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Method for obtaining T1-weighted and T2-weighted NMR images for a plurality of selected planes in the course of a single scan

  • US 4,734,646 A
  • Filed: 09/16/1986
  • Issued: 03/29/1988
  • Est. Priority Date: 09/16/1986
  • Status: Expired due to Term
First Claim
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1. A method for obtaining T1-weighted and T2-weighted NMR image data for a plurality of selected planes in an object in the course of a single scan using nuclear magnetic resonance techniques, said method comprising:

  • a. positioning an object in a static homogeneous magnetic field;

    b. obtaining NMR imaging data for a T1-weighted image and a T2-weighted image in a first selected plane of said object by subjecting said object to a plurality of repetitions of a repetition sequence composed of NMR excitation and magnetic field gradient pulses, each repetition sequence including (i) applying a first excitation pulse and reading out a first NMR signal produced by said first excitation pulse at a time TE1 after said first excitation pulse, and (ii) applying a second excitation pulse and reading out a second NMR signal produced by said second excitation pulse at a time TE2 after said second excitation pulse, said first and second excitation pulses each being applied in a manner so as to only excite selected nuclei in said first selected plane of said object, said first excitation pulse being applied during said repetition sequence after a recovery time interval TR1 from a preceding excitation pulse and said second excitation pulse being applied during said repetition sequence after a recovery time interval TR2 from a preceding excitation pulse, said repetition sequence being repeated at a repetition time interval Trep which is equal to the sum of said TR1 and TR2 intervals, and said plurality of repetitions of said repetition sequence being carried out in a manner to encode spatial information into a collection of said first and second NMR signals to obtain said NMR image data for a T1-weighted image and a T2-weighted image for said first selected plane, said TE1 and TR1 being selected so that said collection of said first NMR signals is representative of T1-weighted imaging data, and said TE2 and TR2 being selected so that said collection of said second NMR signals is representative of T2-weighted imaging data; and

    c. carrying out step (b) set forth above for at least one additional selected plane of said object to obtain NMR imaging data for T1-weighted and T2-weighted images for said at least one additional selected plane, said repetition time interval Trep at which said repetition sequence is repeated for said at least one additional selected plane being substantially the same as said repetition time interval Trep at which said repetition sequence is repeated for said first selected plane, each of said first and second excitation pulses for each repetition of said repetition sequence for said at least one additional selected plane being applied in a manner so as to only excite selected nuclei in said at least one additional selected plane, and each step (i) for each repetition of said repetition sequence for said at least one additional selected plane being carried out during the corresponding repetition of said repetition sequence for said first selected plane at a different portion of said repetition time interval Trep for said first selected plane than said step (i) for said first selected plane, and each step (ii) for each repetition of said repetition sequence for said at least one additional selected plane being carried out during the corresponding repetition of said repetition sequence for said first selected plane at a different portion of said repetition time interval Trep for said first selected plane than said step (ii) for said first selected plane.

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