Sound Advice

Radio-frequency surface coils are an integral part of every MR exam. These ‘radio antenna’ devices receive the signal that will ultimately form your MR-image.

“Most MR imaging today is done with some sort of a surface coil – either quadrature or phased array,” says Dr. Russell Low, Medical Director of Sharp and Children’s Hospital MRI Center (San Diego, CA). “Dedicated coils really are essential technology for spine, musculoskeletal and body imaging. These coils are used on the anatomic area of interest so that we can get a markedly better signal, less noise and improved image quality.”

But why might one coil be better than another? Superb hardware and proprietary imaging techniques may be the answer.

Dedicated RF coils
Philips SENSE-optimized, anatomy-specific body coils designed for the Achieva 1.5T and 3.0T X-series scanners cover all imaging applications:

Of particular interest to Dr. Low is body imaging. It makes up at least a third of his annual imaging business. He and his team at Sharp and Children’s have developed and perfected specific techniques for high quality MR imaging using the SENSE XL Torso coil on the Achieva 1.5T, allowing them to establish strong relationships with referring physicians.

Up to 500 mm FOV coverage for scanning the abdomen and the pelvis, without coil repositioning.

SENSE makes the difference
SENSE is a unique ‘parallel imaging’ technology. Using multiple coil elements to measure the same field of view, only a limited number of phase encoding steps is needed to obtain the same resolution. This, then, can reduce the acquisition time by the number of coil elements. The advantages are clear.

With 16 channels, a high SNR (Signal-to-Noise Ratio) and large anatomic coverage, the SENSE XL (extra large) Torso coil has become Dr. Low’s workhorse. “This is a terrific coil,” concedes Dr. Low. “It allows me to image the abdomen and pelvis or the chest and abdomen without having to move the coil. It also lets me apply SENSE imaging techniques to improve throughput. So not only do I get better image quality, I get it faster. It’s a win, win situation.”

He continues, “In abdominal imaging we can increase the speed by two sometimes three times – that’s a really powerful statement. That means that patients for whom we could not previously perform a breathhold study – now we can. A breathhold that was 30 seconds is now 15.”

“We use SENSE on every single abdominal study and it works very well.”

Ultra-fast scanning with 4D THRIVE: acquiring two dynamics for multiple arterial phase scanning in one breath hold. Using SENSE in two directions up to an acceleration factor of 12 for complete coverage of the abdomen and plevis in one breath hold.

Creative flexibility
As a body imaging specialist, scanning quickly over large areas is important to Dr. Low. Multi-channel coils combine with SENSE parallel imaging to help him achieve desired results.

As he describes it, “There is a lot of flexibility with SENSE and the way it is applied. You can apply acceleration in two different directions - in the phase direction, which is the standard way, and in the slice direction – so now you have acceleration which is the product of the two acceleration factors. The coils are a critical element in this equation. Using better quality coils with more channels and elements means we are more likely to have a successful application of SENSE.”

In fact Dr. Low has been able to scan the abdomen and pelvis in a single breathhold as the table moves between.

Sensible economics
In addition to direct clinical benefits, SENSE coils deliver economical advantages too:

“The SENSE XL Torso coil absolutely improves our throughput,” concludes Dr. Low. “A typical abdomen/pelvis scan with the coil might take 30 minutes or less, but if you don’t have the coil it’s probably 45 minutes.”

[Published: 2007-07-03]