Intracranial Three-Dimensional Time-Resolved Contrast-Enhanced Magnetic Resonance AngiographyPublic Deposited
Magnetic resonance imaging (MRI) allows for the selective visualization of blood vessels via the intravascular injection of a paramagnetic contrast agent and the suppression of background signal. Called magnetic resonance angiography (MRA), this technique can produce three-dimensional images and is useful clinically for the noninvasive diagnosis of vascular disorders. In many anatomic regions, MRA has supplanted catheter-directed X-ray digital subtraction angiography, an invasive procedure. For certain clinical scenarios where dynamic information about blood flow is important, such as for arteriovenous fistulae and malformations, MRA may be performed in a time-resolved manner, where multiple images are acquired sequentially. However, due to the inherent tradeoff between spatial resolution, temporal resolution, and signal-to-noise ratio (SNR) for MRI, it is challenging to achieve sufficient values of these parameters in some cases. Specifically, the intracranial circulation exhibits rapid arteriovenous transit times and contains many small caliber vessels of clinical significance. Successful imaging can be achieved through the use of specific acquisition, reconstruction, and post-processing techniques. In addition, high magnetic field magnets, currently defined as those operating at 3 T or higher, are capable of producing images with higher SNR and minimal side effects. This increased SNR may be traded off for greater spatial or temporal resolution.