Preoperative prediction of lymphovascular and perineural invasion in gastric cancer using spectral computed tomography imaging and machine learning

BACKGROUND Lymphovascular invasion(LVI)and perineural invasion(PNI)are important prognostic factors for gastric cancer(GC)that indicate an increased risk of metastasis and poor outcomes.Accurate preoperative prediction of LVI/PNI status could help clinicians identify high-risk patients and guide treatment deci-sions.However,prior models using conventional computed tomography(CT)images to predict LVI or PNI separately have had limited accuracy.Spectral CT provides quantitative enhancement parameters that may better capture tumor invasion.We hypothesized that a predictive model combining clinical and spectral CT parameters would accurately preoperatively predict LVI/PNI status in GC patients.AIM To develop and test a machine learning model that fuses spectral CT parameters and clinical indicators to predict LVI/PNI status accurately.METHODS This study used a retrospective dataset involving 257 GC patients(training cohort,n=172;validation cohort,n=85).First,several clinical indicators,including serum tumor markers,CT-TN stages and CT-detected extramural vein invasion(CT-EMVI),were extracted,as were quantitative spectral CT parameters from the delineated tumor regions.Next,a two-step feature selection approach using correlation-based methods and information gain ranking inside a 10-fold cross-validation loop was utilized to select informative clinical and spectral CT parameters.A logistic regression(LR)-based nomogram model was subsequently constructed to predict LVI/PNI status,and its performance was evaluated using the area under the receiver operating characteristic curve(AUC).RESULTS In both the training and validation cohorts,CT T3-4 stage,CT-N positive status,and CT-EMVI positive status are more prevalent in the LVI/PNI-positive group and these differences are statistically significant(P<0.05).LR analysis of the training group showed preoperative CT-T stage,CT-EMVI,single-energy CT values of 70 keV of venous phase(VP-70 keV),and the ratio of standardized iodine concentration of equilibrium phase(EP-NIC)were independent influencing factors.The AUCs of VP-70 keV and EP-NIC were 0.888 and 0.824,respectively,which were slightly greater than those of CT-T and CT-EMVI(AUC=0.793,0.762).The nomogram combining CT-T stage,CT-EMVI,VP-70 keV and EP-NIC yielded AUCs of 0.918(0.866-0.954)and 0.874(0.784-0.936)in the training and validation cohorts,which are significantly higher than using each of single independent factors(P<0.05).CONCLUSION The study found that using portal venous and EP spectral CT parameters allows effective preoperative detection of LVI/PNI in GC,with accuracy boosted by integrating clinical markers.

Review on article of preoperative prediction in chronic hepatitis B virus patients using spectral computed tomography and machine learning

This letter comments on the article that developed and tested a machine learning model that predicts lymphovascular invasion/perineural invasion status by combining clinical indications and spectral computed tomography characteristics accurately.We review the research content,methodology,conclusions,strengths and weaknesses of the study,and introduce follow-up research to this work.

Whole-volume histogram analysis of spectral-computed tomography iodine maps characterizes HER2 expression in gastric cancer

BACKGROUND Although surgery remains the primary treatment for gastric cancer(GC),the identification of effective alternative treatments for individuals for whom surgery is unsuitable holds significance.HER2 overexpression occurs in approximately 15%-20%of advanced GC cases,directly affecting treatment-related decisions.Spectral-computed tomography(sCT)enables the quantification of material compositions,and sCT iodine concentration parameters have been demonstrated to be useful for the diagnosis of GC and prediction of its invasion depth,angioge-nesis,and response to systemic chemotherapy.No existing report describes the prediction of GC HER2 status through histogram analysis based on sCT iodine maps(IMs).AIM To investigate whether whole-volume histogram analysis of sCT IMs enables the prediction of the GC HER2 status.METHODS This study was performed with data from 101 patients with pathologically confirmed GC who underwent preoperative sCT examinations.Nineteen parameters were extracted via sCT IM histogram analysis:The minimum,maximum,mean,standard deviation,variance,coefficient of variation,skewness,kurtosis,entropy,percentiles(1st,5th,10th,25th,50th,75th,90th,95th,and 99th),and lesion volume.Spearman correlations of the parameters with the HER2 status and clinicopathological parameters were assessed.Receiver operating characteristic curves were used to evaluate the parameters’diagnostic performance.RESULTS Values for the histogram parameters of the maximum,mean,standard deviation,variance,entropy,and percentiles were significantly lower in the HER2+group than in the HER2–group(all P<0.05).The GC differentiation and Lauren classification correlated significantly with the HER2 status of tumor tissue(P=0.001 and 0.023,respectively).The 99th percentile had the largest area under the curve for GC HER2 status identification(0.740),with 76.2%,sensitivity,65.0%specificity,and 67.3%accuracy.All sCT IM histogram parameters correlated positively with the GC HER2 status(r=0.237-0.337,P=0.001-0.017).CONCLUSION Whole-lesion histogram parameters derived from sCT IM analysis,and especially the 99th percentile,can serve as imaging biomarkers of HER2 overexpression in GC.

Photon-counting computed tomography thermometry via material decomposition and machine learning

Thermal ablation procedures,such as high intensity focused ultrasound and radiofrequency ablation,are often used to eliminate tumors by minimally invasively heating a focal region.For this task,real-time 3D temperature visualization is key to target the diseased tissues while minimizing damage to the surroundings.Current computed tomography(CT)thermometry is based on energy-integrated CT,tissue-specific experimental data,and linear relationships between attenuation and temperature.In this paper,we develop a novel approach using photon-counting CT for material decomposition and a neural network to predict temperature based on thermal characteristics of base materials and spectral tomographic measurements of a volume of interest.In our feasibility study,distilled water,50 mmol/L CaCl2,and 600 mmol/L CaCl2 are chosen as the base materials.Their attenuations are measured in four discrete energy bins at various temperatures.The neural network trained on the experimental data achieves a mean absolute error of 3.97°C and 1.80°C on 300 mmol/L CaCl2 and a milk-based protein shake respectively.These experimental results indicate that our approach is promising for handling non-linear thermal properties for materials that are similar or dis-similar to our base materials.

Prospective observational study on the prognosis of ureteral lesions caused by impacted stones via dual-energy spectral computed tomography

Objective Ureteral lesions caused by impacted ureteral stones are likely to result in postoperative ureteral stricture.On this basis,the study aimed to investigate if dual-energy spectral computed tomography can predict ureteral hardening caused by impacted stones and to explore the relationship between different types of ureteral lesions and the risk of ureteral stricture.Methods This prospective study collected data of 93 patients with impacted stones from hospital automation system during January 2018 to October 2019.They underwent an abdominal scan on a dual-energy spectral computed tomography.During surgery,the operator used ureteroscopy to identify ureteral lesions,which were classified into four categories:edema,polyps,pallor,and hardening.Seven months later,90 patients were reviewed for the degree of hydronephrosis.Results Endoscopic observations revealed 38(41%)cases of ureteral edema,20(22%)cases of polyps,13(14%)cases of pallor,and 22(24%)cases of hardening.There were significant differences in hydronephrosis,the period of impaction,the calcium concentration of the ureter,and the slope of the spectral Hounsfield unit curve between the four groups.After that,we evaluated the factors associated with ureteral hardening and found that the calcium concentration of the ureter and hydronephrosis remained independent predictors of ureteral hardening.Receiver operating characteristic curve analysis showed that 5.3 mg/cm^(3)calcium concentration of the ureter is an optimal cut-off value to predict ureteral hardening.The result of follow-up showed that 80 patients had complete remission of hydronephrosis,with a complete remission rate of 61.9%(13/21)in the hardening group and 97.1%(67/69)in the non-hardening group(p<0.001).Conclusion Calcium concentration of the ureter is an independent predictor of ureteral hardening.Patients with ureteral hardening have more severe hydronephrosis after ureteroscopic lithotripsy.When the calcium concentration of the ureter is less than 5.3 mg/cm^(3),ureteral lesions should be actively treated.

Detection of gallbladder stones by dual-energy spectral computed tomography imaging

AIM:To evaluate the detectability of gallbladder stones by dual-energy spectral computed tomography(CT) imaging.METHODS:Totally 217 patients with surgically confirmed gallbladder stones were retrospectively analyzed who underwent single-source dual-energy CT scanning from August 2011 to December 2013. Polychromatic images were acquired. And post-processing software was used to reconstruct monochromatic(40 ke V and 140 ke V) images,and calcium-lipid pair-wise base substance was selected to acquire calcium base images and lipid base images. The above 5 groups of images were evaluated by two radiologists separately with 10-year experience in CT image reading. In the 5 groups of images,the cases in the positive group and negative group were counted and then the detection rate was calculated. The inter-observer agreement on the scoring results was analyzed by Kappa test,and the scoring results were analyzed by Wilcoxon test,with P < 0.05 indicating that the difference was statistically significant. The stone detection results of the 5 groups of images were analyzed by χ2 test.RESULTS:There was good inter-observer agreement(k = 0.772). In 217 patients with gallbladder stones,there was a statistically significant difference in stone visualization between spectral images(40 ke V,140 ke V,calcium base and lipid base images) and polychromatic images(P < 0.05). 40 ke V monochromatic images were better than 140 ke V monochromatic images(4.90 ± 0.35 vs 4.53 ± 1.15,P < 0.05),and calcium base images were superior to lipid base images(4.91 ± 0.43 vs 4.77 ± 0.63,P < 0.05),but there was no statisticallysignificant difference between 40 ke V monochromatic images and calcium base images(4.90 ± 0.35 vs 4.91 ± 0.43,P > 0.05). In 217 gallbladder stone patients,there were 21,3,28,5 and 12 negative stone cases in polychromatic images,40 ke V images,140 ke V images,calcium base images and lipid base images,respectively,and the differences among the five groups were statistically significant(P < 0.05).CONCLUSION:Monochromatic images and base substance images have a good clinical prospect in the iso-density stone detection.

Spectral computed tomography in advanced gastric cancer: Can iodine concentration non-invasively assess angiogenesis?

AIM To investigate the correlation of iodine concentration(IC) generated by spectral computed tomography(CT) with micro-vessel density(MVD) and vascular endothelial growth factor(VEGF) expression in patients with advanced gastric carcinoma(GC).METHODS Thirty-four advanced GC patients underwent abdominal enhanced CT in the gemstone spectral imaging mode. The IC of the primary lesion in the arterial phase(AP) and venous phase(VP) were measured, and were then normalized against that in the aorta to provide the normalized IC(nI C). MVD and VEGF were detected by immunohistochemical assays, using CD34 and VEGF-A antibodies, respectively. Correlations of nI C with MVD, VEGF, and clinical-pathological features were analyzed.RESULTS Both nI Cs correlated linearly with MVD and were higher in the primary lesion site than in the normal control site, but were not correlated with VEGF expression. After stratification by clinical-pathological subtypes, nI C-AP showed a statistically significant correlation with MVD, particularly in the group with tumors at stage T4, without nodular involvement, of a mixed Lauren type, where the tumor was located at the antrum site, and occurred in female individuals. nI C-VP showed a positive correlation with MVD in the group with the tumor at stage T4 and above, had nodular involvement, was poorly differentiated, was located at the pylorus site, of a mixed and diffused Lauren subtype, and occurred in male individuals. nI C-AP and nI C-VP showed significant differences in terms of histological differentiation and Lauren subtype.CONCLUSION The IC detected by spectral CT correlated with the MVD. n IC-AP and n IC-VP can reflect angiogenesis in different pathological subgroups of advanced GC.

Pancreatic paraganglioma with multiple lymph node metastases found by spectral computed tomography: A case report and review of the literature

BACKGROUND Primary pancreatic paraganglioma is exceedingly rare.Most patients with pancreatic paraganglioma lack a typical clinical presentation,and the tumor is difficult to accurately differentiate from other pancreatic neuroendocrine tumors,making the misdiagnosis rate extremely high.Surgical excision is the primary treatment modality but is considered high risk.Because of its rich vascularity,the tumor easily bleeds during surgery,especially malignant paragangliomas invading large blood vessels.Thus,a thorough preoperative evaluation of the tumor is necessary.Here,we report a primary malignant pancreatic paraganglioma,the second such case in a young patient that was successfully resected surgically.CASE SUMMARY A 26-year-old female patient was admitted to the hospital with unexplained abdominal pain.Dual-layer spectral-detector computed tomography(DLCT)revealed a mixed density mass in the pancreatic body and tail.The patient was transferred to our hospital after previous failed surgical resection at other hospitals.The patient and her family strongly desired surgery.After a thorough preoperative evaluation and adequate preparation,a large mass with the greatest dimension of 8.0 cm was successfully resected.The final pathological diagnosis was malignant paraganglioma.The patient was discharged in good condition 2 wk postoperatively.CONCLUSION The rare malignant pancreatic paraganglioma reported here was difficult to diagnose preoperatively.Early filling of the draining vein may be a crucial diagnostic imaging feature.DLCT can provide more precise information for surgical resection through dual-energy imaging.

Energy enhanced tissue texture in spectral computed tomography for lesion classification

Tissue texture reflects the spatial distribution of contrasts of image voxel gray levels,i.e.,the tissue heterogeneity,and has been recognized as important biomarkers in various clinical tasks.Spectral computed tomography(CT)is believed to be able to enrich tissue texture by providing different voxel contrast images using different X-ray energies.Therefore,this paper aims to address two related issues for clinical usage of spectral CT,especially the photon counting CT(PCCT):(1)texture enhancement by spectral CT image reconstruction,and(2)spectral energy enriched tissue texture for improved lesion classification.For issue(1),we recently proposed a tissue-specific texture prior in addition to low rank prior for the individual energy-channel low-count image reconstruction problems in PCCT under the Bayesian theory.Reconstruction results showed the proposed method outperforms existing methods of total variation(TV),low-rank TV and tensor dictionary learning in terms of not only preserving texture features but also suppressing image noise.For issue(2),this paper will investigate three models to incorporate the enriched texture by PCCT in accordance with three types of inputs:one is the spectral images,another is the cooccurrence matrices(CMs)extracted from the spectral images,and the third one is the Haralick features(HF)extracted from the CMs.Studies were performed on simulated photon counting data by introducing attenuationenergy response curve to the traditional CT images from energy integration detectors.Classification results showed the spectral CT enriched texture model can improve the area under the receiver operating characteristic curve(AUC)score by 7.3%,0.42%and 3.0%for the spectral images,CMs and HFs respectively on the five-energy spectral data over the original single energy data only.The CM-and HF-inputs can achieve the best AUC of 0.934 and 0.927.This texture themed study shows the insight that incorporating clinical important prior information,e.g.,tissue texture in this paper,into the medical imaging,such as the upstream image reconstruction,the downstream diagnosis,and so on,can benefit the clinical tasks.

Monochromatic energy computed tomography image for active intestinal hemorrhage:A model investigation

AIM: To investigate the value of computed tomography(CT) spectral imaging in the evaluation of intestinal hemorrhage.METHODS: Seven blood flow rates were simulated in vitro.Energy spectral CT and mixed-energy CT scanswere performed for each rate(0.5,0.4,0.3,0.2,0.1,0.05 and 0.025 m L/min).The detection rates and the contrast-to-noise ratios(CNRs) of the contrast agent extravasation regions were compared between the two scanning methods in the arterial phase(AP) and the portal venous phase(PVP).Comparisons of the CNR values between the PVP and the AP were made for each energy level and carried out using a completely random t test.A χ2 test was used to compare the detection rates obtained from the two scanning methods.RESULTS: The total detection rates for energy spectral CT and mixed-energy CT in the AP were 88.57%(31/35) and 65.71%(23/35),respectively,and the difference was significant(χ2 = 5.185,P = 0.023); the total detection rates in the PVP were 100.00%(35/35) and 91.4%(32/35),respectively,and the difference was not significant(χ2 = 1.393,P = 0.238).In the AP,the CNR of the contrast agent extravasation regions was 3.58 ± 2.09 on the mixed-energy CT images,but the CNRs were 8.78 ± 7.21 and 8.83 ± 6.75 at 50 and 60 keV,respectively,on the single-energy CT images,which were significantly different(3.58 ± 2.09 vs 8.78 ± 7.21,P = 0.031; 3.58 ± 2.09 vs 8.83 ± 6.75,P = 0.029).In the PVP,the differences between the CNRs at 40,50 and 60 keV different monochromatic energy levels and the polychromatic energy images were significant(19.35 ± 10.89 vs 11.68 ± 6.38,P = 0.010; 20.82 ± 11.26 vs 11.68 ± 6.38,P = 0.001; 20.63 ± 10.07 vs 11.68 ± 6.38,P = 0.001).The CNRs at the different energy levels in the AP and the PVP were significantly different(t =-2.415,-2.380,-2.575,-2.762,-2.945,-3.157,-3.996 and-3.189).CONCLUSION: Monochromatic energy imaging spectral CT is superior to polychromatic energy images for the detection of intestinal hemorrhage,and the detection was easier in the PVP compared with the AP.

Analysis of the Spectral Resolving Power in Tomographic Imaging Spectrometry

From the point of view of design requirements, influence of the width of the output image of an imaging subsystem in a tomographic imaging spectrometer, namely width of the slit, the grating and the size of the CCD pixel are analyzed. For the tomographic imaging spectrometry, if the amplification ratio of the imaging subsystem is not high enough to make the whole object to be compressed within the slit, then either the slit width should be increased or the slit width kept unchanged but scanned to receive information of the object. While the width-increase method reduces the spectral resolving power and the SNR; the scanning method reduces the SNR. Analysis of the two cases and computer simulation results are given.

Immune microenvironment-reshaping Au@Bi_(2)Te_(3) nanoparticles for spectral computed tomography/photoacoustic imaging-guided synergetic photo/radio/immunotherapy

Radiotherapy(RT)mediated tumor immunogenicity offers an opportunity for simultaneous RT and immunotherapy via immunogenic cell death(ICD),which releases damaged-associated molecular patterns and generates“eat me”signals for the innate immune system to modulate the immunogenicity.However,tumor hypoxia significantly reduces the therapeutic efficacy of RT and hampers its mediation of ICD induction.Herein,Au@Bi_(2)Te_(3)-polyethylene glycol(PEG)was rationally constructed as theranostic nanozymes for mild photothermal therapy,tumor hypoxia modulation,and RT adjuvant cancer immunotherapy.The tumor-specific production of oxygen could not only augment the effects of RT by enhanced reactive oxygen species(ROS)generation,but also reduce hypoxia-related cytokines and downregulate programmed cell death-ligand 1(PD-L1)to unleash immune-enhancing T cells.Moreover,Au@Bi_(2)Te_(3)-PEG could act as an immune-blocking inhibitor by efficient ICD induction with the combination of mild-photothermal therapy+RT to inhibit the tumor immune escape and improve antitumor immune response.Increased amounts of CD^(4+) and CD^(8+) Tcells and elevated levels of cytokines could be observed that eventually led to effective post-medication inhibition of primary and abscopal tumors.Spectral computed tomography/photoacoustic imaging allowed noninvasive and real-time tracking of nanoparticle(NP)accumulation and oxygenation status at tumor sites.Collectively,Au@Bi_(2)Te_(3)-PEG NPs could serve as effective theranostic nanoregulators with remarkable synergistic mildphotothermal/RT/immunotherapy effects that helped reshape the immune microenvironment and had remarkable molecular imaging properties.

优化双下肢动脉能谱CT血管造影成像方案

目的优化双下肢动脉能谱CT血管造影(CTA)成像方案。方法回顾性分析30例疑诊双下肢动脉硬化性闭塞症(ASO)患者双下肢动脉能谱CTA资料,经重建获得40~80 keV(间隔5 keV)单能量(共9种)及100 kVp混合能量图像,对比双下肢动脉在不同图像中的CT值、噪声(SD)值、信噪比(SNR)及对比度噪声比(CNR);针对50、60 keV单能量和100 kVp混合能量图像质量及血管节段的可诊断性进行主观评估,观察40、45、50、60 keV单能量和100 kVp混合能量图像的自动去骨能力。结果40~80 keV范围内,随keV升高,各动脉在图像中的CT值、SD值、SNR及CNR均逐渐降低。相比100 kVp,腘动脉(PA)及其近端动脉的CT值、CNR及SNR均在40~55 keV图像中升高(P均<0.05);50~55 keV图像中SD值升高(P均<0.05),而60 keV图像中差异无统计学意义(P>0.05)。50及60 keV图像质量主观评分及可诊断动脉节段数与100 kVp差异均无统计学意义(P均>0.05)。PA以远节段的SNR及CNR在各单能量图像及100 kVp图像中差异均无统计学意义,其CT值在40~45 keV图像中、SD在40 keV图像中均高于100 kVp(P均<0.05),但SD在45 keV与100 kVp图像中差异无统计学意义(P>0.05);50 keV图像中,PA以远节段图像质量主观评分及可诊断节段数均高于60 keV及100 kVp(P均<0.05)。40 keV图像对9例(9/30,30.00%)、45 keV图像对6例(6/30,20.00%)不能自动去骨,50及60 keV、100 kVp对30例(30/30,100%)均可自动去骨。结论行双下肢动脉能谱CTA时,对PA及其近端节段以60 keV单能量成像较佳,对其以远或双下肢全程则以50 keV单能量成像较佳。

能谱CT定量参数联合动脉期碘基图影像组学特征在肺鳞癌与肺腺癌鉴别诊断中的价值

目的基于能谱电子计算机断层扫描(computed tomography,CT)定量参数联合动脉期碘基图影像组学特征构建诺模图模型,探讨能谱CT在肺鳞癌(lung squamous cell carcinoma,LUSC)与肺腺癌(lung adenocarcinoma,LUAD)鉴别诊断中的临床应用价值。方法收集术前行能谱CT增强检查、经病理活检或手术证实的肺癌患者89例,其中LUAD组38例,LUSC组51例。分析LUAD组和LUSC组患者在60keV动脉期单能量图像中病灶水浓度、碘浓度(iodine concentration,IC)、标准化碘浓度(normalizediodineconcentration,NIC)、CT值、能谱曲线斜率(K)、有效原子序数(effective-Z,Eff-Z)及标准化有效原子序数(normalized effective-Z,NEff-Z)。采用Logistic回归分析构建LUAD和LUSC基于能谱CT特征的鉴别诊断模型。应用ITKSnap软件提取动脉期碘基图影像组学特征;采用组内相关系数(intraclass correlation coemcient,ICC)、递归特征消除(recursive featureelimination,RFE)和最小绝对收缩和选择算子(least absolute shrinkage and selection operator,LASSO)对影像组学特征进行降维、筛选,采用Logistic回归构建基于影像组学特征的诊断模型,并计算该模型的影像组学评分(radiomics score,Rad-score),以多因素Logistic回归分析筛选出的能谱CT定量参数与Rad-score构建联合模型,并绘制诺模图。应用受试者工作特征(receiveroperatingcharacteristic,ROC)曲线、Delong检验、校正曲线、Hosmer-Lemeshow检验及临床决策曲线(decision curve analysis,DCA)对能谱CT模型、影像组学模型和诺莫图模型进行效能评价。结果LUAD组和LUSC组患者IC、NIC、CT值、K及NEff-Z比较差异均有统计学意义(P均<0.05)。多因素Logistic回归分析结果显示,IC、NIC及NEff-Z为独立影响因素,基于此构建能谱CT模型预测LUAD和LUSC的效能曲线下面积(areaunderthecurve,AUC)为0.768,准确率、灵敏度、特异度分别为70.73%、76.92%和67.86%;影像组学特征经降维后共筛选出的有意义特征有5个,一阶特征2个、二阶特征2个和形状特征1个,影像组学模型预测LUAD和LUSC的效能AUC为0.848,准确率、灵敏度、特异度分别为80.50%、83.33%和75.00%;诺莫图模型预测LUAD和LUSC的效能AUC为0.912,准确率、灵敏度、特异度分别为85.00%、92.31%和85.71%。经Delong检验显示,诺莫图模型AUC均明显高于影像组学模型和能谱CT模型(P均<0.05)。Hosmer-Lemeshow检验结果显示,能谱CT模型、影像组学模型及诺莫图模型的拟合度均良好(χ^(2)值分别为8.592、6.591、6.686,P值分别为0.378、0.581、0.570)。校准曲线分析显示,诺莫图模型预测LUAD和LUSC的预测概率曲线与理想曲线更接近,优于影像组学模型和能谱CT模型;DCA分析结果显示,诺莫图模型的AUC最大,均高于影像组学模型和能谱CT模型,临床净收益更高。结论基于能谱CT定量参数联合动脉期碘基图影像组学特征构建的诺模图模型在LUSC与LUAD鉴别诊断中具有潜在应用价值。

颅内动脉瘤栓塞术后能谱CTA联合MAR的临床研究

目的:评价颅内动脉瘤栓塞术后能谱CTA联合去金属伪影技术(MAR)的应用价值。方法:收集37例颅内动脉瘤栓塞术后需行能谱头颈CTA检查患者的CT原始数据,分别重建出70~140 keV单能级图像、120 kVp-like混合能量图像及70~140 keV MAR处理图像和120kVp-like MAR图像;感兴趣区(ROI)放置在伪影最严重层面的线圈附近,测量CT值及标准差(SD),计算伪影指数(AI)及信噪比(SNR);在主观分析方面,由两名诊断医生采用Likert 5分量表法对所有图像的伪影程度和血管显示能力进行评估;比较MAR组和非MAR组图像的主观评分和客观参数。采用Wilcoxon秩和检验、配对样本t检验及独立样本t检验比较各组图像之间的差异。结果:8组单能量图像上,MAR图像的AI明显低于非MAR图像;在80~110 keV条件下,MAR图像SNR高于非MAR组,差异具有统计学意义;相同keV下,与非MAR组相比,MAR组图像的伪影评分及周围血管显示主观评分得分均更高。对于非MAR处理图像,AI值与周围血管显示评分在植入不同直径弹簧圈的患者图像上没有统计学差;对于MAR图像,较大直径弹簧圈组(>8.79 mm)患者图像的AI值明显高于常规直径组,而周围血管显示主观评分明显低于常规直径组。结论:能谱CTA成像联合MAR可有效减少颅内动脉瘤栓塞植入物伪影,改善周围血管显示,对于小直径的弹簧圈MAR减少伪影效果最为显著。

对比剂分次团注联合能量成像获得CTU和CTA联合成像的应用研究

目的:探讨对比剂分次团注结合双层探测器光谱CT 50 keV虚拟单能量图像(VMI),在CT泌尿系成像(CTU)与主动脉CTA联合成像中的应用价值。方法:收集2024年3月至4月在首都医科大学附属北京同仁医院Philips IQon双层探测器光谱CT行CTU检查患者32例为试验组。使用对比剂分次团注及团注追踪技术;扫描后重建常规120 kVp混合能量图像为A1组;光谱重建获得50 keV VMI为A2组。收集2023年12月至2024年3月间在相同设备行CTU检查患者32例为对照组,使用对比剂分离团注技术及团注追踪技术;扫描后重建常规120 kVp混合能量图像为B组。客观评价包括:比较3组腹主动脉、双侧肾动脉的CT值、对比噪声比(CNR)、信噪比(SNR);比较输尿管起始部平均CT值和中下部平均CT值,并采用Kruskal-Wallis检验,采用Nemenyi检验进行两两比较。试验组与对照组的有效辐射剂量比较采用Wilcoxon检验。主观评价由两名高年资影像医师分别对3组CTA及CTU图像进行4分法和3分法评价,两名医师主观评分的一致性采用Kappa检验。结果:客观评价指标中,A2组分别与A1组和B组比较,均有统计学差异;A1组与B组仅双侧肾动脉SNR有统计学差异。两组有效辐射剂量有统计学差异,试验组较对照组降低15.1%。3组CTA、CTU图像主观评价无统计学差异;两名医师对CTA图像评分结果一致性非常好,对CTU图像评分结果一致性好。结论:利用对比剂分次团注行CTU检查时,获得泌尿系及主动脉同时显影的融合图像,不仅具有明确的解剖关系及相同的图像质量,而且降低有效辐射剂量;光谱重建获得的50 keV虚拟单能量图像,优化CTU及CTA图像质量,具有临床价值。

影像学在中耳胆脂瘤诊疗中的应用现状及进展

中耳胆脂瘤是一种由角质碎片、角质化鳞状上皮等物质堆积构成的良性肿瘤,其长期存在导致听力下降、面瘫等,甚至危及生命,因此精准诊断对于治疗方案及预后尤为重要。手术作为其最有效的治疗手段,方案选择最重要的依据是胆脂瘤侵犯的范围与深度,同时结合患者病史、症状、体征等多因素进行评估。本文通过文献检索,综述分析了中耳胆脂瘤的病理特点、治疗方式以及不同影像学检查的临床应用。特别关注了能谱CT技术在中耳胆脂瘤诊疗中的潜力和进展,并对能谱CT的价值进行展望。

影响能谱CTU虚拟平扫尿路结石检出的因素分析

目的 基于Logistic回归分析评估影响能谱CT尿路造影(CTU)虚拟平扫图像检出尿路结石的因素。方法 回顾性纳入150例尿路结石并行能谱CTU的患者(记录所用碘对比剂)。将平扫图像重建为120 kVp-like图像,静脉期和排泄期的增强图像采用碘去除技术分别重建为静脉期和排泄期的虚拟平扫图像。2位医师独立评估以上3组图像,并记录3组图像的尿路结石数量、所在解剖位置及虚拟平扫图像是否有碘残留;结石大小和CT值仅在真实平扫图像上测量。结石大小、CT值、结石所在位置和所用碘对比剂纳入Logistic回归分析,用于评估影响虚拟平扫尿路结石检出的因素。受试者工作特征(ROC)曲线用于绘制各指标的曲线下面积(AUC)值、诊断灵敏度和特异度及最佳临界值。结果 真实平扫上检出304枚结石,而静脉期和排泄期虚拟平扫结石检出率分别为92.4%和71.4%。结石大小和CT值是影响静脉期和排泄期虚拟平扫结石检出的独立风险因素(P<0.01),结石大小和CT值在静脉期虚拟平扫结石检出的AUC值达0.96以上,诊断临界值分别是3.52 mm和469 HU,而在排泄期虚拟平扫结石检出的结石大小、CT值及解剖位置等指标的综合AUC值降为0.88。排泄期虚拟平扫结石检出率在碘对比剂组间无统计学差异(P=0.57)。另外,排泄期肾盂肾盏处虚拟平扫结石检出率明显降低(P<0.001)。结论 在增强CT的2个扫描期相中,静脉期虚拟平扫结石检出效果更佳。结石大小和CT值是影响虚拟平扫结石检出的重要因素。肾盂肾盏处排泄期虚拟平扫结石检出率低与碘去除效果欠佳相关。

能谱CT多参数成像术前预测胃癌淋巴结转移

目的观察能谱CT多参数成像术前预测胃癌淋巴结转移(LNM)的价值。方法回顾性分析136例胃腺癌患者,根据术后病理显示淋巴结状态将其分为LNM组(n=74)与非LNM组(n=62);比较组间临床资料、常规CT表现及能谱CT参数,将组间差异有统计学意义的因素纳入多因素logistic回归分析筛选胃癌LNM的独立预测因素,据以分别构建临床+常规CT模型(模型1)、能谱CT模型(模型2)及联合模型(模型3)。绘制受试者工作特征曲线,计算曲线下面积(AUC),评估各模型术前预测胃癌LNM的效能。结果CT-N分期、CT-T分期,动脉期(AP)70、100及140 keV CT值_(肿瘤),动脉增强分数(AEF)及静脉期标准碘浓度(NICVP)均为胃癌LNM的独立预测因素(P均<0.05)。模型3术前预测胃癌LNM的AUC为0.846,高于模型1及模型2(AUC=0.767、0.774,Z=-0.368、-2.373,P均<0.05),而模型1、2间差异无统计学意义(Z=-0.152,P=0.879)。结论能谱CT多参数成像可于术前有效预测胃癌LNM。

光谱CT虚拟单能量冠状动静脉一体化成像的可行性分析

目的应用双层探测器光谱CT虚拟单能量成像技术尝试完成心脏冠状动脉和冠状静脉一体化成像。方法收集了2023年12月—2024年1月采用了个性化扫描方案进行冠状动静脉CT成像的受检者25例作为实验组,随机抽取我院同一时间段采用常规扫描方案进行冠状动脉CT成像的受检者25例作为对照组。将对照组常规图像作为A组,将实验组常规图像作为B1组,B1组通过虚拟单能级重建生成40 keV图像作为B2组。对A组、B1组、B2组的图像质量进行客观评价和主观评价;客观评价内容包括冠状动脉各分支的CT值、信噪比(SNR)和对比噪声比(CNR)。主观评价由两名高年资影像医师按照5分法完成,主观评分两位评分者的一致性分析采用Kappa检验;组间比较采用Mann-Whitney检验。结果实验组B2组的冠状动脉各分支的CT值、SNR和CNR[左冠状动脉主干CT值:(1306.07±185.16)HU、SNR:101.820±38.10、CNR:113.91±42.13;右冠状动脉CT值:(1284.97±203.8)HU、SNR:99.99±37.61、CNR:112.10±41.53;左回旋支CT值:(1191.88±182.83)HU、SNR:93.01±36.10、CNR:105.11±39.92;左前降支CT值:(1202.44±185.50)HU、SNR:88.05±33.57、CNR:106.33±41.84]均较实验组B1组和对照组A组的高,其结果差异具有统计学意义(P均<0.001)。实验组B2组的冠状静脉各分支(冠状静脉窦、心大静脉、后室间静脉、前室间静脉、左心室后静脉、左边缘静脉)的CT值、SNR和CNR值明显高于实验组B1组,结果差异具有统计学意义(P均<0.001)。两位医师对B2组图像质量的主观评分均为5(5,5),优于对照组A组和实验组B1组,且主观评价一致性较好(Kappa>0.7),说明B2组对于冠状动静脉的显示效果和图像质量更好。结论结合光谱CT虚拟单能量成像技术,能实现冠状动脉和冠状静脉的一体化成像。