Image fusion with volume navigation of contrast enhanced ultrasound (CEUS) with computed tomography (CT) or magnetic resonance imaging (MRI) for post-interventional follow-up after transcatheter arterial chemoembolization (TACE) of hepatocellular carcinomas (HCC): Preliminary results

Abstract

Aim: The assessment of the immediate post-interventional microcirculation and perfusion following transcatheter arterial chemoembolization (TACE) with new real time imaging fusion technique (VNav) of computed tomography (CT) or magnetic resonance imaging (MRI) with contrast enhanced ultrasound (CEUS) compared to follow-up. Material: Following TACE an image fusion of CEUS with CT or MRI of the liver was performed in 20 patients (18 men, 2 women; age 29–75 years) with confirmed hepatocelluar carcinoma (HCC) to evaluate the post-interventional tumor vascularization and perfusion of HCC tumor lesions. Image fusion with CEUS performed immediately was compared with the result at the end of TACE (DSA), with post TACE CT (non-enhanced CT within 24hours) and with follow up CT (enhanced CT after 6 weeks) after embolization. Ultrasound was performed using a 1–5 MHz multifrequency SonoVue transducer (LOGIQ 9/GE) after a bolus injection of 2–4ml SonoVue^® with contrast harmonic imaging (CHI). Thirteen examinations were fused with a contrast enhanced CT, 7 with a MRI performed before TACE. Results: The post-interventional volume navigation image fusion of CT or MRI with CEUS showed differences regarding the residual tumor perfusion compared to other modalities. The correlation (Spearman-test) between the perfusion result at the end of TACE, non-enhanced CT after TACE and image fusion with CEUS was 0.42 and 0.50. The difference between the result at the end of TACE and the fusion with CEUS was significant (p < 0.05, Wilcoxon-test). The correlation between fusion of CEUS with CT/MRI and follow-up CT (after 6 weeks) was 0.64, the difference was not significant (p > 0.05). The differences between native CT within 24 hours after TACE and follow up CT after 6 weeks or fusion of CEUS and CT/MRI were significant (p < 0.05). The inter-observer variability was 0.61 at the end of TACE, 0.58 at non-enhanced CT (within 24 hours), 0.87 at fusion CEUS with CT/MRI and 0.74 at follow up CT after 6 weeks (Cohens Kappa test). Conclusion: Image fusion with volume navigation (VNav) of CEUS with CT or MRI allows an accurate localisation of foci in patients with HCC. This exact mapping permits an easier control and evaluation of the results after TACE. The fusion of CEUS and CT or MRI allows a better evaluation of the microcirculation and the residual tumor perfusion at an earlier point of time than usual modalities of therapy control like non-enhanced CT. This might lead to a more differentiated monitoring of therapy.