Method for magnetic resonance imaging or nuclear magnetic resonance spectroscopy comprising: emitting a radio frequency and gradient pulse sequence towards an object being subjected to a magnetic field, wherein said object comprises a molecule having an atom with a nuclear spin differing from 0; encoding, detecting and acquiring a magnetic resonance signal from said object corresponding to said emitted radio frequency and gradient pulse sequence, wherein the radio frequency and gradient pulse sequence comprises a first weighting block, a mixing block with duration t m and a second weighting block, wherein the first weighting block is a first diffusion weighting block with diffusion weighting b 1 and the second weighting block is a second diffusion block with diffusion weighting b 2; characterized in that encoding, detecting and acquiring the magnetic resonance signal from said object is limited to an initial decay of a signal intensity I with increasing b 1 or b2, wherein the variation of the initial signal decay rate with t m is analysed to obtain an apparent exchange rate AXR between compartments with different diffusion characteristics, wherein the encoding, detecting and acquiring is made for multi-site exchange and AXR is calculated according to the following: I n b = I 0, n exp − ADC ⋅ 1 − σ exp − AXR ⋅ t m, n ⋅ b wherein I n is the initial signal intensity in a data series n, t m,n is the duration t m of a mixing block in the data series n, the variable b refers to either b 1 or b 2, σ = 〈 D 0 〉 − 〈 D 1 〉 〈 D 0 〉. wherein σ is limited in the range of 0 < σ < 1 and < D 0 > is the apparent diffusion coefficient < D n > at equilibrium and < D 1 > is the apparent diffusion coefficient < D n > at t m,n = 0, and wherein ADC = < D 0 >. emitting a radio frequency and gradient pulse sequence towards an object being subjected to a magnetic field, wherein said object comprises a molecule having an atom with a nuclear spin differing from 0; encoding, detecting and acquiring a magnetic resonance signal from said object corresponding to said emitted radio frequency and gradient pulse sequence, wherein the radio frequency and gradient pulse sequence comprises a first weighting block, a mixing block with duration t m and a second weighting block, wherein the first weighting block is a first diffusion weighting block with diffusion weighting b 1 and the second weighting block is a second diffusion block with diffusion weighting b 2; characterized in that encoding, detecting and acquiring the magnetic resonance signal from said object is limited to an initial decay of a signal intensity I with increasing b 1 or b2, wherein the variation of the initial signal decay rate with t m is analysed to obtain an apparent exchange rate AXR between compartments with different diffusion characteristics, wherein the encoding, detecting and acquiring is made for multi-site exchange and AXR is calculated according to the following: I n b = I 0, n exp − ADC ⋅ 1 − σ exp − AXR ⋅ t m, n ⋅ b wherein I n is the initial signal intensity in a data series n, t m,n is the duration t m of a mixing block in the data series n, the variable b refers to either b 1 or b 2, σ = 〈 D 0 〉 − 〈 D 1 〉 〈 D 0 〉. wherein σ is limited in the range of 0 < σ < 1 and < D 0 > is the apparent diffusion coefficient < D n > at equilibrium and < D 1 > is the apparent diffusion coefficient < D n > at t m,n = 0, and wherein ADC = < D 0 >.