Method and apparatus for NMR detection and imaging of flowing fluid nuclei
First Claim
1. An NMR method for imaging flowing fluid nuclei, said method comprising the steps of:
- exciting flowing nuclei to produce an NMR response signal by applying successive slice selective NMR excitation signals to the flowing nuclei at corresponding successive spatial locations of the moving nuclei;
detecting the resulting NMR response signal and measuring at least one of its signal parameters which is representative of nuclei velocity; and
generating an NMR velocity image of the flowing nuclei using said measured signal parameter.
2 Assignments
0 Petitions
Accused Products
Abstract
A unit volume of moving nuclei is spatially tracked by successive selectively applied NMR rf nutation pulses which solicit NMR spin-echo responses from the tracked moving nuclei. For relatively fast moving nuclei, the NMR responses will come only from the successfully tracked moving nuclei. For relatively slowly moving nuclei (where some stationary nuclei in the overlap of selective excitation regions may also be excited to give NMR responses) and/or even for faster moving nuclei, controlled de-phasing/re-phasing magnetic gradients can be applied before and after a 180° rf nutation pulse so as to effectively phase-encode the spin echo response with respect to only those nuclei having velocity. The same NMR excitation/response sequence is repeated a number of times using different de-phasing/re-phasing magnetic gradients and the velocity of the nuclei may then be derived by regression analysis. A succession of such sequences is used to generate a succession of spin-echo signals having intensity and/or phase parameters which may be two-dimensionally transformed or otherwise processed to provide an NMR image of only the moving nuclei which may be quantitatively analyzed for fluid flow parameters. In the case of pulsatile fluid flows (i.e. such as with arterial blood flow in the human body) the NMR excitation/response sequences are synchronized so as to begin each repetition thereof at a predetermined portion of the pulsatile flow cycle.
75 Citations
30 Claims
-
1. An NMR method for imaging flowing fluid nuclei, said method comprising the steps of:
-
exciting flowing nuclei to produce an NMR response signal by applying successive slice selective NMR excitation signals to the flowing nuclei at corresponding successive spatial locations of the moving nuclei; detecting the resulting NMR response signal and measuring at least one of its signal parameters which is representative of nuclei velocity; and generating an NMR velocity image of the flowing nuclei using said measured signal parameter. - View Dependent Claims (2, 3, 4)
-
-
5. A method for NMR detection of plusatile fluid flow velocity, said method comprising the steps of:
-
(a) generating a trigger signal synchronized to a predetermined temporal portion of said pulsatile fluid flow; (b) in synchronization with said trigger signal, exciting to NMR signal response a selected and tracked subvolume of moving nuclei contained within said fluid flow; (c) detecting said NMR signal response; (d) measuring a predetermined NMR signal response parameter representative of the velocity of said moving nuclei; and (e) repeating said steps (a)-(d) to accumulate said measurements of the predetermined NMR signal response parameter and to thus generate quantitative measurements of the pulsatile fluid flow. - View Dependent Claims (6, 7, 8)
-
-
9. An NMR method of detecting nuclei flowing within an object in a given direction, said method comprising the steps of:
-
selectively nutating by 90°
NMR nuclei then located at a first location within the object a first time;selectively nutating by 180°
NMR nuclei then located at a second location disposed in said given direction from said first location within the object at a second time, said displacement and second time being chosen to track the movement of said NMR nuclei from said first location at a predetermined rate of movement; andthereafter detecting an NMR spin echo signal emanating from the NMR flowing nuclei thus selectively nutated in succession by said 90° and
said 180°
. - View Dependent Claims (10, 11, 12, 13)
-
-
14. A non-invasive NMR method of measuring blood flow velocity within a living body, said method comprising the steps of:
-
(a) selectively exciting nuclei of the body to NMR by applying successive excitation signals within a planar volume which spatially tracks the movements of blood nuclei flowing in a predetermined velocity range; and (b) detecting and quantitatively measuring an NMR response signal from nuclei which remain disposed within said planar volume throughout step (a). - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
-
-
23. An NMR apparatus for imaging flowing fluid nuclei, said apparatus comprising:
-
means for exciting flowing nuclei to produce an NMR response signal by applying successive slice selective NMR excitation signals to the flowing nuclei at corresponding successive spatial locations of the moving nuclei; means for detecting the resulting NMR response signal and measuring at least one of its signal parameters which is representative of nuclei velocity; and means for generating an NMR velocity image of the flowing nuclei using said measured signal parameter. - View Dependent Claims (24)
-
-
25. Apparatus for NMR detection of pulsatile fluid flow velocity, said apparatus comprising:
-
(a) means for generating a trigger signal synchronized to a predetermined temporal portion of a pulsatile fluid flow; and (b) means for repetitively exciting to NMR signal response a selected and tracked subvolume of moving nuclei contained within said fluid flow in synchronization with said trigger signal, for detecting said NMR signal response, for measuring a predetermined NMR signal response parameter representative of the velocity of said moving nuclei and to accumulate said measurements of the predetermined NMR signal response parameter and to thus generate quantitative measurements of the pulsatile fluid flow.
-
-
26. An NMR apparatus for detecting nuclei flowing within an object in a given direction, said apparatus comprising:
-
means for selectively nutating by 90°
NMR nuclei then located at a first location within the object at a first time;means for selectively nutating by 180°
NMR nuclei then located at a second location displaced in said given direction from said first location within the object at a second time, said displacement and second time being chosen to track the movement of said NMR nuclei from said first location; andmeans for thereafter detecting an NMR spin echo signal emanating from the NMR flowing nuclei thus selectively nutated in succession by said 90° and
said 180°
. - View Dependent Claims (27, 28)
-
-
29. A non-invasive NMR apparatus for measuring blood flow velocity within a living body, said apparatus comprising:
-
(a) means for selectively exciting nuclei of the body to NMR by applying successive excitation signals within a planar volume which spatially tracks the movements of blood nuclei flowing in a predetermined velocity range; and (b) means for detecting and quantitatively measuring an NMR response signal from nuclei which remain disposed within said planar volume throughout step (a). - View Dependent Claims (30)
-
Specification