Multidetector CT of the lung: image quality with garnet-based detectors.
OBJECTIVE
To evaluate the image quality of both standard- and reduced-dose computed tomography (CT) by comparing multidetector CT with garnet-based detectors with multidetector CT with conventional detectors.


METHODS
The study was approved by the internal ethics review board. Informed consent was obtained. Eleven cadaveric lungs inflated and fixed by using the Heitzman method were scanned by using both CT with garnet-based detectors and CT with conventional detectors. Tube current was 400 mA for standard-dose and 10 mA for reduced-dose CT, and voltage was 120 kVp. Either normal scan mode with 984 views (conventional and garnet-based detectors) or high-resolution mode with 2496 views was used. Image quality at conventional-detector CT and garnet-based-detector CT in all modes was graded by two independent observers with a five-point scale. The evaluation items included normal lung structures, subjective visual noise, and abnormal CT findings. Quantitative image noise measurements were calculated by measuring the standard deviations in a circular region of interest on each selected image.


RESULTS
At standard-dose CT, image quality at CT with garnet-based detectors (high-resolution mode) was significantly improved (P < .001, Tukey-Kramer). However, there was no significant difference between quantitative image noise measurements (P > or = .24). At reduced-dose CT, only noise differed significantly, with both subjective visual noise and quantitative image noise measurements significantly greater at CT with garnet-based detectors (high-resolution mode) (P < or = .01). There was no significant difference in image quality except for noise between conventional-detector CT and garnet-based-detector CT (P > or = .06).


CONCLUSIONS
The image quality of standard-dose garnet-based-detector CT (high-resolution) was significantly improved. Although highly reduced-dose garnet-based-detector CT (high-resolution mode) provided more image noise, overall image quality was not different between conventional-detector CT and garnet-based-detector CT.
Yanagawa
Masahiro
M
Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871, Japan. m-yanagawa@radiol.med.osaka-u.ac.jp
Tomiyama
Noriyuki
N
Honda
Osamu
O
Kikuyama
Ayano
A
Sumikawa
Hiromitsu
H
Inoue
Atsuo
A
Tobino
Kazunori
K
Koyama
Mitsuhiro
M
Kudo
Masayuki
M
D002102:Cadaver; D006801:Humans; D008171:Lung Diseases / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*