Nuclear magnetic resonance diagnostic apparatus

Claim 2

Nuclear magnetic resonance diagnostic apparatus for producing the density distribution image of specified atomic nuclei in a slice of an object by image reconstruction procedure on projection data of the specified atomic nuclei density distribution which are achieved in a variety of directions in the plane of said slice of said object by using nuclear magnetic resonance phenomena, the apparatus comprising means (1, 2, 3-1, 3-2, 4, 5, 6) for applying a gradient magnetic field to form an equivalent plane in the magnetic field corresponding to said slice in a predetermined region to be measured to obtain the projection data; means (7, 8, 9) for selectively saturating magnetization vectors in the entire region to be measured other than the region corresponding to said slice by applying radio frequency waves which are composed of continuous waves the frequency of which is successively varied in a range not inclusive of the resonance frequency of the specific atomic nuclei; and means (10, 11, 12, 16-18) for obtaining the projection data in the predetermined directions in said slice by measuring the resonance signals obtained by applying 90° pulses of the resonance frequency of the specified atomic nuclei to the region including the equivalent magnetic field plane region, while the saturation state of the magnetization vectors is maintained.

Claim 3

Nuclear magnetic resonance diagnostic apparatus according to claim 1, wherein the setting of projection direction of the measured resonance signals is performed by applying the gradient magnetic field of the desired magnetic field gradient after selection of the equivalent magnetic field plane.

Claim 4

Nuclear magnetic resonance diagnostic apparatus for producing the density distribution image of specified atomic nuclei in a slice of an object by an image reconstruction procedure on projection data of the specified atomic nuclei density distribution in a plurality of directions in the plane of said slice by using nuclear magnetic resonance phenomena, the apparatus comprising: gradient magnetic field generating means (1, 2, 3-1, 3-2, 4, 5, 6) for generating gradient magnetic fields each having a magnetic field intensity gradient which is three-dimensionally controllable; 90° pulse generating means (10, 11, 12) for generating 90 0 pulses, which correspond to the gradient magnetic field to excite to resonance the specified atomic nuclei in a selected region corresponding to the specified slice of the object disposed within the gradient magnetic field; continuous wave generating means (7, 8, 9) for generating radio frequency waves which are composed of continuous waves the frequency of which is variable but does not include the resonance frequency of the specified atomic nuclei in a selected region, so as to selectively saturate the magnetization vectors in the region excluding said selected region and within the gradient magnetic fields; excitation and detection means (15-18) for selectively applying to the object disposed within the gradient magnetic fields the r.f. signals delivered from the continuous wave generating means (7-9) and the 90 0 pulses delivered from the 90° pulse generating means (10-12), and for detecting the resonance signals delivered from the object after application of the 90° pulses; and control means for controlling the timing of the operation of each of the preceding means.

Claim 5

Nuclear magnetic resonance diagnostic apparatus for producing the density distribution image of specified atomic nuclei in a slice of an object by an image reconstruction procedure on projection data of the specified atomic nuclei density distribution in a plurality of directions in the plane of said slice by using nuclear magnetic resonance phenomena, the apparatus comprising: gradient magnetic field generating means (1, 2, 3-1, 3-2, 4, 5, 6) for generating gradient magnetic fields each having a magnetic field intensity gradient which is three-dimensionally controllable; 90° pulse generating means (10, 11, 12) for generating 90 0 pulses, which correspond to the gradient magnetic field to excite to resonance the specified atomic nuclei in a selected region corresponding to the specified slice of the object disposed within the gradient magnetic field; continuous wave generating means (7, 8, 9) for generating radio frequency waves which are composed of continuous waves the frequency of which is variable but does not include the resonance frequency of the specified atomic nuclei in a selected region, so as to selectively saturate the magnetization vectors in the region excluding said selected region and within the gradient magnetic fields; excitation and detection means (15-18) for selectively applying to the object disposed within the gradient magnetic fields the r.f. signals delivered from the continuous wave generating means (7-9) and the 90 0 pulses delivered from the 90° pulse generating means (10-12), and for detecting the resonance signals delivered from the object after application of the 90° pulses; and control means for controlling the timing of the operation of each of the preceding means.

Claim 6

Nuclear magnetic resonance diagnostic apparatus according to claim 3, wherein the gradient magnetic field generating means comprise coil apparatus (1, 2) generating a uniform magnetic field and three gradient magnetic field coils (3-1, 3-2, 5) for generating the gradient magnetic fields, each generating a magnetic field gradient in a direction orthogonal to those of the others and in superimposition to the uniform static magnetic field.