Patient-tailored scan delay for multiphase liver CT: improved scan quality and lesion conspicuity with a novel timing bolus method.
OBJECTIVE
The purpose of this study was to compare scan quality and lesion conspicuity for late arterial and portal venous phase liver CT scans using fixed versus patient-tailored scan delay derived with an evidence-based timing bolus method.


METHODS
We retrospectively identified the cases of 73 patients who underwent both multiphase liver CT with fixed late arterial and portal venous phase scan delay times of 45 and 80 seconds and subsequent multiphase liver CT with patient-tailored scan delay determined with a timing bolus and a previously reported relation between the time to peak aortic and liver enhancement. Both late arterial and portal venous phase scans were graded in terms of scan quality. Hepatic lesion conspicuity (difference in attenuation between lesion and liver parenchyma) for hypervascular lesions (late arterial phase) and hypovascular lesions (portal venous phase) was recorded.


RESULTS
Patient-tailored scan delay reflected a wide range of times to peak aortic enhancement (mean, 24 seconds; range, 18-32 seconds) and yielded a greater proportion of optimal scans compared with fixed scan delay for both late arterial phase (92% versus 74%, p < 0.01) and portal venous phase (86% versus 70%, p < 0.05) scans. Mean hypervascular lesion conspicuity was greater for lesions imaged with patient-tailored scan delay rather than fixed scan delay (84.0 versus 57.0 HU, p < 0.01).


CONCLUSIONS
Compared with examinations with fixed scan delay, multiphase liver CT that incorporates patient-tailored scan delay produces more optimally timed late arterial and portal venous phase CT scans with greater lesion conspicuity.
1 All authors: Department of Radiology, University of California San Francisco, Box 0628, M372, 505 Parnassus Ave, San Francisco, CA 94143-0628.
J Gabriel
JG
Schneider
Zhen J
ZJ
Wang
Wilbur
W
Wang
Judy
J
Yee
Yanjun
Y
Fu
Benjamin M
BM
Yeh
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D008107:Liver Diseases / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media; D007472:Iohexol