Work

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

Year: 2025

Type: article

Abstract: Purpose 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 19 F‐labeled immune cells. The high Larmor frequency of 19 F (∼95% of that for 1 H‐nuclei) leads to similar technical hurdles in acquiring MR images at UHF that originate from the heterogeneity of B 1 + . We aimed to develop a system of transmit/receive (Tx/Rx) arrays exploiting parallel transmit (pTX) technology for B 1 + ‐shimming to acquire a combination of high‐quality anatomical 1 H MR‐images of a pig heart and 19 F images of labeled immune cells at 7T. Method The 16‐element twin‐arrays for 1 H and 19 F nuclei were designed using electromagnetic simulations with a focus on optimal B 1 ‐shimming and g‐factor in the region of the pig heart. pTX support allows for the subject‐specific B 1 ‐shimming for 1 H cardiac MRI and transfer of settings for the B 1 ‐shimming to the 19 F twin‐array. Results 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 B 1 + shimming setting between the 1 H to 19 F 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 19 F‐labeled immune cells in the heart of the pig was demonstrated both in‐vivo and ex‐vivo. Conclusion The 7T MRI of perfluorocarbon‐labeled immune cells in a large‐animal myocardial infarction model becomes feasible using a novel dedicated twin‐arrays system.

Source: Magnetic Resonance in Medicine

DOI: 10.1002/mrm.70105