Quantitative parameters in novel spectral computed tomography:Assessment of Ki-67 expression in patients with gastric adenocarcinoma

BACKGROUND The level of Ki-67 expression has served as a prognostic factor in gastric cancer.The quantitative parameters based on the novel dual-layer spectral detector computed tomography(DLSDCT)in discriminating the Ki-67 expression status are unclear.AIM To investigate the diagnostic ability of DLSDCT-derived parameters for Ki-67 expression status in gastric carcinoma(GC).METHODS Dual-phase enhanced abdominal DLSDCT was performed preoperatively in 108 patients with gastric adenocarcinoma.Primary tumor monoenergetic CT attenuation value at 40-100 kilo electron volt(kev),the slope of the spectral curve(λ_(HU)),iodine concentration(IC),normalized IC(nIC),effective atomic number(Z^(eff))and normalized Z^(eff)(nZ^(eff))in the arterial phase(AP)and venous phase(VP)were retrospectively compared between patients with low and high Ki-67 expression in gastric adenocarcinoma.Spearman’s correlation coefficient was used to analyze the association between the above parameters and Ki-67 expression status.Receiver operating characteristic(ROC)curve analysis was performed to compare the diagnostic efficacy of the statistically significant parameters between two groups.RESULTS Thirty-seven and 71 patients were classified as having low and high Ki-67 expression,respectively.CT_(40 kev-VP),CT_(70 kev-VP),CT_(100 kev-VP),and Z^(eff)-related parameters were significantly higher,but IC-related parameters were lower in the group with low Ki-67 expression status than the group with high Ki-67 expression status,and other analyzed parameters showed no statistical difference between the two groups.Spearman’s correlation analysis showed that CT_(40 kev-VP),CT_(70 kev-VP),CT_(100 kev-VP),Z^(eff),and n Z^(eff) exhibited a negative correlation with Ki-67 status,whereas IC and nIC had positive correlation with Ki-67 status.The ROC analysis demonstrated that the multi-variable model of spectral parameters performed well in identifying the Ki-67 status[area under the curve(AUC)=0.967;sensitivity 95.77%;specificity 91.89%)].Nevertheless,the differentiating capabilities of singlevariable model were moderate(AUC value 0.630-0.835).In addition,the nZ_(VP)^(eff) and nIC_(VP)(AUC 0.835 and 0.805)showed better performance than CT_(40 kev-VP),CT_(70 kev-VP) and CT_(100 kev-VP)(AUC 0.630,0.631 and 0.662)in discriminating the Ki-67 status.CONCLUSION Quantitative spectral parameters are feasible to distinguish low and high Ki-67 expression in gastric adenocarcinoma.Z^(eff) and IC may be useful parameters for evaluating the Ki-67 expression.

Multi-epitope chimeric antigen used as a serological marker to estimate Plasmodium falciparum transmission intensity in the border area of China-Myanmar

Background:Following the decline of malaria transmission in many countries and regions,serological parameters have become particularly useful for estimating malaria transmission in low-intensity areas.This study evaluated a novel serological marker,Malaria Random Constructed Antigen-1(M.RCAg-1),which contains 11 epitopes from eight Plasmodium falciparum antigens,as a tool for assessing malaria transmission intensity along the border area of China-Myanmar.Method:Serum from Plasmodium falciparum and P.vivax patients was used to detect the properties of M.RCAg-1 and antibody responses.Cross-sectional surveys were conducted at the China-Myanmar border and in Hainan province in 2012 and 2013 using cluster sampling.Filter blood spot papers were collected from all participants.Antibodies against M.RCAg-1 were detected using indirect ELISA.The Mann–Whitney test and Spearman’s rank correlation test were performed to analyze antibody data.P.falciparum malaria transmission intensity was estimated using a catalytic conversion model based on the maximum likelihood of generating a community seroconversion rate(SCR).Results:M.RCAg-1 was well-recognized by the naturally acquired anti-malaria antibodies in P.falciparum patients and had very limited cross-reactivity with P.vivax infection.The total amount of IgG antibodies was decreased with the decrease in parasitemia after taking medication and lasted several weeks.In a population survey,the antibody levels were higher in residents living close to the China-Myanmar border than those living in non-epidemic areas(P<0.0001),but no significant difference was observed between residents from Hainan and non-epidemic areas.The calculated SCR was 0.0128 for Jieyangka,0.004 for Susuzhai,0.0047 for Qiushan,and 0.043 for Kayahe.The estimated exposure rate obtained from the anti-M.RCAg-1 antibody level correlated with traditional measures of transmission intensity derived from altitude.Conclusion:Our study demonstrates that M.RCAg-1 is potentially useful as a serological indicator of exposure to P.falciparum malaria,especially for malaria surveillance in low transmission areas.