Duan Haifeng MMed, Presenter: Nothing to Disclose

He Taiping MMed, Abstract Co-Author: Nothing to Disclose

Yang Chuangbo MMed, Abstract Co-Author: Nothing to Disclose

Ma Guangming MMed, Abstract Co-Author: Nothing to Disclose

Guo Youmin MD, Abstract Co-Author: Nothing to Disclose

Lei Yuxin MMed, Abstract Co-Author: Nothing to Disclose

Yu Yong MMed, Abstract Co-Author: Nothing to Disclose

To evaluate the clinical value of detecting ureteral stones with the virtual nonenhanced (VNE) images generated in the enhanced spectral CT imaging.

38 adults (21 males and 17 female, ages: 24-76years) with positive calculi in the urinary system found during abdominal CT for lesion diagnosis or clinical emergency were retrospectively analyzed. True nonenhanced (TNE) CT was performed with 120kVp with noise index of 12 at 5mm slice thickness. Contrast-enhanced scans in the venous phase (VP) and delayed phase (DP) were performed with spectral CT mode. VNE images were generated from the 2 enhanced phases. 2 board-certified radiologists reviewed both TNE and VNE images for image quality and stone detection rate. Mean CT number, size and contrast-noise-ratio (CNR) of stones were measured.

52 stones were detected from TNE images, including 11 in the renal parenchyma, 25 in the renal pelvises, 4 in the ureters of abdominal segments, 7 in the ureters of pelvis segments and 5 in the bladder; 51 and 52 stones were detected with VNE images at VP and DP, respectively. The missed stone at VP located in renal parenchyma with diameter less than 0.8mm and low CT number of 86HU, similar to that of renal parenchyma. The mean CT number (in HU) for the stones from TNE was 310.15±154.85, higher than the 244.33±153.20 from VNE at VP and 251.78±155.73 at DP (p<0.05). The maximum stone areas (in mm2) determined from VNE images were 39.0±32.7 and 38.8±33.4, within 83% of the 47.0±36.8 determined by TNE images. The 3 sets images produced similar image quality scores and CNR values at 22.51±12.99, 19.25±15.69 and 20.91±17.71, respectively with no difference. The dose reduction achieved by omitting TNE scan was 21.4%.

The use of VNE images generated from the enhanced spectral CT provides very high sensitivity in detecting ureteral stones with good image quality and 21% dose reduction compared with the TNE images. There is good correlation in stone CT number and size measurement between TNE and VNE images.

VNE images from enhance spectral CT may be used to replace TNE for ureteral stone detection with excellent sensitivity and dose reduction.  

Haifeng, D, Taiping, H, Chuangbo, Y, Guangming, M, Youmin, G, Yuxin, L, Yong, Y, Ureteral Stone Detection Using Virtual Nonenhanced Images in Enhanced Spectral CT Imaging: A Preliminary Study.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14016101.html