Assessing the Relationship Between MR Elastography Liver Stiffness and Histologic Liver Fibrosis in Children and Young Adults With Autoimmune Liver Disease 

Introduction 

A study conducted by Cincinnati Children’s Hospital Radiology’s Jonathan R. Dillman, MD, MSc, and Andrew T. Trout, MD, that was featured in the American Journal of Roentgenology (July 3, 2024) explores the relationship between MR elastography (MRE) liver stiffness and histologic liver fibrosis in children and young adults with autoimmune liver disease (AILD). The findings emphasize the importance of noninvasive imaging tools in monitoring liver fibrosis, a key clinical endpoint in the progression of AILD. 

Objectives 

The primary goal of the study was to assess the relationship between MRE liver stiffness measurements and histologic liver fibrosis. Additionally, the study aimed to evaluate the effectiveness of MRE and biochemical-based clinical markers in stratifying the severity of histologic liver fibrosis in children and young adults with AILD. 

Methods 

This study looked at children and young adults with autoimmune liver disease (AILD) from a registry. It included conditions like primary sclerosing cholangitis (PSC), autoimmune sclerosing cholangitis (ASC), and autoimmune hepatitis (AIH). The researchers focused on patients who had both an abdominal MRI scan (including MR elastography, or MRE) and a liver biopsy within six months. 

One analyst measured how stiff the liver was using MRE, while laboratory tests recorded markers of liver fibrosis. A pathologist, who didn’t know the clinical and MRI results, determined the stage of liver fibrosis using the METAVIR scoring system. 

Results 

The study included 46 patients, with an average age of 16.6 years. There were 20 female patients and 26 male patients. Among them, 12 had PSC, 10 had ASC, and 24 had AIH. The average MRE liver stiffness was 2.9 kPa, and there was a strong positive relationship between MRE liver stiffness and METAVIR fibrosis stage (? = 0.68). 

For identifying advanced liver fibrosis: 

• MRE liver stiffness had an AUC of 0.81, with 65.4% sensitivity and 90.0% specificity. 

• APRI had an AUC of 0.72, with 64.0% sensitivity and 80.0% specificity. 

• FIB-4 score had an AUC of 0.71, with 60.0% sensitivity and 85.0% specificity. 

Conclusion 

The study concluded that MRE liver stiffness measurements are associated with histologic liver fibrosis severity. These findings support the use of MRE as a noninvasive method for monitoring liver stiffness, serving as a surrogate for fibrosis, in children and young adults with AILD. 

Clinical Impact 

The incorporation of MRE into clinical practice could significantly enhance the noninvasive monitoring of liver fibrosis in pediatric and young adult patients with AILD, offering a reliable alternative to traditional liver biopsies. 

“While MT elastography is not perfect, and no other imaging or blood test is, it can help to noninvasive stratify patients by the amount of liver scarring and help direct medical and surgical management.” JRD