A tailored passive driver for liver MRE in pediatric patients

Orane Lorton; Seema Toso; Hayat El-Begri Talbi; Mehrak Anooshiravani; Pierre-Alexandre Poletti; Sylviane Hanquinet; Rares Salomir

doi:10.3389/fped.2022.999830

A tailored passive driver for liver MRE in pediatric patients

Front Pediatr. 2022 Dec 7:10:999830. doi: 10.3389/fped.2022.999830. eCollection 2022.

Authors

Orane Lorton^{1

2}, Seema Toso³, Hayat El-Begri Talbi³, Mehrak Anooshiravani³, Pierre-Alexandre Poletti², Sylviane Hanquinet³, Rares Salomir^{1

2}

Affiliations

¹ Image Guided Interventions Laboratory (GR 949), Faculty of Medicine, University of Geneva, Geneva, Switzerland.
² Radiology Division, University Hospitals of Geneva, Geneva, Switzerland.
³ Unit of Pediatric Radiology, Radiology Division, University Hospitals of Geneva, Geneva, Switzerland.

Abstract

Objectives: Magnetic resonance elastography (MRE) is increasingly used in the pediatric population for diagnosis and staging of liver fibrosis. However, the MR-compatible driver and sequences are usually those used for adult patients. Our feasibility study aimed to adapt the standardized adult MRE passive driver and vibrational parameters to a pediatric population.

Methods: We designed an elliptic passive driver shaped on a torus equipped with an elastic membrane and adapted to children's morphologies. As a first step, eight children (aged 8-18 years) were enrolled in a prospective pilot study aiming to determine the threshold vibrational amplitude for MRE using a custom passive driver, based on phase aliasing assessment and the occurrence of signal void artifacts on magnitude MR images. In the second step, the practicality and the consistency of the custom driver were assessed in a further 11 pediatric patients (aged 7-18 years). In the third step, we compared our custom driver vs. the commercial driver on six adult volunteers, in terms of the reliable region of interest area within the acquired MRE slices, the shear wave maps' quality, and measured stiffness values obtained.

Results: Based on pediatric patient data, the threshold vibrational amplitude expressed as percentage of maximum output was found to be 0.4 and 1.1 times the body weight (kg) at 40 and 60 Hz frequencies, respectively. In comparison to the commercial passive driver, the custom driver improved threefold the contact with the body surface, also enabling a more comfortable examination as self-assessed by the volunteers.

Conclusions: Our custom driver was more comfortable for the volunteers and was able to generate more homogenous shear waves, yielding larger usable hepatic area, and more reliable stiffness values.

Keywords: MRE workflow; liver stiffness; patient-specific vibrational excitation; pediatric MRE; toroidal passive driver.

Grants and funding

This study has received funding by PRD “Jeune Chercheur” (PRD 14-2018-II) University Hospitals of Geneva, November 2018. Open access funding was provided by the University Of Geneva.