Theory of coherent and incoherent nuclear spin dephasing in the heart

We present an analytical theory of susceptibility induced nuclear spin deph asing in the capillary network of myocardium. Using a strong collision appr oach, equations are obtained for the relaxation rate of the free induction and the spin echo decay. Simulation and experimental data are well predicte d by the theory. Since paramagnetic deoxyhemoglobin as the origin of nuclea r spin dephasing has a higher tissue concentration in myocardium supplied b y a stenotic, i.e., significantly narrowed, coronary artery, spin dephasing might serve as a diagnostic tool. Our approach can be modified for capilla ry networks in other tissues than myocardium and may be applied in material science.