Imaging Techniques in the Assessment of Liver Tumoral Vascularization

Abstract

Several imaging methods may describe the vascular pattern of a solid tumor and assess through this its benign/malignant character. Gray-scale ultrasound (US) represents the first method of detecting a liver tumor. Doppler US helps further in establishing the vascularization of the tumors and their architectural pattern. The detectability rate of intratumoral vessels is higher in Power Doppler comparative to B-flow, especially in deep seated lesions. Malignancy is suggested at contrast-enhanced US (CEUS) by hypoenhancing areas (in late phases) and washout (portalvenous phase), but benign tumors with high-shunt flow, atypical focal nodular hyperplasias (FNH) and adenomas should not be excluded. Classical scintigraphy used alone had not specific images in FNH, adenomas, abscesses, cysts, hepatocarcinomas and pseudotumors; colloidal and in vivo labeled SPECT are important in diagnosing hemangiomas>2cm. There exists a correlation at liver angioscintigraphy (LAS) between increased hepatic perfusion index (HPI) values and large tumoral volumes (r=0.313, p<0.001) in benign tumors, although it is known that arterialisation usually correlates with malignancy. Lack of detection of the central scar in 60% cases of FNH at MR appears because of the large tumoral volume and/or underlying steatosis. Resovist administration enhances the diagnostic specificity in FNH and malignant transformed nodules. Dynamic imaging methods using contrast agents, always interpreted in the patient’s clinical and biological context, are important methods of investigation, used in order to enable positive and differential diagnosis in tumor masses of the liver.