Objective To observe the value of intravoxel incoherent motion(IVIM)histogram parameters for predicting perineural invasion(PNI)of rectal cancer.Methods Fifty-five patients with rectal cancer were retrospectively enrolled and divided into positive group(n=23)and negative group(n=32)according to PNI or not.Histogram parameters of apparent diffusion coefficient(ADC),perfusion fraction(f),true diffusion coefficient(D)and pseudo diffusion coefficient(D*)were obtained based on MR IVIM images,including the mean,skewness,kurtosis,entropy,as well as the 25th,50th and 75th percentiles(25th,50th,75th).The above IVIM histogram parameters were compared between groups,and those with significant difference were included in binary stepwise logistic regression analysis to screen independent factors for predicting PNI status of rectal cancer.Then a combined parameter model was established.Receiver operating characteristic curve was drawn,and the area under the curve(AUC)was calculated to evaluate the efficacy of IVIM histogram parameters and combined parameter model for predicting PNI of rectal cancer.Results ADCmean,ADC25th,ADC50th,ADC75th,fmean,f25th,f50th,f75th and Dentropy in positive group were all lower than those in negative group(all P＜0.05).AUC of the above parameters for predicting PNI of rectal cancer was 0.693,0.665,0.701,0.675,0.831,0.847,0.835,0.722 and 0.785,respectively.The sensitivity,specificity and AUC of combined parameter model based on f25th and Dentropy for predicting PNI of rectal cancer was 95.65％,65.63％and 0.897,respectively.Conclusion IVIM histogram parameters could be used to predict PNI of rectal cancer effectively.

Objective To observe the value of advanced patient motion correction(APMC)technology for improving imaging quality of low-dose pediatric chest CT.Methods Ninety-six children who received low-dose chest CT scan were retrospectively enrolled.CT images were reconstructed using full reconstruction technique(FULL)or APMC for both lung window and mediastinal window.Then the imaging qualities were subjectively evaluated according to image clarity,degree of motion artifacts,sharpness of structural edges and overall quality.The indexes of objective evaluation of imaging quality included the mean CT values of unit density pixel within ROI on lung window and mediastinal window,the standard deviation of CT values(SDCT)representing image noise,as well as signal-to-noise ratio(SNR).Sobel operator edge detection was performed on images,recording the mean gray level(G)and the standard deviation of gray value in Sobel(SDsobel)within ROI.Comparisons were made between FULL reconstruction and corrected images with APMC reconstruction in terms of subjective and objective evaluations,as well as parameters obtained from Sobel output images.Results Compared to FULL reconstruction,APMC corrected images showed reduced motion artifacts,improved edge structure sharpness and enhanced overall image quality(all P＜0.05),while there was no significant difference of image clarity(P＞0.05).Meanwhile,with APMC reconstructions,the mean CT values,SDCT on lung window and SDCT on mediastinal window increased(all P＜0.05),but there was no significant difference for the mean CT values on mediastinal window(P＞0.05),and SNR on both lung window and mediastinal window decreased(both P＜0.05).Besides,for Sobel output images,compared to FULL reconstruction,APMC reconstruction had increased G and SDsobel on both lung window and mediastinal window(all P＜0.05).Conclusion APMC technology applicated in low-dose chest CT scan of children could effectively reduce motion artifacts,improve edge clarity and imaging quality,hence enhance diagnostic sensitivity.

Objective To observe the value of advanced patient motion correction(APMC)technology for improving imaging quality of low-dose pediatric chest CT.Methods Ninety-six children who received low-dose chest CT scan were retrospectively enrolled.CT images were reconstructed using full reconstruction technique(FULL)or APMC for both lung window and mediastinal window.Then the imaging qualities were subjectively evaluated according to image clarity,degree of motion artifacts,sharpness of structural edges and overall quality.The indexes of objective evaluation of imaging quality included the mean CT values of unit density pixel within ROI on lung window and mediastinal window,the standard deviation of CT values(SDCT)representing image noise,as well as signal-to-noise ratio(SNR).Sobel operator edge detection was performed on images,recording the mean gray level(G)and the standard deviation of gray value in Sobel(SDsobel)within ROI.Comparisons were made between FULL reconstruction and corrected images with APMC reconstruction in terms of subjective and objective evaluations,as well as parameters obtained from Sobel output images.Results Compared to FULL reconstruction,APMC corrected images showed reduced motion artifacts,improved edge structure sharpness and enhanced overall image quality(all P＜0.05),while there was no significant difference of image clarity(P＞0.05).Meanwhile,with APMC reconstructions,the mean CT values,SDCT on lung window and SDCT on mediastinal window increased(all P＜0.05),but there was no significant difference for the mean CT values on mediastinal window(P＞0.05),and SNR on both lung window and mediastinal window decreased(both P＜0.05).Besides,for Sobel output images,compared to FULL reconstruction,APMC reconstruction had increased G and SDsobel on both lung window and mediastinal window(all P＜0.05).Conclusion APMC technology applicated in low-dose chest CT scan of children could effectively reduce motion artifacts,improve edge clarity and imaging quality,hence enhance diagnostic sensitivity.

Objective To observe the value of intravoxel incoherent motion(IVIM)histogram parameters for predicting perineural invasion(PNI)of rectal cancer.Methods Fifty-five patients with rectal cancer were retrospectively enrolled and divided into positive group(n=23)and negative group(n=32)according to PNI or not.Histogram parameters of apparent diffusion coefficient(ADC),perfusion fraction(f),true diffusion coefficient(D)and pseudo diffusion coefficient(D*)were obtained based on MR IVIM images,including the mean,skewness,kurtosis,entropy,as well as the 25th,50th and 75th percentiles(25th,50th,75th).The above IVIM histogram parameters were compared between groups,and those with significant difference were included in binary stepwise logistic regression analysis to screen independent factors for predicting PNI status of rectal cancer.Then a combined parameter model was established.Receiver operating characteristic curve was drawn,and the area under the curve(AUC)was calculated to evaluate the efficacy of IVIM histogram parameters and combined parameter model for predicting PNI of rectal cancer.Results ADCmean,ADC25th,ADC50th,ADC75th,fmean,f25th,f50th,f75th and Dentropy in positive group were all lower than those in negative group(all P＜0.05).AUC of the above parameters for predicting PNI of rectal cancer was 0.693,0.665,0.701,0.675,0.831,0.847,0.835,0.722 and 0.785,respectively.The sensitivity,specificity and AUC of combined parameter model based on f25th and Dentropy for predicting PNI of rectal cancer was 95.65％,65.63％and 0.897,respectively.Conclusion IVIM histogram parameters could be used to predict PNI of rectal cancer effectively.

Objective To investigate the value of dual-energy CT quantitative parameters combined with CT features for predicting perineural invasion(PNI)of colorectal adenocarcinoma.Methods Preoperative whole-abdominal CT data of 79 patients with colorectal adenocarcinoma confirmed by postoperative pathology were retrospectively analyzed.The patients were divided into PNI group(n=31)or no PNI group(n=48).Univariate analysis was used to compare CT features and dual-energy CT quantitative parameters between groups,and the variables with significant differences were included in binary logistic regression analysis to construct a combined model.Receiver operating characteristic(ROC)curves were drawn and area under the curve(AUC)were calculated,the efficacy of single CT parameters and combined model for predicting PNI of colorectal adenocarcinoma were evaluated.Results There were significant differences of the location of the primary lesion,the maximum thickness of the diseased intestinal wall,the presence or absence of peritumoral lymph node metastases,peritumoral mesenteric streak shadow and tumor deposits shown on CT between groups(all P＜0.05).Significant differences of the arterial phase slope of energy spectrum curve(λHU),iodine concentration(IC),normalized IC(NIC),dual energy index and the venous phase NIC of dual energy index were found between groups(all P＜0.05).AUC of the above single parameters for predicting PNI of colorectal adenocarcinoma ranged from 0.615 to 0.698,while of the combined model was 0.864.Conclusion Dual-energy CT quantitative parameters combined with CT features could be used to effectively predict PNI of colorectal adenocarcinoma.

Objective:To evaluate the application value of liver acquisition volume acceleration(LAVA)integrated with array spatial sensitivity encoding technique(ASSET)in demonstrating the vasculature of the liver carcinoma.Methods:42 patients with liver carcinoma underwent routine and contrast-enhancement MR examination of liver.LAVA integrated with ASSET was used in contrast-enhancement MR examination.The ability of LAVA integrated with ASSET to reveal the lesion and the hepatic vessels and the advantage to shorten the acquisition time were analyzed.Results:44 foci were revealed clearly.After integrated with ASSET,acquisition time shortened.Earlier and peak artery phase images were obtained in 24 cases,and earlier,peak and late artery phase images were acquired in 18 cases.Using MIP technique,tumor vessels were found in arterial phase images in 30 cases;tumor supply arteries were found in 20 cases;arteriovenous shunt was found in 1 case;portal vein invasion was found in 25 cases,and portal vein tumor embolus was found in 6 cases.Conclusion: LAVA integrated with ASSET has high application value,which can obtain high quality multi-phase dynamic enhancement images in a short time and supply the information of the anatomy of hepatic vessels.

Objective To evaluate the reproducibility and agreement in the measurement of liver volume with multi-slice spiral computed tomography(CT).Methods Spiral CT was performed in 20 cases(14 healthy volunteers and 6 patients with cirrhosis).Images were transferred to a workstation,and volumes were measured by three observers with 5-year abdominal CT experience.Each observer performed the measurements in all subjects twice.Intra-observer and inter-observer variability was calculated using analysis of variance of the repeatedly measured results.The agreement was analyzed with the intra-class correlation coefficient(ICC).Reliability analysis in inter-observer was performed with Cronbach's alpha coefficient.Results Data measured by Observer A were(1 265.53?421.43)cm3 and(1 272.30?414.73)cm3 [difference:(0.80?2.20)%,P=0.15,ICC=0.998 8],Observer B(1 299.97?403.48)cm3 and(1 310.23?404.04)cm3 [difference:(0.90?1.90)%,P=0.07,ICC=0.998 3],Observer C(1 282.18?425.91)cm3 and(1 289.73?424.66)cm3 [difference:(0.70?2.60)%,P=0.19,ICC=0.998 3],respectively.The mean liver volumes by the three observers were(1 268.91?418.07)cm3,(1 305.10?403.59)cm3,and(1 285.97?425.10)cm3,respectively(P=0.07,ICC=0.986 9,Cronbach's alpha coefficient=0.995 6).Conclusion High reproducibility and agreement in the measurement of liver volume can be achieved with multi-slice spiral CT.

Objective To investigate the multi-phase dynamic spiral CT findings of small hepatic hemangioma with arterioportal shunts,and to discuss its mechanism and influencing factors.Methods Multi-phase dynamic contrast-enhancement CT findings of 52 small hepatic hemangiomas in 33 cases were analyzed retrospectively.The criteria for diagnosing arterioportal shunts were as follow:①Transient wedge-shape or irregularly shape homogenous enhancement in the liver parenchyma adjacent to the tumor on hepatic arterial phase and slight hyper-or iso-attenuation in the area on portal venous phase and delayed phase;②Some branches of portal vein showed early appearance within the wedge-shaped homogenously hyper-attenuating area on the arterial phase.The correlation between the enhancement patterns of homangiomas and the prevalence of arterioportal shunts in small hepatic homangiomas were analyzed.Results Arterioportal shunts were found in 13(25%)of 52 small hepatic hemangiomas,all of them showed transient wedge-shaped enhancement peripheral to the tumor and in 7 of 13 hemangiomas showed early enhancement of branches of the portal veins on the arterial phase.Eleven(52.4%)of the 21 small hepatic hemangiomas with rapid enhancement had arterioportal shunt shunts,whereas only 2(6.5%)of the 31 hemangiomas with slow enhancement had arterioportal shunt shunts(P