Nov 28, 2007
Grand plans for CT
"Re-inventing CT" is the take-home message from GE Healthcare this week at the Radiological Society of North America (RSNA) annual meeting in Chicago, IL. Specifically, the company unveiled a range of work-in-progress technical developments that will ultimately enable it to offer high-definition (HD) CT scanning on its next-generation imaging systems.
First up, a new CT detector material. GE's Gemstone detector is a garnet-based scintillator that exploits the gemstone's unique optical properties to significantly improve X-ray conversion speed and spatial resolution. GE has also extended the capabilities of its Volara data acquisition system by boosting the sampling speed to more than twice that of the competition, while maintaining low-signal performance for dose efficiency.
Another development in the pipeline is a scheme that enables helical dual-energy data acquisition with a single source and detector, using an HDCT tube that can switch X-rays between 80 and 140 kVp in less than 1 ms. According to GE, this feature enables dual-energy acquisitions with temporal registration around 150 times better than those obtained by current technologies.
Not content with redesigning the X-ray tube, detector and data acquisition system, GE is also looking to rewrite the basic way that CT images are reconstructed. Its new Adaptive Statistical Iterative Reconstruction algorithms differ from traditional filtered back-projection techniques in that they use statistical noise profiles in an iterative manner to ramp image clarity and suppress noise.
"The overwhelming feedback we receive is the demand for better spatial resolution," said Gene Saragnese, vice-president of GE's CT business. "Spatial-resolution improvements through HDCT technologies represent our largest R&D investment area today. We believe the recent advances made possible by the HDCT technologies we're unveiling today will allow us to re-imagine CT and fulfil that demand in the future."
• RSNA also saw GE highlight its VolumeShuttle and SnapShot Pulse options for the LightSpeed VCT XT system. SnapShot Pulse, a prospectively-gated diagnostic cardiac CT exam, has been proven by clinicians to reduce a patient's radiation exposure by up to 83% and to improve image quality. VolumeShuttle, meanwhile, is said to deliver twice the anatomical coverage with up to 24% less radiation exposure than a conventional 40 mm cine perfusion protocol.
• At the RSNA technical conference, GE presented early results from a multicentre trial comparing the diagnostic accuracies of 64-row coronary CT angiography (CCTA) and quantitative coronary angiography for detecting obstructive coronary stenosis. Preliminary data from 232 patients with chest pain demonstrate the high accuracy of CCTA to reliably detect stenosis (91% sensitivity and 84% specificity for a >70% stenosis) in patients referred for invasive coronary angiography.