Tomography, Spiral Computed; D014057:Tomography, X-Ray Computed