Combination of fluid-attenuated inversion-recovery complex images acquired using magnetic resonance imaging

A method of magnetic resonance imaging, said method comprising:

• (a) supporting a subject in an examination region of an MRI scanner;
• (b) setting up a spin system with a net magnetization in the subject;
• (c) producing an inversion-recovery pulse sequence with the MRI scanner, said producing including:
• (1) applying an RF inversion pulse via the MRI scanner, said RF inversion pulse inverting the magnetization of the spin system in a selected volume of the subject, and as the magnetization re-grows, generating a first set of raw data by acquiring MR signals from a series of regions within the selected volume, wherein for the first set of raw data the series of regions are acquired in a first temporal order with respect to the RF inversion pulse;
• (2) re-applying the RF inversion pulse, and as the magnetization re-grows, generating a second set of raw data by acquiring MR signals from the same series of regions used to generate the first set of raw data, wherein for the second set of raw data the series of regions are acquired in a second temporal order with respect to the RF inversion pulse, said second temporal order being different from the first temporal order with respect to RF inversion pulse;
• (d) generating first and second sets of complex image data from the first and second sets of raw data, respectively;
• (e) determining a complex phase correction factor;
• (f) applying the complex phase correction factor to one of, or both, the first and second sets of complex image data to thereby phase match the first and second sets of complex image data with one another;
• and,
• (g) generating a combined image, said combined image being generated via a pixel by pixel complex combination of the phase matched first and second sets of complex image data, said complex combination including an application of pixel type specific coefficients in conjunction therewith such that separate coefficients are applied to those pixels identified as representing the pixel type to which the specific coefficient corresponds, said pixel type specific coefficients being multiplicative amplitude corrective factors related to the magnetization re-growth for the respective pixel type.

A magnetic resonance imaging apparatus comprising:

• a main magnet that generates a substantially uniform temporally constant main magnetic field through an examination region wherein an object being imaged is positioned;
• a magnetic gradient generator that produces magnetic gradients in the main magnetic field across the examination region;
• a transmission system which includes an RF transmitter that drives an RF coil which is proximate to the examination region;
• a sequence control which manipulates the magnetic gradient generator and the transmission system to produce an NS-IR sequence including an RF inversion pulse, said NS-IR sequence inducing detectable magnetic resonance signals from the object;
• a reception system which includes a receiver that receives and demodulates the magnetic resonance signals to obtain first and second sets of raw data from respective NS-IR sequences, said first set of raw data representing a series of regions from a selected volume of the object that was excited by the RF inversion pulse from its NS-IR sequence, wherein the series of regions for the first set of raw data are acquired in a first temporal order with respect to its RF inversion pulse, and said second set of raw data representing the same series of regions from the selected volume of the object that was excited by the RF inversion pulse from its NS-IR sequence, wherein the series of regions for the second set of raw data are acquired in a second temporal order with respect to its RF inversion pluse, said second temporal order being different from the first temporal order with reference to the respective RF inversion pulses;
• a k-space storage device into which the first and second sets of raw data are rebinned as first and second sets of k-space data, respectively;
• a reconstruction processor that subjects the first and second sets of k-space data to a reconstruction algorithm to generate first and second sets of complex image data, respectively, which are loaded into a complex image data storage device;
• a phase correction processor which operates on one of, or both, the first and second sets of complex image data to thereby phase match the first and second sets of complex image data with one another;
• an image generator that combines the phase matched first and second sets of complex image data into combined image data;
• and,
• an output device that produces human-viewable image representations of the object from data output by the image generator.