Magnetic Resonance Cholangiopancreatography (MRCP) in the Setting of Acute Pancreaticobiliary Disease: Can Certain Clinical Factors Guide Appropriate Utilization?

Abstract

Magnetic resonance cholangiopancreatography (MRCP) is a widely available imaging technique that enables rapid and non-invasive assessment of the biliary tree and localization of pathology. T2-weighted imaging is useful for assessing the fluid components of lesions or collections, and provides detailed evaluation of the pancreaticobiliary ductal system. In the emergency setting, MRCP may be applied as an adjunct to US, CT or nuclear medicine (HIDA) imaging to detect cholelithiasis, biliary obstruction, acute cholecystitis, acute biliary (gallstone) pancreatitis (ABP) or provide clinically relevant information in patients with trauma. When compared with MDCT, MRCP has the distinct advantage of avoiding ionizing radiation. Unlike Endoscopic Retrograde Cholangiopancreatography (ERCP), which requires contrast opacification of bile ducts, MRCP utilizes intrinsic high T2 signal of bile to image the biliary tree in the physiologic non-distended state. At present, the utilization of MRCP in the acute setting varies between institutions and is dependent upon the clinical scenario and MRI availability. In a single center retrospective review, Yahya et al evaluated inpatient and emergency department patients with suspected acute pancreaticobiliary disease over a two year period that underwent urgent MRCP following initial US examination to identify factors that might improve MRCP diagnostic yield. Of 155 patients included, the majority (N 1⁄4 125, 81%) had an abnormal initial US and 68 (54%) had concordant MRCP findings. An abnormal preceding ultrasound was a significant predictor of subsequent abnormal MRCP (p < 0.001). A sizeable number of patients (N1⁄4 50, 40%) with abnormal initial US had additional findings identified at MRCP; the majority (N 1⁄4 33, 66%) with clinically significant findings such as choledocholithiasis, pancreaticobiliary neoplasm, complicated pancreatitis and biliary stricture. 17 patients (33%) had non-clinically significant findings such as uncomplicated pancreatitis while 7 (6%) patients with positive US result had a normal subsequent MRCP. Conversely, of 30 (19%) patients with normal preceding US, 21 (70%) had a concordant negative MRCP. Importantly, 9, (30%) had a discordant MRCP with findings of CBD stones, pancreatitis and cholelithiasis. Overall, concordant results were demonstrated in the majority (N1⁄4 89, 57%) with discordant results in remainder (N1⁄4 66, 43%). However, this latter group included patients with a prior normal US and subsequent abnormal MRCP (N 1⁄4 9, 14%), abnormal US and abnormal MRCP with additional significant findings such as CBD stones or pancreatic neoplasm (N 1⁄4 50, 76%) or abnormal US with subsequent normal MRCP (N 1⁄4 7, 10%). Predictive factors for abnormal MRCP included preceding abnormal US, hyperlipasemia and increased age. Age was the sole predictor of significant US/MRCP discrepancy providing new information impacting subsequent management. MRCP proved useful in confirming the suspected clinical diagnosis and avoiding further investigations. Gallstones are common in Western countries and pose a substantial burden on health care systems. The majority of gallstones remain asymptomatic, however the yearly risk of progression to symptomatic gallstones is 2%. An impacted gallstone in the gallbladder neck or cystic duct results in intense pain-attacks, often associated with nausea and vomiting. After a first episode of gallstone-associated pain, the risk of acute cholecystitis, cholangitis and pancreatitis increase from