Multislice CT moves into PET
The multislice capabilities of computed tomography (CT) invaded nuclear medicine's space at RSNA 2003, as vendors added more slices to combined positron emission tomography (PET) and CT systems. PET also advanced as redesigned detectors bring sharper patient images to clinicians for better diagnoses.

CTI Molecular Imaging Inc. introduced its new LSO Hi-Rez Reveal PET-CT system. CTI says the Hi-Rez Reveal PET-CT - designed for small lesion detection -- has three times higher spatial resolution than current technology. The company credits its LSO (lutetium oxyorthosilicate) detector technology as one essential component of the next-generation technology, along with a redesign of the block detector itself.

 "Our existing technology provides for an 8-by-8 [rows] block of 6.4 mm crystals," noted Greg Brophy, president of CPS Innovations, CTI's PET development and manufacturing division. "We have moved to a 13-by-13 block and a total of 169 crystals that are 4 mm in size. That [4 mm size] roughly translates into the size of a lesion."

 The University of Tennessee Medical Center took delivery of the first Hi-Rez Reveal in mid-November. As of RSNA 2003, the facility had imaged approximately 20 patients under the direction of David Townsend, Ph.D., professor and director of cancer imaging and tracer development research and co-inventor of PET-CT.

 "We have done imaging in as little as 5.7 minutes," he added. "If you want a very fast image, you can get it down to six minutes … a 30-minute scan will get the very best resolution. The challenge is to get the best image quality in people who are 350 pounds."

 Townsend said the system offers the potential to visualize disease that is smaller in size or earlier in development and which might be overlooked in some patients using existing PET technology. The facility will conduct larger scale trials to demonstrate the potential benefits in lesion detection and improvements in quantitative accuracy.

 CTI anticipates commercial shipments of the Hi-Rez Reveal to begin in March 2004.

Through its partnership with CTI, Siemens Medical Solutions also is offering a new PET-CT system with the Hi-Res PET option. Siemens' biograph PET-CT also has new features, such as a six-slice CT biograph system to complement its two- and 16-slice models, and further integration with Siemens' Leonardo post-processing IT workplace.

 Leonardo is designed for clinical flexibility and efficiency by integrating more than 50 syngo-based multimodality imaging applications with one user interface with the capabilities of Siemens' nuclear medicine e.soft package.

 Siemens also displayed its new, cardiac gamma camera system which reclines at a 20-degree angle for patient comfort. The features High-Definition Dynamic Digital Detectors (HD4) and Flash 3D technology with 3D collimator beam modeling and iterative reconstruction for enhanced image quality, contrast resolution and lesion detection.

GE Medical Systems (GEMS) displayed its InfiniaVC, complete with its new one-inch Elite detector with 95 photomultiplier tubes for imaging with high and medium energy isotopes and the preservation of image quality at low energies. With enhanced localization of diseases, the detector is designed to improve diagnostic accuracy in thyroid cancer because of its high sensitivity.

 The Infinia Hawkeye SPECT-CT imaging technology includes attenuation correction, an anatomically specific correction map.

 GEMS also promoted its Discovery ST PET-CT system with 2D, 3D and 4D imaging modes and a 70 cm-wide patient bore. 4D imaging includes 2D or 3D dynamic imaging, 2D or 3D cardiac gated imaging and works-in-progress respiratory-gated imaging.

Philips Medical Systems has added a 16-slice CT option to its Gemini PET-CT system. Gemini combines the Allegro PET system and its GSO-based (gadolinium-oxyorthosilicate) detector technology with the Brilliance 16-slice CT scanner. The design of the Gemini remains the same, with the ability to separate the Allegro and Brilliance to perform separate PET and CT scans, respectively.

 Philips' Forte gamma camera has added JetStream acquisition technology to accelerate the imaging process, as well as concurrent imaging that allows physicians to acquire multiple image sets simultaneously. A single data acquisition produces as many as 15 different image sets configured around various agent and imaging parameters.

 Philips Syntegra 2.0 is the company's new auto-fusion toolkit that automatically co-registers metabolic data with anatomical data, eliminating the need for clinicians to do it manually.

 Philips also showed its works-in-progress Astonish software for advanced image processing for molecular imaging. Astonish is designed to provide control of the resolution recovery technique and an application-specific optimization of noise suppression.

Toshiba America Medical Systems (TAMS) led its RSNA nuclear medicine exhibit with its Signature series variable angle, dual detector gamma camera. The has a new e.soft version 3.0 software platform, which provides new 3D imaging features. Version 3.0 incorporates more image slices and optimizes the automated workflows for faster procedure times.

 The also has post-processing capabilities designed for 3D imaging, the display of multimodality images and the fusion of nuclear medicine data with CT or MR images.