Xiaohu Li MD, Presenter: Nothing to Disclose

Bing Liu MD, Abstract Co-Author: Nothing to Disclose

Yu Yongqiang MD, PhD, Abstract Co-Author: Nothing to Disclose

To evaluate the accuracy for Urinary Stone Characterization using Effective Atomic Number（Zeff) on spectral CT

Twenty freshly excised pig kidneys with 120 extracted human Urinary stones in them ( two in the upper calices, two in the renal pelvis, two in the lower calices of each kidney) which were immersed in a 15cm-deep water tank underwent GSI using spectral CT(Discovery CT750 HD). All data were transferred to Workstation (AW4.4, GE Healthcare) GSI Viewer to obtain Effective Atomic Number(Zeff) images for measurement of the mean Zeff. The mean Zeff was compared among the stone groups. The composition of stones was determined by infrared spectrom

Dual energy imaging is dependent upon accurate attenuation measurements. From our observations we find that the Zeff measurements closely match expected values.The measured Zeff correlates well with the analytically calculated Zeff for each stone type . Our results showed good separation in effective Z for Uric Acid vs. Cystine/Struvite group vs. Calcium based stones.There was some overlap between the Cystine and Struvite stones. However, in conjunction with density measurements,we are able to differentiate all 4 stone types. We color coded the stones using a threshold in Zeff combined with a threshold in density  

The combination of effective atomic number and monochromatic attenuation demonstrated good separation of all four stone types considered – even Cystine and Struvite which have poor separability in conventional CT. These results are encouraging and motivate further study to confirm the role of spectral CT in the diagnostic imaging of urinary stones

Determination of stone composition by Effective Atomic Number can help urologist choose the optimal treatment project to minimize complications and costs

Li, X, Liu, B, Yongqiang, Y, Effective Atomic Number Accuracy for Urinary Stone Characterization Using Gemstone Spectral Imaging (GSI) on Spectral CT.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14002453.html