Non-Invasive MR Elastography Could Provide Alternative to Liver Biopsy in Obese Patients

By MedImaging International staff writers
Posted on 17 Mar 2023

Image: New approaches to 3D MRE sequences could help measure liver fibrosis and inflammation simultaneously in obese patients (Photo courtesy of KCL)

Three-dimensional MR elastography (MRE) scans have the potential to simultaneously assess liver fibrosis and inflammation. However, existing 3D MRE methods present several challenges, such as requiring multiple sequences, each requiring the patient to hold their breath, which can reduce the precision of the liver’s geometric alignment and hinder clinical acceptance. This issue is exacerbated in obese patients, as their high body mass index (BMI) can interfere with the penetration of mechanical waves. To address these challenges, researchers have investigated a new approach that involves a single breath-hold, which obese patients can more easily tolerate and reproduce.

In a technical development study, researchers at King’s College London (KCL, London, UK) have demonstrated how a single 17-second breath-hold successfully reduced the overall MRE sequence acquisition time including multiple slices, wave offsets and motion encodings. For the study, the researchers prospectively enrolled individuals between the period November 2020 and December 2021 and divided them into two groups. Group 1 comprised healthy volunteers (n = 10) who acted as controls to compare the single breath-hold 3D MRE sequence with a multiple–breath-hold 3D MRE sequence. Group 2 comprised liver patients (n = 10) who served as participants to evaluate the clinical feasibility of the single breath-hold 3D MRE sequence in measuring liver fibrosis and inflammation. The controls and participants were scanned at 60 Hz mechanical excitation with the single breath-hold 3D MRE sequence to retrieve the magnitude of the complex-valued shear modulus (|G*| [kPa]), the shear wave speed (Cs [m/s]), and the loss modulus (G" [kPa]). Additionally, the controls were scanned with a multiple–breath-hold 3D MRE sequence for comparison, and the participants had histopathology (Ishak scores) for correlation with Cs and G".

Among the 10 controls, five were female with a mean age and body mass index of 33.1 ± 9.5 years and 23.0 ± 2.1 kg/m2, respectively. Among the 10 participants, eight were female with a mean age and body mass index of 45.1 ± 16.5 years and 33.1 ± 4.0 kg/m2 (obese range), respectively. All the study participants were suspected of having nonalcoholic fatty liver disease. Bland-Altman analysis of the comparison in controls exhibited non-significant differences in |G*|, Cs, and G" below 6.5%, indicating good consensus between the two sequences. For the participants, Cs and G" correlated significantly with Ishak fibrosis and inflammation grades, respectively (ρ = 0.95, P < 0.001, and ρ = 0.84, P = 0.002). Based on the findings, the researchers concluded that the single breath-hold 3D MRE sequence may be effective in measuring liver fibrosis and inflammation in obese patients.

“Non-alcoholic fatty live disease is a health crisis across the globe and evaluating patients in a time efficient fashion is becoming of high importance in medicine,” said Omar Darwish, PhD student, School of Biomedical Engineering & Imaging Sciences. “Liver biopsy is invasive, costly, and accompanied with complications. These could be mitigated by a successful proof of concept in 3D MRE sequencing and warrants a larger clinical study to further evaluate diagnostic accuracy and performance.”

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King’s College London