Application of iterative reconstruction technique in CT imaging of adrenal gland in obese patients

Objective: To apply adaptive statistical iterative reconstruction (ASiR) technique in CT imaging of adrenal gland in obese patients to reduce the radiation dose and improve the image quality. Methods: Adrenal gland CT scans of 200 obese patients were collected, including male 112 cases, female 88 cases, age 17-78 years old, mean age 54.22 ± 18.63 years old. Classified patients into 2 groups, 100 cases each. Group A underwent routine filtered back projection (FBP), and group B underwent ASiR using 4 grades (None, 30%, 50%, and 100%). The data of all patients were transmitted to the workstation (AW4.6), and were evaluated by three doctors with double-blind method. A t test was used to compare radiation dose two between the 2 groups. One way ANOVA with post hoc LSD-t test was used to compare the objective image quality indicators (noise, SNR, and CNR) and the subjective score. Kappa test was used to evaluate the consistency of subjective scores among the three doctors. Results Compared to the group A, the reconstructed image noise of the adrenal gland, muscle and fat were decreased with the increasing of the iterative rank, while SNR and CNR were increased with the increasing of the iteration level (P < 0.05) in the group B. Among the sub-groups of group B, when ASiR 50% was used, the SNR, FBP, and reconstruction noise did not significantly differ at each region of adrenal gland (P > 0.05). The subjective scores from three doctors were consistent well (Kappa = 0.76). ASiR100% achieved the best image quality, followed by group A FBP, ASiR50%, ASiR30%, and ASiR None (P < 0.05). Conclusion: The ASiR technique in CT imaging of adrenal gland in obese patients could reduce the radiation dose. ASiR 50%∼100% is comparable even better than FBP in image quality. (authors)