Non-invasive magnetic resonance elastography accurately measures hepatic stiffness in children with NAFLD

Hepatic stiffness in children with non-alcoholic fatty liver disease (NAFLD), the most common cause of chronic liver disease in children, can be accurately and non-invasively estimated using 2D-magnetic resonance elastography (MRE), although automated analysis techniques need refinement as well as validation, according to results from a recent study published in the journal Hepatology.

“One of the challenges we face when evaluating a child with NAFLD is to determine the severity of their disease. A major component of that assessment is the staging of the amount of scar tissue seen from a liver biopsy. In MAGNET, we demonstrated that 2D MRE could be used to estimate hepatic stiffness (scarring) in these children,” said co-author Jeffrey Schwimmer, MD, professor of pediatrics, UC San Diego School of Medicine, CA. “We also identified a roadmap to help navigate future use of MRE technology. Ultimately, MRE may be most useful for monitoring the progression or improvement in children with NAFLD.”

NAFLD currently affects almost 25% of all adults in the United States, and 5% to 10% of all children, in whom the average age of diagnosis is 12 years.

“One of the challenging parts of evaluating liver disease in children is determining the numeric cut-off for a positive diagnosis of fibrosis. Radiologists and gastroenterologists using MRE should be aware that the interpretation in children may not be the same as in adults. Getting this right has real-world implications,” noted Claude B. Sirlin, MD, professor of radiology, UC San Diego School of Medicine, who co-led the study with Dr. Schwimmer.

The MAGNET (MRI Assessment Guiding NAFLD Evaluation and Treatment) study was the first multi-center study to use non-invasive imaging to assess liver fibrosis in children. Drs. Schwimmer and Sirlin and colleagues sought to assess the accuracy of 2D-MRE in the detection of fibrosis and advanced fibrosis in children with NAFLD. They also studied the agreement between manual and novel automated reading methods.

In all, 90 children (mean age: 13.1 years; median hepatic stiffness: 2.35 kPa) were enrolled and underwent 2D-MRE. MR-elastograms were analyzed at two reading centers, both manually and using a new automated technique. Researchers assessed any correlations between the MRE analysis methods and fibrosis stage, and computed and cross-validated thresholds for classifying the presence of fibrosis and advanced fibrosis.

These researchers found that the stiffness values arrived at by each reading center strongly correlated with each other (r=0.83). All three analyses were significantly correlated with fibrosis stage:

• Center 1: P=0.53;
• Center 2: P=0.55; and
• Automated analysis: P=0.52 (P < 0.001).

For all methods, overall cross-validated accuracy for detecting any fibrosis was the same: 72.2% (61.8-81.1), but overall cross-validated accuracy for assessing advanced fibrosis varied:

• Center 1: 88.9% (80.5%-94.5%);
• Center 2: 90.0% (81.9%-95.3%); and
• Automated analysis: 86.7% (77.9%-92.9%).

This research was supported, in part, by the National Institute of Diabetes and Digestive and Kidney Diseases (DK088925, DK088925-02S1, DK090350), the National Institute of Biomedical Imaging and Bioengineering (EB001981), and the National Center for Advancing Translational Sciences for the Altman Clinical and Translational Research Institute at UC San Diego (UL1RR031980).