Setting <math>k_{\textrm{AB}}p_D</math> to zero, amounts to neglecting magnetisation that starts on the ground state ensemble and end on the excited state ensemble and vice versa. <br>
This will be a good approximation when <math>p_A \gg p_B</math>.<br>
In practise, significant deviations from the Carver Richards equation can be incurred if <math>p_B > 1\%</math>.<br>Incorporation of the correction term into equation (50), results in an improved description of the CPMG experiment over the Carver Richards equation.