Di Hu, Presenter: Nothing to Disclose

Tong Yu, Abstract Co-Author: Nothing to Disclose

Xiaomin Duan MD, Abstract Co-Author: Nothing to Disclose

Yun Peng MD, Abstract Co-Author: Nothing to Disclose

To determine the best energy level in contrast-enhanced spectral CT imaging for displaying abdominal vessels in pediatric patients.

15 children (8 males), at least 5 years old, underwent contrast-enhanced spectral CT imaging for diagnosing solid tumors were included. Scan regions included 8 abdomen, 2 pelvic and 5 abdomen and pelvic. A single contrast-enhanced scan was performed using a dual energy spectral CT mode with a new split contrast injection scheme (Iodixanol at 1-1.5ml/kg dose. 2/3 first, 1/3 at 7-15s after the first injection). Enhanced scan started at 35-41s after the first contrast injection. A set of monochromatic images with energy ranges of 40-140keV with 10keV interval were reconstructed. 2 board-certified radiologists interpreted the images independently for image quality scores. Signal-noise-ratio (SNR) and contrast-noise-ratio (CNR) for hepatic portal or vein were measured and compared at every energy level to determine the optimal energy to maximize vessel SNR and CNR.

As photon energy decreased from 140 to 40keV CT values for the vessels increased: abdominal aorta 52.09±12.01-569.81±137.48HU, inferior vena cava 47.13±11.39-341.08±60.82HU, and portal 52.06±6.80-312.94±92.52HU. CNR also increased: abdominal aorta 0.002±0.756-15.01±7.04, inferior vena cava 0.23±1.08-7.05±2.22, and portal 0.29±0.98-5.82±4.93. Monochromatic images at 40-70keV could display vessels above three levels clearly, and with excellent image quality scores of 3.06±0.25 points (κ=0.50). 40keV was considered to be the best energy level to display the hepatic portal and vein based on the highest SNR (8.90±1.56), and CNR (15.01±7.04) values for vessels.

Spectral CT imaging provided a set of monochromatic images to optimize image quality and enhance vascular visibility, especially in the hepatic portal and vein system. 40keV was considered to be the best energy level for abdominal vessels in children in terms of the highest SNR and CNR. This energy level is much lower than the conventional 80kVp and may provide more clinical benefit in contrast-enhanced imaging in children.

The 40keV monochromatic images in dual energy spectral CT provide the highest CNR for vascular imaging in pediatric patients, greatly extending the range of conventional CT.

Hu, D, Yu, T, Duan, X, Peng, Y, Determination of the Best Energy Level in Spectral CT Imaging for Displaying Abdominal Vessels in Pediatric Patients.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12031808.html