METABOLIC IMAGING - PET OR NMR

With positron emission tomography (PET) in combination with compounds labeled with short-lived positron emitting radio nuclides like 11C, 13N, 15O and 18F, it is possible to study regional metabolism in vivo quantitatively in a noninvasive way. Nuclear magnetic resonance (NMR) imaging takes advantage of the spin of protons in water molecules to measure both their number and relaxation times in vivo; NMR is not limited to protons but can also be used for other nuclei with a non-zero spin like 13C and 31P. PET can be used for metabolic imaging. The question arises if it is also possible to study metabolism by NMR in combination with 13C-labeled compounds. To answer this question which method, PET or NMR, is the appropriate technique for metabolic imaging, it is important to know the sensitivity of each technique. Calculations based on the physical properties of the PET and the NMR technique show that, due to the low sensitivity of NMR, PET is the appropriate technique for metabolic imaging in most cases.