by
Carol Ko, Staff Writer | October 30, 2013
From the October 2013 issue of HealthCare Business News magazine
Coils are called such because they’re just that: a loop of wire similar to the bunny ears on old television sets. Conventional wisdom always held that this was the best shape for optimal MR imaging, but researchers now know that at higher field strengths, coil antennas should look more like cell phone antennas, which are shaped like strips.
By combining strips with loops, researchers are able to capture more signal-to-noise ratio than they could using either of these shapes alone. “It’s a reminder that as the field gets higher, the body goes from being an invisible passive recipient of these fields to becoming an active participant in the behavior of the fields, so we need to account for that,” says Sodickson.
Coils in charge
But these discoveries also led researchers to realize that the body’s tendency to bend the fields at higher field strengths could be an opportunity rather than a nuisance, since the curvature of these fields could help doctors create a noninvasive map of the conductivity and permittivity of the tissue — in other words, the electrical properties of the body.
Electrical properties of the tissue convey important information about the anatomy. Tumors, for instance, have drastically different electrical properties than normal tissue. In fact, the medical community has sought to measure electrical properties of tissue for a long time but lacked the technology to do so — until now.
“So we’re developing a whole new kind of imaging — electrical property imaging,” says Sodickson. “Up till now, coils have been seen as the slaves of the MRI scanners. Their job was just to get you information about the system. Now, higher in frequency, as coils have become richer and richer, they’ve become the mediator of a whole new imaging contrast, a new imaging modality almost,” he adds.
Sodickson brings up one area where such imaging could be useful: currently, electrophysiologists study the electrical properties of the heart by sending a catheter through it. “Down the line in the distant future, if we could do that sort of thing noninvasively from the outside, wouldn’t that be beautiful?” he says.
Channel debate
However, some research trends don’t have an immediate impact on sales, and not everyone in the industry agrees on what constitutes a trend in coils. Though major manufacturers and researchers see higher channel counts as the way of the future, other industry insiders who determine trends based on what they see hospitals buying, beg to differ.
“The biggest trend over the last 12-18 months is the lack of a trend,” claims Randy Walker, vice president of sales at Genesis Medical Imaging/BC Technical, citing the failure of the OEMs to create wider demand for 16 channel coils. “That was supposed to be the latest and greatest opportunity, but we don’t see many being sold or purchased by our users,” he says.
