Improvement in imaging time and quality of 3D negative-contrast computed tomography cholangiography with minimum intensity projections: application of vari-slice manual cut and erosion functions.
OBJECTIVE
To investigate the improvement in postprocessing time and image quality of 3D negative-contrast CT cholangiography (nCTC) with minimum intensity projection (minIP).


METHODS
Thirty-eight patients with suspected biliary obstruction who underwent portal phase helical CT were retrospectively studied. Three-dimensional nCTC was generated using 3D tools with manual cut function in three methods: one-slice, two-slice, and vari-slice cut slab, respectively. After adjusting the threshold level to about -20 HU, the erosion function with a value of one voxel was employed each time for further cleaning up hypodense interfering voxels such as fat and air that remained and the procedure was stopped before the biliary and pancreatic ducts were overeroded.


RESULTS
Mean values of the total postprocessing time of the three manual cut methods for 3D nCTC were 57.8, 29.9, and 20.6 min, respectively. After the first erosion, interfering voxels were removed in more than half of the cases and they could be primarily eliminated following the second erosion. Meanwhile, the pancreaticobiliary ducts showed obvious erosion findings at the third erosion.


CONCLUSIONS
The vari-slice manual cut method was shown to be the most timesaving postprocessing method and the image quality for 3D nCTC can be improved when one to two frequencies of erosion are applied.
Department of Radiology, Wuxi Second People's Hospital Affiliated to Nanjing Medical University, Jiangsu, P.R. China.
Zhui-Yang
ZY
Zhang
Jian-Ping
JP
Li
Chun-Hong
CH
Hu
Zhong
Z
Ding
Dong
D
Wang
Yuan-Liang
YL
Shen
Ming-Hua
MH
Hu
Lei
L
Zhang
Jian-Yong
JY
Ma
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002758:Cholangiography / Q000379:methods*; D002779:Cholestasis / Q000000981:diagnostic imaging*; D003287:Contrast Media; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
D003287:Contrast Media