Current and Advanced Applications of Gadoxetic Acid-enhanced MRI in Hepatobiliary Disorders.

Gadoxetic acid is an MRI contrast agent that has specific applications in the study of hepatobiliary disease. After being distributed in the vascular and extravascular spaces during the dynamic phase, gadoxetic acid is progressively taken up by hepatocytes and excreted to the bile ducts during the hepatobiliary phase. The information derived from the enhancement characteristics during dynamic and hepatobiliary phases is particularly relevant in the detection and characterization of focal liver lesions and in the evaluation of the structure and function of the liver and biliary system. The use of new MRI sequences and advanced imaging techniques (eg, relaxometry, multiparametric imaging, and analysis of heterogeneity), the introduction of artificial intelligence, and the development of biomarkers and radiomic and radiogenomic tools based on gadoxetic acid-enhanced MRI findings will play an important role in the future in assessing liver function, chronic liver disease, and focal liver lesions; in studying biliary pathologic conditions; and in predicting treatment responses and prognosis. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

IgG4-related Disease from Head to Toe.

Immunoglobulin G4 (IgG4)-related disease is a relatively recently proposed clinical-pathologic entity that is characterized by fibro-inflammatory lesions rich in IgG4-positive plasma cells and, often but not always, elevated serum IgG4 concentrations. IgG4-related disease was recognized as a systemic disease in 2003, when extrapancreatic manifestations were identified in patients with autoimmune pancreatitis. Since then, the disease has been reported as affecting virtually every organ system and has been identified in the biliary tree, salivary and lacrimal glands, periorbital tissues, lungs, lymph nodes, thyroid gland, kidneys, prostate gland, testicles, breasts, and pituitary gland. Its pathogenesis is poorly understood, but findings are consistent with both an autoimmune and an allergic disorder. Although definitive diagnosis requires histopathologic analysis, imaging plays an important role in demonstrating infiltration and enlargement of involved organs. Because of the systemic nature of the disease, imaging workup of IgG4-related disease should always include whole-body examinations to detect multiorgan involvement. Patients often present with subacute development of a mass in or diffuse enlargement of the affected organ, sometimes mimicking a neoplastic process. In every anatomic location, several inflammatory and neoplastic entities must be considered in the differential diagnosis. Because IgG4-related disease usually shows a marked response to corticosteroid therapy, radiologists should be familiar with its clinical and imaging manifestations to avoid a delay in diagnosis and unnecessary surgical interventions.

Unusual Case of Superior Vena Cava Syndrome Caused by Intravascular Thyroid Metastasis.

Superior cava venous obstruction use to show a typical clinical presentation and a CT scan or even an ultrasonography can be sufficient to achieve an accurate diagnosis, but in this case, to obtain the final diagnosis, a multimodal assessment is needed. This case report shows a multidisciplinary approach which helped diagnose a complicated case, where conventional diagnostic methods were not enough.

Unusual Forms of Adrenal and Extra-Adrenal Myelolipomas.

Myelolipomas are rare benign tumors of poorly understood tumorigenesis composed of mature hematopoietic tissue and fat. They mostly occur in the adrenal glands, but extra-adrenal myelolipomas have been reported in other locations such as the presacral region or retroperitoneum. It is not unusual that they are incidental findings revealed in the study of different diseases. We report 3 unusual examples of myelolipomas. The first is a multiple, unusually large, extra-adrenal myelolipoma, presented as an autopsy finding in an individual who had died suddenly from a central nervous system hemorrhage. The remaining 2 were incidental findings in patients studied for different reasons. Both were located within another neoplasm, namely an adrenal adenoma and a liver focal nodular hyperplasia. Moreover, the first showed infiltration by a non-Hodgkin lymphoma.