RESUMO
Abstract A large number of gadolinium chelates have recently been tested in clinical trials. Some of those have already been approved for clinical use in the United States and Europe. Thus, new diagnostic perspectives have been incorporated into magnetic resonance imaging studies. Among such gadolinium chelates are hepatobiliary-specific contrast agents (HSCAs), which, due to their property of being selectively taken up by hepatocytes and excreted by the biliary ducts, have been widely used for the detection and characterization of focal hepatic lesions. In comparison with conventional magnetic resonance cholangiography (MRC), HSCA-enhanced MRC provides additional information, with higher spatial resolution and better anatomic evaluation of a non-dilated biliary tree. A thorough anatomic assessment of the biliary tree is crucial in various hepatic surgical procedures, such as complex resection in patients with colorectal cancer and living-donor liver transplantation. However, the use of HSCA-enhanced MRC is still limited, because of a lack of data in the literature and the poor familiarity of radiologists regarding its main indications. This pictorial essay aims to demonstrate the use of HSCA-enhanced MRC, with particular emphasis on anatomical analysis of the biliary tree, clinical applications, and the most important imaging findings.
Resumo Recentemente, um grande número de quelantes de gadolínio tem sido testado em ensaios laboratoriais. Alguns deles já foram inclusive aprovados para uso clínico nos Estados Unidos e na Europa. Com isso, novas perspectivas diagnósticas foram incorporadas nos estudos de ressonância magnética. Dentre estes quelantes de gadolínio, os contrastes hepatobiliares específicos (CHBEs) têm sido amplamente utilizados para a caracterização e detecção de lesões focais hepáticas, essencialmente pela propriedade de serem captados pelos hepatócitos e excretados na via biliar. Além disso, os CHBEs trouxeram novas informações na avaliação da árvore biliar quando comparados à colangiorressonância convencional, proporcionando uma maior resolução espacial e melhor avaliação da anatomia da árvore biliar não dilatada. A avaliação da anatomia biliar é de fundamental importância em cirurgias hepáticas, como ressecções complexas em tumores colorretais ou no transplante hepático com doador vivo, porém, o uso dos CHBEs ainda é restrito para estes propósitos. Em razão da escassa literatura sobre o tema e da pouca familiaridade dos radiologistas com as principais indicações, o presente ensaio iconográfico tem por objetivo demonstrar o uso de CHBEs na avaliação perioperatória das vias biliares, ressaltando a avaliação anatômica, as indicações e os principais achados de imagem.
RESUMO
Gadolinium-enhanced magnetic resonance for the evaluation of hepatic lesions is increasingly being used in clinical practice, especially in patients with suspicious focal lesions, whether benign or malignant. In regard to hepatocellular carcinoma, the diagnostic performance of magnetic resonance through the «conventional¼ protocols and multi-detector computerized tomography consisting of multiphase evaluation with intravenous contrast, largely depends on the size of the lesion. They are more reliable in lesions>2cm. However, in lesions measuring 1-2cm, establishing the definitive diagnosis is a real challenge, with sensitivity values of 45-65%, but generally with excellent specificity (>95%). Furthermore, if the lesion has a diameter<1cm, diagnosis is usually unreliable. In these last 2 settings, the complementary use of liver-specific contrast agents can be advantageous. The aim of our article was to review the current evidence on the usefulness of this new non-invasive diagnostic method in hepatic lesions.
