T1-weighted turbo-spin-echo mri sequence for producing high quality dark blood images at high heart rates

Abstract

A T1-weighted turbo-spin-echo magnetic resonance imaging system configured to capture data associated with a subject's heart during a time period and produce MR images has a dark-blood preparation module, a data capture module, and an image reconstruction module. The dark-blood preparation module performs dark-blood preparation through double inversion during some, but not all of the heartbeats within the time period. The data capture module configured performs data readouts to capture imaging data of an imaging slice during every heartbeat in which dark-blood preparation is performed. The data capture module also performs a steady state maintenance step during every heartbeat in which dark-blood preparation is not performed in order to maintain maximum T1-weighting. The image reconstruction module configured to reconstruct a T1-weighted image based on the imaging data.

1 . A computer-implemented method for performing a cardiovascular T1-weighted turbo-spin-echo magnetic resonance imaging sequence, comprising:
 receiving a physiological signal from a subject, the physiological signal representative of the subject's heartbeat;   performing dark-blood preparation according to a trigger pulse of N, wherein the dark-blood preparation occurs only in every Nth heartbeat and N is greater than 1;   performing a data readout in every Nth heartbeat, wherein the data readout includes capturing imaging data associated with an imaging slice;   performing a steady-state maintenance step, wherein the steady-state maintenance steps are performed only for every heartbeat which does not include a data readout;   reconstructing a T1-weighted image of the imaging slice based on the imaging data received as a result of the data readouts.   
     
     
         2 . The computer-implemented method of  claim 1 , wherein the physiological signal is an electrocardiogram wave. 
     
     
         3 . The computer-implemented method of  claim 2 , wherein the dark-blood preparation is triggered by at the R-wave preceding every Nth heartbeat. 
     
     
         4 . The computer-implemented method of  claim 1 , wherein the physiological signal is a pulse oximetry wave. 
     
     
         5 . The computer-implemented method of  claim 1 , wherein the steady-state maintenance step is a “dummy” readout in which imaging data is collected. 
     
     
         6 . The computer-implemented method of  claim 5 , wherein the image is reconstructed from a data set which does not include the imaging data associated with the “dummy” readouts. 
     
     
         7 . The computer-implemented method of  claim 1 , wherein the steady-state maintenance step is a slice selective saturation pulse which saturates transverse and longitudinal magnetization of the tissue and does not include a data readout. 
     
     
         8 . The computer-implemented method of  claim 1 , wherein the steady-state maintenance step is integrated with the dark-blood preparation for a combined dark-blood and saturation preparation step. 
     
     
         9 . The computer-implemented method of  claim 8 , wherein the combined dark-blood and saturation preparation step comprises a slice selective saturation pulse which saturates transverse and longitudinal magnetization of the tissue. 
     
     
         10 . A computer-implemented method for producing a cardiovascular T1-weighted magnetic resonance image, comprising:
 receiving a parameter representative of a subject's heartrate;   determining a trigger pulse value N for an MRI sequence based on the parameter representative of the subject's heartrate;   performing the MRI sequence, including:
 performing dark-blood preparation according to a trigger pulse of N, wherein the dark-blood preparation occurs only in every Nth heartbeat; and 
 performing one of a data readout or a steady-state maintenance step for every heartbeat, wherein the data readout includes capturing imaging data associated with an imaging slice and both the data readout and the steady-state maintenance step saturate transverse and longitudinal magnetization of the tissue; and 
   reconstructing a T1-weighted image of the imaging slice based on the imaging data received as a result of the data readouts.   
     
     
         11 . The computer-implemented method of  claim 10 , wherein the parameter representative of the subject's heartrate is a physiological signal. 
     
     
         12 . The computer-implemented method of  claim 10 , wherein the parameter representative of the subject's heartrate is an average value for the heartrate. 
     
     
         13 . The computer-implemented method of  claim 10 , wherein determining the trigger pulse value N includes comparing the parameter representative of the subject's heartrate to one or more threshold values or using a lookup table. 
     
     
         14 . The computer-implemented method of  claim 10 , wherein the data readout and the maintenance pulse occur while the subject's heart is in diastole. 
     
     
         15 . The computer-implemented method of  claim 10 , wherein the maintenance steady-state step includes a data readout that produces a data set which is not used in the image reconstruction. 
     
     
         16 . The computer-implemented method of  claim 10 , wherein the steady-state maintenance step is integrated with the dark-blood preparation performed during a subsequent heartbeat. 
     
     
         17 . A T1-weighted turbo-spin-echo magnetic resonance imaging system configured to capture data associated with a subject's heart during a time period and produce MR images, comprising:
 a dark-blood preparation module configured to perform dark-blood preparation through double inversion during some, but not all of the heartbeats within the time period;   a data capture module configured to perform data readouts to capture imaging data of an imaging slice during every heartbeat within the time period; and   an image reconstruction module configured to reconstruct a T1-weighted image based on the imaging data, wherein the image reconstruction module discards or ignores imaging data received from the data capture module which was captured during heartbeats in which the dark-blood preparation module did not perform dark-blood preparation.   
     
     
         18 . The system of  claim 17 , wherein the dark-blood preparation module determines a trigger pulse N and performs dark-blood preparation only for every Nth heartbeat. 
     
     
         19 . The system of  claim 18 , wherein N is greater than one. 
     
     
         20 . The system of  claim 18 , wherein the dark-blood preparation module determines the trigger pulse N based on a parameter representative of the subject's heartrate.