A method to improve MRI resolution during breathing
The accuracy and precision of many therapeutic imaging interventions is challenged by respiratory motion. Ventilation-induced tumor and organ-at-risk oscillations are of concern primarily for imaging lung and upper abdominal malignancies. Four dimensional (4D) computerized tomography (CT) is currently the most widely adopted modality for imaging organs that are subject to respiratory motion. However, the mechanical design of CT scanners limits the sampling pattern and often leads to resampling artifacts. This modality also provides poor soft tissue contrast. Magnetic resonance imaging (MRI) can provide improved soft tissue contrast relative to CT. Further, the sampling function of an MR imager can be easily modified and adapted to, e.g., facilitate imaging of particular portions of anatomy, to detect a flow tensor or other specialized properties of tissue, to emphasize imaging of certain types of tissue or contrast agents, or to provide some other benefit. However, MRI can impose strict timing requirements when imaging tissue, requiring extensive time for acquisition and/or numerous MR scans to generate an adequate image of tissue. These factors have limited application of MRI to the imaging of tissues that are in motion, for example, the lungs, heart, and other tissues of the abdominal and/or thoracic cavities during respiration.
Inventors at Duke have developed methods for high spatiotemporal resolution for a family of 4D-MRI pulse sequences by measuring respiratory-induced motion. This invention is intended to improve the imaging of abdominothoracic organs, tumors, or other biological tissues while compensating for respiratory-induced motion. The use of a quasi‐random sampling function and view‐sharing driven by the average breathing curve provide a feasible method for self‐sorted 4D MRI at reduced acquisition times. This approach allows for the extent of data sharing to be inversely proportional to the average breathing motion hence improving resolution and decreasing artifact levels. The sampling and reconstruction technique were tested and validated in simulation, dynamic phantom, animal, and human studies with varying breathing periods/amplitudes.
- Can measure respiratory motion faster than any known 4D MRI method without compromising spatial resolution and coverage
- Provides the highest coverage and spatial resolution for a given total scan time
- Soft-tissue contrast is achieved without the use of ionizing radiation
- The availability of pulses-sequences exploiting various contrast mechanisms inherent in living tissue, will make the proposed method a valuable addition to treatment planning.