COMPACT CARDIAC SPECT

Geared for patient comfort and technologist safety, the CardiArc system from CardiArc Inc (Lubbock, Tex) represents a break from other cardiac single photon emission computed tomography (SPECT) systems. Its prime design goals—higher performance than conventional systems, a new level of patient comfort, and practical placement for small, real-world office exam rooms—necessitated rethinking every aspect of camera design from the ground up.

Rather than moving collimators and detectors around the patient, the CardiArc detector surrounds most of the patient's chest, eliminating all detector movement. The system dispenses with traditional parallel-hole collimators and instead splits the collimation into two parts. One of these provides slice separation and is completely stationary; the other is a thin aperture arc, weighing only 15 pounds, which provides within-slice collimation. This is the only moving part of the entire detector assembly. This considerable reduction in moving parts results in a scanner much smaller than existing systems with much greater expected reliability.

CardiArc’s detector (shown in green) is completely stationary. Rotation of the 15-pound aperture arc (shown in gray) scans the lines of sight across the field of view. Five complete projection sets are obtained simultaneously (d) at high sampling density. (Click image for larger view)

Thin, motionless, horizontal lead vanes separate slices, providing axial collimation (a–c). The moving aperture arc collimates in the transaxial plane. Multiple detector pixels use each aperture slot (d). (Click image for larger view)

These images of the Data Spectrum anthropomorphic phantom were obtained with the CardiArc. Perfusion “defects” have been placed in the anterior and inferobasal walls. Image quality remains high, even at very short acquisition times—(a) 10.7-minute acquisition; (b) 2.8-minute acquisition. (Click image for larger view)

The system can be used comfortably in even a 6- x 7-foot exam room. Because detector position need not be customized for each patient, and because the detector does not move around the patient, scan setup time is reduced—typically to just a few seconds.

CardiArc's unique collimation design magnifies the heart while obtaining five complete projection sets simultaneously. The company claims that this process results in image resolution higher than any other available SPECT (or PET) system and excellent image quality—even with scan times as short as 2 to 4 minutes. Alternatively, patient dose can be reduced substantially while scan times are kept at current standards.

The CardiArc scanner received FDA 510(k) approval in January. More information is available at www.cardiarc.com.

The Spec Sheet

1. At 4.2 mm, reconstructed resolution is higher, creating images that are twice as fine as any other SPECT available and 15% to 20% sharper than any PET scanner, CardiArc claims.
2. Accommodates patients up to 350 pounds, and enables patients to remain in a comfortable, seated position throughout the short scan time. Also, the open right side creates additional comfort for claustrophobic patients.
3. The camera is shielded, completely protecting the technologist from radiation when he or she is standing at the operating position.

The Visable Difference

The CardiArc's stationary detector and unique collimation result in a compact, high-performance device that provides very high signal-to-noise ratio images with high lesion contrast.