Myocardial infarction (MI) and associated morbidity and mortality is one of the major health care problems in western societies. Although novel imaging techniques including magnetic resonance (MR) are now available for MI imaging, tissue characterization with T1 and T2 mapping still lacks the ability to accurately detect and quantify subclinical myocardial remodeling (collagen and elastin deposition) or the presence of inflammatory cells. Inflammation orchestrates the healing of injured myocardium and is thought to have a major impact on myocardial remodeling and function. Previous studies have shown that inflammatory cells can be imaged using ¹⁹F perfluorocarbons(PFCs). As ¹⁹F is present in extremely low concentrations in the body, the measured ¹⁹F signal corresponds to exogenous ¹⁹F-PFCs that have been phagocytosed by inflammatory cells¹. Elastin, a major component of the extracellular matrix(ECM), is upregulated during post-MI remodeling. We have recently shown that elastin can be imaged post-MI using a gadolinium-based elastin-specific MR contrast agent(Gd-ESMA)². Both measurements offer a unique opportunity to simultaneously detect the temporal and spatial evolution of inflammatory response post-MI and to correlate it with functional recovery. The aim of this study was to investigate the recruitment of inflammatory cells into injured myocardium using ¹⁹F-PFCs and to evaluate changes of elastin content in the ECM post-MI using Gd-ESMA. This approach may have great potential for more accurate characterization of early or persistent inflammation and associated diffuse myocardial remodeling at molecular level, and may serve as a new biomarker for monitoring treatment response, predict future cardiovascular events and ultimately improve cardiovascular health.MI was induced in 16 female C57BL/6J mice by permanent ligation of the left anterior descending coronary artery(LAD). In vivo MRI was performed 7, 14 and 21days after surgery using a 3T Philips Achieva system. Animals were placed in prone position on a ¹⁹F/¹H surface coil (diameter=23mm and 33mm). Anesthesia was maintained with 1.5-2% isoflurane in oxygen, and body temperature was maintained using a heating system and a rectal temperature probe. ECG was monitored with two metallic needles placed subcutaneously into the front paws. ¹H and ¹⁹F cardiac ECG-triggered images were acquired after intravenous injection of 0.5mmol/kg of Gd-ESMA and 400mL of ¹⁹F-PFCs, 1 and 48h before the scan, respectively. Following 3D-GRE scout scan, 2D-cine images were acquired in short-axis covering the whole left ventricle(LV). 80-100min after Gd-ESMA injection, a 2D-Look-Locker sequence was used to identify the optimal inversion time(TI) to null healthy myocardium. 3D late-gadolinium-enhancement(LGE) images were acquired in short-axis for visualization of contrast uptake with the following parameters: FOV=35x35x12mm, in-plane resolution=0.3x0.3x1mm, slices=12, TR/TE=6.4/2.6ms, 5 heart beats between subsequent IR pulses, and flip angle=25°. T1-mapping was performed using one non-selective inversion pulse. The inversion pulse was followed by eight segmented readouts, spaced one RR-interval apart, for eight individual images resulting in TI from 10ms to 1000ms. To allow full magnetization recovery, 12 pause heart beats were performed before the next inversion pulse. T1-mapping sequence used GRE-readout with following parameters: FOV=35x35x1.5mm, in-plane resolution=0.3x0.3mm, slices=1, TR/TE=7.5/3.1ms, flip angle=16°. ¹⁹F scans were acquired in short-axis using a 3D turbo-spin echo sequence, FOV=35x35x12mm, in plane resolution=1x1x2mm, slices=12, TR/TE=4beats/8.9ms, TSE factor=5, offset frequency=10200Hz. A saturation slice was used to suppress liver signal. To enable SNR calculation, a noise-scan was acquired with the same imaging parameters but without any RF pulses. Data analysis: Systolic and diastolic frames were analyzed and functional/volumetric parameters were estimated: LV end-diastolic volume, LV end-systolic volume, LV mass and ejection fraction. Infarct area was calculated using semi-automated cardiac preclinical software³. T1 values were analyzed using OsiriX (OsiriX Foundation, Geneva, Switzerland).Functional and volumetric data are reported in Figure 1. End-diastolic, end-systolic volumes and LV mass were increased, while ejection fraction was reduced during MI remodeling. LGE and R1 map images post-MI are shown in Figure 2. Gd-ESMA LGE scans show areas of enhancement at all time points, allowing infarct size quantification(Fig. 3A). Figure 3B shows the R1 values of control and infarcted mice in blood, infarcted, and remote myocardium. Infarcted myocardium showed an increase in R1 values after Gd-ESMA injection 21days after MI, suggesting ECM remodeling. ¹H and ¹⁹F images are shown in Figure 4. Simultaneous acquisition of morphologically matching proton(¹H) and fluorine(¹⁹F) images enabled an exact anatomical localization of PFCs after application. ¹⁹F signal is detected in the infarcted area at 7days, as well as in the surgical incision and adjacent lymph nodes at all time-points.Our preliminary results demonstrate the feasibility of simultaneous assessment of inflammation and remodeling in a mouse model of MI using ¹⁹F-nanoparticles and Gd-ESMA and a ¹H/¹⁹F dual coil at 3T.