Cardiac MR isn't just loud noises and excitable #whycmr posts, it's also an amazing tool that can look directly at the chemical composition of living, breathing tissues inside your body - like the amount of ATP inside your heart. https://twitter.com/DGlaucomflecken/status/1262945131117723648

The MR is tuned to hydrogen for imaging, but re-tune to phosphorus and you'll those atoms occupying different 'chemical shifts' (frequencies) as they sit in different chemical environments. Here's the P spectrum from a human heart: Phosphocreatine and ATP.

The ratio between Phosphocreatine and ATP shows how much energy reserve (or 'headroom') is available - correlating with degree of heart failure. Work a heart too hard for too long and Phosphocreatine has been shown to drop as it runs out of fuel.

Even more clever is saturation transfer, where the speed by which Phosphate is moving from Phosphocreatine to ATP can be quantified by labelling (saturating) the phosphate at a certain frequency.

We can correlate these observations with our biochemical knowledge of ATP generating and consuming reactions to help bridge the gap between theory and knowledge of how things work in vivo https://twitter.com/DrWillWatson/status/1281636547062833152?s=20

This is all a shameless plug for my review which shows a little of how this can work in a research framework - http://cdt.amegroups.com/article/view/37723/html - and the cool, almost star trek science of showing chemical reactions inside living people!