MRI
Faster scan times, faster image processing and more automated scan options on new and upgraded MRI scanners were on display around the exhibit floor at RSNA 2003. The focus continues on 1.5T scanners, while greater functionality is migrating up to 3.0T units and down to open systems as well.Siemens Medical Solutions at RSNA announced the first installation of the MAGNETOM Avanto 1.5 Tesla MR system, which is the first product to incorporate Siemens Total imaging matrix (Tim) technology, at New York University (NYU) Medical Center. Tim uses a whole body surface coil concept to combine up to 76 coil elements and 32 RF channels [76x32]. Tim allows the user to select exams, not coils, and provides the highest acquisition speed without image artifacts or restrictions in coverage, giving radiologists the opportunity to conduct advanced applications, such as metastasis evaluation. The Tim Application Suite includes a comprehensive set of clinical applications, including Neuro, Angio, Cardiac, Body, Oncology, Orthopedic, and Pediatric. Siemens MAGNETOM Symphony, Sonata and Trio systems are upgradeable to include Tim technology. Image quality is increased by up to 100 percent signal-to-noise ratio, according to Siemens. The Avanto's Tim technology means that patient repositioning and manual coil changes are virtually eliminated during exams, enabling full body imaging in a single exam.
The MAGNETOM Avanto offers high-resolution full-body images for metastasis evaluation, whole CNS imaging and visualization of vascular diseases in a shorter acquisition time. It also features Siemens iPAT (integrated Parallel Acquisition Technique) that provides fast image acquisition with parallel imaging in all dimensions, including head to toe, front to back, and side to side. Phoenix software allows clinicians to transfer protocol for medical images from a CD, making it possible to initiate a scan directly from the image. Additionally, the system allows more audio comfort due to 97 percent noise reduction.
At RSNA, Philips Medical Systems launched its new Intera Achieva family of high-cylindrical MR systems. The series includes FreeWave scalable, 32-channel architecture and is built around SENSE technology, for increases in imaging speed up to a factor of eight and increase image quality, Philips says. The new Vequion-compliant user interface features ExamCards, entire clinical studies selectable at a single touch.
The new members of the family include the Intera Achieva 1.5T, Intera Achieva 3.0T, the Intera Achieva Mobile MR, the Intera Achieva CV for cardiac exams and Intera Achieva I/T for interventional MR work.
The Intera Achieva 1.5T offers applications in neurological, musculoskeletal and abdominal imaging as well as cardiac and functional studies, contrast-enhanced angiography and spectroscopic imaging thanks to powerful gradients up to 66 mT/m and 160 SR.
The Intera Achieva 3.0T is the most compact whole-body MR system available, sharing the same footprint as the 1.5T unit. A 400mm field-of-view enables high-quality, full coverage body imaging. New Quasar Dual gradients, developed for 3.0T imaging, enable ultra-short TEs and sub-millisecond TRs. RF-SMART (Radio Frequency Superior Management ArchiTecture) manages Specific Absorption Rate (SAR).
The Intera Achieva Mobile MR features the same functionality and patient-friendliness of the Achieva 1.5T, yet travels at-field for park, plug and scan operations. The unit can be used for scanning as soon as it pulls into a site, while its compact lightweight design allows easy travel in standard traffic.
For cardiac work, the Achieva CV allows clinicians to perform a single-session cardiac check-up - providing information on morphology, function, flow, rest and stress studies, coronary artery imaging and peripheral vasculature. The new PhysioTrak patient handling and monitoring system enables fast patient set up, continuous patient monitoring and fast evacuation if needed. MotionTrak Plus provides motion correction, while Vector Cardiogram (VCG) enables near 100-percent triggering and gating accuracy, even for patients with severely disturbed ECG patterns.
Philips' new interventional MR family, the Achieva I/T, has three configurations: the Achieva I/T is optimized for minimally invasive interventions; the Intera Achieva I/T Neurosurgery supports neurosurgery applications including MR-supported brain biopsies, tumor resections and functional neurosurgery; and the Achieva I/T Cardiovascular combines the Achieva 1.5T CV with a cardiovascular x-ray syste, for cardiovascular diagnostics, interventions and therapy. The system also can be used for general imaging.
GE Medical Systems used RSNA as the springboard to launch three new imaging techniques for its EXCITE technology for Signa MR systems for optimizing neuroradiology, angiography and breast imaging.
Propeller technology creates T2-weighted and diffusion-weighted brain images, improving contrast-to-noise ratio by 20 to 30 percent, reducing tissue-to-air image distortions in diffusion-weighted imaging and reduces the problem of patient motion by allowing good images despite patient twitches, jerks or "sightseeing," when a patient looks around the gantry. Propeller accounts for these movements, creating crisp, usable images.
TRICKS (Time Resolved Imaging of Contrast Kinetics) data acquisition for MR angiography requires about 10 times the data volume and 12 times the data processing power of conventional methods, GE says. The method works by collecting one image of the static background, then adds a rapid series of only the dynamic components of the image (which is key to high temporal resolution). The final result is an integration of the background and dynamic information, in a clinically practice timeframe.
VIBRANT (Volume Imaged Breast Assessment) imaging provides simultaneous, high-resolution bilateral breast imaging with a single injection in the sagittal plane (which is preferred by mammographers). The field of view is also smaller. GE said it provides similar resolution to a single-breast MR exam with no scan time penalty. VIBRANT also includes bilateral shimming for each patient, breast-specific spectral inversion and automated image subtraction for fast suppression.
GE debuted EXCITE technology in 2002 to improve signal-to-noise ratio (SNR), resolution and speed. At RSNA, the company also announced the migration of EXCITE to the 0.7 T Signa OpenSpeed system. EXCITE is upgradeable to the installed base of OpenSpeed systems. Gurney Radiology in Illnois is the first working site.
GE also highlighted the Signa Excite 3.0T MRI scanner at the show, which was introduced in 2003. The scanner's Perform feature enables users to monitor power deposition in the patient over time, helping users avoid sequences that might exceed guidelines on specific absorption rates (SAR) - which is common in 3-tesla scanning. The company has installed five Signa Excite 3.0Ts and expected to shipped 15 by the end of 2003.
Toshiba America Medical Systems showcased its Excelart Vantage for general imaging - and its first U.S. installation at Radiology, Ltd. at Tucson Imaging Associates. The company also introduced enhancements to the Ultra open MRI system.
The Excelart Vantage offers linear 30 mT/m gradients with a slew rate of 50 T/m/s or 130 T/m/s. The Vantage features half-fournier R/F refocused sequence for very high-speed 2D and 3D T2 weighted imaging for vascular imaging of the chest and abdomen. The system utilizes the world's shortest magnet with the highest homogeneity in the industry over a full 50 cm diameter spherical volume (DSV), according to Toshiba.
In addition to the Ultra open's high-gradient performance, the system now offers new pulse sequences and a Silicon Graphics Octane2 visual workstation designed to optimize procedural accuracy and boost productivity 15 to 20 percent. The new pulse sequences include:
- Spin Echo Sequence in 2D (SE2D)
- Water Fat Separation
- Sliding Slab Interleaf
- Flow Averaging for 2DTOF
Hitachi Medical Systems at RSNA debuted the new AIRIS Elite open MRI scanner. The 0.3T system features a vertical field magnet with Active Shim technology that provides high uniformity to support advanced imaging techniques and applications such as RF fat saturation. It also is self-shielded for a small 5G footprint and provides a 42.5cm bore height for easy patient access. AIRIS Elite will include Hitachi's advanced 4-channel RF system Scalable DualQuad and RAPID Parallel Imaging. The AIRIS Elite's gradient system has maximum amplitude of 21 mT/m and maximum slew rate of 55 T/m/sec, enabling high resolution scanning, short TR/TE and advanced sequences such as Single-shot EPI-DWI. The 80cm wide patient table supports 500 pounds and is power-driven in six directions.
Hitachi also unveiled many new capabilities for its Altaire 0.7T MR system. PEAKs, a centric k-space filling technique, provides optimal arterial and venous separation enabling advanced MR angiography imaging. Additionally, RAPID Parallel Imaging will be available with Altaire along with a host of new coils including a Multiple Array Breast, Peripheral Vascular and Neuro Vascular coils. A new, dedicated Cardiac coil and advanced cardiac imaging package are also under development.
ONI Corp. made RSNA the launching pad for the ORTHONE 1T extremity scanner, which the company touts as the "first 1 Tesla high field performance, low cost, dedicated MRI for extremity imaging." The ORTHONE offers a compact designed superconducting magnet and can be sited in 200 square feet. The preferred configuration of 12x20 feet allows the overall space to be partitioned into three spaces, operator's console, patient scan room and compressor/equipment room. The system's hardware design is optimized for extremity imaging and offers pulse sequences with broad imaging option. Predefined protocols and automatic scan setup make the system easy to operate, ONI says, while an ergonomically designed free-floating chair (capacity 350 pounds) ensures patient comfort and easy positioning.