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Objective@#To investigate the feasibility of contrast-enhanced computer tomography (CT) texture analysis in predicting early recurrence after transarterial chemoembolization (TACE) in patients with liver cancer.@*Methods@#A retrospective analysis was performed for 47 patients with liver cancer confirmed by liver biopsy and digital subtraction angiography who underwent upper abdominal contrast-enhanced CT scan before TACE, and according to the presence or absence of focal recurrence within half a year, these patients were divided into early recurrence (ER) group and non-early recurrence (NER) group. The texture analysis was used to delineate tumor boundary layer by layer on the axial contrast-enhanced CT image before liver cancer surgery, and related parameters of tumor heterogeneity, including entropy, mean, non-uniformity, skewness, and kurtosis, were obtained. The independent samples t-test was used for comparison of texture parameters between the two groups. The receiver operating characteristic (ROC) curve was used for the analysis of entropy, mean, and non-uniformity, and the area under the ROC curve (ROC), optical cut-off value, sensitivity, and specificity were calculated to evaluate the efficiency of texture analysis in predicting early focal recurrence after TACE.@*Results@#There were 20 patients in the ER group and 27 in the NER group. The ER group had a maximum major axis length of 88.2±36.3 mm and a maximum minor axis length of 41.4±21.4 mm, and the NER group had a maximum major axis length of 66.9±30.2 mm and a maximum minor axis length of 29.3±19.8 mm; the ER group had significantly higher maximum major and minor axis lengths than the NER group (t = 4.89 and 4.62, P < 0.001). The ER group had significantly higher entropy and non-uniformity values than the NER group, and there were no significant differences in skewness and kurtosis between the two groups. Entropy, non-uniformity, and mean had high efficiency in predicting early recurrence after TACE, and the optimal cut-off value of entropy was 4.135.@*Conclusion@#Volumetric texture analysis of contrast-enhanced CT images before liver cancer surgery has a high value in predicting early recurrence after TACE.
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Objective To evaluate the effect of different tube voltages on the radiation dose and image quality of a full field digital mammography system.Methods Both experiments were performed under manual exposure mode.In one experiment,the tube voltages were kept constant at 25,28 and 31 kVp,and the CIRS 015 phantom was exposed at three target/filter combinations molybdenum/molybdenum (Mo/Mo),molybdenum/rhodium (Mo/Rh),and rhodium/rhodium (Rh/Rh) and at tube current-exposure time products of 32-140mAs.The entrance skin exposure (ESE) and average glandular dose (AGD) were recorded,the signal-to-noise ratio(SNR) and contrast-to-noise ratio (CNR) and figure of merit (FOM) were measured to evaluate the influences of different tube voltages on dose and image quality at same target/filter combination.The univariate of randomized completed block-design was used for statistics.In second experiment,the phantom were exposed using Mo/Rh combination when the tube current-exposure time product was kept constant at 56 mAs,and the tube voltage varied between 23 and 33 kVp in 1-kVp increments.The ESE and AGD were recorded,the SNR,CNR and FOM were measured for plotting the curves against tube voltages.Results At Mo/Mo combination,the AGD,ESE,SNR,CNR and FOM of 25,28 and31 kVp were(1.25 ±0.56) mGy,(6.46±2.86) mGy,71.52±8.37,1.91 ±0.26,3.21 ± 0.68; (1.94 ±0.85) mGy,(9.18±4.07) mGy,144.46 ± 11.31,2.41 ±0.28,3.37 ±0.96 and (3.01 ±1.38) mGy,(12.60±5.59) mGy,128.89 ±15.29,2.47 ±0.31,2.31 ±0.76 respectively; at Mo/Rh combination were (1.23 ±0.55) mGy,(5.26 ±2.33) mGy,67.31 ±4.11,1.82 ±0.19,3.01 ± 0.82; (1.86 ±0.84) mGy,(7.57 ±3.34) mGy,139.54 ± 12.16,2.30 ±0.25,3.23 ±0.92 and (2.81 ±1.24) mGy,(10.48 ±4.62) mGy,127.77 ±15.14,2.59 ±0.31,2.67 ±0.68; and at Rh/Rh were(1.09 ±0.48) mGy,(4.89 ±2.16) mGy,67.46 ±2.23,1.48 ±0.72,3.08 ± 1.69; (1.75 ± 0.78) mGy,(6.88 ±3.03) mGy,137.74 ± 14.65,2.37 ±0.26,3.62 ± 1.07 and (2.59 ± 1.13) mGy,(9.32 ± 4.12) mGy,117.91 ± 19.05,2.51 ± 0.31,2.74 ± 0.84.Both experiments indicated that,for a given target/filter combination,the AGD,ESE and CNR increased,but the ESE/AGD decreased with the tube voltage increasing; The first experiment indicated both SNR and FOM of 28 kVp were higher than that of 25 kVp and 31 kVp; the second experiment showed both SNR and FOM decreased with tube voltages increasing.The differences of AGD、ESE、ESE/AGD、SNR、CNR and FOM among the three tube voltages were significant (F =4.391-528.848,P ＜ 0.05) ; but the difference of CNR between 28 and 31 kVp at Mo/Mo and Rh/Rh had no statistical significance (P ＞ 0.05) ; and the differences of FOM between 25 and 28 kVp at the three target/filter combinations were not statistically significant (P ＞ 0.05).Conclusion For a breast with 4.2 cm thickness and 50％ adipose 50％ glandular composition,different tube voltages have significant effects on the radiation dose and image quality.
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Objective To insestigate the pathophysiological mechanisms of spontaneous transient hyperperfusion after cerebral ischemia-reperfusion in rats.Methods Fifty-two SD rats were randomly allocated into sham-operation(group A),cerebral ischcmia 2-hour(group B), and cerebral ischemia 6-hour(group C)groups.Group B were redivided into 0-,0.5-,1-,2-,4-,6-,and 24-hour subgroups according to the reperfusion time;group C were redivided into 0-,0.5-,1-,2-,and 24-hour subgroups according to the reperfusion time (n=4 in each subgroup). Multislice spiral CT perfusion imaging(CTPI)was performed at different time points after ischemia-reperfusion in each group.After completing the scanning.the rats were sacrificed immediately for optical and electron microscopy examinations.Results In group A,compared to the contralateral sides.there were no significant differences in the relatise value of the cerebral blood flow parameters and the results of optical and electron microscopy in the sham-operated regions. In group B, the relative cerebral blood flow (rCBF) and relative cerebral blood volume (rCBV) in the ischemic core area were increased gradually with the extension of reperfusion time. The relative mean transit time (rMTT) and the relative time to peak (rTTP) were decreased gradually, There were no significant differences compared to group A at 6-hour after reperfusion. The optical and electron microscopy revealed that neuronal density in the ischemic core area in group B were decreased, part of the cell volume enlarged and showed vacuolated changes, and part of the neuronal cell bodies and nuclei shrinked, rCBF in the ischemic core area still maintained lower level with the extension of reperfusion time in group C. The ischemic core area showed the increased transient rCBV and rCBV at 0.5 hour after reperfusion in group B and C. The optical and electron microscopy showed that the ischemic core area presented a large number of necrotic and apoptotic cells, and inflammatory cell infiltration. At 6 hours after reperfusion in group B, the increased blood density was observed under the electron microscope in the ischemic core area, showing capillary engorgement and increased pressure. Conclusions The dynamic changes of CTPI in the process of rat middle cerebral artery occlusion and reperfusion have a certain correlation with the pathological mechanisms of injury. The ultra-early spontaneous and transient hyperperfusion after cerebral ischemia-reperfusion in rats is associated with the transient inflammatory hyperemia after reperfusion injury.