Post-cholecystectomy syndrome (PCS) is defined as a complex of heterogeneous symptoms, consisting of upper abdominal pain and dyspepsia, which recur and/or persist after cholecystectomy. Nevertheless, this term is inaccurate, as it encompasses biliary and non-biliary disorders, possibly unrelated to cholecystectomy. Biliary manifestations of PCS may occur early in the post-operative period, usually because of incomplete surgery (retained calculi in the cystic duct remnant or in the common bile duct) or operative complications, such as bile duct injury and/or bile leakage. A later onset is commonly caused by inflammatory scarring strictures involving the sphincter of Oddi or the common bile duct, recurrent calculi or biliary dyskinesia. The traditional imaging approach for PCS has involved ultrasound and/or CT followed by direct cholangiography, whereas manometry of the sphincter of Oddi and biliary scintigraphy have been reserved for cases of biliary dyskinesia. Because of its capability to provide non-invasive high-quality visualisation of the biliary tract, magnetic resonance cholangiopancreatography (MRCP) has been advocated as a reliable imaging tool for assessing patients with suspected PCS and for guiding management decisions. This paper illustrates the rationale for using MRCP, together with the main MRCP biliary findings and diagnostic pitfalls.

Purpose:To investigate the relevance of increasing b-values in evaluating liver fibrosis through the agreement of two diffusion-weighted (DW) sequences. Materials and Methods:A total of 29 cirrhotic patients and 29 healthy volunteers were studied on a 1.5T system. Two single-shot spin-echo echo-planar sequences were acquired using sets of increasing b-values: 0, 150, 250, and 400 seconds/mm 2 (first sequence: DW1a) and 0, 150, 250, 400, 600, and 800 seconds/mm 2 (second sequence: DW2a). Apparent diffusion coefficients (ADCs) of the hepatic parenchyma were calculated on ADC maps. Noisescaled single-point ADCs were calculated for each sequence from b ϭ 400 seconds/mm 2 .Results: ADCs resulted significantly lower in cirrhotic patients compared to controls using both DW1a (mean 1.14 Ϯ 0.20 ϫ 10 2 /second vs. 1.04 Ϯ 0.18 ϫ 10 Ϫ3 mm 2 /second; P ϭ 0.0089). DW1 and DW2, respectively significantly differed in diagnostic performance at receiver operating characteristic (ROC) curve analysis (P ϭ 0.003), showing AUCs of 0.93 (sensitivity 89.7%, specificity 100%) and 0.73 (sensitivity 62.1%, specificity 79.3%), respectively. Noise-scaled single-point ADCs showed a progressive convergence to similar values in cirrhotic and healthy livers at b ϭ 800 seconds/mm 2 (1.12 Ϯ 0.27 ϫ 10 Ϫ3 mm 2 /second vs. 1.13 Ϯ 0.17 ϫ 10 Ϫ3 mm 2 /second). Conclusion:A DW sequence is accurate in assessing liver fibrosis using intermediate (400 seconds/mm 2 ) rather than high (800 seconds/mm 2 ) maximum b-values, but after proper recalculation of ADCs the effects of perfusion rather than diffusion should be considered responsible for the higher accuracy at lower b-values.

Incidental pancreatic cysts represent a frequent finding at MRCP, correlating positively with increasing age, and negatively with biliary autoimmune disease. Cysts more frequently present with IPMN-like pattern.

The most accurate indicator of hepatic arterial stenosis or thrombosis was a change in the spectral waveform to a tardus-parvus pattern, with 91% sensitivity and 99.1% specificity. Among the other parameters, an increase of the SAT value (> 0.08 second), when associated with the morphologic modification of the systolic peak, is a more reliable parameter than the RI for early detection of artery stenosis, especially when the type of anastomosis is unknown.

Orthotopic liver transplantation (OLT) represents a major treatment for end-stage chronic liver disease, as well as selected cases of hepatocellular carcinoma and acute liver failure. The ever-increasing development of imaging modalities significantly contributed, over the last decades, to the management of recipients both in the pre-operative and post-operative period, thus impacting on graft and patients survival. When properly used, imaging modalities such as ultrasound, multidetector computed tomography, magnetic resonance imaging (MRI) and procedures of direct cholangiography are capable to provide rapid and reliable recognition and treatment of vascular and biliary complications occurring after OLT. Less defined is the role for imaging in assessing primary graft dysfunction (including rejection) or chronic allograft disease after OLT, e.g., hepatitis C virus (HCV) recurrence. This paper: (1) describes specific characteristic of the above imaging modalities and the rationale for their use in clinical practice; (2) illustrates main imaging findings related to post-OLT complications in adult patients; and (3) reviews future perspectives emerging in the surveillance of recipients with HCV recurrence, with special emphasis on MRI.