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 evaluate if high energy spectral CT images of contrast-enhanced phase could replace the plain scan for radiation dose reduction.

30 children (16 males, older than 5 years), underwent CT for solid tumor diagnosis in the abdomen, were analyzed. Plain CT was performed with 120kVp, noise index of 15 at 5mm slice thickness. The contrast-enhanced scan was performed with spectral CT imaging mode. 11 sets of monochromatic images were reconstructed from the enhanced spectral CT with energies from 40-140keV with 10keV interval. 2 board-certified radiologists reviewed both plain and contrast-enhanced spectral images for image quality, calcification and tumor characterization. CT values for liver, spleen, kidney, pancreas, muscle and tumors were measured on both the plain and contrast-enhanced spectral images and statistically compared.

As the photon energy (keV) increased, the CT values of the contrast-enhanced spectral images decreased. Subjective image quality decreased slightly as keV increased (2.93±0.25 at 40-70keV to 2.74±0.47 at 80-140keV) with no statistical difference (p=0.35). There were 8 tumors with calcifications greater than 2mmx2mm detected in the plain phase, which were also detected at every keV level, and were more prominent at higher keV. At 140keV, CT values of the contrast-enhanced spectral images had good correlations with those of plain scan for various organs. The paired CT values between the 140keV and plain phase images were (68.08±5.77, 60.67±6.26), (53.09±4.03, 50.36±5.08), (39.17±4.72, 37.56±3.83), (51.33±5.13, 51.50±3.98), (52.41±3.47, 54.57±5.53), and (38.23±12.35, 33.76±10.37) for liver, spleen, kidney, pancreas, muscle and tumor, respectively.

140keV images of the contrast-enhanced spectral scan in pediatric patients provided adequate image quality for describing solid tumor features and calcification (>2mm) depicted in plain CT. The maximum CT value difference for various organs and tumors between the 140keV image and real plain CT was less than 10HU, indicating the possibility of replacing plain CT with 140keV contrast-enhanced spectral images to reduce radiation dose.  

The contrast-enhanced images at 140keV in spectral CT provide adequate image quality and accurate CT numbers for describing solid organs, tumors and calcification (>2mm) depicted in plain CT.  

Hu, D, Yu, T, Duan, X, Peng, Y, Spectral CT Imaging in Pediatric Patients: Preliminary Evaluation of Whether High Energy Contrast-enhanced Spectral Images Could Replace Pain Scan for Radiation Dose Reduction.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12031819.html