Carolyn Lee Wang MD, Presenter: Nothing to Disclose

Lee M. Mitsumori MD, MS, Abstract Co-Author: Nothing to Disclose

Cherise Athay BA, Abstract Co-Author: Nothing to Disclose

Orpheus Kolokythas MD, Abstract Co-Author: Consultant, Koninklijke Philips Electronics NV Advisory Board, Koninklijke Philips Electronics NV Grant, Koninklijke Philips Electronics NV

Bill H. Warren MD, Abstract Co-Author: Nothing to Disclose

Manjiri K. Dighe MD, Abstract Co-Author: Nothing to Disclose

Patrick C. Freeny MD, Abstract Co-Author: Nothing to Disclose

To quantitatively compare a fixed-duration (30s) versus a fixed-rate (5 mL/s) algorithm with a weight based contrast bolus protocol for multiphase liver CT.

Attenuation of the liver and aorta were measured on the arterial and portal venous phases in two groups of patients who had undergone 64 slices multiphase liver CT. The absolute enhancement of the liver and aorta were calculated as the difference of the mean attenuation on the contrast-enhanced minus noncontrast images. Threshold levels of adequate enhancement were obtained from the literature (aortic enhancement-arterial phase > 215 HU; liver enhancement-portal venous phase > 50 HU). Iohexol (350 mg I/mL) was the contrast used for all cases. The first group of 48 patients underwent liver CTs with weight based contrast dosing with variable rate and fixed injection duration (30s). The second group of 50 patients underwent weight based contrast dosing with fixed injection rate (5 mL/s) and variable injection duration. The results of each study group was compared to prior liver CT scans performed in each patient done with the control contrast protocol that consisted of a fixed volume of contrast (155 mL) injected at a fixed rate (5 mL/s) regardless of patient weight.

The mean attenuation of the aorta on arterial phase was 263 HU ± 74 for the fixed-duration versus 288 ± 80 for the control protocol, and 250 ± 68 for the fixed-rate versus 286 ± 80 for the control. The mean attenuation of the liver on portal venous phase was 53 HU ± 22 for the fixed-duration versus 67 ± 30 for the control, and 57 ± 17 for the fixed-rate versus 63 ± 20 for the control. The percentage of scans above the selected enhancement thresholds for the aorta in the arterial phase were 75% with the fixed-duration group, 70% for the fixed-rate group, and 85% and 78% for the respective controls. The percentages of scans above the liver enhancement threshold on the portal venous phase were 43% fixed-duration, 75% fixed-rate, and 65% and 85% for the respective controls.

Weight-based contrast dosing with fixed injection rate resulted in similar degrees of aortic enhancement but a higher percentage of cases with adequate liver enhancement than the fixed-duration protocol.

Weight-based contrast dosing with a fixed injection rate may result in improved portal venous phase liver enhancement when compared to protocols with a fixed injection duration.

Wang, C, Mitsumori, L, Athay, C, Kolokythas, O, Warren, B, Dighe, M, Freeny, P, Evaluation of Fixed-Duration vs Fixed-Rate Weight-based Contrast Bolus Algorithm Protocols for Multiphase Liver MDCT.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9015154.html