Imaging and diagnostic methods, systems, and computer-readable media
Inventors
Abd-Elmoniem, Khaled Z. • Gharib, Ahmed M. • Pettigrew, Roderic I.
Assignees
US Department of Health and Human Services
Publication Number
US-11464413-B2
Publication Date
2022-10-11
Expiration Date
2033-08-21
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Abstract
One aspect of the present subject matter provides an imaging method including: receiving a trigger signal; after a period substantially equal to a trigger delay minus an inversion delay, applying a non-selective inversion radiofrequency pulse to a region of interest followed by a slice-selective reinversion radiofrequency pulse to a slice of the region of interest of a subject; and after lapse of the trigger delay commenced at the cardiac cycle signal, acquiring a plurality of time-resolved images of the slice of the region of interest from an imaging device.
Core Innovation
The invention provides an imaging method that receives a trigger signal, applies a single non-selective inversion radiofrequency pulse followed by a slice-selective reinversion radiofrequency pulse to a slice of a region of interest, and then acquires a plurality of time-resolved cine images of the slice. The acquisition uses both phase and magnitude components of the k-space for each individual image to obtain phase-sensitive, signed-magnitude, time-resolved image frames with short acquisition windows, accompanied by navigator pulses for tracking and compensating lung-motion-induced changes.
This method solves the technical challenges of imaging vessel walls, particularly coronary arterial walls, hindered by aperiodic intrinsic cardiac and chest wall motions and blood flow-induced motion. Existing vessel wall imaging techniques suffer from motion artifacts and limitations in maintaining slice-vessel orthogonality, leading to unreliable vessel wall thickness measurements. By acquiring multiple time-resolved images during a cardiac cycle and compensating for lung motion, this invention increases imaging success and accuracy.
The invention further includes non-transitory computer-readable media and MRI devices programmed to perform these imaging sequences. Additionally, it provides image processing methods to generate signed-magnitude images by removing magnetic field phase inhomogeneities. It also offers methods for quantifying vessel wall thickness based on these images and diagnosing vascular disease based on measured vessel wall thickness thresholds.
Claims Coverage
The patent claims disclose multiple inventive features related to a novel imaging method, computer-readable medium, and MRI device, focused on time-resolved phase-sensitive imaging of vessel walls with lung motion compensation.
Imaging method with phase-sensitive time-resolved cine image acquisition
The method receives a trigger signal, applies a single non-selective inversion RF pulse followed by a slice-selective reinversion RF pulse to a slice of a region of interest, then acquires multiple consecutive phase-sensitive, signed-magnitude time-resolved cine image frames using both phase and magnitude k-space components with short acquisition windows (20 ms or less), optionally applying a navigator pulse before acquisition and compensating for lung motion.
Use of cardiac cycle signal and trigger delays to time imaging
The imaging is triggered by a cardiac cycle signal (e.g., R-wave), with trigger delay corresponding to the period between the cardiac signal and minimal myocardial motion, facilitating imaging during a quiescent vessel state.
Imaging various vessels with defined regions of interest
The region of interest framed by the method can include blood vessels such as coronary arteries or peripheral vessels (e.g., carotid, femoral, pulmonary, gastrointestinal, or renal arteries).
Temporal control of image acquisition
The plurality of cine images are consecutive, captured with substantially uniform temporal offsets between 5 ms and 50 ms (often about 25 ms), generally between 150 ms and 225 ms after the inversion pulse application.
Data storage and user interaction
The method includes storing the acquired cine images in a non-transitory computer-readable medium, presenting images to users, receiving selection of one or more images, and calculating vessel thickness from selected images with at least 75% vessel visibility.
Repetition of imaging sequence in cardiac cycles
The imaging sequence can be repeated every cardiac cycle, every other, or every n-th cardiac cycle (n a positive integer), enhancing data acquisition flexibility.
Calculation of vessel thickness from image slices
The slice can be two- or three-dimensional, containing a cross-section of a vessel, with subsequent calculation of vessel thickness from the images.
Phase and polarity image processing
The method involves determining a magnetic field phase of vessel lumen regions, utilizing polarity variations to obtain polarity images of vessel wall and lumen, and combining polarity images with magnitude images to obtain multiple signed-magnitude images across time.
Non-transitory computer-readable medium storing imaging instructions
Program instructions for executing the imaging method steps, including trigger reception, pulse application, cine image acquisition using phase and magnitude data, navigator application, and lung-motion compensation.
MRI device configured for time-resolved phase-sensitive imaging
An MRI device with controllers for magnetic field gradients, RF pulse transmission, analog/digital signal conversion, and imaging sequence controller programmed to perform trigger-based RF pulse sequences, acquire multiple phase-sensitive signed-magnitude cine images with short acquisition windows, apply navigator pulses, and compensate lung motion to maintain vessel location.
The claims collectively cover a comprehensive system comprising an imaging method, corresponding computer-readable media, and an MRI device capable of time-resolved, phase-sensitive vessel wall imaging that compensates for cardiac and respiratory motion to improve vessel wall visualization and measurement accuracy.
Stated Advantages
Improves the success rate of imaging coronary and other vessel walls by acquiring multiple time-resolved images rather than a single image.
Provides more accurate and robust vessel wall thickness measurements through selection of optimal image frames with minimal wall thickness.
Mitigates effects of aperiodic intrinsic cardiac and chest wall motion and blood flow-induced motion on image quality.
Increases precision and separation in measurements between healthy subjects and subjects with vascular disease risk factors.
Enables imaging during free-breathing by using navigator pulses for lung motion tracking and compensation.
Documented Applications
Early detection of vascular disease, including atherosclerosis.
Research in the field of vascular disease assessment and progression.
Assessment of medication and lifestyle efficacy in subjects for vascular health.
Evaluation of new medications or new uses of existing medications on vascular disease.
Non-medical applications such as imaging of industrial tubing subject to periodic motion and robotic applications where periodic movements affect imaging quality.
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