Edinburgh Imaging

01 May 22. FAPI Fibrosis study anniversary

It has been a year since the first FAPI PET-MR scan took place at the Edinburgh Imaging Facility QMRI, for the study assessing scarring response within the myocardium and vasculature following a heart attack.

Dr Anna Barton and a celebratory cake to mark the one year anniversary of the first FAPI PET-MR scan.
Dr Anna Barton and a celebratory cake to mark the one year anniversary of the first FAPI PET-MR scan.

The FAPI Fibrosis study is an ongoing research project using PET-MR to assess the scarring response within the myocardium & vasculature following a heart attack. The project utilises fibroblast activation protein inhibitor radiolabelled with 68Gallium (68Ga-FAPI) which binds to areas of active scar formation within the body.

In this project, the team will scan patients & healthy volunteers to determine the scarring response in acute & prior established myocardial infarction as well as healthy subjects.

The 21st April 2022 marked the one year anniversary of the first FAPI PET-MR scan, which took place at the Edinburgh Imaging Facility QMRI. Since then, the study team have now scanned 13 patients with acute ST-elevation myocardial infarction, the majority of whom have undergone 4 PET-MR scans at 1,2,4, and 12 weeks following myocardial infarction, as well as 9 patients with prior established myocardial infarction, and 8 healthy volunteer participants.

Studies of other conditions using 68Ga-FAPI PET have commenced, including heart failure with reduced ejection fraction and lung cancer. Several other studies are on the horizon and will begin over the next 6-12 months including aortic stenosis and heart failure with preserved ejection fraction.

The FAPI Fibrosis study is in collaboration with NHS Lothian Radiopharmacy, who have worked hard to finesse the production method of 68Ga-FAPI. Their findings have allowed greater radiochemical yield to be generated which has allowed the UoE study team to reliably perform 2 PET-MR scans from every batch of 68Ga-FAPI.

Dr Anna Barton explains: On several occasions we have performed 3 PET scans using a single vial of 68Ga-FAPI, with one of the scans being PET-CT and the remainder PET-MR. This is a massive achievement involving exemplary levels of co-ordination, organisation, and teamwork between radiopharmacy, the radiography team, the researchers, and of course the study participants. Scheduling and scanning with this efficiency is a major cost-saver, and also allows recruitment to proceed smoothly for my own study as well as my colleagues. I think this is probably what I am most proud of over the past year; initially we thought we would struggle to even scan 2 cases with one vial of FAPI!

The next steps for the study are to continue to recruit and scan participants with acute and prior established myocardial infarction as well as healthy volunteer participants (those aged 50 years or over with no known heart disease). The study team have also begun to perform the final study visit which is a cardiac MR 12 months after the heart attack for those recruited with acute myocardial infarction. The team hope to complete recruitment for participants with acute myocardial infarction over the coming months.

Dr Barton, Clinical Research Fellow and leading the FAPI fibrosis study has recently been awarded a Fellowship position at Cedars Sinai Medical Center, Los Angeles, which will run for 6 months starting in August 2022. Dr Barton will be afforded the incredible opportunity to work with Dr Dan Berman and his team of foremost PET imaging experts to optimise the image analysis process for myocardial fibrosis imaging with 68Ga-FAPI. Dr Barton will return to Edinburgh in early 2023.

 

Fused 68Ga-FAPI positron emission tomography (PET) & cardiovascular magnetic resonance (CMR) of inferior wall ST-elevation myocardial infarction (MI). Apical 4 chamber view used with PET signal demonstrates intense 68Ga-FAPI uptake not only within the inferior wall (maximum tissue to background ratio [TBRmax] 3.4) but also the right ventricular free wall (TBRmax 2.4), suggesting ongoing right ventricular scarring therefore involvement in the index MI.
Fused 68Ga-FAPI positron emission tomography (PET) & cardiovascular magnetic resonance (CMR) of inferior wall ST-elevation myocardial infarction (MI). Apical 4 chamber view used with PET signal demonstrates intense 68Ga-FAPI uptake not only within the inferior wall (maximum tissue to background ratio [TBRmax] 3.4) but also the right ventricular free wall (TBRmax 2.4), suggesting ongoing right ventricular scarring therefore involvement in the index MI.
We asked Dr Barton her thoughts on the study’s progress over the past year and where she hopes it will lead to.

"It has been a privilege to have worked with NHS radiopharmacy and the Edinburgh Imaging Facility team over the past 12 months to commence and continue this challenging but exciting PET imaging study. I am so proud of the all the progress we have made in terms of setting up the tracer, commencing my own scanning, and supporting colleagues to commence their 68Ga-FAPI studies.

I am particularly grateful to all the patients and healthy volunteer participants who have given up their own time to take part in the FAPI Fibrosis study. It has recently been particularly rewarding to see the first participants return for their 12-month follow up and to hear how they have been getting on.

Reviewing the initial results, I am confident that 68Ga-FAPI PET-MR will teach us lots about the scarring process within the myocardium as well as the remainder of the cardiovascular system, something that remains incompletely understood. One example is that many cases have demonstrated right ventricular FAPI uptake. Existing evidence would suggest that the right ventricle is involved in only around 1 in 5 heart attacks affecting the inferior wall, but we have identified FAPI uptake in a far greater proportion of similar cases than this suggesting this is more common (see figure). Imaging myocardial scar outside the left ventricle has always been challenging and it is very exciting indeed to see FAPI appear to overcome the issues encountered by other currently fibrosis detection techniques including late gadolinium enhancement and T1 mapping.

68Ga-FAPI PET appears to be the first non-invasive measure of myocardial fibrosis activity which is very exciting. I am very proud to be contributing to the evidence base for this exciting technique through this collaborative project"

 

 

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It has been a year since the first FAPI PET-MR scan took place at the Edinburgh Imaging Facility QMRI, for the study assessing scarring response within the myocardium and vasculature following a heart attack.

@EdinUniMedicine @EdinUniCVS @TheBHF @BHFScotland @EdRadiopharmacy @AnnaKateBarton @MarcDweck @EdinUniREA @TzolosEvangelos