New MR Technologies Offer Better, Quieter Scans

CHICAGO - MRI is recognized by doctors as one of the most significant developments ever to occur in healthcare, and now, three technologies are improving or set to improve its effectiveness and ease-of-use.

PET/MR systems are already the market or in development from Siemens, Phillips and GE, and the units are helping produce shorter examinations and better-synced scans. “The two technologies are very complementary,” said David A. Bluemke, MD, PhD, and director of Radiology and Imaging Sciences at the National Institutes of Health Clinical Care, speaking at RSNA 2013. “MRI excels at structural anatomy, and PET is good on the cellular level.”

PET/MR scans have the edge over CT scans in minimizing radiation exposures in patients needing multiple tests, and can produce a full-body scan in about 20 minutes with fewer shifts in patient position. PET/MR scans are particularly effective in spotting neuroendocrine tumors and bone lesions, Bluemke said, and in testing, PET/MR scans produced better imaging in 24 out of 134 instances, while a PET/CT combination was superior in just two. “The sensitivity is comparable to the current state of the art,” he said.

MR Elastography (MRE) follows the same principles as palpation to test the mechanical properties of tissue in conjunction with conventional MR, using an acoustic driver to generate vibrations that are imaged in color by a special MRI pulse sequence. The technology is particularly effective in identifying hepatic fibrosis and determining the severity of meningiomas in the brain, and is less invasive than a biopsy. “It’s an excellent tool for diagnosing liver disease,” said Richard L. Ehman, M.D., Professor of Radiology at the Mayo Medical School in Rochester, Minn. “Fibrosis can be reversed if diagnosed early and treated.”

While MRI’s capabilities are almost limitless, the machines tend to be loud, and that noise often adds to patient anxiety. With the continuous chirp of the cryocooler and the rattling clunks of magnetic field gradients switching on and off, a typical MRI scan can be in the 95 to 115 dB range. “People have reported transient hearing loss, just like going to a rock concert,” said Frank R. Korosec, PhD, director of Research Resources in the Department of Radiology at the University of Wisconsin.

The days of earplugs and headphones may soon be over, he said, as companies introduce “silent MR” systems that use software to reduce noise levels. A new parallel imaging strategy can bring an MRI’s sound down to about 70 dB, while radial sampling techniques can cut machine noise by about 30 dB. The bonuses? Improved patient comfort and communication; soon, machines may be quiet enough to scan sleeping children, Korosec said.