How Much Can MRI, and PET, Neuroimaging Machines Magnify.

Magnification in an imaging system is determined by the ratio of the distances from the illuminating source ( light, X-ray, etc ) to the object, and from the object to the image (detector or receptor). Commonly referred to as SOD and SID.

Point sources are theoretical, and every current source has a definite size and profile. ( N-med and MRI notable exceptions however, there are other factors restricting their resolutions )

One considers the relative size of the source, object, and distance separating the detectors in order to calculate basic resolution. The Principle involved is that radiated energy diverges from a point source in a uniform manner, and that an object occluding or absorbing the radiant energy will produce a shadow that measures larger and larger as the distance from object to detector increases. This is why there are practical limits to the size of machines such as CT. for one, the amount of energy required in the beam reduces by the square of the distance, so there are limits to the amount of energy one can reasonably expose the object to, without harming it.

While detectors can be made with increasingly smaller dimensions in order to space them more closely for better resolution, there comes a trade off in sensitivity as the available sensor material decreases. Again this is a problem with conversion of the available energy to a useable output. Operating within the safe limits of object radiation exposure is a factor in this limitation.

As object - to - image distance ( and magnification ) increases, there increase possible sources of noise and signal interference - signal degradations, although most systems are tuned to the specific radiation invloved, with a tolerance ( not a perfect sensor ).

Imaging in most modes is a transmissive measurement, where the variation in expected radiation recieved is used to compare densities shapes and positions of objects within the radiation field. For Emissive technologies such as N-med, the objects themselves become the source, and different detection methods are used than those of X-ray for example, and have their own limiting factors, one of which is also safe dose to the object.

So you see there is much to consider in learning how the various technologies produce their images - suffice it to say that while research into better imagers continues, we are far from the resolutions you desire for now.

Bear in mind that imaging something is never non-invasive in terms of affecting the object in some way. The process of observation almost invariably produces changes in the object observed. For live studies, this limits the application of these technologies to levels well within the patients' abilities to endure the imaging without harm. Subjecting a person to radiation for an extended time in order to observe minute functions such as you propose using CURRENT technologies would likely pose an unacceptable risk of harm to the individual.

Good luck in your search for these answers.