New real-time image fusion technique for characterization of tumor vascularisation and tumor perfusion of liver tumors with contrast-enhanced ultrasound, spiral CT or MRI: first results

Abstract

Aim: Evaluation and characterization of the vascularisation and perfusion of liver tumors by means of image fusion of dynamic contrast-enhanced ultrasound (CEUS), multidetector-CT (MD-CT) or magnetic resonance imaging (MRI) with the ultrasound navigation technique.

Material: For interventional planning a real-time image fusion involving CEUS (LOGIQ E9, GE) was performed in 20 patients (12 men, 8 women, age 43-69 years, median 54) with histologically confirmed malignant liver tumors (9 x hepatocellular carcinoma (HCC), 5 x metastases, 2 x hemangiomas, 1 x cholangiocellular carcinoma (CCC), 1 x lymphoma, 1 x neuroendocrine tumor, 1 x focal nodular hypoplasia (FNH)). In 17 patients the real-time CEUS was fused with contrast-enhanced MD-CT and in three patients with contrast-enhanced MRI (Gd-DTPA and liver-specific contrast medium Resovist. All of the ultrasound examinations were performed by an experienced examiner with a multi-frequency probe (2-5 MHz, LOGIQ E9, GE); dynamic image sequences up to 3 minutes in true agent detection mode of contrast harmonic imaging (CHI) were documented. An evaluation of the tumor was performed by the characterization of the dynamics of the contrast medium and microperfusion with CEUS, fused with MD-CT or MRI.

Results: In 18/20 cases there was an accurate agreement with respect to the segmental localization of the tumor lesion. In 2/20 cases the localization was comparable with the image fusion of CEUS and reference imaging (a total of at least 65 lesions: 3 x 1 lesion, 5 x 2 lesions, 8 x 3 lesions, 2 x 5 lesions, 1 x 8 lesions, 1 x at least 10 lesions (multifocal)). With image fusion a certain characterization was attained in 17/20 cases. In 3/20 cases (lymphoma after liver transplantation, multifocal CCC, metastases of a neuroendocrine tumor) the diagnosis was at first doubtful and had to be confirmed histologically. In patients with HCC an evaluation of the tumor perfusion was feasible in all 9 cases (8/9 after local trans-arterial chemoembolization (TACE), 1/9 after radio frequency ablation (RFA)). A tendency toward the identification of more lesions with image fusion of CEUS and CT than with contrast-enhanced CT alone could be recognized (p=0.059).

Conclusion: Applying a new real-time fusion technique of MD-CT or MRI with CEUS new possibilities for the evaluation, intervention and monitoring of the therapy of liver lesions were made possible, since the method also comprised the dynamic microperfusion.