Open MRI systems have provided some hope for claustrophobic patients.

But the technology has been slow to catch on as a universal tool because lower field strength magnets could not quite match the level of image quality offered by traditional high-field systems. Hitachi Medical Systems America (Twinsburg, Ohio) has just launched the first high-field open MRI system with images that are equivalent to conventional MRI.

In addition to serving patients who become anxious in tight spaces, the Oasis is optimal for pediatric, limited mobility and overweight patients. Hitachi placed its first system this week at St. Mary Medical Center (Langhorne, Pennsylvania).

"We can now do procedures like angiography and diffusion-weighted imaging. It allows us the full range of diagnostic abilities and is equivalent to high-field MRI systems," Daniel Cohen, MD, St. Mary Medical's director of MRI, told Diagnostics & Imaging Week. "We can now offer patients the security of a spacious design for added comfort during scans while simultaneously providing the most accurate scan results to aid physicians in their diagnoses."

Typical MRIs have an enclosed circle design within which a magnet rotates. The $3 million Hitachi Oasis has a wide table that's open on two sides and a vertical-field magnet. Its price varies, depending on the options chosen. In addition, the high-field open unit was designed to include faster scan times and motion-compensation technology for clearer imaging.

A variety of specialized coils are used for advanced detailed studies of the brain, spine, shoulders, legs, breast, neurovascular and abdomen.

"Our target for this product is all patients," Sandy Malek, director of MRI clinical science and applications for Hitachi, told D&IW. "It's all about the patient who needs to be comfortable. But radiologists need the highest imaging quality they can get. The patient has a 270-degree access of vision in Oasis. The magnet is above and below the patient. The new engineering design allows us to have this vertical field."

As with other MRI systems, the Oasis does produce significant noise, although Malek said additional insulation was added to mitigate that thumping noise that characterizes this technology. The procedure still takes about 30 minutes.

Unique to the Oasis system, is what is called a higher-order active shim technology (HOST), which provides maximum imaging capabilities. Oasis users adjust multiple higher order channels of per-patient shimming (adjustments that make images clearer).

"We preferentially use it for claustrophobic patients, but I anticipate all MRIs will eventually be of this open design," said Cohen. "There's no downside to the imaging quality. It's basically a more comfortable experience. I think if it performs to the level we expect it to, [there will be] no reason to use a board magnet. Our expectation is that this kind of design will become a lot more prevalent."

Indeed, Malek said Hitachi is hoping to replace all tube-type MRIs. "We see no reason not to replace the tube-type magnets. But that will remain to be seen."

Both Malek and Cohen said reimbursement for imaging studies performed on the Oasis will be no different than those provided for traditional MRIs.

"The payers don't care what kind of unit it is, as long as it does the same job," Cohen said. "There's no added reimbursement for this."

With the development of open systems, MRI has evolved into the best imaging procedure for many organs and structures, including the brain, spine, bones, and joints, leading MRI equipment to become a $3.5 billion worldwide industry, according to a 2006 study from Kalorama Information (New York) and it's expected to top $4 billion by 2010.