# Multi-institutional MRI-based radiomic pilot study to measure the variations between scanner vendors and imaging sessions

## TL;DR

This study uses a 3D radiomic phantom to assess how MRI scanner differences affect radiomic feature consistency across multiple institutions.

## Contribution

The study introduces a standardized 3D radiomic phantom to evaluate scanner and sequence variability in multi-institutional MRI studies.

## Key findings

- Grid-shaped objects showed better radiomic feature reproducibility compared to egg-shaped objects.
- GE scanners demonstrated better reproducibility than other scanners tested.
- ViewRay scanners showed high consistency with the TrueFISP sequence, with median CV <10%.

## Abstract

Multi-institutional clinical trials frequently use MRI imaging for critical decisions and guidance for medical treatments. Collecting and analyzing images produced by various MR vendors and models is quite difficult since image quality can be highly variable. No unifying quality control targeting protocol studies exists to ensure MRI images used in that study are comparable. This project will investigate variations between imaging sessions and between various scanners using radiomic parameters from prototype MRI QA phantom.

To develop a 3D radiomic phantom for quantifying radiomic feature consistency between MRI scanners across multi-institutions.

The prototype phantom consists of five 3D-printed objects (3 grid and 2 egg-shape) using Polylactic Acid (PLA) with/without 20% wood particles placed in a water container. The grid objects consisted of PLA scaffolding with 245 cubic voids (flood-filled by water) stacked in 7rows x 7columns x 5layers with volumes of 3x3x3 mm3 or 5x5x5 mm3, and scaffolding thickness of 1mm or 2mm. The egg-shaped objects are 5cm long with a 2cm or 4cm maximum diameter, filled with vitamin D3-capsules and olive-oil. It was scanned 10 times using T1- and T2-weighted sequences on Philips (1.5T Elekta Unity), GE (1.5T, Signa Artist), Siemens (1.5T MAGNETOM Sola), and Philips (1.5T Ingenia) across four institutions. TrueFISP and T2w sequences were used on ViewRay (0.35T MRIdian) scanners at two institutions. Per object, 107 radiomic features were extracted using the Pyradiomics extension in 3D Slicer. Coefficients of Variation (CV) of individual radiomic features were compared across 10 scans acquired on each scanner and used to compare radiomic feature consistency between objects and MRI scanners.

The radiomic feature consistency varied across objects with less reproducibility for the egg-shaped objects and more reproducibility for the grid objects, with slightly better reproducibility for T1w than T2w sequences. The GE scanner demonstrated better reproducibility than the other scanners. Both ViewRay scanners showed consistency for acquisitions with the TrueFISP sequence; the median CV of 107 radiomic features between objects was <10%). The consistency was summarized in a heat map.

Some radiomic features showed significant intra-scanner variations. This study demonstrated that a standardized radiomic phantom is required to characterize individual scanners and MR sequences for establishing the baseline of radiomic features, which could be important for multi-institutional radiomic studies using MRI.