This article appeared as an introduction to the magnetic resonance imaging (MRI) systems chart that appeared in the October 2010 issue of Imaging Technology News.
A quick glance across news headlines covering the imaging field shows that many major developments involve discoveries and improvements that are being made when multiple modalities are combined. Magnetic resonance imaging (MRI) is often one of the modalities used in combination with others, and studies continue to underscore its usefulness in a variety of areas. In recent months, there have been several MRI-related developments and research. Following is a small sampling:
- When doctors added contrast agent gadolinium during MRI, they improved primary tumor assessment for detecting lymph node metastases, according to a recent study published online by the Journal of the National Cancer Institute. The study’s authors concluded that incorporating contrast enhancement in the malignancy criteria improves the accuracy of this diagnostic test.
- New software called synthetic magnetic resonance, currently in the hands of one pilot customer, is designed to allow clinicians to quantify tissue and identify and determine its volume. This can help hospital personnel reduce the time required per patient for MRI exams. The product is SyMRI Suite from Synthetic MRI, a partner of Sectra.
- Another software development is a new MRI advanced image analysis module, OmniLook, which applies analysis using a pharmacokinetic model for organs such as the liver, kidney and brain, where dynamic contrast imaging may provide additional clinical insight. iCAD Inc. added OmniLook to its SpectraLook and VividLook products, which are solutions for breast MRI and prostate MRI, respectively. OmniLook was due to be available in August.
- As a tool for real-time imaging in the operating room, the U.S. Food and Drug Administration (FDA) has given clearance for the launch of the PoleStar N30 surgical MRI system in the United States. The Medtronic system is designed to provide greater flexibility.
- A newly released advanced visualization software package with MRI tools for neuroscience research includes a new option that provides efficient calculation of perfusion results. Amira 5.3 from Visage Imaging also provides analysis and display of multichannel functional image data, including gradients, tensors and fiber tracking.
- Another research tool is the M2 MRI system, a compact system for use in laboratories and animal houses, featuring proprietary permanent magnet technology. Aspect Magnet Technologies Ltd. recently formed a scientific advisory board to continue its development for research, but also feels the product has ultimate clinical potential.
7 Tesla On the Horizon
The exploration into applications for MRI stretches beyond the 3T level and includes work with 7T systems. Several facilities in the United States and overseas are using 7T systems for research, especially in neuroscience.
There have been mammography studies as well. One study conducted in Germany last year indicated the feasibility of doing dynamic contrast-enhanced breast imaging at 7T with good results. However, it noted there were limitations due to the coil.
In July 2010, QED announced the development and commercialization of a high multi-channel RF coil for breast imaging that creates an additional opportunity for practical clinical applications for 7T MRI systems. The breast coils offer parallel excitation capabilities to eliminate spatially non-uniform transmission fields and produce the highest signal-to-noise ratio (SNR) available.
As explained by Hiroyuki Fujita, Ph.D., CEO of QED, the 7T breast array coil uses a separate set of coils for transmitting and receiving, allowing the transmit coil to achieve optimized B1 uniformity and efficiency while the receive array coils achieve optimized SNR. In addition, it has a high number of receiving elements, arranged in a pattern to optimize parallel imaging performance. This feature, combined with the benefit of high 7T field strength, enables users to acquire high-resolution breast images with relatively short scan time.
There is a prototype waiting to be volunteer tested at New York University’s Langone Medical Center.
1. Wenche M. Klerkx, Leon Bax, Wouter B. Veldhuis, A. Peter M. Heintz, Willem PThM. Mali, Petra H. M. Peeters, and Karel G. M. Moons. “Detection of Lymph Node Metastases by Gadolinium-Enhanced Magnetic Resonance Imaging: Systematic Review and Meta-analysis.” Journal of the National Cancer Institute, Feb. 24, 2010; 102: 244-253.
2. Lale Umutlu, Stefan Maderwald, Oliver Kraff, Jens M. Theysohn, Sherko Kuemmel, Elke A. Hauth, Michael Forsting, Gerald Antoch, Mark E. Ladd, Harald H. Quick, Thomas C. Lauenstein. “Dynamic Contrast-Enhanced Breast MRI at 7 Tesla Utilizing a Single-Loop Coil; A Feasibility Trial.” Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Germany; Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Germany.