Start-up company cools coils to boost MRI image quality

SuperSensor coil aimed at low-field segment

A California start-up firm is hoping to transfer recent advancesin high-temperature superconducting technology into success inthe medical imaging industry. Superconductor Technologies (STI)has developed a high-temperature superconducting MRI surface coilthat can improve the quality of low-field MRI images by up to180%, according to the company.

STI of Santa Barbara filed a 510(k) application with the Foodand Drug Administration last month for its SuperSensor MRI surfacecoil. SuperSensor is one of the first of many high-temperaturesuperconducting products that STI hopes to market in a varietyof industries, including medical imaging.

SuperSensor's antenna is set in a two-inch wafer of lanthanumaluminate coated with a thin film of thallium-based high-temperaturesuperconducting material. The coil is located in a liquid nitrogen-filleddewar, or insulated container, that keeps the coil at a temperatureof 77º Kelvin and prevents it from freezing the patient'sskin.

Operating an MRI coil at low temperatures reduces the coil'sresistance, improving signal-to-noise ratio and thus improvingimage quality, according to Daniel C. Hu, STI president and CEO.

SuperSensor is most effective with low-field MRI scanners,where STI has found that it can improve image quality by 150%to 180%, he said. The coil is less effective at higher field strengths.With 0.3-tesla machines, for example, SuperSensor improves imagequality by 50% to 70%. It can also improve image quality on 0.5-teslamachines, according to Hu.

SuperSensor initially will be used for extremity scans. STIplans to develop other coils, such as a coil for spine imaging,Hu said. The company is also working on very small coils to examineeye muscles.

STI intends to market SuperSensor to users of low-field scannerswho want to improve their system's performance. For these users,STI believes SuperSensor will both improve image quality and reduceimaging exam times. STI estimates that the market for retrofittedcoils will be worth $225 million by 1998.

STI also sees potential for its products in the emerging nicheMRI market. The company believes its technology would complementdedicated scanners such as Magna-Lab's Magna-SL and Lunar's Artoscanunit. MR mammography is another application that could benefitfrom STI coils.

"The most exciting developments in the future are thesmall MRI machines," Hu said. "There are too many machinesout there and the market is saturated. You have to develop newapplications and different markets."

STI was founded in 1987 by two of the three venture capitalistswho founded microprocessor giant Intel. To start STI, the venturecapitalists enlisted the technical assistance of Dr. Robert Schrieffer,a Nobel laureate in superconductivity working at the Universityof California at Santa Barbara.

The company went public in March 1993 with an initial publicoffering that raised $15 million. The thallium material used inthe MRI coil is licensed from the University of Arkansas.

STI will market SuperSensor through OEM relationships, accordingto Hu. One OEM partner could be Philips Medical Systems NorthAmerica, whose parent, Philips N.V. of the Netherlands, has madea strategic investment in the company. Hu confirmed that STI isinvestigating MRI applications with Philips.

SuperSensor's price will be in the $10,000 to $20,000 range,competitive with other MRI coils, according to Hu. The coil isfully compatible with existing MRI machines, but users must alsopurchase a liquid nitrogen replenishment station because the liquidnitrogen in the coil's dewar boils off after 90 minutes. The stationswill cost between $10,000 and $20,000 and can service a numberof SuperSensors.

STI is also developing high-temperature superconducting productsfor the defense, cellular and computer industries. While SuperSensoris the company's first medical imaging product, other productsin its development pipeline could have a more profound effecton the industry.

For example, STI is working on technology to cool microprocessorsand other key processing chips to increase their speed. The technologycould be used to develop high-temperature superconducting medicalimaging workstations capable of processing much more data at fasterspeeds than workstations now on the market.