SPECT camera promises two-minute cardiac scans

Developers of a novel SPECT camera found their device suddenly basking in the cardiologic limelight March 13, when FDA reviewers cleared the system just prior to the American College of Cardiology meeting in Atlanta. The clearance caught CardiArc of Lubbock, TX, by surprise and triggered a scramble by device inventor Dr. Jack Juni, chairman and CTO of CardiArc, to get the word out before the conference ended.

In meetings with cardiologists at the ACC meeting, Juni, a nuclear medicine specialist at Beaumont Hospital in Royal Oak, MI, characterized the CardiArc SPECT Imaging System as an ultracompact, ultrafast, high-resolution cardiac camera optimized for an outpatient cardiology setting or emergency room.

The system lists for $250,000. Seven sales reps are now assigned to the product, and CardiArc is recruiting three more. In-house engineers will be available to service and maintain the system, but the company plans to actively support customers who want to do their own maintenance.

CardiArc is designed to perform scans in two to four minutes rather than the 10 to 15 typically required for a cardiac study. Data are acquired using a series of detector boards, fashioned from either sodium iodide or CZT (cadmium zinc telluride) semiconductors. The detector boards, each measuring about 18 x 4 cm, are aligned edge-to-edge along a 180° arc that wraps around the seated patient.

The design was originally developed to use either detector material. The two clinical prototypes developed by the company used CZT detectors, but initial production units will likely use sodium iodide because of the high cost and sporadic availability of CZT.

"The pricing and availability of CZT are not where we need them to be in order to price these systems affordably for cardiologists," Juni said.

A sodium iodide detector has been tested, and the R&D team found no appreciable difference from the one made with CZT, according to CardiArc CEO Don Stull.

"The speed and other benefits are not from the detector material. They are from the patented design of CardiArc," he said.

The first of two prototypes began testing in 2004 under Juni's supervision on patients at Beaumont Hospital. A total of about 15 patients have now been scanned with these machines.

The company has done patient scans in less than two minutes. Some images were acquired in as little as 30 seconds. Juni plans to recommend scan times of two to four minutes.

"CardiArc is several times sharper than any existing SPECT system," he said.

Comparisons of CardiArc to conventional SPECT systems are found on the company's Web site. Results are based on phantom testing, Juni said.

There are no substantial differences between the prototypes and production models in the way data are acquired. The commercial product, however, will be engineered to allow easier installation. Whereas the prototypes could fit through a doorway 36 inches wide, production models will fit through a 25- or 26-inch opening.

The commercial design calls for shielding to reduce technologist exposure to radiation coming from the patient. The shielding also gives hospitals the option to install several cameras in a single larger imaging room. No other gamma cameras offer these options, according to Juni.

The sit-up gamma camera, which plugs into an ordinary wall outlet, is extraordinarily compact, allowing installation in a 6 x 7-foot examination room. Yet CardiArc is built for patient comfort. The seated patient places his or her left arm on the detector housing that extends across the chest. The right arm joins the left or rests at the patient's side.

"An uncomfortable patient moves, especially in a scanner where you require someone to be still for 10 or 15 minutes," Juni said. "This causes blurring and artifacts. Fifteen or more percent of scans can be compromised to some extent by motion."

The CardiArc system is the first of what could become a portfolio of products for the Texas firm of the same name. Other products in the pipeline will address the breast, brain, and whole body. The company is also planning the 2007 release of a SPECT/CT device, using the x-ray source for localization and attenuation. This product will include an ultrasmall CT imaging chain fitted inside the existing design such that the footprint of the gamma camera is not changed.

For the next year, early adopters of the CardiArc will do without attenuation correction. This should not be a major problem, however.

"If you took a poll of users, I think you would find that the bulk of attenuation correction systems sold now are not used for routine patient care," Juni said. "It has a lot to do with the complexity of using them and maintaining quality control. We do feel that attenuation correction is worthwhile, and we plan to be among the first with really good working attenuation correction."