Objectives: To determine the optimal iodine mass (IM) to achieve a 50-HU increase in hepatic attenuation for the detection of liver metastasis based on total body weight (TBW) or body surface area (BSA) at 80-kVp computed tomography (CT) imaging of the liver.
Methods: One-hundred and fifty patients who underwent contrast-enhanced CT at 80-kVp were randomised into three groups: 0.5 gI/kg, 0.4 gI/kg and 0.3 gI/kg. Portal venous phase images were evaluated for hepatic parenchymal enhancement (∆HU) and visualisation of liver metastasis. Iodine mass per BSA (gI/m(2)) calculated in individual patients were evaluated.
Results: Mean ∆HU for the 0.5 gI/kg group (84.2 HU) was higher than in the 0.4 gI/kg (66.1 HU) and 0.3 gI/kg (53.7 HU) groups (P < 0.001). Linear correlation equations between ∆HU and IM per TBW or BSA are ∆HU = 7.0 + 153.0 × IM/TBW (r = 0.73, P < 0.001) and ∆HU = 11.4 + 4.0 × IM/BSA (r = 0.75, P < 0.001), respectively. The three groups were comparable for the visualisation of hepatic metastases.
Conclusions: The iodine mass to achieve a 50-HU increase in hepatic attenuation at 80-kVp CT was estimated to be 0.28 gI/kg of body weight or 9.6 gI/m(2) of body surface area.
Key points: • Hepatic enhancement is expressed as ∆HU = 7.0 + 153.0 × IM [g]/TBW [kg]. • Hepatic enhancement is expressed as ∆HU = 11.4 + 4.0 × IM [g]/BSA [m(2)]. • Essential iodine dose at 80-kVp CT was 0.28 gI/kg or 9.6 gI/m(2).