Daniella Ferraro Fernandes Costa Pinho MD, Presenter: Nothing to Disclose

Naveen Kulkarni MD, Abstract Co-Author: Nothing to Disclose

Benjamin Ayer Beatty, Abstract Co-Author: Nothing to Disclose

Gaurav Shyam Desai MBBS, Abstract Co-Author: Nothing to Disclose

Michelle Doyle RT, Abstract Co-Author: Nothing to Disclose

Brian H. Eisner MD, Abstract Co-Author: Nothing to Disclose

Dushyant V. Sahani MD, Abstract Co-Author: Grant, General Electric Company Consultant, Bracco Group

DE-CT is emerging as useful technology for variety of clinical indications but the appropriate scan protocols to lower dose remains unclear. To determine scanning technique with lowest possible dose in characterizing renal stone in-vitro using two dual energy CT techniques DSDE and SSDE.

25 urinary stones (mean -5 mm) of known composition (5 uric acid, 5 cystine, 5 brushite, 5 calcium oxalate monohydrate (COM) and 5 struvite stones), were inserted into 5 lamb kidneys and scanned at different radiation doses on DSDE (Siemens, DS-Flash) [Ref mA (265-40) & CTDI (1.49-10) range] & SSDE (GE, HD-750) [Rot time (0.5, 0.8 & 1.0 sec) CTDI (12.5 – 26.7) range]. Using the vendor specific post processing material decomposition and effective atomic number (effective Z- Zeff) (SSDE CT) stone composition was predicted.  

Both DECT techniques had 100% sensitivity and accuracy in the detecting uric acid (UA) and non-UA stones across all dose levels. On DSDE, lowest dose for stratification of cystine, struvite and calcium stone (COM & brushite) types accurately was at CTDI of 4.99. On SSDE, cystine, struvite and calcium based stone (COM & brushite) could be stratified correctly by estimating Zeff at a lowest dose CTDI 20.71. On both DECT techniques differentiation between COM and brushite was not possible. 

Phantom study reveals that DECT can differentiate UA & non-UA types at ultra-low dose levels (CTDI 1.49) however for substratification of non-UA stones is possible at the modest dose of CTDI 4-20. 

In patients evaluated for renal stones on CT radiation remains a concern. Our study validates that stone composition can be predicted on DE-CT using a substantially lower dose that currently practised

Pinho, D, Kulkarni, N, Beatty, B, Desai, G, Doyle, M, Eisner, B, Sahani, D, Optimal Scanning Technique for Assessing Kidney Stone Composition in Vitro Using Two Dual-Energy Techniques (Dual-Source Dual-Energy and Single-Source Dual-Energy MDCT).  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11016137.html