Nuclear magnetic resonance diagnostic apparatus

DETAILED DESCRIPTION To achieve the foregoing objects, and in accordance with the purpose of the invention as embodied and broadly described herein, nuclear magnetic resonance diagnostic apparatus is provided wherein a uniform static magnetic field is generated, a first gradient magnetic field is superimposed on the static magnetic field aligned in the direction of the static magnetic field, and a second gradient magnetic field is superimposed on both the static magnetic field and the first gradient magnetic field in a direction perpendicular to the static magnetic field direction.
The gradient direction of the second gradient magnetic field is rotatively shifted some unit index angle at a time until it is rotated substantially 360 degrees to acquire the tomographic image on the basis of nuclear magnetic resonance signals due to specified atomic nuclei existing within a slice of an object.
The NMR diagnostic apparatus comprises: (a) coil means for generating the second gradient magnetic field; (b) means for controlling the operation of the coil means to rotatively shift the gradient direction of the second gradient field in a slice of an object to be diagnosed in angular steps equivalent to several times the unit index angle until the gradient direction is rotated through a plurality of rotations to assume all of the expected rotative shift positions of the second gradient direction; (c) a memory device for storing nuclear magnetic resonance signals for each gradient direction of the second gradient magnetic field; (d) a rough image reconstructor for reconstructing a rough tomographic image on the basis of nuclear magnetic resonance signals acquired during a single rotation of the gradient direction of the second gradient magnetic field; (e) a first image display for depicting the rough tomographic image; (f) a final image reconstructor for reconstructing a final tomographic image on the basis of nuclear magnetic resonance signals corresponding to all of the expected rotation shift positions acquired during a plurality of rotations; and (g) a second image display for depicting the final tomographic image