T2-weighted MR signal of the cartilage knee has shown to be better explained by the biexponential relaxation model. The short and long T2 signal components presumably describe tightly bound and loosely bound macromolecular water components of the knee, respectively. More precise estimation of these two parameters might help in the better diagnosis of Osteoarthritis in reasonable scanning times. Here, Cramér-Rao Lower Bound method was used to find optimum echo times that improve estimation of these relaxation components. It was shown that using maximum echo times of twice as much as what is routinely used might substantially improve the biexponential estimates. Echo time optimization might play a role as important as increasing acceleration factors in reducing acquisition times.