Magnetic resonance imaging (MRI) departments may face a variety of issues when conducting MR exams. Things like patient motion or artifacts in the image can cause technologists to spend more time scanning the patient than originally expected. As a result, manufacturers and researchers have been working toward a few different sequences and solutions that are designed to take productivity in the MR suite to the next level.
These options could be the solution technologists have been looking for, allowing them to correct for or eliminate artifacts caused by patient motion and susceptibility. This technology is able to be upgraded and customized in order to meet the needs of different practices.
Traditionally, technologists used a portion of the scan time positioning the patient with phased array coils and determining the best way to scan a region of interest. Because of this, the scans were often impacted by variability. That is to say, they were dependent on the MR scanner and the technologist themselves. The variability also spawns from a patient's ability to lie still and susceptibility effects.
Patient motion in MR1
One common issue that impacts the productivity is patient motion during the exam. Because MR images are acquired by comparing the signals produced by the patient's body during and after pulse sequences, changes in the patient's position can cause distortions, called artifacts, to appear in the images. Each time a patient moves, it may cause the radiology technologist to have to scan the patient again to obtain a more accurate image.
In addition, involuntary motions like those caused by breathing may also cause artifact degradation. Elderly patients or those who are acutely ill could have trouble holding their breath for the duration of the acquisition. During MR scans, patients may have to hold their breath multiple times.
There are a number of approaches to reducing the artifacts caused by voluntary and involuntary motion. One of the approaches to reducing motion artifacts is to increase the scanning speed, which could reduce the overall exam time. This can be done using acceleration techniques, such as parallel imaging or compressed sensing techniques. Free-breathing techniques, including gating, triggered and Auto Navigator techniques can help to reduce artifacts related to involuntary motion.
Susceptibility in MRI1
Differences in the magnetic field can cause susceptibility artifacts. The manufacturers work to maximize the homogeneity, or uniformity, in the magnetic field. Magnetic field distortions can lead to signal loss, but this is not the only cause. Certain MR-Conditional devices are designed to be safe for scanning as long as specific conditions are met. The metal in such devices can also cause susceptibility artifacts around the implant itself. In order to eliminate these artifacts, distortion correction techniques may be used.
Motion correction, distortion correction and acceleration techniques can provide important approaches to artifact reduction. In return, technologists may use some of these methods to reduce the overall time required for the scan because of the lesser need to scan an area again. This can help to reduce the issues that may present itself during scanning.
- SIGNA™ Works: tuned for productivity and efficient workflows. SIGNA Pulse of MR. http://www.gesignapulse.com/signapulse/spring_2019/MobilePagedArticle.action?articleId=1488827&app=false. Last accessed September 12, 2019.