Magnetic resonance imaging with combined single point and back projection data taking method

A magnetic resonance method for imaging an object comprising the steps of:

• a) locating the object in a homogeneous base magnetic field;
• b) acquiring, using a back projection method n>>1 different projections with different directions .phi.(i) by carrying out the following steps ba) to bd) n times with i=1 to n:
• ba) applying a gradient magnetic field G.phi.(i) having a predetermined direction .phi.(i), different for every i, and a strength G(i) for acquiring a projection p(i);
• bb) irradiating a high frequency excitation pulse into the object;
• bc) waiting a time t.sub.w ';
• bd) measuring, at a predetermined sampling rate, (j-m) >>1 measuring points S.sub.m+1 (i) to S.sub.j (i), which are sequential in time, of a nuclear resonance signal from the object, the signal dephasing under the influence of the gradient magnetic field G.phi.(i), the measuring points S.sub.m+1 (i) to S.sub.j (i) corresponding to j-m points in k-space lying along a vector extending from a k-space origin in the direction .phi.(i) of the gradient magnetic field G.phi.(i), whereby the separation of each of the j-m points S.sub.m+1 (i) to S.sub.j (i) in k-space from the k-space origin is given by a product of the strength G(i) of the gradient magnetic field G.phi.(i) and a time interval between the high frequency excitation pulse and the sampling time of the corresponding measuring points.sub.m+1 (i) to S.sub.j (i);
• c) acquiring, using a single point imaging method (S by PI), n'.ltoreq.n*m additional measuring points S(i') by carrying out the following steps ca) to cd) n' times with i'=1 to n':
• ca) applying a gradient magnetic field G.phi.(i') having a predetermined direction .phi.(i') and a strength G(i') for acquiring only one measuring point S(i');
• cb) irrdiating the high frequency excitation pulse into the object;
• cc) waiting time t.sub.w ';
• cd) measuring only one measuring point S(i') of a nuclear resonance signal from the object, the signal dephasing under the influence of the gradient magnetic field G.phi.(i'), the measuring point S(i') corresponding to a point in k-space lying along a vector extending from a k-space origin in the direction .phi.(i') of the gradient magnetic field G.phi.(i'), whereby the separation of the point S(i') in k-space from the k-space origin is given by a product of the strength G(i') of the gradient magnetic field G.phi.(i') and the time t.sub.w ';
• d) reconstructing an image of the object from a total number of n*(j-m) measuring points S.sub.m+1 (i) to S.sub.j (i) plus n' measuring points S(i') in k-space.