What kind of advances have been made in this field (since I don't stay on top of it)? If I wanted to image, say, where my fluorinated drug is going within a rat, is it possible? NMR is inherently not a sensitive modality. Hydrogen is vastly more abundant in a living organism than fluorine (typical MRI vs F19 MRI), so given the fact that most therapeutic doses of drugs occur probably in the millimolar to nanomolar range, is it even possible to produce a good image with F19 MRI? Is it practically impossible to produce a decent S/N ratio? What if I incorporated more fluorines into my compound?