Adaptive statistical iterative reconstruction for volume-rendered computed tomography portovenography: improvement of image quality.
OBJECTIVE
Adaptive statistical iterative reconstruction (ASIR) is a reconstruction technique for computed tomography (CT) that reduces image noise. The purpose of our study was to investigate whether ASIR improves the quality of volume-rendered (VR) CT portovenography.


METHODS
Institutional review board approval, with waived consent, was obtained. A total of 19 patients (12 men, 7 women; mean age 69.0 years; range 25-82 years) suspected of having liver lesions underwent three-phase enhanced CT. VR image sets were prepared with both the conventional method and ASIR. The required time to make VR images was recorded. Two radiologists performed independent qualitative evaluations of the image sets. The Wilcoxon signed-rank test was used for statistical analysis. Contrast-noise ratios (CNRs) of the portal and hepatic vein were also evaluated.


RESULTS
Overall image quality was significantly improved by ASIR (P < 0.0001 and P = 0.0155 for each radiologist). ASIR enhanced CNRs of the portal and hepatic vein significantly (P < 0.0001). The time required to create VR images was significantly shorter with ASIR (84.7 vs. 117.1 s; P = 0.014).


CONCLUSIONS
ASIR enhances CNRs and improves image quality in VR CT portovenography. It also shortens the time required to create liver VR CT portovenographs.
Department of Radiology, The University of Tokyo, Bunkyo-ku, Japan. imatsuda-tky@umin.ac.jp
Izuru
I
Matsuda
Shohei
S
Hanaoka
Masaaki
M
Akahane
Jiro
J
Sato
Shuuhei
S
Komatsu
Shinichi
S
Inoh
Shigeru
S
Kiryu
Naoki
N
Yoshioka
Kenji
K
Ino
Kuni
K
Ohtomo
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006503:Hepatic Veins / Q000000981:diagnostic imaging; D006801:Humans; D007472:Iohexol; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D015588:Observer Variation; D011172:Portography; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media; D007472:Iohexol