Welcome to the Fall 2023 newsletter of the Cardiac Diffusion SIG!

It’s been a hectic quarter with SCMR and ISMRM abstract deadlines that will have kept many of us busy. We would like to say a special thank you those who have generously given their time and expertise to contribute to the SIG. Please find latest updates below. If you have any questions or would like to get more involved, please feel free to get in touch with us. Everyone is very welcome to join in building up the SIG together.

Kevin and Irvin

kevin.moulin@cardio.chboston.org

i.teh@leeds.ac.uk

1.    Call for Nominations

A Call for Nominations for a new Vice-Chair of the SIG will be opened at our next meeting in end Nov. The position is for a 3-year term, with one year each serving as Vice-Chair, Chair and Past-Chair. We will aim to follow the following timeline:

-       The call for Nomination will be open throughout the month of December

-       The election will be held online through the SCMR website during January 2024.

-       The results of the election will be announced during the annual SCMR conference in London in Jan 2024.

The two main criteria for being elected are 1) Having an active SCMR membership and 2) Being involved in the field of cardiac diffusion MRI.  Please remember to renew your SCMR membership if it has expired. Full details of the Call for Nominations will be provided at our next SIG meeting.

One of the core mission of the SIG is inclusivity, we strongly encourage persons from different backgrounds e.g. age, gender, race, sexual orientation, seniority, geographical location and disability status, to run / be nominated for the governing and other committees.

2.    Website/Archive

We are in the process of setting up a website for the SIG! The plan is to include scientific and educational material. We hope to be able to show you an early draft of the website during the next online meeting.

We are still in the process of compiling a list of publications relevant to the cardiac diffusion field that will be shared to the community!

3.    Social Media

We are in the process of setting up and testing an X/Twitter account. This effort has been led by Camila Munoz, kudos for the initiative and enthusiasm!

4.    Scientific Program

Following discussion of the Scientific sub-committee, the SIG proposes a multi-centre investigation of repeatability and reproducibility in cardiac DTI. This would be a travelling and non-travelling volunteer study, where participants are scanned with standardized and/or customized cardiac DTI, and data analyzed at single/multiple sites. The primary objective is to quantify variation in data arising from relevant factors such as site/operator/scanner, acquisition methods and post-processing pipeline. The intention is to conduct this study starting in 1^st half of 2024.

We are currently in the planning stage, and would like to consult with SIG members on the study design. Please see details of the study in Annex A, and send any questions or feedback to Kevin/Irvin by 17 Nov 2023. Thank you.

5.    Sub-committees

A special thank you to those who have volunteered to serve on the sub-committees, including (in no particular order) Iva Minga, Christopher Nguyen, Jurgen Schneider, Maryam Afzali, Daniel Ennis, Camila Escobar, Cyril Tous, Nahla Elsaid, Ariel Hannum and Sam Coveney. Your time and expertise is greatly valued. If anyone would like to get involved in a sub-committee (Archive, Communications, Education, Scientific, Website & Workshops), you are more than welcome to get in touch with us.

6.    Next Meeting:

The next scheduled virtual meeting will be:

30 Nov 2023 (Thu), 8.00 – 9.30pm (PST) / 11.00 – 12.30pm (EST) / 3.00 – 4.30pm (UTC)

Please keep your diaries free. An invitation and agenda will be sent beforehand. We hope to see you at our upcoming online meeting.

Annex A:  “Multi-centre investigation of repeatability and reproducibility in cardiac DTI in healthy volunteers” from SIG Scientific Sub-committee, 26 Oct 2023

Background

Cardiac diffusion MRI is a a fast-emerging area in myocardial tissue characterisation.There exists a wide range of reported DTI metrics in the literature (Moulin et al, 2023). This will be influenced by the subject cohort e.g. health vs disease. Other potential sources of variation include differences in sites/operators/scanners, acquisition and post-processing methods. This variation needs to be better understood to support clinical validation of the technique.

Early work has evaluated reproducibility in a ten-site study in isotropic phantoms (Teh et al, 2022), and in a two-site study in healthy volunteers (Tunnicliffe et al, 2014).

In this study, we propose a broad multi-centre collaborative effort to evaluate inter-site variation due to differences in (i) site/operator/scanner, (ii) acquisition and (iii) post-processing methods. The results will guide interpretation of the cardiac diffusion MRI literature, and help to refine strategies for standardisation and harmonisation of protocols.

Specific Aims

To evaluate variation in DTI data due to differences in (i) site/operator/scanner, (ii) acquisition and (iii) post-processing methods.

To identify the greatest source(s) of variation, and to inform strategies for optimisation, standardisation and harmonisation of cardiac DTI.

To inform power calculations and data interpretation in future larger studies, in particular, where different sites/methods are used.

To provide reference data (same subject at multiple sites) to support future studies e.g. larger multi-centre studies, developing techniques for harmonisation of dMRI data, etc.

Methods

To maximise inclusion of sites, the study has been designed with two phases: acquisition and post-processing (See Figure 1). Sites may choose to participate in either or both phases.

PHASE 1: ACQUISITION

There will be two branches to the acquisition, with sites participating using either (i) travelling or (ii) non-travelling volunteers. The use of both travelling and non-travelling volunteers will help to elucidate the contribution of inter-subject differences to variation in DTI. Inter-site/scan variation can be evaluated in the same volunteer in the travelling volunteers cohort, whilst the involvement of non-travelling volunteers will maximise inclusivity and participation by sites and minimise costs for travel.

Cardiac DTI scans will be run using standardised (identical sequences) and harmonised (different sequences, similar parameters) sequences, and repeated in the same session. Data will be anonymised, blinded and for data analysis.  A travelling phantom will be used for data quality checks.

PHASE 2: POST-PROCESSING

Data acquired in the acquisition phase will be made available to participating sites. Post-processing sites will reconstruct DTI parameter maps from DICOM data. The DTI parameter maps will be blinded and evaluated by an independent site.

Sample size calculation

A sample size of n = 12 travelling volunteers would enable estimation of limits of agreement in a Bland-Altman plot to within +/-1 standard deviation of the differences between measurements. Based on previous work (Tunnicliffe et al, 2014), this would be around +-10% of the mean for both MD and FA, and applies to the comparison of any two sites, or two scans on the same person. Inclusion of additional sites and/or subjects, would improve precision of the estimate over and above this level, however sample size will be limited due to practical reasons. The non-travelling volunteer group could be 12 or greater, depending on individual site resources.

For context, similar studies in brain involving travelling volunteers used:

Travelling volunteers = 14, scanners = 3, acquisition methods = 5 (Tax et al, Neuroimage, 2019)

Travelling volunteers = 3, scanners = 10 (Cai et al, MRM, 2021)

Travelling volunteers = 9, scanners = 4, scans = 1; Travelling volunteers = 4, scanners = 1, scans = 2 (Only data analysed included; Kurokawa et al, Neuroimage, 2021)

Site Participation

Sites may choose to participate in Phase 1 and/or 2, in any of the following capacities (below). Sites would be asked to confirm ability to meet the relevant requirements (in italics). All participating sites would need to sign a collaboration agreement governing data sharing and usage.

☐ Phase 1: Data acquisition site (Travelling volunteers)

Funding and scanner capacity for N = 12 healthy volunteer scans and N = 1 phantom scan within 3 months (target 1^st half 2024); including setting up  and data quality checks as needed

Able to recruit 12 travelling healthy volunteers for single in-house scan

Able to support travel expenses for 3 healthy volunteers to travel to all travelling volunteer data acquisition sites for scans.

Have ethics covering data acquisition and sharing data with local/international collaborators.

☐ Phase 1: Data acquisition site (Non-travelling volunteers)

Funding and scanner capacity for N ≥ 12 healthy volunteer scans and N = 1 phantom scan within 3 months (target 1^st half 2024); including setting up and data quality checks as needed

Able to recruit ≥ 12 non-travelling healthy volunteers for single in-house scan

Have ethics covering data acquisition and sharing data with local/international collaborators.

☐ Phase 1: Central data analysis

Capacity to analyse datasets (from DICOM to generation of DTI maps) from all sites, and to evaluate, compare and report post-processed data, within 3 months of completion of data acquisition.

☐ Phase 2: Data post-processing site`

Capacity to analyse datasets (from DICOM to generation of DTI maps), within 3 months.

☐ Phase 2: Central data analysis

Capacity to evaluate, compare and report post-processed data from sites, within 3 months.