Contrast Enhanced Ultrasound: A Novel Imaging Modality for Evaluation of Focal Hepatic Lesions

Abstract

Background and Aims: Contrast enhanced ultrasound (CEUS) is a novel ultrasound technique for hepatic imaging. It can depict the intranodular hemodynamics and thus characterize focal hepatic lesion (FHL), akin to that done by multiphasic CT/MRI. We present the spectrum of cases of FHLs evaluated by CEUS in characterizing and assessing response following locoregional therapy in malignant masses as a part of an ongoing work. Methods: Patients presenting to our Liver clinic with diagnosis of FHL were subjected to CEUS and multiphasic CT/MRI as part of the diagnostic work up. CEUS was performed on Supersonic aixplorer ultrasound machine using intravenous Sonovue (Bracco, Milan, Italy) contrast media (2.4 ml per nodule). The FHL was evaluated for enhancement characteristics in cine mode in three vascular phases—arterial (AP) at 15–25 s, venous (VP) at 45–90 s and delayed phase (DP) at 180 s. Findings were compared with MRI. Hepatocellular carcinoma (HCC) was staged and allocated locoregional therapy [(trans arterial chemo-embolization (TACE), radiofrequency ablation (RFA) and acetic acid ablation (PAI)], based on the Barcelona clinic staging system. CEUS and MRI was repeated at one month post therapy in HCC to assess treatment response based on mRECIST criteria. CT/MRI findings were considered for patient management. Results: Of the 10 FHLs evaluated, 5 depicted characteristics of malignant nodule (HCC) on CEUS which was hyperenhancement in AP and hypoenhancement in DP. The remaining 5 nodules showed features of benign lesions. These were-hemangiomas depicting progressive centripetal enhancement, persisting in DP (n = 3) or no enhancement in any vascular phase suggestive of abscess (n = 2). Five HCCs when assessed again post treatment, showed complete response (3), partial response (2). CEUS findings corroborated with the MRI in all cases. Conclusion: CEUS can accurately characterize focal hepatic lesions and assess the response in malignant masses following locoregional therapy.