Gadolinium-based relative contrast enhancement in primary sclerosing cholangitis: additional benefit for clinicians?

Primary Sclerosing Cholangitis: Diagnostic Criteria

Primary sclerosing cholangitis is a chronic cholestatic liver disease characterized by inflammation and fibrosis of intra- and/or extrahepatic bile ducts leading to the formation of multifocal strictures alternated to bile duct dilatations. The diagnosis of the most common subtype of the disease, the large duct PSC, is based on the presence of elevation of cholestatic indices, the association of typical cholangiographic findings assessed by magnetic resonance cholangiography and the exclusion of causes of secondary sclerosing cholangitis. Liver biopsy is not routinely applied for the diagnosis of large duct PSC but is mandatory in the case of suspicion of small duct PSC or overlap with autoimmune hepatitis.

Reporting standards for primary sclerosing cholangitis using MRI and MR cholangiopancreatography: guidelines from MR Working Group of the International Primary Sclerosing Cholangitis Study Group

Primary sclerosing cholangitis (PSC) is a chronic inflammatory disorder affecting the bile ducts and is characterized by biliary strictures, progressive liver parenchymal fibrosis, and an increased risk of hepatobiliary malignancies primarily cholangiocarcinoma (CCA). PSC may lead to portal hypertension, liver decompensation, and liver failure with the need for liver transplantation. Magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) are considered the imaging standard for diagnosis and follow-up in patients with PSC. Currently, there are no universally accepted reporting standards and definitions for MRI/MRCP features. Controversies exist about the definition of a high-grade stricture and there is no widely agreed approach to their management. The members of the MRI working group of the International Primary Sclerosing Cholangitis Study Group (IPSCSG) sought to define terminologies and reporting standards for describing MRI/MRCP features that would be applied to diagnosis and surveillance of disease progression, and potentially for evaluating treatment response in clinical trials. In this extensive review, the technique of MRI/MRCP and assessment of image quality for the evaluation of PSC is briefly described. The definitions and terminologies for severity and length of strictures, duct wall thickening and hyperenhancement, and liver parenchyma signal intensity changes are outlined. As CCA is an important complication of PSC, standardized reporting criteria for CCA developing in PSC are summarized. Finally, the guidelines for reporting important changes in follow-up MRI/MRCP studies are provided. KEY POINTS: • Primary sclerosing cholangitis is a chronic inflammatory disorder affecting the bile ducts, causing biliary strictures and liver fibrosis and an increased risk of cholangiocarcinoma. • This consensus document provides definitions and suggested reporting standards for MRI and MRCP features of primary sclerosing cholangitis, which will allow for a standardized approach to diagnosis, assessment of disease severity, follow-up, and detection of complications. • Standardized definitions and reporting of MRI/MRCP features of PSC will facilitate comparison between studies, promote longitudinal assessment during management, reduce inter-reader variability, and enhance the quality of care and communication between health care providers.

Gadoxetic acid-enhanced MRI in primary sclerosing cholangitis: added value in assessing liver function and monitoring disease progression

PURPOSE

To investigate the added value of gadoxetic acid-enhanced MRI in monitoring liver function and disease progression in patients with primary sclerosing cholangitis (PSC).

METHODS

We retrospectively identified 104 consecutive patients (75 males; mean age 41.98 ± 12.5 years) with confirmed diagnosis of PSC who underwent 227 gadoxetic acid-enhanced MRI examinations between January 2008 and May 2019. Relative enhancement (RE) of the liver was correlated with the results of liver function tests (LFTs), scoring models (Model for End-Stage Liver Disease (MELD) score, Mayo Risk Score (MRS), Amsterdam-Oxford model (AOM)), and qualitative MRI findings. In addition, results were analyzed separately for excretory MRI examinations (n = 164) and nonexcretory examinations (n = 63) depending on excretion of gadoxetic acid into the common bile duct in the hepatobiliary phase (HBP).

RESULTS

There was a significant correlation of RE with MRS (r = - 0.652), MELD score (r = - 0.474), AOM (r = - 0.468), and LFTs (P < 0.001). RE and albumin were significantly higher in the excretory group whereas scoring models, bilirubin, aspartate aminotransferase, alkaline phosphatase, and international normalized ratio were lower (P < 0.001). RE was lower in segments with absent HBP gadoxetic acid excretion into dilated bile ducts, reduced HBP parenchymal enhancement, atrophy, T2 hyperintensity, and bile duct abnormalities (P < 0.001).

CONCLUSION

Relative enhancement of the liver in gadoxetic acid-enhanced MRI can be used to evaluate global and regional liver function and monitor disease progression in patients with PSC. Hepatobiliary phase gadoxetic acid biliary excretion appears to be a reproducible qualitative parameter for evaluating disease severity that can be easily integrated into routine clinical practice.

Magnetic resonance imaging features of small-duct primary sclerosing cholangitis

PURPOSE

To evaluate the biliary tree and hepatic parenchymal findings on magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) in small-duct primary sclerosing cholangitis (SD-PSC).

METHODS

Thirty-nine patients with biopsy-proven primary sclerosing cholangitis (PSC) without any bile duct abnormality on MRCP (n = 15) or ERCP (n = 24) at the time of diagnosis were identified. Follow-up MRCP was available in 36/39 patients (12/15 Baseline MRCP group and 24 Baseline ERCP group). Two radiologists in consensus assessed the MRI/MRCP findings. The baseline MRI/MRCP of 15 SD-PSC patients was compared with MRI/MRCP of 15 normal healthy potential liver donors (Control group). Comparisons were made between SD-PSC patients and the Control group, and between baseline and follow-up MRI/MRCP findings in the SD-PSC patients.

RESULTS

In the 15 Baseline MRCP SD-PSC subjects, the biliary tree was normal with a trend of larger bile ducts compared to the Control group. Periductal enhancement (arterial phase: 70%, 7/10; delayed phase: 90%, 9/10), heterogeneous parenchymal signal on T2-weighted (53%, 8/15) and post contrast-enhanced images (70%, 7/10), and enlarged periportal lymph nodes (73%, 11/15) were frequently present in patients with SD-PSC. Eight (33%) of 24 SD-PSC patients who had normal MRCP at baseline MRCP or initial follow-up MRCP after normal baseline ERCP showed large-duct PSC (LD-PSC) features on follow-up and the 10-year cumulative incidence for progression to LD-PSC rate was 8.5%.

CONCLUSION

SD-PSC patients have a normal biliary tree but frequently have peribiliary enhancement, abnormal parenchymal signal intensity, and periportal lymphadenopathy. One-third shows progression to LD-PSC on follow-up.

Evolving role of magnetic resonance techniques in primary sclerosing cholangitis

Development of non-invasive methods to risk-stratify patients and predict clinical endpoints have been identified as one of the key research priorities in primary sclerosing cholangitis (PSC). In addition to serum and histological biomarkers, there has been much recent interest in developing imaging biomarkers that can predict disease course and clinical outcomes in PSC. Magnetic resonance imaging/magnetic resonance cholangiopancreatography (MRI/MRCP) continue to play a central role in the diagnosis and follow-up of PSC patients. Magnetic resonance (MR) techniques have undergone significant advancement over the last three decades both in MR data acquisition and interpretation. The progression from a qualitative to quantitative approach in MR acquisition techniques and data interpretation, offers the opportunity for the development of objective and reproducible imaging biomarkers that can potentially be incorporated as an additional endpoint in clinical trials. This review article will discuss how the role of MR techniques have evolved over the last three decades from emerging as an alternative diagnostic tool to endoscopic retrograde cholangiopancreatography, to being instrumental in the ongoing search for imaging biomarker of disease stage, progression and prognosis in PSC.