T mapping performance and measurement repeatability: results from the multi-national T mapping standardization phantom program (T1MES).1

Gabriella Captur; Abhiyan Bhandari; Rüdiger Brühl; Bernd Ittermann; Kathryn E Keenan; Ye Yang; Richard J Eames; Giulia Benedetti; Camilla Torlasco; Lewis Ricketts; Redha Boubertakh; Nasri Fatih; John P Greenwood; Leonie E M Paulis; Chris B Lawton; Chiara Bucciarelli-Ducci; Hildo J Lamb; Richard Steeds; Steve W Leung; Colin Berry; Sinitsyn Valentin; Andrew Flett; Charlotte de Lange; Francesco DeCobelli; Magalie Viallon; Pierre Croisille; David M Higgins; Andreas Greiser; Wenjie Pang; Christian Hamilton-Craig; Wendy E Strugnell; Tom Dresselaers; Andrea Barison; Dana Dawson; Andrew J Taylor; François-Pierre Mongeon; Sven Plein; Daniel Messroghli; Mouaz Al-Mallah; Stuart M Grieve; Massimo Lombardi; Jihye Jang; Michael Salerno; Nish Chaturvedi; Peter Kellman; David A Bluemke; Reza Nezafat; Peter Gatehouse; James C Moon;
Abstract
The T Mapping and Extracellular volume (ECV) Standardization (T1MES) program explored T mapping quality assurance using a purpose-developed phantom with Food and Drug Administration (FDA) and Conformité Européenne (CE) regulatory clearance. We report T measurement repeatability across centers describing sequence, magnet, and vendor performance.1Phantoms batch-manufactured in August 2015 underwent 2 years of structural imaging, B and B, and "reference" slow T testing. Temperature dependency was evaluated by the United States National Institute of Standards and Technology and by the German Physikalisch-Technische Bundesanstalt. Center-specific T mapping repeatability (maximum one scan per week to minimum one per quarter year) was assessed over mean 358 (maximum 1161) days on 34 1.5 T and 22 3 T magnets using multiple T mapping sequences. Image and temperature data were analyzed semi-automatically. Repeatability of serial T was evaluated in terms of coefficient of variation (CoV), and linear mixed models were constructed to study the interplay of some of the known sources of T variation.0Over 2 years, phantom gel integrity remained intact (no rips/tears), B and B homogenous, and "reference" T stable compared to baseline (% change at 1.5 T, 1.95 ± 1.39%; 3 T, 2.22 ± 1.44%). Per degrees Celsius, 1.5 T, T (MOLLI 5s(3s)3s) increased by 11.4 ms in long native blood tubes and decreased by 1.2 ms in short post-contrast myocardium tubes. Agreement of estimated T times with "reference" T was similar across Siemens and Philips CMR systems at both field strengths (adjusted R ranges for both field strengths, 0.99-1.00). Over 1 year, many 1.5 T and 3 T sequences/magnets were repeatable with mean CoVs < 1 and 2% respectively. Repeatability was narrower for 1.5 T over 3 T. Within T1MES repeatability for native T was narrow for several sequences, for example, at 1.5 T, Siemens MOLLI 5s(3s)3s prototype number 448B (mean CoV = 0.27%) and Philips modified Look-Locker inversion recovery (MOLLI) 3s(3s)5s (CoV 0.54%), and at 3 T, Philips MOLLI 3b(3s)5b (CoV 0.33%) and Siemens shortened MOLLI (ShMOLLI) prototype 780C (CoV 0.69%). After adjusting for temperature and field strength, it was found that the T mapping sequence and scanner software version (both P < 0.001 at 1.5 T and 3 T), and to a lesser extent the scanner model (P = 0.011, 1.5 T only), had the greatest influence on T across multiple centers.0The T1MES CE/FDA approved phantom is a robust quality assurance device. In a multi-center setting, T mapping had performance differences between field strengths, sequences, scanner software versions, and manufacturers. However, several specific combinations of field strength, sequence, and scanner are highly repeatable, and thus, have potential to provide standardized assessment of T times for clinical use, although temperature correction is required for native T tubes at least.1
Journal JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE : OFFICIAL JOURNAL OF THE SOCIETY FOR CARDIOVASCULAR MAGNETIC RESONANCE
ISSN 1532-429X
Published 07 May 2020
Volume 22
Issue 1
Pages 31
DOI 10.1186/s12968-020-00613-3
Type Journal Article
Sponsorship