Pitfalls in MR Cholangiopancreatographic Interpretation

Abstract

Magnetic resonance (MR) cholangiopancreatography (MRCP) is widely used in the evaluation of pancreatobiliary disorders. However, numerous related pitfalls may simulate or mask pancreatobiliary disease. Maximum-intensity-projection (MIP) reconstructed images completely obscure small filling defects and may demonstrate respiratory motion artifacts. T2 weighting may vary with different MR imaging sequences and influence MRCP findings. Incomplete imaging may create confusion regarding ductal anatomy or disease. Furthermore, MRCP yields only static images and thus may fail to depict various anomalies. Limited spatial resolution makes differentiation between benign and malignant strictures with MRCP alone extremely difficult. Susceptibility artifacts may be caused by metallic foreign bodies or gastric-duodenal gas. Fluid accumulation may produce a pseudolesion or pseudostricture, although changing the imaging angle or section thickness may be helpful. Pneumobilia may be misinterpreted as bile duct stones, and true stones may be overlooked. Pulsatile vascular compression can cause pseudo-obstruction of the bile duct. Use of both source and MIP reconstructed images obtained from different angles can help avoid cystic duct-related pitfalls. Repeat MRCP or conventional MR imaging can help avoid pitfalls related to the periampullary region. Segmental collapse of the normal main pancreatic duct may be misinterpreted as stenosis, but administration of secretin is helpful. An awareness of these pitfalls and possible solutions is crucial for avoiding misinterpretation of MRCP images.

Use of carbon dioxide as negative contrast agent for magnetic resonance cholangiopancreatography

“…It allows obtaining images of the pancreaticobiliary similar to the endoscopic retrograde pancreatography (ERCP) without the morbidity associated with the complications resulting from diagnostic ERCP [12][13][14] . Although MRCP has been shown to be accurate in the diagnosis of choledocholithiasis, malignant biliary obstruction and other congenital biliary tract anomalies, awareness of several potential pitfalls is crucial to avoid inappropriate interpretation [6] . High signal intensity from the intestinal fluids superimposed on the biliary tract is one of the pitfalls that interfere with the interpretation (Figure 1).…”

“…Lastly, the CO2 might enter the papilla of Vater in patients with incompetent papilla. This would subsequently lead to pneumobilia which may mimic choledocholithiasis [6] .…”

“…With the use of thin-section singleshot fast-spin echo sequences and thick-section heavily T2-weighted sequences, MRCP can demonstrate the anatomy of the biliary tract, pancreatic duct (PD) and gallbladder, since the fluid within them serves as an intrinsic contrast medium [4] . However, high signal intensity from intestinal fluids would decrease the quality of MRCP images due to superimposition with the biliary tract [4][5][6] . Therefore, how to…”

Obstetric MRI

“…In cases where ductal stones are of concern, MR cholangiography offers 90% sensitivity for detection of common duct stones (50). This can be performed with thick-slab, heavily T 2 -weighted sequences and with thin-slice axial sequences to ensure that artifacts are not misinterpreted as stones (51). Stones are visualized as hypointense filling defects with respect to the adjacent hyperintense bile on T 2 -weighted imaging.…”

O papel da colangiografia por ressonância magnética na avaliação da anatomia biliar em doadores de transplante hepático intervivos

“…As previously reported, the utilization of MR cholangiography with specific contrast agents for studying the biliary tract, as well as further investigation about the utilization of paramagnetic contras agents such as gadobenate dimeglumine have contributed for improvement of the method. Recently, single-shot fast spin echo sequences were adopted as a standard method for MR cholangiography (26) , and new sequences such as half Fourier RARE have demonstrated technical advances, allowing imaging of the whole biliary tract during a single 18-second breath-hold (27) . Maybe the utilization of the described sequences, if available, could result in better images as those already reported by some authors (9,11) .…”