Improved characterisation of histologically proven liver tumours by contrast enhanced ultrasonography during the portal venous and specific late phase of SHU 508A

Purpose: Ultrasound is reported to be relatively unreliable in the characterisation of liver tumours. The purpose of this study was to assess the ability of contrast enhanced phase inversion ultrasound (PIUS), a new highly sensitive contrast specific technique, performed during the liver specific phase of Levovist, to differentiate between benign and malignant lesions of the liver. Patients and methods: A total of 174 patients with histologically proven liver tumours were prospectively examined with conventional B mode ultrasound and two minutes after intravenous bolus injection of SHU 508A (Levovist). The examination technique comprised: Siemens Sonoline Elegra, phase inversion harmonic imaging (ECI); high mechanical index (1.2-1.7) using a delayed two minute post contrast scanning technique. Results: In all patients with malignant disease, hypoechoic contrast enhancement was seen during the portal venous phase, and convincing but variably less demarcated in 13 patients with hepatocellular carcinoma compared with all patients with liver metastases. The liver tumours proved to be histologically benign in 95 patients and malignant in 79 patients. Homogenous contrast enhancement with a mainly isoechogenic appearance in the portal venous and liver specific late phase was seen in almost all patients with benign liver lesions with the exception of one patient with an inflammatory pseudotumour of the liver and five patients with abscesses. These six exceptions all demonstrated a hypoechoic appearance in the portal venous and liver specific late phase. Discussion: The ability of unenhanced ultrasonography to characterise liver disease is known to be limited. PIUS performed during the portal venous and liver specific late phase of Levovist may differentiate between benign and malignant liver tumours in most cases, with the exception of, for example, abscesses, scars, necrosis, cysts, and calcifications, which need to be excluded clinically and by conventional B mode ultrasonography.