December 15, 2014 — The new version of the Siemens Somatom Definition Edge CT system, which debuted at the Radiological Society of North America (RSNA) 2014 annual meeting, allows dual energy images to be acquired using a single-source system in clinical routine.
The TwinBeam Dual Energy X-ray tube concept of the relaunched Definition Edge enables simultaneous imaging at two different energy levels for the first time in single-source computed tomography (CT).
In dual energy imaging, the same region of the body is examined using two different energy levels. The resulting two datasets offer more detailed information about tissue composition that extends beyond pure morphology. However, in cases where data have been acquired using fast kV-switching or dual layer detector technology, dual energy imaging has had significant drawbacks. In the past, single-source dual energy images acquired with these methods were excluded from routine clinical use because the X-ray tube did not emit the two energy spectra simultaneously, but rather in succession through rapid switching or spectral separation at the detector side. With kV-switching, the segmentation of the measuring points impairs image quality significantly due to the limited data per energy level. Also, increased X-ray doses are inevitable because the dose cannot be modulated to reduce radiation.
Siemens’ approach to dual energy imaging technology in general offers tissue characterization that could be applicable in clinical situations like the evaluation of kidney stones to differentiate between uric acid and non-uric acid stones, which provides additional diagnostic information. Another example: When examining liver lesions, the material information contained in the dual energy imaging acquisition can indicate liver lesions, with information that is based on the determination of contrast uptake in the tumor (iodine maps).
The new version of the Somatom Definition Edge also can simplify the radiology workflow considerably. Unlike other single-source dual energy CT imaging, the Edge’s acquired dual energy datasets are preprocessed intelligently directly after acquisition.
Metal Artifact Reduction
To further improve not only the quality of dual energy examinations but also conventional CT scans using the Definition Edge, Siemens is introducing imam — a new iterative algorithm for metal artifact reduction. With iMAR, metal artifacts can be reduced. Installed Definition Edge and Definition AS+ CT scanners can be retrofitted with TwinBeam technology, iMAR and ADMIRE (in combination with the Stellar detector). iMAR is pending 510(k) clearance and is not yet commercially available in the United States.