Vascular disorders of the gallbladder and bile ducts: Imaging findings.

Vascular disorders of the gallbladder and biliary tree are many and varied. In the acute setting, the clinical presentation of vascular conditions such as hemorrhagic cholecystitis and gangrenous cholecystitis are non-specific and rely on imaging for diagnosis and triaging for emergent surgery. These hemorrhagic and ischemic complications of acute cholecystitis are uncommon but potentially fatal. Hemorrhage into the gallbladder and biliary tree, from other causes, may itself result in acute cholecystitis. Knowledge of vascular anatomy of the gallbladder and biliary tree is essential for surgeons to prevent significant operative bleeding complications, particularly in laparoscopic cholecystectomy. The unique venous drainage of the gallbladder and biliary tree, with their connections to the portal venous system, lends itself to less well-recognised vascular phenomena such as gallbladder varices, portal biliopathy, and gallbladder bed perfusion abnormalities.

Patterns of enhancement in the hepatobiliary phase of gadoxetic acid-enhanced MRI.

A variety of patterns of enhancement of liver lesions and liver parenchyma is observed in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI. It is becoming increasingly apparent that many lesions may exhibit HBP enhancement. Much of the literature regarding the role of gadoxetic acid-enhanced MRI in characterising liver lesions is dichotomous, focusing on whether lesions are enhancing or non-enhancing in the HBP, rather than examining the patterns of enhancement. We provide a pattern-based description of HBP enhancement of liver parenchyma and of liver lesions. The role of OATP1B3 transporters, hepatocyte function and lesion composition in influencing patterns of HBP hyperintensity are discussed.

Hepatic disorders associated with exogenous sex steroids: MR imaging findings.

OBJECTIVE: To describe the MRI findings of the effects of exogenous sex steroids on the liver. FINDINGS: Estrogens, progesterone and synthetic testosterone are exogenous sex steroids that may result in a variety of liver diseases, including tumour formation and vascular disorders. These hormones are mainly administered in the form of the oral contraceptive pill (OCP) and anabolic steroids. Both are implicated in hepatic adenoma formation. The HNF-1α-mutated and inflammatory adenoma subgroups are more commonly seen in association with the OCP whereas there is an increased incidence of the ß-catenin positive subtype with anabolic steroid use. Furthermore, anabolic steroids are associated with hepatocellular carcinoma resulting from malignant transformation of ß-catenin positive adenomas. The oral contraceptive pill may also induce vascular disorders within the liver, some of which are related to the prothrombotic effect of the hormones, such as hepatic and portal vein thrombosis. Other hepatic vascular abnormalities resulting from exogenous sex steroids include veno-occlusive disease and peliosis hepatis.

Extramedullary fat fluid level on MRI as a specific sign for osteomyelitis.

The role of MR in the early diagnosis of acute osteomyelitis is well known. In the context of florid cellulitis, abnormalities of marrow signal are not uncommon, although they are often non-specific. Marrow oedema and enhancement in the context of deep cellulitis might reflect either reactive marrow oedema or true osteomyelitis. More specific signs lend favour to the diagnosis of osteomyelitis: these include focal bone destruction, periosteal reaction and sequestra. The observation of an extramedullary fat-fluid sign is also a specific sign for osteomyelitis, as illustrated in the following case report. This sign is an indication of cortical breach and, thus, in the setting of infection and in the absence of trauma confirms the presence of osteomyelitis. To our knowledge, this additional specific sign of osteomyelitis has not been previously reported on MR.