Radiology      Computed Tomography
In a heartbeat

Siemens Medical Solutions will be exhibiting the Somatom Definition at Arab Health 2007. Middle East Health provides a sneak preview of the world’s most advanced CT system.

The Somatom Definition scanner is the industry’s first dual source CT. It moves beyond the current generation of 64-slice scanners enabling faster and earlier diagnosis in acute care patients while maintaining the highest image quality.

The Somatom Definition will be on show at Arab Health 2007 at the Dubai International Exhibition Centre from 29 January to 1 February.

Siemens unveiled its innovative unit in November 2005, claiming it would spark a new era of medical imaging, and since then several of the scanners have been installed at medical facilities around the world. Cardiac CT has witnessed continued growth from 16- slice to 64-slice scanners.

However, administration of beta-blockers to slow the heart rate before imaging still poses a challenge in emergency situations. Exposure to radiation is another concern with multislice CT technology, which generally goes up with higher temporal resolution.

  The Somatom Definition addresses many of these challenges and moves beyond the current generation of 64-slice scanners, using its patented Straton X-ray tube, almost four times smaller than conventional X-ray tubes.

The Somatom Definition is particularly valuable in imaging heart patients with high or irregular heart beats, and who have problems holding their breath. Imaging can be done in a breath hold of five to six seconds, achieving one of the highest temporal resolutions of 83 milliseconds per slice, almost twice as fast as a single source CT system at 165 milliseconds per slice. This helps in imaging a patient at any heart rate without the use of betablockers.

The scanner is an ideal tool for one-stop diagnosis in acute care imaging, including the assessment of patients with acute chest pain, abdominal pain and suspicion of stroke.

The system independent of patient size and condition. It scans with two different X-ray energies simultaneously, which allows physicians to better differentiate, characterise, isolate and distinguish bone, soft tissue and fluid.

“Siemens has long been committed to creating products that will shape the future of healthcare. We are truly redefining what CT can do and are setting a new benchmark for the industry to follow,” said Erich Reinhardt, president and CEO for Siemens Medical Solutions.

“With more than 55 million procedures conducted in the United States each year, CT already has a tremendous impact on detecting disease. “The Somatom Definition will allow physicians to utilise CT technology in new areas of research, bring the benefits of CT to more patients, and enable physicians to diagnose disease earlier and most cost effectively.”

Faster, sharper

The system is faster than any existing CT technology, using two X-ray sources and two detectors at the same time, compared to all other CT systems that use only one source and detector. With 0.33 seconds per rotation, electrocardiogram (ECG) synchronised imaging can be performed with 83 millisecond temporal resolution, independent of the heart rate, resulting in motion free cardiac images.

Featuring a 78cm bore opening and a 200cm scan range, the Somatom Definition increases patient comfort and access. Equipped with z-Sharp Technology and CARE solution, the scanner has all the tools necessary to enable a new gold standard in early detection, faster evaluation, and more precise follow-up of disease states.

The first unit was installed at the University of Erlangen, Germany, in October 2005 and is being used for technical and clinical research as well as regular patient care. “Siemens’ newest CT system provides very valuable clinical information for patients presenting in our department with acute chest pain and suspicion of coronary artery disease,” said Dr Stephan Achenbach, associate professor of cardiology, University of Erlangen.

“We expect that the Somatom Definition will have a significant role in even the most demanding environments, such as emergency departments,” said Prof Werner Bautz, chairman of radiology at Erlangen.

The Mayo Clinic in Minneapolis and the NYU Medical Centre (NYUMC) in New York City were the first facilities in the US to install the scanners. These two leading institutions are using the systems for cardiac and vascular exams, as well as research into new applications for CT imaging.

“In cardiac imaging, the ability to image the heart with very short exposure times is essential,” said Cynthia McCollough, associate professor radiologic physics at the Mayo Clinic College of Medicine. “Our current systems, which require 0.16 seconds per exposure, perform very well at lower heart rates. However, dual source CT requires only half of that time – 0.08 seconds – and thus allows us to successfully image patients with higher heart rates.” “Siemens dual-source CT technology is another giant step forward in CT imaging,” said Jill E Jacobs, chief, Cardiac Imaging, NYUMC.

“The reduced scan acquisition times and decreased need for patient preparation helps ensure quick results and speeds workflow and patient throughput. “The Definition will also enable us to better evaluate patients with suspected neurologic, thoracic, abdominal/pelvic or vascular abnormalities.” “The improved temporal resolution of 83 milliseconds aids diagnosis of cardiac arterial pathology while allowing diagnostic imaging of cardiac structures at higher heart rates than were previously possible,” added Jacobs.

According to McCollough, physicians at Mayo Clinic have been able to use the Definition’s increased speed to produce sharp images of the heart in all phases of the cardiac cycle, allowing the coronary arteries to be well visualised, not only when the heart is moving more slowly (diastole), but also when the heart is rapidly contracting (systole).

Because various X-ray energies interact differently with different tissue types, the flexibility inherent in the Siemens dual source CT technology will enable physicians to better differentiate and isolate tissues. Researchers at the Mayo Clinic have begun exploring the feasibility of using two different X-ray energies for a number of potential applications. “Traditional CT imaging provides detailed images of anatomy, but less information about physiological function,” said McCollough.

“We are seeing a broad interest from the scientific community in using the information from different energies to tell physicians more about what a material is comprised of and how it is functioning. I expect this to become an area of active CT research.”

“The ability to image patients using two different X-ray energy levels has exciting potential for better isolation and characterisation of neurologic, abdominal, and pelvic pathology,” said Jacobs.

Ongoing research using the Definition at NYUMC will include the evaluation, quantification and characterisation of coronary artery plaque; evaluation and quantification of tumour angiogenesis within the liver; and evaluation of neurologic abnormalities using carotid angiography. “The Definition is enabling medical professionals at Mayo Clinic and NYU Medical Centre to uncover new uses for CT technology while delivering unmatched diagnostic capabilities to physicians and their patients,” said Bernd Montag, president, CT Division, Siemens Medical Solutions.

“We are pleased that the top institutions in the US are implementing this technology. This demonstrates the continued success of our process for bringing innovative technologies to market following close collaboration with our customers.”


Last year Siemens received a Product Innovation Award from Frost & Sullivan for the Definition. The award, in the field of cardiac CT imaging, recognises Siemens’ pioneering work on developing the unit. Siemens also won a Stevie Award at the International Business Awards (IBA) for the Definition.

In November, Siemens announced that it had received 510(k) approval from the US Food and Drug Administration (FDA) for the first of many Syngo Dual Energy applications for the Definition.

The FDA clearance allows for use of Definition’s two X-ray sources at two different energy levels in simultaneous spiral scanning, which essentially paves the way for dual energy to become part of the standard daily clinical routine.

                                                     Copyright © 2007 All Rights Reserved.