Effects of high-resolution CT of the lung using partial versus full reconstruction on motion artifacts and image noise.
OBJECTIVE
The purpose of our study was to evaluate the effects of 0.3-second high-resolution CT (HRCT) of the lung using partial reconstruction on cardiac motion artifacts and image noise.


METHODS
Thirty-seven pairs of 0.3-second (partial reconstruction) and 0.75-second (full reconstruction) HRCT images were obtained for the lower lung zone during full-inspiration breath-holding. Imaging parameters other than temporal resolution were identical for each patient. Two radiologists visually graded motion artifacts of the cardiac border, bronchi, pulmonary vessels, and fissure in the left lung on a 4-point scale (with 4 indicating no artifacts). The maximum width of motion along the left cardiac border and the area percentage of motion artifacts in the left lung were calculated. Image noise in the air and lung was also determined. Cardiac motion artifacts and image noises were compared between the two sets of CT images.


RESULTS
Visual grades for the cardiac border (4 +/- 0), bronchi (3.8 +/- 0.7), pulmonary vessels (3.6 +/- 0.8), and fissure (3.9 +/- 0.5) were higher for 0.3-second images than for 0.75-second images (1.7 +/- 0.7, 2.0 +/- 1.0, 1.6 +/- 0.7, and 2.4 +/- 0.9, respectively) (p < 0.001). The maximum width of motion along the left cardiac border (0.1 +/- 0.5 mm) and the area percentage of motion artifacts in the left lung (6.7% +/- 18.4%) were smaller for 0.3-second images than for 0.75-second images (4.5 +/- 1.7 mm and 36.2% +/- 20.9%, respectively) (p < 0.001). Image noises in the air (38.0 +/- 9.2) and the lung (86.0 +/- 23.1) were greater for 0.3-second images than for 0.75-second images (35.6 +/- 9.6 and 76.0 +/- 20.3, respectively) (p < 0.01).


CONCLUSIONS
Compared with 0.75-second HRCT using full reconstruction, 0.3-second HRCT using partial reconstruction substantially reduces cardiac motion artifacts in the lung at the expense of increasing image noise.
Ha
Hong Il
HI
Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poongnap-2 dong, Songpa-gu, Seoul, South Korea 138-736.
Goo
Hyun Woo
HW
Seo
Joon Beom
JB
Song
Jae-Woo
JW
Lee
Jin Seong
JS
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D002648:Child; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009068:Movement; D015588:Observer Variation; D012119:Respiration; D014057:Tomography, X-Ray Computed / Q000379:methods*