fig1 shows k - space or the fourier domain with a measurement signal after the longitudinal magnetization has been one - dimensionally modulated . in addition to the primary maximum 10 , two secondary maxima 11 and 12 arise to the left and right of this due to the modulation of the magnetization . the positions of the secondary maxima result from the sequence of the pulses for modulation of the magnetization . for example , these secondary maxima lie further outward in fourier space the higher the frequency of the magnetization pulses . to summarize , in addition to the primary maximum that contains the primary information of the mr image to be reconstructed , the position of the secondary maxima is precisely determined by the magnetization pulse sequence . the modulation of the magnetization by the spamm technique or cspamm technique is known to those skilled in the art and need not be explained in detail herein . in order to now obtain information about the movement of the examined subject , i . e . in particular the perfusion of the subject , the information contained in the secondary maximum is now used in order , for example , to place a grid in the perfused subject ( for example the heart ). from the temporal sequence of the grid movement , the movement of the grid can be tracked by acquisition of multiple images during the movement cycle , for example of the heart cycle . this grid movement now provides information about the perfusion of the examined subject . one field of application of this technique is , for example , in the determination of the perfusion of the myocardium . these techniques ( used as harp and dense ) are known to those skilled in the art . the secondary maximum 12 should now be acquired in the present example . it is an important aspect of the present invention that the magnetization is only modulated in one spatial direction such that only two ancillary maxima result . namely , when the magnetization is modulated in more than one spatial direction , a number of such secondary maxima 11 and 12 result , such that a number of secondary maxima would have to be acquired for information about the perfusion , which would undesirably lengthen the acquisition time . in fig2 it is shown how the ancillary maximum 12 is preferably acquired during the three - dimensional imaging sequence . the ancillary maximum 12 has an essentially radially - symmetrical expansion such that the space around the maximum is read out in a circular shape in the x / y direction of k - space . the gradients in the x - or y - direction are the phase coding directions as well as the 3d direction . the signal readout preferably ensues constant in the k z - direction , such that k - space specifying the maximum 12 is read out via the cylinder 20 . other k - space acquisition techniques are naturally also possible , but it should be noted that the center of gravity in k - space 21 coincides with the harmonic maximum 12 . a constant readout time is simple to effect , but other acquisition schemata such as , for example , a radial or spherical acquisition of k - space are also possible . if the maximum 12 is acquired cylindrically as shown in fig2 , the maximum should lie on the longitudinal axis 22 in the center of gravity of the cylinder . as can be seen in fig2 , only a small volume around the maximum 12 must be read out , so that very small image acquisition times are possible , and an optimal signal / noise ratio is achieved by the three - dimensional acquisition of k - space around the maximum . the various steps that are necessary for the measurement of the myocardium perfusion or for any other perfusion measurement are shown in fig3 . the longitudinal magnetization in one spatial direction is modulated in a first step 31 , for example via the spamm or cspamm technique . the position of an ancillary maximum can be definitely calculated with the magnetization pulses used in step 31 , this secondary maximum being subsequently acquired in step 32 with a three - dimensional imaging sequence . this three - dimensional imaging sequence , for example , can be a gradient echo sequence or an epi ( echo planar imaging ) sequence . any other imaging sequence is possible with which images of the examination subject can be three - dimensionally acquired in short acquisition times , the imaging sequence also depending on the examined subject . as shown in fig2 , the secondary maximum is acquired via a cylindrical sampling [ scanning ] of fourier space . the acquired data are subsequently fourier - transformed in step 33 , so a three - dimensional fourier transformation is necessary due to the three - dimensional imaging . the perfusion is subsequently determined in step 34 from the fourier - transformed data . for example , among other things a phase image can be calculated in step 34 . the method for calculation of the perfusion from the acquired ancillary maxima are known to those skilled in the art and correspond to the methods known in the prior art ( for example harp and dense ). in step 35 it is queried whether two - dimensional or three - dimensional information about the perfusion should be acquired . if this is not the case , the method ends in step 36 . if two - dimensional or three - dimensional perfusion information is desired , the steps 31 through 34 are repeated . for two - dimensional information , the magnetization is modulated in a direction perpendicular to the first spatial direction ; the steps 32 through 34 are subsequently repeated . for a three - dimensional perfusion determination , the magnetization is subsequently modulated in the third spatial direction perpendicular to the first two spatial directions and the steps 32 through 34 are subsequently repeated in turn , whereby fourier space is again read out in the form of a solid cylinder . according to the invention , the associated secondary maximum is acquired in one spatial direction via a three - dimensional imaging sequence after the magnetization modulation . a good signal / noise ratio can be achieved in a short image acquisition time . this is subsequently repeated for both other spatial directions . overall the perfusion can be determined in short image acquisition times with good signal / noise ratio with the method according to the invention . although modifications and changes may be suggested by those skilled in the art , it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art .