Apparatus and method for real time and real flow-rate measurement of multi-phase fluids with MRI

1. A method for measuring the flow velocity of at least one fluid of interest in a multi-phase fluid flowing in a pipe at a known overall flow rate, comprising the steps of:

a) providing an MRI-compatible device comprising:

a magnetic resonance module through which the fluid phases flow; and

at least one pre-polarization module producing a pre-polarization magnetic field of variable effective length through which the multi-phase fluid flows before entering the magnetic resonance module;

wherein a previously determined calibration, of the magnetic resonance module, between a slope:intercept ratio and the flow rate for a fluid of interest flowing through the device is known;

b) conducting a measurement comprising the steps of:

i) setting the pre-polarization module such that a first effective length of the pre-polarization magnetic field is produced;

ii) applying a RF pulse sequence for measuring flow velocity of a fluid of interest in the magnetic resonance module;

iii) determining the intensity of a pre-determined number of spin echoes that are produced by the RF pulse sequence;

iv) determining a line that approximates the attenuation of the intensity of the pre-determined number of spin echoes with increasing time during which the RF sequence is applied;

v) determining slope and y-intercept of the line determined in step iv);

vi) determining the ratio of the slope and the intercept determined in step v);

vii) applying the previously determined calibration in order to determine the flow velocity of the fluid of interest in the multi-phase fluid; and

viii) providing the flow velocity determined in step b)vii) to a user; and

c) when more than one fluid flow rate is desired is desired, repeating step b) one or more times, each time using a different setting of the pre-polarization module so as to determine the flow velocity of a different fluid of interest in the multi-phase fluid.

2. The method according to claim 1 , further including repeating step b) with different magnetic field pre-polarization lengths until fluid flow velocities for all multi-phase fluid components which have different spin-lattice relaxation times have been determined.

3. The method according to claim 2 , further including using the determined flow velocity of each fluid to determine its respective fluid fraction in the multi-phase fluid.

4. The method according to claim 1 , wherein step b) ii) comprises applying a RF pulse using a Carr Purcell Meiboom Gill (CPMG) sequence.

5. The method according to claim 1 wherein using a different setting of the pre-polarization module permits includes using a different effective polarization length.

6. The method according to claim 1 , further including the steps of:

A) applying a first combination of magnetic field gradient strengths and orientations in order to isolate a fluid volume element in the magnetic resonance module;

B) carrying out steps a)-c) until fluid flow velocities for all multi-phase fluid components having different spin-lattice relaxation times have been determined for said volume element;

C) applying a different combination of magnetic field gradient strengths and orientations so as to isolate a different fluid volume element in the magnetic resonance module;

D) carrying out steps a)-c) until fluid flow velocities for all multi-phase fluid components having different spin-lattice relaxation times have been determined for said different fluid volume element; and

E) repeating steps C)-D) until all volume elements in the pipe have been analyzed.

7. The method according to claim 6 , wherein steps a)-c) are carried out using a volume-selective RF pulse sequence.

8. The method of claim 6 , further including the step of using a plurality of fluid flow velocities to generate a two-dimensional image of flow velocity in the multi-phase fluid.