This invention is an improved process for three-dimensional cardiac magnetic resonance imaging (MRI), designed to overcome the limitations of current MRI systems in imaging dynamic phenomena such as the beating heart, flow of contrast agents in blood vessels, brain excitation, or joint movement. This invention produces motion movies of the beating heart, and other dynamic phenomena, with significantly higher spatial and temporal resolution than currently feasible.
The data in an MRI scanner is acquired by applying electromagnetic signals to the subject, and receiving the induced signals. The computational process of forming an image of the anatomy of interest from the received signals is called image reconstruction. By virtue of its non-invasive and non-ionizing nature, MRI technology has been used widely for imaging static anatomy, such as the brain, knees and joints.
However due to MRI's relatively slow acquisition speed it yields limited and unsatisfactory results in dynamic cardiovascular applications, since the heart moves during data acquisition. Cardiovascular disease represents the leading cause of death in the industrialized word and clinical practice in the treatment of this disease is severely limited by this.
The typical resolution to this problem is to attempt to "freeze" cardiac and respiratory motion through Electro Cardigram (ECG) gating and breath-holding, or other respiratory gating and are averaged over time. These methods are ineffective in patients with any form of arrhythmia, and the time averaging provides an inaccurate view of the dynamic process of every patient.
Patient-Adaptive Reconstruction and Acquisition in Dynamic Imaging with Sensitivity Encoding (PARADISE) is a revolutionary imaging algorithm, which delivers an optimal acquisition and reconstruction scheme for highly accelerated imaging. PARADISE is capable of creating highly accurate real-time motion movies of the beating heart without requiring cardiac triggering or additional hardware on any existing MRI scanners.
PARADISE uses three main components to overcome the acquisition speed limitations in MRI. First, to acquire more data in a given time interval, PARADISE uses parallel coils with sensitivity encoding that allows simultaneous acquisition of several sets of MR data. Second, to focus the acquisition to the most informative data, PARADISE constructs a mathematical model capturing each patient's unique cardiac dynamics, and then adapts the MR data acquisition to this model and to the parallel coil properties. Third, to make the best use of the acquired data, PARADISE adapts the reconstruction process to the parallel acquisition and to the patients unique dynamics model. These components are then optimally combined to form a high spatial- and temporal-resolution movie of the patient's cardiovascular system, which has accounted for the patient's cardiovascular movement and respiratory motion.
PARADISE can easily be incorporated into many existing MRI apparatus to produce highly accurate motion movies of the structure, function, perfusion and viability of various anatomical regions in MRI subjects.
In general, PARADISE can be used to offer the following technological improvements over current MRI methods:
- Provide artifact-free motion movies of rapidly moving organs
- Enhance temporal resolution with fixed SNR and total scan time.
- Enhance spatial resolution with fixed SNR and total scan time.
- Enhance SNR with fixed spatial resolution and total scan time.
- Reduce total scan time with fixed SNR and spatial resolution.
- Maximize contrast-to-noise ratio with a consideration of all three of the above.
These improvements are expected to have considerable clinical impact in the diagnosis and treatment of cardiac disease, including:
- Expanding the application of MRI scans to a larger patient population than currently possible, e.g., patients with arrhythmias (nearly 4 million in the U.S.)
- Improving the diagnosis of valvular and congenital heart disease and impairment of regional wall function
- Potentially extending the diagnostic capabilities of cardiac MRI to previously infeasible or unforeseen applications
- Improving patient safety by eliminating the need for medication to lower the heart rate during imaging