Bulky coils have been a challenge for members of radiology teams across the country. The traditional coils used in magnetic resonance imaging began as extremely stiff, heavy coils that were placed around the area of the patient's body that was being imaged. These coils were made for the average sized person, with smaller ones that were available for children.
Since that time, there has been a shift to a more lightweight, flexible coil design. At first, this included coils that were still rather stiff, but these newer coils could not be used in specialized areas of the body, like the knee or shoulder. This is because they were not able to get as close to the patient's body as desired. Recently, the shift has moved toward coils that are more durable, more multi-purpose and even more lightweight than both of the previous generations.
The impact of the new generation of coils
The radiology team at Erasmus Medical Center in Rotterdam, Netherlands, and their students have recently invested in some of the latest generation of coils. In the past, they have struggled with the bulky, heavyweight coils that caused difficulties with positioning of patients, as well as reducing the usability certain advanced techniques at 3.0T.1 Different members of their team have seen advantages in a variety of areas in the MR suite, including versatility and increased image quality.
Coils designed for patient comfort
The coils that they recently invested in are designed to fit all patients, whether they are the average size of patients or bigger or smaller than the average. With the increased versatility that these coils present, the Erasmus MR team believes that the coils allow flexibility in any direction and have the ability to wrap closely around the patient's anatomy for greater visibility of hard to scan areas with excellent image quality.1 While the coil conforms to the patient, it brings the coil elements closer as well, which can lead to improved signal quality and a higher signal-to-noise ratio (SNR). This can help reduce imaging artifacts when compared to previous generations of conventional coil technology.
Brendan Bakker is an MR radiographer who works with a cardiologist, Dr. Alexander Hirsch, to create cardiac MR (CMR) protocols for the medical center. His scans are frequently done at 1.5T, as it is the preferred signal strength for CMR.1 He has found that the new coils are much easier to handle, because they are lightweight. Bakker even notes that they can fit like a blanket on children, possibly increasing the patient's comfort, while maintaining excellent image quality.
Additionally, the coils can be used in a variety of areas of the patient's body, anywhere from the chest to the knees. Sita Ramman, another MR radiographer at Erasmus Medical Center, reports seeing a reduction in the nervousness of her patients thanks to the center's new, lightweight coils.1
Coils for excellent quality
One member of the team, Alexander Hirsch, MD, is a cardiologist who specializes in non-invasive cardiac imaging, especially in cases of cardiomyopathy and ischemic heart disease.1 To image his patients, Dr. Hirsch uses one technique that has been problematic at 3.0T in the past. However, with the upgrade in coil technology, he finds that the signal is more homogeneous (or uniform) across the field. He also notes that there is excellent contrast between blood and myocardium (muscular tissue of the heart).
Dr. Edwin Oei, MD, PhD, Associate Professor of Musculoskeletal Imaging and Section Chief of Musculoskeletal Radiology at Erasmus Medical Center spends half of his time working with researchers and PhD students.1 Through his research, he has noticed that musculoskeletal imaging generally suffers more from artifacts and movement than imaging of other areas of the body. This could be due to injury or alignment issues and may have traditionally require the use of specially designed coils, especially for the shoulder, wrist and ribs.
The new generation of coils helps reduce this need by allowing for imaging of these body parts with greater accuracy, because of the ability of these coils to wrap around the body. This is especially true for patients with chronic diseases, such as arthritis, who may have more trouble lying still for long periods of time with a rigid coil.
Juan Hernandez Tamames, PhD, Associate Professor of MR and Head of the MR Physics group in the radiology department at Erasmus, uses compressed sensing as an acceleration technique for his scans.1 Compressed sensing samples data at semi-random intervals to create the background of the image produced by the MR scan.2 Because compressed sensing collects less data, it can take less time.2 When Dr. Tamames used compressed sensing with the new coils, he noticed an improvement in the SNR, because the coils are closer to the patient's anatomy and tissue.1
The newest generation of coils may be the most helpful generation yet for patients and radiographers alike. The lightweight design makes them easier for the radiographer to position and reduces the amount the coil pushes down on the patient. The increase in comfort may lead to a decrease in movement, especially in patients who were unable to lay still with the previous generation. When you combine the patient comfort with the increased signal-to-noise ratio at both 1.5T and 3.0T field strengths, the Erasmus Medical Center seems to have taken a step in the right direction. Hospitals may want to consider switching to these lightweight, versatile and durable coils.
For more information, please read SIGNA Pulse "AIR Technology: a brilliant improvement in high-quality imaging and patient comfort."
1. Edwin Oei, et al. "AIR Technology: a brilliant improvement in high-quality imaging and patient comfort." SIGNA Pulse. Spring 2019. Web. 22 May 2019. <http://www.gesignapulse.com/signapulse/spring_2019/MobilePagedArticle.action?articleId=1488814&app=false#articleId1488814>.
2. "Compressed Sensing: What is compressed sensing and what is it good for?" MRIQuestions.com. Web. 28 May 2019. <https://mriquestions.com/compressed-sensing.html>.