Precision imaging of cardiac function and scar size in acute and chronic porcine myocardial infarction using ultrahigh-field MRI.

ABSTRACT

BACKGROUND: 7 T cardiac magnetic resonance imaging (MRI) studies may enable higher precision in clinical metrics like cardiac function, ventricular mass, and more. Higher precision may allow early detection of functional impairment and early evaluation of treatment responses in clinical practice and pre-clinical studies. METHODS: Seven female German Landrace pigs were scanned prior to and at three time points (3-4 days, 7-10 days, and ~60 days) post myocardial infarction using a whole body 7 T system and three radiofrequency (RF) coils developed and built in-house to accompany animal growth. RESULTS: The combination of dedicated RF hardware and 7 T MRI enables a longitudinal study in a pig model of acute and chronic infarction, providing consistent blood tissue contrast and high signal-to-noise ratio (SNR) in measurements of cardiac function, as well as low coefficients of variation (CoV) for ejection fraction (CoVintra-observer 2%, CoVinter-observer 3.8%) and infarct size (CoVintra-observer 8.4%, CoVinter-observer 3.8%), despite drastic animal growth. CONCLUSIONS: Best results are achieved via manual segmentation. We define state-of-the-art procedures for large animal studies at 7 T.

In magnetic resonance imaging (MRI), scanners use magnets to generate detailed images of structures in the body, such as the heart. Stronger magnets can produce stronger magnetic fields, which can be leveraged for better image quality and developing new methods for disease diagnosis. In clinical practice, such systems using strong magnets are not yet used for imaging of the heart and some safety aspects remain challenging. We apply such an imaging approach in pigs, in which heart structure and function are similar to humans. We focus on the most important clinical imaging aspects following a heart attack, namely heart function and scar detection. We demonstrate that the high magnetic strength system enabled consistent image quality and accuracy. These findings may help to guide future developments in MRI of the heart, for example in patients who have had a heart attack.