Sylvia Wilharm, Presenter: Nothing to Disclose

Yiannis Kyriakou, Abstract Co-Author: Nothing to Disclose

Robert Michael Lapp, Abstract Co-Author: Employee, VAMP GmbH, Erlangen, Germany

Gregor Richter, Abstract Co-Author: Nothing to Disclose

Arnd R. Doerfler MD, Abstract Co-Author: Nothing to Disclose

Willi A. Kalender PhD, Abstract Co-Author: Consultant, Siemens AG Founder, VAMP GmbH Scientific Advisor, VAMP GmbH Shareholder, VAMP GmbH

To improve diagnostic performance and clinical workflow in neuroradiological applications with flat-detector CT (FD-CT) for cases where both small high-contrast structures, e.g. stents, and larger low-contrast structures, e.g. parenchymal bleedings, have to be investigated.

We developed a method which allows for an interactive variation of spatial resolution by means of a 3D Gaussian filter which also ensures isotropic resolution. Starting with the highest resolution level, lower noise is achieved at reduced resolution without the need of performing new reconstructions with a smoother kernel. The tool offers an MPR view of the datasets and the resolution can be varied continuously and isotropically in all three directions. For validation we used a water phantom containing several low-contrast spheres with diameters of 3, 5, 10 and 20 mm and densities of 10, 20, 30 and 50 HU, respectively. Measurements were performed on a C-arm CT system (Axiom Artis, Siemens Medical Solutions, Forchheim, Germany) equipped with a flat detector of 40 x 30 cm2. Two experienced radiologists determined the perceived position and diameter of the spheres. Detectability and time needed for evaluation were recorded and compared to standard evaluation procedures which included MPR evaluation, multiple reconstructions and windowing.

The standard procedure requires at least one additional reconstruction with a smoother kernel for the detection of the spheres. By varying resolution interactively comparable results were achieved with considerable time savings. Furthermore the possibility of a finer adjustment of the appropriate resolution and noise is given compared to the restricted choice of reconstruction kernels.

With the proposed method the appropriate isotropic resolution levels for the evaluation of both high- and low-contrast structures are made interactively available making multiple reconstructions obsolete.

The proposed tool can contribute to a faster and more reliable detection of bleedings for many radiological applications.

Wilharm, S, Kyriakou, Y, Lapp, R, Richter, G, Doerfler, A, Kalender, W, Interactively Variable Spatial Resolution as a New Diagnostic Approach in Neuroradiological Applications with Flat-detector CT.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5003824.html