For isotropic diffusion weighting during magnetic resonance imaging, a motion-probing magnetic field gradient pattern is manufactured from a template by searching for an optimum value of a skew parameter (.epsilon.) of the template. The gradient pattern includes a first pattern before at least one RF refocusing pulse and a second pattern after the refocusing pulse in which the second pattern is symmetrical with the first pattern. For example, gradient coils produce a respective gradient component along each of three orthogonal directions, and for each component and each pattern, the gradient pattern has one cycle of opposite polarity lobes about a crossing point, and for each pattern, the crossing point of the cycle in one of the orthogonal directions is a midpoint of the cycle; and the skew parameter (.epsilon.) specifies a difference in time between the crossing points of the cycles in the other orthogonal directions.