Application of low-dose MSCTC combined with iDOSE 4 iterative reconstruction technique in preoperative T staging of colon cancer

Objective: To investigate the feasibility of low-dose multi-slice spiral computed tomographic-colonography (MSCTC) combined with iDOSE 4 iterative reconstruction technique to reduce the radiation dose while ensuring the accuracy of T staging of colon cancer. Methods: Patients with colon cancer diagnosed with colonoscopy were collected retrospectively. All of 73 patients (41 males and 32 females, mean age 60.8 ± 11.0 years) who underwent low dose MSCTC scan before operation were taken as low dose group, and 65 patients (29 males and 36 females, mean age 64.6 ± 11.6 years) who underwent conventional dose MSCTC scan before operation were taken as conventional dose group. All patients had preoperative T staging with CT. The total of dose length product (DLP) and volume CT dose index (CTDI_vol) were recorded, and the effective dose (ED) was calculated. The surgical-pathological T staging was used as gold standard. Kappa test was used to analyze the consistency between the CT T staging and the surgical-pathological T staging, Chi-square test or Fisher exact probability test was used to compare the diagnostic efficacy of CT T staging evaluation, and independent sample t-test was used to compare the radiation dose between the two groups. Results: The consistency of preoperative CT T staging and surgical pathological T staging in both groups was moderate, the consistency of CT T staging and pathological T staging in the conventional dose group was higher than that in the low dose group. There was no significant difference in accuracy, sensitivity, specificity, positive predictive value and negative predictive value for ≤ T₂, T₃ and T₄ between the two groups (all P > 0.05). Compared with the conventional dose group, the accuracies, specificities and positive predictive values of ≤ T₂ and T₃ were slightly lower in the low dose group while those values of T₄ were slightly higher; the sensitivities of ≤ T₂ and T₄ were slightly lower, while the sensitivity of T₃ were slightly higher; the negative predictive values of ≤ T₂ and T₃ were slightly higher, while that of T₄ was slightly lower. The total DLP, CTDI_vol and ED were significantly lower in the low dose group than in the conventional dose group, and decreased by about 67%, 69% and 67%, respectively (P < 0.05). Conclusion: The low dose MSCTC combined with iDOSE 4 iterative reconstruction technology can significantly reduce the radiation dose, and at the same time it has little effect on the evaluation of CT T staging, so it can be used as an effective method for preoperative staging of colon cancer. (authors)