Ralf W. Bauer MD, Presenter: Research Consultant, Siemens AG Speakers Bureau, Siemens AG

Stephan Hohertz, Abstract Co-Author: Nothing to Disclose

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

Thomas G. Graf PhD, Abstract Co-Author: Employee, Siemens AG

Firas Al-Butmeh, Abstract Co-Author: Nothing to Disclose

Josef Matthias Kerl MD, Abstract Co-Author: Research Consultant, Siemens AG Speakers Bureau, Siemens AG

Thomas Josef Vogl MD, PhD, Abstract Co-Author: Nothing to Disclose

Cholesterol gallstones elude detection on regular 120 kV abdominal CT scans. Dual Energy CT (DECT) has shown promising results for their identification under optimized in-vitro setting. In this study, we tried to assess the potential of DECT post-processing for the correct detection of cholesterol gallstones in an anthropomorphic phantom model.

34 gallbladder stones (4 – 24 mm diameter) with known chemical composition (n = 11 pure homogenous cholesterol, n = 12 non-cholesterol, n = 11 cholesterol core and non-cholesterol shell) were analyzed. Each sample was put into a standard plastic specimen container filled with formalin. The containers functioning as artificial gallbladders were put into a water-filled cylindrical acrylic glass phantom with a diameter of 32 cm that contained pig organs and spine to simulate noise similar to a human abdomen. DECT was performed using a standard abdomen protocol (14 x 1.2 mm collimation, 140 kV/83 mAs on tube A, 80 kV/340 mAs on tube B). Regular grayscale images were reconstructed at a slice thickness of 3 mm for high and low kV data. Further, DECT prototype post-processing software was used to elaborate dual-energy behavior of cholesterol; cholesterol information was then color-coded blue whereas every other tissue components were coded green. Grayscale and color-coded images were analyzed for the presence and characteristic of gallstones.

6/11 pure cholesterol stones were detected on 80 kV images while none of them was visible at 140 kV. Only the post-processed color-coded DE images enabled correct detection of all cholesterol stones. Non-cholesterol stones appeared hyperdense on both the 140 kV and 80 kV images and were hence correctly identified in every case on grayscale images already. The appearance of core/shell stones was best defined at 80 kV, however the conspicuity of cholesterol parts was more pronounced on the color-coded DE images.

Dual Energy CT post-processing allowed for reliable identification of cholesterol gallstones with superior results than grayscale images in this anthropomorphic phantom simulating a human abdomen.

Reliable identification of cholesterol gallstones with DECT may add important information in patients presenting with acute abdominal pain and no primary finding on regular abdominal CT.

Bauer, R, Hohertz, S, Krauss, B, Graf, T, Al-Butmeh, F, Kerl, J, Vogl, T, Improved Detection of Cholesterol Gallstones Using Dual Energy CT Post-processing.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043472.html