High Relaxivity Contrast Agent for Cardiac MR in the Myocardial Scar Assessment

Myocardial Fibrosis

Elucirem (Gadopiclenol) is a new macrocyclic gadolinium-based contrast agent (GBCA) with high relaxivity indicated for use in adults and children aged 2 years and older for contrast-enhanced magnetic resonance imaging. The product was approved in 2022 by FDA to be used to detect and visualize lesions with abnormal vascularity in the central nervous system (brain, spine and associated tissues) and the body (head and neck, thorax, abdomen, pelvis, and musculoskeletal system). However, given its at least twofold higher relaxivity than other GBCAs, the performance of Elucirem in cardiac MR (CMR) has yet to be demonstrated. The hypothesis for the study: Half dose (0.05mmol/kg) Elucirem is not inferior to double dose (0.2 mmol/kg) Dotarem in the myocardial scar assessment. All participants will be selected from the investigators previous CMR study cohort with double-dose Dotarem T1 mapping and LGE images. Ten participants without scars will be recruited for the Phase I dose evaluation. Five for 0.05 mmol/kg and five for 0.075 mmol/kg. The investigators have identified 15 participants with LGE findings from double-dose Dotarem CMR acquired in the years 2021, 2022, or earlier years. This study was performed in August 2022. The same protocol will be used for single-dose Elucirem.

Elucirem (Gadopiclenol) is a new macrocyclic gadolinium-based contrast agent (GBCA) with high relaxivity indicated for use in adults and children aged 2 years and older for contrast-enhanced magnetic resonance imaging. The product was approved in 2022 by FDA to be used to detect and visualize lesions with abnormal vascularity in the central nervous system (brain, spine, and associated tissues) and the body (head and neck, thorax, abdomen, pelvis, and musculoskeletal system). Based on the investigators previous experience with 0.2 mmol/kg Dotarem, the optimal post-contrast T1 for LGE was when the remote myocardium (i.e. area without scar) had T1 of around 400ms at 12 mins post-contrast. The investigators hypothesize that with 0.05 mmol/kg Elucirem, post T1 will recover to 400 ms faster than 12 minutes after injection. It will likely be between 6 to 10 minutes post-contrast. A serial of T1 mapping will provide the information for timing. However, if myocardial T1 were not reduced short enough or recovers to 400 ms in less than 5 minutes post-contrast with 0.05 mmol/kg Elucirem, that is a sign of inadequate dose. Same evaluation will be performed for 0.075 mmol/kg Elucirem. The investigators hypothesize that if 0.05 mmol/kg falls short, 0.075 mmol/kg should be adequate. Since a single dose (0.1 mmol/kg) of Dotarem is proved to be adequate for LGE in many literatures, less Elucirem should be used to demonstrate its benefit. Study Procedure: It is a non-randomized cohort study. Participants with precious double dose Dotarem CMR will be recruited. The study has two phases. Phase I is to evaluate the optimal dose, 0.05 mmol/kg (N=5) or 0.075 mmol/kg (N=5) by assessing a serial of the myocardial T1 mapping in normal volunteers. T1 mapping will be acquired every 2.5 minutes after injection to 25 minutes post-contrast. Based on the results of Phase I, the optimal dose will be used in the Phase II scar assessment in patients with a scar from a previous double-dose Dotarem study.

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