Catherine Roy MD, Presenter: Nothing to Disclose

Philippe Host MD, Abstract Co-Author: Nothing to Disclose

Gauthier Bazille MD, Abstract Co-Author: Nothing to Disclose

Isham Labani, Abstract Co-Author: Nothing to Disclose

Mickael Ohanna, Abstract Co-Author: Nothing to Disclose

Herve Lang, Abstract Co-Author: Nothing to Disclose

To evaluate MDCT Spectral Imaging Quantitative assessment of water within the kidney parenchyma in cases of hydronephrosis in order to diagnose urinary obstruction. 

140 patients with unilateral urinary tract dilatation divided in two groups of 70 patients : Group I with various causes of known chronic dilatation ; Group II coming from the emergency unit with acute renal colic underwent three acquisitions : non-contrast scan using Helical CT (GE Discovery CT750HD 64-slice scanner with Spectral Imaging single source fast switching) ; non contrast and enhanced conventional acquisition at excretory phase. All patients had normal renal function. There was no special recommendation for hydration. We used same helical pitch and detector collimation for all scans (1.375, 0.625mm). Among monochromatic CT images ranging from 40 to 140 keV, images were reconstructed at 70 KeV. An identical ROI was drawn in the medium part of renal parenchyma. With the dedicated Gemstone Spectral Imaging (GSI) Viewer® for material-density decomposition values of water in mg/cc with standard deviation were calculated on unenhanced images on both sides. Differences in UH between both sides were recorded on conventional unenhanced acquisition. We also recorded the presence of delayed urinary excretion on conventional enhanced scan. Statistical analysis was performed using SPSS software. Mean values and standard deviation of each group were calculated and compared using Student T-test.  

On conventional unenhanced acquisition, there was no difference of UH value in group I between both sides. For Group II, mean difference in UH value was 4 UH+ 2. All patients of Group II presented an excretory delay from at least 5 min. Mean water content in contralateral normal kidney for both groups was 1010 ±13 mg/cc (range : 997 – 1030). Water contents of abnormal side were of 1014 ±18 mg/cc and 1106±16 mg/cc for Group I and II, respectively. There was no statistically significant difference in renal water content between both sides for the Group I, but difference was significant for Group II (p<0.001).  

The water content calculated by spectral imaging can detect urinary obstruction without any contrast medium injection, in patients with urinary tract dilatation. It seems more sensitive than the UH value. 

Calculation of water content using spectral imaging is can diagnose urinary obstruction in hydronephrosis.    

Roy, C, Host, P, Bazille, G, Labani, I, Ohanna, M, Lang, H, Potential Role of MDCT Spectral Imaging by Using Material Density Analysis to Diagnose Urinary Obstruction.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13044209.html