Shuai Leng PhD, Presenter: Nothing to Disclose

Katharine Grant PhD, Abstract Co-Author: Employee, Siemens AG

Terri Jo Vrtiska MD, Abstract Co-Author: Nothing to Disclose

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

Maria Shiung, Abstract Co-Author: Nothing to Disclose

Cynthia H. McCollough PhD, Abstract Co-Author: Research grant, Siemens AG

Nikkole Weber, Abstract Co-Author: Nothing to Disclose

Lifeng Yu PhD, Abstract Co-Author: Nothing to Disclose

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

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

To prospectively demonstrate the feasibility of differentiating uric acid (UA) and non-uric acid (NUA) renal stones using two consecutive scans on a single source CT scanner and a non-rigid 3D registration algorithm.

A total of 10 patients undergoing clinically-indicated dual source (DS), dual energy CT scanning for the purpose of differentiating UA and NUA kidney stones were recruited in this IRB approved prospective study. On the same day as the clinically-indicated DS exam, the patient was scanned on a single source CT scanner (Definition AS+, Siemens Healthcare, Germany). An 80 kV CT scan was performed in a cranial-caudal range limited to the identified stones, immediately followed by a 140 kV scan at the same region. The combined radiation dose for the 80 and 140 kV scans was set to be equivalent to that applied with the DS CT scan. Images from the 80 and 140 kV scans were registered using a 3D non-rigid registration program, followed by dual-energy material differentiation analysis to differentiate UA (in red) and NUA (in blue) stones. Accuracy of stone classification was calculated using the results from dual source scanner as gold standard. A GU radiologist recorded the number, size and composition of stones in each patient, and performed a side by side comparison for the image quality of the single source and dual source scans.

A total of 52 NUA stones were identified from the DS CT scans (no UA stones). Among these stones, 41 were correctly identified as pure NUA stones from the single source CT scan; 6 were majority blue but with a little dot or linear region of red along the periphery, which will be classified as NUA stones clinically; 2 (size=2mm) were incorrectly identified as UA stones and 3 (size=1mm) unclassified. The accuracy of stone classification was 90.4%. Image quality of single source CT scan was considered similar to that of the dual source scan for all patients.

Using a 3D non-rigid registration algorithm on two consecutive single energy scans at different beam energies, UA and NUA stones can be accurately differentiated using a single source CT scanner with stone size larger than 2mm.

This technique may enable stone composition differentiation to be performed on widely available standard CT scanner with the use of a 3D non-rigid registration algorithm.

Leng, S, Grant, K, Vrtiska, T, Krauss, B, Shiung, M, McCollough, C, Weber, N, Yu, L, Schmidt, B, Flohr, T, Renal Stone Composition Differentiation Using Two Consecutive CT Scans and a Non-Rigid Registration Algorithm.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11008237.html