Konstantin Nikolaou MD, Presenter: Nothing to Disclose

1) Identify suitable indications for Perfusion CT and Dual-Energy CT. 2) Apply optimized dose reduction strategies for these CT applications. 3) Correctly and systematically analyze dynamic CT imaging and Dual-Energy-based CT angiographic data. 4) Demonstrate understanding of the influence of functional CT imaging to optimize therapeutic strategies. 5) Compare indications and contraindications of dynamic CT and Dual-Energy CT, especially under the light of dedicated magnetic resonance imaging (MRI) acquisition strategies.

Dual Energy CT Angiography Dual-source CT is performed with a CT scanner with two tubes and two detectors mounted orthogonally to each other. With this type of CT scanner, different tube voltages can be used, resulting in different energies of the emitted x-ray spectra (dual-energy CT). Use of this technique allows material differentiation based on the different absorption characteristics of different types of tissue. Iodine, a commonly used CT contrast material, is generally known to produce higher attenuation at low tube voltage settings. Because of this effect, the spectral information on images obtained at different voltage settings allows differentiation of iodine. Selective visualization of iodine distribution in body tissues such as the pulmonary parenchyma is therefore a potential advantage of dual-energy imaging. The application of dual-energy based bone removal may help to assess supra-aortic vessels without overlay of calcified plaques and bones at the skull base and in the cervical spine around the vertebral arteries. Perfusion CT With recent scanner generations, providing large detectors or so-called “shuttle modes” of acquisition, time-resolved CT imaging of larger areas of the body (large detectors: up to 16 cm range, shuttle-modes: up to 48 cm range) becomes feasible. This technique offers a variety of new options for functional angiographic CT angiography. These include time-resolved CTA of the aorta, e.g., to depict endoleaks after endovascular repair. Time-resolved CTA of the lower legs improves detectability of smaller vessels and facilitates the differentiation of calcifications vs. patent vessels. Perfusion imaging of the brain allows for an accurate visualization of perfusion defects in order to assess the penumbra in an acute stroke. Perfusion imaging of abdominal organs will offer new ways of tumor perfusion imaging, e.g. for therapy-monitoring of antiangiogenic therapies.  

Nikolaou, K, Applications for CT Perfusion and Dual-Energy Imaging.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9000708.html