WARF TECHNOLOGIES

Phase contrast magnetic resonance imaging (PC MRI) can be used to improve diagnostic accuracy of vascular, musculoskeletal and cerebrospinal exams. PC MRI functions by receiving a signal emitted by the “spins” of excited nuclei in the tissue as well as encoding spin motion into the phase of the acquired signal. Then the signal is processed to form an image.

Use of PC MRI in areas with significant fat surrounding vessels presents a unique set of challenges. The magnetic resonance signal of fat is at a different frequency that that of water. As a result, fat signals interfere with neighboring water signals, which leads to spreading of the fat signal away from its actual location in the resulting image. The fat signal also may spread into the water signal, resulting in image artifacts and reducing the diagnostic value of the images.

Solutions for errors in many other types of phase contrast exams have been developed, but limited options are available for reliable fat suppression with phase contrast. The most robust methods currently available require a scan time three times longer than conventional scans to obtain sufficient measurements and temporal resolution. An accurate method to correct for fat chemical shift artifacts in PC MRI which circumvents this requirement of several image reconstructions is needed.

UW-Madison researchers have developed an improved method of PC MRI that allows for accurate fat and water signal separation. The method simultaneously performs several measurements of echo-time and velocity encoding so that data is acquired from both an on-resonance water signal and an off-resonance fat signal. A set of images is reconstructed by estimating a common magnitude image and a plurality of phase images from the acquired phase contrast image data. Accurate flow velocity quantification is enabled by accurately separating the fat signal from the water images. The resulting image is created with minimal noise and improved quality.

• Fat-water signal separation and chemical shift error elimination in PC MRI techniques
• PC MRI in vascular, musculoskeletal and cerebrospinal exams

• Significantly improves image quality over other fat suppression methods
• Enables fat-water separation and chemical shift error elimination with substantially fewer measurements
• Allows incorporation of image constraints such as a varying off-resonance map to further reduce influence of noise

For More Information About the Inventors

• Kevin Johnson

Tech Fields

• Medical Imaging : MRI