[Multiphasic helical computerized tomography of hepatocarcinoma. Assessment after chemoembolization]

To report our personal experience with the addition of contrast-enhanced multiphase helical CT to unenhanced CT (Lipiodol CT) in the evaluation of patients with hepatocellular carcinoma treated with chemoembolization and to analyze the present role of oily agent CT.

We retrospectively reviewed the examinations of 42 consecutive patients submitted to global chemoembolization over a 2-year period. CT was performed 18-30 days after the treatment. The Lipiodol CT study was carried out with volume acquisitions. We considered as nodules all well-defined areas with dense oily agent uptake; uptake itself was classified as: 0 = absent, I = lower than 10% of the tumor volume, II = lower than 50%, III = higher than 50%, IV = homogeneous. Contrast-enhanced helical CT was performed with the 2-phase technique in 28 patients and with the 3-phase technique in 14; we considered as nodules all well-defined and relatively homogeneous areas with hyperattenuation in the arterial phase and hypo-isoattenuation in the portal and/or delayed phase, or with hypo-isoattenuation in the arterial phase and in the portal and/or delayed phase.

Lipiodol CT permitted to recognize 65 nodules (1-5/patient, mean 1.5), namely 15 grade I, 21 grade II, 20 grade III and 9 grade IV. Multiphase CT identified 6 additional nodules in 5 patients, 5 hypervascular and 1 hypovascular, and better assessed the correct morphology and volume of grade I nodules. Only 4 of 6 nodules missed on Lipiodol CT showed oily agent uptake after a new chemoembolization session. Moreover after retreatment, carried out in 6 of 9 patients with grade I uptake (11 nodules in all), we found persistence of the grade I pattern in 5 nodules, grade II in 5, and grade III in 1.

Lipiodol CT may miss liver nodules and underestimate the volume of nodules with poor uptake. Though Lipiodol CT should still be considered slightly more sensitive than multiphase CT, in our opinion this technique has several limitations, as also shown in recent literature papers, and its clinical applications should be reduced. Multiphase helical studies may provide useful information and should be performed routinely in patients treated with chemoembolization. The present availability of alternative tools such as contrast-enhanced Doppler US and MRI should also be stressed and their potential role investigated.