# 7T 19F/ 1H MRI with perfluorocarbon‐labeled immune cells in pigs: Pilot results with a dedicated twin‐array system with pTX support

## TL;DR

Researchers developed a new MRI system to track immune cells labeled with perfluorocarbon in pig hearts at 7T, improving the study of cardiac inflammation.

## Contribution

A novel twin-array MRI system with pTX support enables combined 1H and 19F imaging of immune cells in large animals at 7T.

## Key findings

- The twin-array system successfully demonstrated B1+ shimming transfer between 1H and 19F arrays.
- Parallel imaging acceleration up to a factor of 4 was achieved with low g-factors (<1.3).
- 19F MRI of labeled immune cells was successfully demonstrated in vivo and ex vivo in a pig model.

## Abstract

Cardiac inflammation plays a key role in many diseases. However, its underlying mechanisms and progression remain poorly understood. Using an ultra‐high field (UHF) may increase the sensitivity of MRI of inflammatory processes with 19F‐labeled immune cells. The high Larmor frequency of 19F (∼95% of that for 1H‐nuclei) leads to similar technical hurdles in acquiring MR images at UHF that originate from the heterogeneity of B1
+. We aimed to develop a system of transmit/receive (Tx/Rx) arrays exploiting parallel transmit (pTX) technology for B1
+‐shimming to acquire a combination of high‐quality anatomical 1H MR‐images of a pig heart and 19F images of labeled immune cells at 7T.

The 16‐element twin‐arrays for 1H and 19F nuclei were designed using electromagnetic simulations with a focus on optimal B1‐shimming and g‐factor in the region of the pig heart. pTX support allows for the subject‐specific B1‐shimming for 1H cardiac MRI and transfer of settings for the B1‐shimming to the 19F twin‐array.

The twin‐array system was implemented and tested in a pig‐thorax‐‐shaped phantom, in‐vivo in a myocardial infarction pig model, and in an excised heart. A transfer of static B1+ shimming setting between the 1H to 19F arrays was demonstrated. The parallel imaging acceleration of up to a factor 4 was possible with a g‐factor <1.3 for both arrays. The 7T MRI of 19F‐labeled immune cells in the heart of the pig was demonstrated both in‐vivo and ex‐vivo.

The 7T MRI of perfluorocarbon‐labeled immune cells in a large‐animal myocardial infarction model becomes feasible using a novel dedicated twin‐arrays system.