Magnetic resonance elastography measured shear stiffness as a biomarker of fibrosis in pediatric nonalcoholic fatty liver disease

Abstract

Magnetic Resonance Elastography (MRE) is promising for non-invasive assessment of fibrosis, a major determinant of outcome in nonalcoholic fatty liver disease (NAFLD). However, data in children are limited. Study aims were to determine accuracy of MRE for detection of fibrosis and advanced fibrosis in children with NAFLD, and to assess agreement between manual and novel automated reading methods. We performed a prospective, multi-center study of 2D-MRE in children with NAFLD. MR-elastograms were analyzed manually at 2 reading centers and using a new automated technique. Analysis using each approach was done independently. Correlations were determined between MRE analysis methods and fibrosis stage. Thresholds for classifying the presence of fibrosis and of advanced fibrosis were computed and cross-validated. In 90 children with mean age of 13.1 ± 2.4 years, median hepatic stiffness was 2.35 kPa. Stiffness values derived by each reading center were strongly correlated with each other (r=0.83). All three analyses were significantly correlated with fibrosis stage (center 1, ρ=0.53; center 2, ρ=0.55; and automated analysis, ρ=0.52; p<0.001). Overall cross-validated accuracy for detecting any fibrosis was the same for all methods: 72.2% (61.8 – 81.1). Overall cross-validated accuracy for assessing advanced fibrosis varied by method: 88.9% (80.5% – 94.5%) for center 1, 90.0% (81.9% – 95.3%) for center 2, and 86.7% (77.9 – 92.9) for automated analysis. Conclusions 2D-MRE can estimate hepatic stiffness in children with NAFLD. Further refinement and validation of automated analysis techniques will be an important step in standardizing MRE. How to best integrate MRE into clinical protocols for the assessment of NAFLD in children will need prospective evaluation.

Diagnostic Performance of MR Elastography for Liver Fibrosis in Children and Young Adults with a Spectrum of Liver Diseases

“…Although MR elastography is used in pediatric and young adult patients, the data to support its use in this population are currently limited. Some of the larger, primarily adult, studies have included pediatric and young adult subjects, but to date there have only been two primary pediatric studies (6,7). Those studies showed good diagnostic performance of MR elastography for identification of fibrosis in pediatric patients and support the use of MR elastography.…”

Magnetic resonance elastography of liver and spleen: Methods and applications

“…17 However, many recent reports rely on a single encoding direction. [18][19][20][21][22][23][24][25][26] For gradient echo sequences, the absence of refocusing pulses makes it necessary to acquire reference phase maps for removing systematic phase errors. This is achieved by acquiring a non-encoded reference scan, 27 by timing the encoding gradients on alternating lobes of the acoustic motion, 28 or by acquiring a second dataset with an opposed motion encoding gradient polarity.…”

“…Multiple studies and meta-analyses have shown that MRE has high diagnostic performance for diagnosing advanced fibrosis in NAFLD with AUROCs > 0.90 24,26,101,102,104,[143][144][145][146] (see Table 4 on salient MRE findings in NAFLD populations). The diagnostic performance of MRE for diagnosing advanced fibrosis in NAFLD is higher than that of ultrasound elastography and serum biomarkers.…”

Methods to improve the noninvasive diagnosis and assessment of disease severity in children with suspected nonalcoholic fatty liver disease (NAFLD): Study design

“…While MRE has somewhat comparable accuracy to ultrasound-based elastography, it has some significant drawbacks such as cost and increased test time. 52 And though it’s becoming more widely available, MRE is still performed only at specialized centers, which limits accessibility to relatively few f patients.…”