CT and MR Imaging of Benign Hepatic and Biliary Tumors

Abstract

Benign hepatic and biliary tumors can present a difficult diagnostic challenge. Spiral computed tomography (CT) and magnetic resonance (MR) imaging are useful in the detection and characterization of these tumors. Imaging characteristics of lesions such as hepatic cyst, hemangioma, focal nodular hyperplasia (FNH), and hepatic adenoma are well known. Hepatic cysts demonstrate water attenuation at CT, are isointense relative to water at MR imaging, and do not enhance after intravenous administration of contrast material. Hemangiomas demonstrate characteristic nodular peripheral enhancement on early-phase images with subsequent fill-in centrally at both modalities. FNH classically demonstrates intense early enhancement with washout on delayed images. Although hepatic adenoma can also demonstrate intense early enhancement, it has a tendency to bleed and thus often appears more heterogeneous than FNH due to hemorrhage. Benign hepatic tumors that are less well described in the imaging literature include hepatic lipoma or angiomyolipoma, infantile hemangioendothelioma, and mesenchymal hamartoma. Hepatic lipoma has fat attenuation at CT, is isointense relative to fat at MR imaging, and does not enhance after intravenous administration of contrast material. Hepatic angiomyolipomas contain a variable amount of soft tissue in addition to fat and may therefore demonstrate enhancement at both modalities. The CT and MR imaging appearances of infantile hemangioma are similar to those of adult hemangioma. Infantile hemangioendothelioma occurs in infants under 6 months of age and is typically a larger lesion. Mesenchymal hamartoma also occurs in children, and its imaging appearance depends on the presence of stromal elements and the protein content of the cyst fluid. Familiarity with these imaging features can help distinguish particular disease entities.

Hemangioma of the Interatrial Septum: CT and MRI Features

“…Similar enhancement characteristics were previously described for pericardial hemangioma [8]. This nodular peripheral puddling of contrast material on early images with later filling in from the periphery is pathognomonic for hemangioma of the liver [10]. In our opinion, the absence of tumor blush of cardiac hemangioma described by Kasmani et al was caused by a very short delay during pulmonary CT angiography [11] and that filling from the periphery would have been observed if delayed scanning had been performed.…”

Diferenciação entre cisto simples e hemangioma hepático utilizando seqüência de ressonância magnética ponderada em T2 com técnica gradiente-eco (B-FFE)

“…In this context, hepatic nodules are most frequently found, the benign ones corresponding to simple cysts present in 2%-7% of the general population, and hemangiomas present in up to 20% of cases of autopsy (2,8) . Generally these nodules are asymptomatic, being incidentally found on imaging studies.…”

“…Diagnosis confirmation in these cases is most frequently achieved by means of a combination of imaging methods including US, CT and/or MRI (4,8) . Hepatic simple cysts and hemangiomas are considered as benign lesions, representing a diagnostic challenge considering that, at imaging studies, these lesion could be mistaken with primary of secondary malignant neoplasms, leading to unnecessary surgical procedures or incorrect cancer staging (8) . MRI is considered as a reliable method for detecting and characterizing hepatic lesions.…”

“…MRI is considered as a reliable method for detecting and characterizing hepatic lesions. Advantages of this method include multiplanar imaging capability, higher specificity due to T2-weighted images, and absence of ionizing radiation and more nephrotoxic iodine-based contrast agents like those utilized at CT (8) . The strategy adopted in MRI studies for differentiation between benign and malignant hepatic nodules combines a visual evaluation of signal intensity on dynamic contrast-enhanced, heavily T2-weighted and T1-weighted images.…”

“…So, considering the similarity of signal intensity between cysts and hemangiomas, paramagnetic contrast (Gd-DTPA) injection becomes necessary for differentiation between these lesions. Cysts do not enhance after administration of Gd-DTPA, and hemangiomas present an early, discontinuous peripheral, progressive and centripetal enhancement (2,8) . Despite of the safety and low toxicity, especially as compared with iodinated contrast agents, the utilization of a paramagnetic contrast agent results in an increase in the cost of the study.…”