Satoshi Goshima MD, PhD, Abstract Co-Author: Nothing to Disclose

Yoshifumi Noda MD, Abstract Co-Author: Nothing to Disclose

Hiroshi Kondo MD, Abstract Co-Author: Nothing to Disclose

Haruo Watanabe MD, Abstract Co-Author: Nothing to Disclose

Hiroshi Kawada MD, Abstract Co-Author: Nothing to Disclose

Tomohiro Ando MD, Presenter: Nothing to Disclose

Masayuki Kanematsu MD, Abstract Co-Author: Nothing to Disclose

Kyongtae Tyler Bae MD, PhD, Abstract Co-Author: Patent agreement, Covidien AG Patent agreement, Bayer AG

To determine the optimal iodine dose required for the detection of liver metastasis based on i) total body weight (TBW) and ii) body surface area (BSA) at 80-kVp CT imaging of the liver.

Institutional review board approval and written informed consent was obtained. We studied 116 patients (59 men, 57 women; mean age, 63.6 years; range, 28-86 years) who underwent contrast-enhanced CT for screening liver metastasis. The patients were randomized into three groups according to the following iodine-dose per body-weight protocols: 500 mgI/kg (500 mg of iodine per kilogram TBW), 400 mgI/kg, and 300 mgI/kg groups. All CT examination were performed with low tube voltage (80 kVp), high tube current (with the use of automatic exposure control), and adaptive statistical iterative reconstruction. The three groups were compared in terms of hepatic parenchymal CT enhancement during the portal venous phase (∆HU) and qualitative score for visualization of liver metastasis, if present, in a five point scale. Iodine-dose per BSA (mgI/m2) was also calculated and compared with ∆HU and visualization of liver metastasis.

Liver metastases were found in sixteen patients (mean size, 19.5 mm; size range, 7-84 mm). The mean ∆HU for the 500 mgI/kg group (83.7 HU) was higher than those of the 400 mgI/kg (66.1 HU) and 300 mgI/kg (47.8 HU) groups (P < 0.001). The relationship between the enhancement and iodine-dose from a linear regression analysis was ∆HU = -5.15 + 0.178*mgI/kg (P < 0.001) and ∆HU = 5.79 + 4.34*mgI/m2 (P < 0.001). The three groups were comparable in qualitative scores for the visualization of all hepatic metastases.

With the use of 80-kVp CT imaging, iodine dose required for hepatic enhancement can be substantially reduced. The iodine dose estimated to achieve the hepatic parenchymal enhancement of 50 HU was 310 mgI/kg or 10.2 mgI/m2.

Our study estimated the optimal amount of iodine-dose for the detection of liver metastasis in 80kVp CT imaging. This information is useful for designing routine hepatic CT imaging.

Goshima, S, Noda, Y, Kondo, H, Watanabe, H, Kawada, H, Ando, T, Kanematsu, M, Bae, K, Determining Optimal Iodine Dose with 80-kVp CT Imaging: Part I- Detection of Liver Metastasis.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13044154.html