Urgent MRI with MR cholangiopancreatography (MRCP) of acute cholecystitis and related complications: diagnostic role and spectrum of imaging findings.

Acute cholecystitis, which is usually associated with gallstones, is one of the commonest surgical causes of emergency hospital admission and may be further complicated by mural necrosis, perforation, and abscess formation. Magnetic resonance imaging (MRI) is increasingly available in the emergency setting. Technically improved equipment and faster acquisition protocols allow excellent tissue contrast and MRI is now an attractive modality for imaging acute abdominal disorders. The use of MRI with MR cholangiopancreatography in the emergency setting provides rapid, noninvasive, and confident diagnosis or exclusion of acute cholecystitis and of coexistent choledocholithiasis. To familiarize the reader with these cross-sectional imaging appearances, this paper reviews MRI findings consistent with uncomplicated cholecystitis. These include gallbladder distension, intraluminal sludge and gallstones, impacted stones obstructing the gallbladder neck or cystic duct, thickening of the gallbladder wall, abnormal signal intensity and edematous stratification, and pericholecystic and perihepatic fluid, plus increased enhancement of the gallbladder wall and adjacent liver parenchyma when intravenous paramagnetic contrast is used. Furthermore, MRI allows prompt detection and comprehensive visualization and characterization of cholecystitis-related complications such as gangrene, perforation, pericholecystic abscess, and intrahepatic fistulization. Some previous literature reports, and our experience, suggest that, when available, MRI should be recommended to provide prompt and efficient triage of patients with suspected cholecystitis and inconclusive clinical, laboratory, and sonographic findings. It facilitates appropriate therapeutic planning, including the timing of surgery (emergency or delayed), approach (laparoscopic or laparotomic), and need for preoperative or intraoperative removal of stone(s) in the common bile duct.