Magnetic-resonance image diagnostic apparatus and method of controlling the same

Abstract

A magnetic resonance imaging diagnostic apparatus includes a generating unit which generates a slice gradient magnetic field, a phase-encode gradient magnetic field and a read-out gradient magnetic field that extend in a slice axis, a phase-encode axis and a read-out axis, respectively, a setting unit which sets a dephase amount for weighting a signal-level decrease resulting from flows in the arteries and veins present in a region of interest of a subject, with respect to at least one axis selected form the slice axis, phase-encode axis and read-out axes, and a control unit which controls the generating unit by using a pulse sequence for a gradient echo system, which includes a dephase gradient-magnetic-field pulse that corresponds to the dephase amount set by the setting unit for the at least one axis.

1 . A magnetic resonance imaging diagnostic apparatus comprising:
 a generating unit which generates a slice gradient magnetic field, a phase-encode gradient magnetic field and a read-out gradient magnetic field that extend in a slice axis, a phase-encode axis and a read-out axis, respectively; and   a control unit which performs a first-order rephasing to an nth-order rephasing (wherein n is 2 or a greater integer) on a spin with respect to at least one axis selected from the slice, phase-encode and read-out axes, and which controls the generating unit to achieve a pulse sequence for a gradient echo system in which an echo period is set to a value appropriate for canceling a phase shift of a vein present in a region of interest of a subject.   
     
     
         2 . The magnetic resonance imaging diagnostic apparatus according to  claim 1 , wherein the pulse sequence uses a spin warp method. 
     
     
         3 . The magnetic resonance imaging diagnostic apparatus according to  claim 1 , wherein the pulse sequence is an echo planar planner imaging sequence. 
     
     
         4 . The magnetic resonance imaging diagnostic apparatus according to  claim 1 , wherein:
 the pulse sequence is an echo-shifted sequence.   
     
     
         5 . The magnetic resonance imaging diagnostic apparatus according to  claim 1 , wherein the pulse sequence is a multi-echo sequence. 
     
     
         6 . A method of controlling a magnetic resonance imaging diagnostic apparatus comprising a generating unit which generates a slice gradient magnetic field, a phase-encode gradient magnetic field and a read-out gradient magnetic field that extend in a slice axis, a phase-encode axis and a read-out axis, respectively, the method comprising:
 performing a first-order rephasing to an nth-order rephasing (wherein n is 2 or a greater integer) on a spin with respect to at least one axis selected from the slice, phase-encode and read-out axes, and which controls the generating unit and controlling the generating unit achieving a pulse sequence for a gradient echo system in which an echo period is set to a value substantially reducing appropriate for canceling a phase shift of a vein present in a region of interest of an a subject.