Research On The Effects Of Various Energy Combination, Reconstruction Algorithms, And ROI Selection Of Dual-Energy CT On The Quantification Of Iron In Rabbit Livers

Objective To discuss the effects of different energy combination, reconstructing algorithms and ROI selection of dual-energy CT on the quantitative detection of iron in livers of rabbit models.Methods 32 healthy New Zealand white rabbits were administered with 15mg/kg of iron dextran each week through intramuscular injection in 16 weeks, with 2 rabbits being treated each week. The double-source and dual-energy 128-layer CT scanner from Siemens was adopted, and the Dual Energy scan mode was utilized for scanning, and the two kinds of energy combination were set as 80-140kVp and 100-140kVp. Under the combination of 80-140kVp, two algorithms, which were the default filtered back projection (FBP) and the sonogram-affirmed iterative reconstruction (SAFIRE) with the intensity of 3 were set for construction; and FBP algorithm was adopted for construction under the combination of 100-140kVp. The rabbits were sacrificed and dissected immediately after being scanned to take the liver for hepatic iron content analysis and for obtaining LIC. Images obtained through scanning under the energy combination of 80-140kVp and FBP algorithm were measured with whole liver ROI and small ROI methods by two veteran measurers, while images under the remaining scanning conditions were measured through small ROI method, thus the CT values of the VIC figures that took various energy combination, reconstruction algorithms and ROI as the variables, respectively, were obtained and compared by paired t test, and were conducted Spearmen correlation analysis together with LIC.Results:(1) There was excellent consistency of the two energy combination, reconstruction algorithms and ROI measuring methods between different measurers (both the interclass correlation coefficients ICC were greater than 0.98). (2) There was statistically significant difference (p<0.01) of the CT values in VIC figures measured through scanning under different energy combination so long as other conditions were kept the same; and the difference of the CT values in VIC figures measured with different ROI methods was of statistical significance (p<0.01); while the difference of those measured with various reconstruction algorithms being the variables was of no statistical significance (p>0.05). (3) The correlation between the CT value in VIC figure measured through the energy combination of 80-140Kvp, FBP reconstruction algorithm as well as small ROI method and LIC was 0.895 (p<0.01), that between the CT value measured through 100-140Kvp scanning and LIC was 0.835 (p<0.01), that between the CT value measured through SAFIRE algorithm and LIC was 0.915 (p<0.01), and that between CT value measured by whole liver ROI method and LIC was 0.917 (p<0.01).Conclusion:(1) Dual-energy CT conducted liver iron quantitative detection through three-substance separation method, and there was excellent repeatability of various scanning and measuring methods between different measurers. (2) The CT values in VIC figures measured through two kinds of energy combination, reconstruction algorithms and ROI measuring methods could reflect the LIC. (3) Different energy combination and ROI methods had certain effects on the measured value; comparatively speaking,80-140KVp and whole liver ROI were superior; and different reconstruction algorithms did not affect the measured value.