Spectral CT imaging in pediatric patients with solid tumor in abdomen: preliminary evaluation of whether high energy contrast-enhanced spectral images could replace plain scan for radiation dose reduction / 中华放射学杂志

ABSTRACT

Objective To evaluate if high energy spectral CT images of contrast-enhanced phase could replace the plain scan for radiation dose reduction in children with solid tumor in abdomen.Methods Thirty children with solid tumor in the abdomen underwent CT scan.Plain CT scan was performed as usual,and the contrast-enhanced scan was performed with spectral CT imaging mode.Eleven sets of monochromatic images were reconstructed from the enhanced spectral CT with energies from 40 to 140 keV with 10 keVinterval.CT values for liver,spleen,kidney,pancreas,muscle,vessel and tumors were measured on both the plain and contrast-enhanced spectral images and were statistically compared.Two board-certified radiologists reviewed both plain and contrast-enhanced spectral images for image quality,calcification and tumor characterization.Radiation dose was recorded(CTDIvol,DLP).Pair t test was used to analyze the difference.Results At 140 keV,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 140 keV and plain phaseimages were (62.8± 1.1 vs.59.8±4.0),(69.4±2.6vs.63.1 ±5.6),(52.7 ±5.1 vs.51.4±4.0),(35.4± 5.9 vs.35.7 ±5.3),(51.4±8.6vs.50.0±5.7),(55.5±6.6vs.54.7±5.7) and (33.2± 10.4vs.35.4± 12.1) HU for vessel,liver,spleen,kidney,pancreas,muscleand tumor,respectively.There was no significant difference between two groups(t=0.335 to 2.127,P＞0.05).140 keV images of the contrast-enhanced spectral scan in pediatric tumor patients provided adequate image quality (4.4±0.8 points and 3.7±0.5 points)for describing solid tumor features and calcification.The radiation dose of plain phase and contrast-enhanced phase were [CTDIvol (1.6±0.8) mGy,DLP(46.4±36.8)mGy·cm and CTDIvol(12.7±0.1)mGy,DLP(378.6±91.4)mGy·cm.Conclusion It isfeasible to replace plain CT with 140 keV contrast-enhanced spectral images to reduce 10％ radiation dose.