Ultrasound mimics CT and MR in providing anatomic visualizations

January 10, 2005

Ultrasound is incomparable in its niche as a safe, cost-effective, and portable imaging technique. Nevertheless, standard 2D ultrasound suffers because its display of anatomy lacks reproducibility and precision. Unlike CT and MR, which produce uniform sequential pictures of the anatomy wherever and whenever they are done, ultrasound examinations differ from clinic to clinic, operator to operator.

Ultrasound is incomparable in its niche as a safe, cost-effective, and portable imaging technique. Nevertheless, standard 2D ultrasound suffers because its display of anatomy lacks reproducibility and precision. Unlike CT and MR, which produce uniform sequential pictures of the anatomy wherever and whenever they are done, ultrasound examinations differ from clinic to clinic, operator to operator.

Making matters worse, ultrasound lacks the postprocessing power of CT and MR, whose images can be reformatted on a workstation to meet specific needs long after the data have been acquired. Ultrasound scans, if they do not provide what's needed, must be redone from scratch on patients in the sonography lab.

Advancements in ultrasound seen at the 2004 RSNA meeting are tackling the weaknesses of the technology vis-à-vis CT and MR. Automated image optimization is helping to reduce the variability of image acquisition. Newfound postprocessing capabilities are making ultrasound more like the volumetric modalities.

Building on native TEQ dynamic ultrasound technology, Siemens Medical Solutions has incorporated automatic image optimization in its Encompass release for the superpremium sonography system, Acuson Sequoia. In the previous iteration of TEQ, introduced in 2003, sonographers had to push a button to optimize axial and lateral gain during an examination. With the Encompass upgrade, images optimize as soon as a transducer touches a patient. There is no need for sonographers to engage in the back-and-forth process of modifying the radio-frequency gain or adjusting depth-gain-compensation slide pots.

"A technologist working with a vascular transducer can set up the field-of-view at 10 cm deep, put the transducer on the patient, and walk away from the ultrasound system. Residents who are not proficient in ultrasound and have to do an exam at 2 a.m. can turn on the machine, set the field-of-view, touch the transducer to the patient, and get consistent, reliable images," said Bill Carrano, vice president of worldwide marketing for Siemens Ultrasound.

With its inMotion upgrade, Siemens has added fourSight 4D imaging to the G60 and G50 systems, which are less than half the price of superpremium ultrasound units. Suitable for obstetric imaging, the 4D software release offers volumetric multiplanar rendering measurements and automated calculations of specific aspects of fetal development, including the circumference of the head and the length of the femur.

Four-D imaging capabilities on the Nemio system from Toshiba America Medical Systems include automatic 3D volume acquisition to reduce operator dependence and enhance imaging accuracy, said Gordon Prahar, director of the ultrasound business unit.

Intelligent automation, available on Philips' new iU22 ultrasound system, dynamically adjusts up to 40 controls with the touch of a button to improve the consistency of results obtained by operators across the spectrum of skill levels.

In its new 3D-eXtended Imaging (3D-XI) comprehensive diagnostic ultrasound image-processing package for the flagship Accuvix XQ system, Medison is transferring the concept of multislice CT to the ultrasound data set by transforming volume data obtained from a 3D ultrasound scan into information a physician wants and needs, the company said.

3D-XI has three principal features. The Multi-Slice View option translates 3D ultrasound scan data into a series of sequential images captured in 0.5 to 3-mm intervals so physicians can view scans systematically from beginning to end in a specific order and in a desired slice thickness. Oblique View allows physicians to view and study 3D volume data from the anatomy of interest in any oblique position simply by spinning a dial on the keyboard. Volume CT reveals the relationships between axial, coronal, and sagittal views in the form of a cube on a scan that can be rotated to any view, providing depth perspective and a spatial rendering of longitudinal, transverse, and coronal intersections as well as step-through navigation of anatomy.

The Logiq 9 from GE Healthcare obtains volumetric, multidimensional images in real-time at speeds up to 30 volumes per second. It capitalizes on TruScan architecture to store raw data early in the imaging chain and provide flexible postprocessing analysis and advanced reconstruction in multiple planes. The LogiqWorks workstation, which accepts raw data created by the Logiq console platform, handles image evaluation and, if necessary, performs virtual rescanning of patients.

"Once an ultrasound image is digitized and moved through the information management system, it can be reanalyzed or reoptimized on the workstation instead of bringing the patient back for another scan," said Al Lojewski, global marketing manager for cardiovascular ultrasound.

Volumetric ultrasound needs to migrate down from high-end to midrange systems to gain widespread market acceptance. Such 3D systems are already beginning to appear in outpatient imaging centers and private physicians' offices.

TeraRecon is best known as a developer of workstations and servers for 3D applications in CT and MR, but through its partnership with Fukuda, it has been producing a range of portable and midrange ultrasound units based on its XTrillion digital multibeam processing chip technology. TeraRecon expects to bring 3D imaging to its UF-750XTD portable ultrasound unit in spring 2005. A 3D upgrade may be available by summer for the UF-850XTD midrange system, which currently is being sold in Japan and will be marketed in the U.S. after the first of the year.

"Ultrasound is a relatively immature technology in that we see tremendous opportunities to gather more clinical information for a wider variety of patients in the hospital and at the point of care of the patient," said GE's Lojewski. "The more image processing power that can be brought to bear on ultrasound, the better the quality of the images and the information."