Magnetic resonance evaluations of biliary malignancy and condition at high-risk for biliary malignancy: Current status

Table 1 Characteristics of magnetic resonance of each diseaseson

	MR characteristics	Differential diagnosis	Comparison to other modalities	Sensitivity and specificity	Pitfall of MRI
PSC	Diffuse stricture and/or beaded appearance of the bile duct on MRCP	Cholangitis, Cholangiocarcinoma	ERCP is considered the standard method. MRCP is considered being sufficient for diagnosis of PSC	High sensitivity and very high specificity	It is often difficult to differentiate malignant tumors from PSC
Cholan- giocarci- noma			MRI with MRCP is usually considered the modality of choice in the diagnosis of cholangiocarcinoma	Diagnosis of biliary stenosis by MRCP is high sensitivity and specificity. The ability of differentiation between benign obstruction and malignant is low	Minimal invasion along the mucosa and in the perineural space is difficult to diagnose
Intrahepatic cholangio- carcinoma	The tumor shows an irregular shaped solid mass with peripheral rim enhancement and incomplete concentric pooling of contrast material on dynamic study	Metastasis, Mixed HCC, cholangiocellular carcinoma
Extrahepatic cholangio- carcinoma	The most common pattern of the tumor growth is focal infiltration of the ductal wall or the periductal-infiltrating type, resulting in focal strictures	PSC, cholangitis (IgG4, infection, AIDS), sarcoidosis
Gallbladder carcinoma	In the diffusely infiltrative type, the tumor appears as a large solid mass in the gallbladder fossa In the polypoid and mural thickening types, lesion more than 10 mm in diameter or which enhance after intravenous contrast material, are usually malignant	Polyp, adenomyomatosis, xanthogranulomatous cholecystitis, chronic cholecystitis	Usually, US is used as an initial diagnostic modality As a second step, CT, MRI with MRCP, and /or traditional cholangiography is often used for obtaining additional information	Conventional MRI showed 74% of sensitivity and 68%-83% specificity, while DWI set added to conventional MRI showed high sensitivity and specificity	It is often difficult malignant from benign tumors
Ampullary carcinoma	It is difficult to diagnose because of the small tumor on MRI. DWI has the potential for differentiating malignant from benign ampullary tumors	Cholangiocarcinoma, Pancreas cancer, adenoma, inflammatory diseases, carcinoid	MRI with MRCP is more accurate than CT in differentiating between malignant and benign lesions	High sensitivity (100%) and low specificity (59.1%-63.6%). Adding of DWI to conventional MRI improve specificity	It is often difficult to diagnose because of the small tumor

PSC: Primary sclerosing cholangitis; MRCP: Magnetic resonance cholangiopancreatography; ERCP: Endoscopic retrograde cholangiopancreatography; HCC: Hepatocellular carcinoma; MRI: Magnetic resonance imaging; US: Ultrasonography; CT: Computed tomography.