Takuya Ishikawa, Presenter: Nothing to Disclose

Haruhiko Machida MD, Abstract Co-Author: Nothing to Disclose

Xiao Zhu Lin MD, Abstract Co-Author: Nothing to Disclose

Etsuko Tate, Abstract Co-Author: Nothing to Disclose

Yun Shen PhD, Abstract Co-Author: Employee, General Electric Company Researcher, General Electric Company

Eiko Ueno MD, Abstract Co-Author: Nothing to Disclose

Rika Fukui, Abstract Co-Author: Nothing to Disclose

Isao Tanaka, Abstract Co-Author: Nothing to Disclose

He Qing Wang MSc, Abstract Co-Author: Nothing to Disclose

To investigate single-source dual-energy CT (DECT) with fast kVp switching to reduce iodine load of multiphase abdominal CT in patients with renal insufficiency.

We retrospectively assessed 100 consecutive patients who underwent multiphase contrast-enhanced abdominal CT by DECT. Patients were administered iodine contrast medium (CM) based on estimated glomerular filtration rate (eGFR) (300 mgI/kg, 10 patients, eGFR 30-40; 450 mgI/kg, 25 patients, eGFR 40-50; 600 mgI/kg, 65 patients, eGFR > 50). All with eGFR of ≤ 50 and 19 (29%) with eGFR > 50 underwent ssDECT; the other 46 with eGFR > 50 underwent conventional CT (CCT) at 120 kVp. We placed regions of interest (ROIs) in the abdominal aorta, pancreas, liver, spleen, and sacrospinalis muscle (as background). For each anatomy, we calculated the mean difference of CT value (ΔHU) between pre- (HUpre) and post-contrast (HUpost) as HUpost - HUpre and contrast-to-noise ratio (CNR) as (HUpost – background HUpost)/background noise. In the abdominal aorta and pancreatic parenchyma, we measured HUpost during the late arterial phase (LAP; 40 s after start of CM) and in the hepatic and splenic parenchyma, during the hepatic parenchymal phase (HPP, 100 s). In the 3 dosage groups by DECT, we assessed the energy level of monochromatic images needed to achieve similar ΔHU with that of CCT (equivalent keV) and the optimal CNR (optimal keV) for each anatomy and used 2-sample independent t test to compare CNR at the equivalent keV and both ΔHU and CNR at the optimal keV between CCT and DECT.  

In all anatomies, CNRs at both the equivalent and optimal keVs were significantly higher by ssDECT than CCT in those given 450 and 600 mgI/kg but comparable in the 300 mgI/kg group; ΔHU at the optimal keV was significantly higher by DECT in the 600 mgI/kg group and lower in the 300 mgI/kg group. ΔHU was significantly higher by DECT during the LAP (abdominal aorta and pancreas) and comparable between CCT and DECT during the HPP (liver and spleen) in the 450 mgI/kg group.

In patients with renal insufficiency, DECT can reduce iodine load 50% in multiphase abdominal CT with similar CNR and 25% with better CNR and similar or better ΔHU.

Use of single-source DECT with fast kVp switching can reasonably reduce iodine load in multiphase abdominal CT 25 to 50% in patients with renal insufficiency.

Ishikawa, T, Machida, H, Lin, X, Tate, E, Shen, Y, Ueno, E, Fukui, R, Tanaka, I, Wang, H, Reduced Iodine Load in Multiphase Abdominal CT for Patients with Renal Insufficiency by Single-source Dual-energy CT with Fast kVp Switching: Comparison with Conventional CT—A Feasibility Study.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14012729.html