Michael Grasruck PhD, Abstract Co-Author: Employee, Siemens AG

Rajiv Gupta, Presenter: Nothing to Disclose

Benjamin Reichardt, Abstract Co-Author: Nothing to Disclose

Bernhard Schmidt PhD, Abstract Co-Author: Employee, Siemens AG

Ernst Klotz PhD, Abstract Co-Author: Nothing to Disclose

Christoph Suess PhD, Abstract Co-Author: Employee, Siemens AG

Thomas G. Flohr PhD, Abstract Co-Author: Employee, Siemens AG, Forchheim, Germany

et al, Abstract Co-Author: Nothing to Disclose

A Flat-panel detector based Volume CT (fpVCT) prototype scanner, in contrast to conventional multi-detector CT, provides large scanning area along the z-axis and enables complete organ coverage in one rotation. By implementing a mode with continuous scanning in a prototype fpVCT, we are able to reconstruct the complete volume at any point in time during the propagation of a contrast bolus. Multiple volumetric reconstructions over time result in elucidation of the first pass dynamics of a bolus of contrast resulting in 4-D angiography and whole organ perfusion maps.

We mounted a Varian 4030CB a-Si flat-panel detector in a multi slice CT-gantry (Siemens Medical Solutions) with 18 cm z-coverage at isocenter. The sampling of the tomographic information in time can be varied freely by subsequent reconstruction of partial overlapping data sets. Pixel based permeability and blood volume images are calculated with a modified two compartment (plasma, interstitium) Patlak approach based on first pass data. Experimental validation was performed by imaging evolution of contrast bolus in 10 New Zealand rabbits. From a 45sec scan we reconstructed 30 volumetric data sets to capture the dynamics of first pass bolus transit.

In the reconstructed 4-D data sets, the arterial as well as the venous phase of circulation can be clearly separated in time and and space. The spatial resolution approaching 200 microns enables visualization of even small perforator arteries in the brain stem. Animal models of subclavian steal and AV fistulas can be easily diagnosed using the acquired data sets. In addition, the perfusion parameters flow and permeability of the whole brain and the liver can be evaluated using Patlak’s model.

Our research clearly demonstrated the feasibility of dynamic 4D CT angiography and whole organ perfusion using the large z-coverage offered by a flat-panel based Volume CT scanner. Despite the fast heart rate of a rabbit, the temporal resolution was sufficient to discriminate between various phases in the first pass of contrast bolus.

With increasing z-coverage also clinical Scanners will be touching the field of 4D-Perfusion.

Grasruck, M, Gupta, R, Reichardt, B, Schmidt, B, Klotz, E, Suess, C, Flohr, T, et al, , Dynamic CT Angiography and Perfusion Using a Wide Coverage, Flat-panel Volume CT: Technical Development and Feasibility Demonstration.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4433558.html