3D MRE: More Precise for Measuring Liver Stiffness in Adults with Severe Obesity
Technique offers better precision with modest tradeoff in technical failure rate
In adults with severe obesity, 3D MR elastography (MRE) offers more precise liver stiffness measurements than conventional 2D MRE, but this precision comes with a slightly higher failure rate, according to a recent Radiology study.
The findings from the study have implications for patients with metabolic dysfunction-associated steatotic liver disease (MASLD), the most common cause of chronic liver disease.
If not properly treated, MASLD may progress to metabolic dysfunction-associated steatohepatitis (MASH), a more advanced form of liver disease that may lead to fibrosis, cirrhosis or end-stage liver disease.
An intermediate stage, known as pre-fibrotic MASH, carries an increased risk of progression to cirrhosis and other serious liver complications. With two recently approved therapies now available for this condition, accurate identification of these patients is more important than ever.
While accurate staging is critical, liver biopsy remains the gold standard for diagnosing MASH. Yet, its invasive nature has driven interest in noninvasive alternatives such as MRE, which quantifies liver stiffness as a biomarker of fibrosis.
However, in patients with severe obesity, the performance of conventional ‘2D’ MRE might degrade—a key concern given obesity is frequently associated with MASLD and fibrotic MASH.
“Whereas conventional ‘2D’ MRE captures wave motion across a single section, the newer 3D MRE technique captures the wavefield over the entire liver by encoding motion of sheer waves in each of three orthogonal directions, hence ‘3D’,” said Scott Reeder, MD, PhD, a radiologist at the University of Wisconsin-Madison.
To evaluate this, Dr. Reeder and colleagues evaluated MRE performance in patients with severe obesity who were undergoing weight loss surgery.
The study was performed at both the University of Wisconsin-Madison and the University of California, San Diego (UCSD) together with UCSD radiologist and co-principal investigator Claude B. Sirlin, MD.
An Across-the-Board Advantage
During the study, participants were imaged at multiple time points using both 2D and 3D MRE. The study established same-day test-retest repeatability for both 2D and 3D MRE using a 3T system. It also evaluated reproducibility across different days at 1.5 T and 3T, as well as reproducibility between field strengths.
The study also quantified the precision of 3D MRE-derived viscoelastic parameters (liver stiffness, storage modulus, loss modulus, damping ratio).
Dr. Reeder and colleagues found that compared to 2D MRE, 3D MRE had better repeatability, superior between-field-strength reproducibility and superior between-day reproducibility at 3.0 T for liver stiffness measurement.
“Our results show a consistent, across-the-board precision advantage of 3D MRE over 2D MRE in severe obesity—an advantage that may reduce stiffness measurement variability near clinically relevant liver stiffness thresholds and help avoid misclassification of patients with an incorrect stage of fibrosis,” Dr. Reeder explained.
3D MRE demonstrated higher precision despite requiring a greater breath-hold burden (six breath-holds) and has a slightly higher failure rate than its 2D counterpart (4.9% vs 2.9%).
“While 3D MRE provides higher precision for liver stiffness compared to 2D MRE, it comes with the tradeoff of a slightly higher technical failure rate and the need for a few more breath-holds,” Dr. Reeder added.
“Our results show a consistent, across-the-board precision advantage of 3D MRE over 2D MRE in severe obesity—an advantage that may reduce stiffness measurement variability near clinically relevant liver stiffness thresholds and help avoid misclassification of patients with an incorrect stage of fibrosis.”
— SCOTT REEDER, MD, PHD
Addressing the Tradeoff
It is uncertain whether 3D MRE’s failure rate remains a barrier to its full integration into clinical practice.
“Like 2D MRE, 3D MRE will need to undergo rigorous validation for precision analysis across sites, equipment manufacturers, and protocol implementations to establish its own repeatability and reproducibility metrics,” said H. Harry Hu, PhD, a professor of radiology and MRI physicist at the Mayo Clinic in Jacksonville, FL.
Dr. Hu, who authored an accompanying commentary to the Radiology study, pointed to the RSNA Quantitative Imaging Biomarker Alliance’s former MRE subcommittee, which validated the precision of 2D MRE through numerous studies and meta-analyses. The subcommittee also established benchmark repeatability and reproducibility metrics that radiologists currently adopt in clinical workflows.
“3D MRE needs to be evaluated under similar precision frameworks before it can be widely adopted globally,” Dr. Hu noted.
Don’t Abandon 2D MRE Just Yet
Despite 3D MRE’s superior precision, Dr. Reeder said radiologists shouldn’t discard 2D MRE just yet.
“3D MRE may be better suited for settings where maximal precision is critical, such as the longitudinal monitoring of therapeutic response,” Dr. Reeder explained. “2D MRE may be an adequate and practical alternative when 3D MRE is either unavailable or there is concern for potential technical failure.”
For example, 2D MRE might be the preferred option when imaging patients with high iron overload in the liver or those who cannot hold still or perform the required breath-hold.
Finding the 3D MRE Niche
While recognizing when to and when not to employ 3D MRE is critical to its clinical adoption, the real breakthrough may happen when its advantage is shown not in just quantifying liver stiffness and fibrosis in obese subjects, but also in characterizing other organs.
“A new method can be more accurate and precise, but if it doesn’t change a patient's clinical management after imaging, it may not add value to the clinical workflow,” Dr. Hu said.
This is why Dr. Hu emphasized the need for additional research focused on proving 3D MRE’s worth in applications that 2D MRE or other MRI techniques cannot currently address. “It needs to find its own niche where radiologists and referring physicians can easily recognize its added value,” he concluded.
For More Information
Access the Radiology study, “Comparative precision of 3D-MRE and 2D-MRE for measurement of liver stiffness in adults with severe obesity,” and the related editorial, “Improving the Precision of Measuring Liver Stiffness with Three-Dimensional MR Elastography.”
Read previous RSNA News stories on liver fibrosis imaging: