Parallel processing model for low-dose computed tomography image denoising

Low-dose computed tomography(LDCT)has gained increasing attention owing to its crucial role in reducing radiation exposure in patients.However,LDCT-reconstructed images often suffer from significant noise and artifacts,negatively impacting the radiologists’ability to accurately diagnose.To address this issue,many studies have focused on denoising LDCT images using deep learning(DL)methods.However,these DL-based denoising methods have been hindered by the highly variable feature distribution of LDCT data from different imaging sources,which adversely affects the performance of current denoising models.In this study,we propose a parallel processing model,the multi-encoder deep feature transformation network(MDFTN),which is designed to enhance the performance of LDCT imaging for multisource data.Unlike traditional network structures,which rely on continual learning to process multitask data,the approach can simultaneously handle LDCT images within a unified framework from various imaging sources.The proposed MDFTN consists of multiple encoders and decoders along with a deep feature transformation module(DFTM).During forward propagation in network training,each encoder extracts diverse features from its respective data source in parallel and the DFTM compresses these features into a shared feature space.Subsequently,each decoder performs an inverse operation for multisource loss estimation.Through collaborative training,the proposed MDFTN leverages the complementary advantages of multisource data distribution to enhance its adaptability and generalization.Numerous experiments were conducted on two public datasets and one local dataset,which demonstrated that the proposed network model can simultaneously process multisource data while effectively suppressing noise and preserving fine structures.The source code is available at https://github.com/123456789ey/MDFTN.

Low-dose computed tomography with 4th-generation iterative reconstruction algorithm in assessment of oncologic patients

AIM To compare radiation dose and image quality of lowdose computed tomography(CT) protocol combined with hybrid-iterative reconstruction algorithm with standarddose CT examinations for follow-up of oncologic patients. METHODS Fifty-one patients with known malignant diseases which underwent, during clinical follow-up, both standarddose and low-dose whole-body CT scans were enrolled. Low-dose CT was performed on 256-row scanner, with 120 kV and automated m A modulation, and iterative reconstruction algorithm. Standard-dose CT was performed on 16-rows scanner, with 120 kV, 200-400 m As(depending on patient weight). We evaluated density values and signal-to-noise ratio, along with image noise(SD), sharpness and diagnostic quality with 4-point scale.RESULTS Density values in liver, spleen and aorta were higher in lowdose images(liver 112.55 HU vs 103.90 HU, P < 0.001), as SD values in liver and spleen(liver 16.81 vs 14.41). Volumetric-Computed-Tomographic-Dose-Index(CTDIvol) and Dose-Length-Product(DLP) were significantly lower in low-dose CT as compared to standard-dose(DLP 1025.6 m Gy*cm vs 1429.2 m Gy*cm, P < 0.001) with overall dose reduction of 28.9%. Qualitative analysis did not reveal significant differences in image noise and diagnostic quality.CONCLUSION Automatic tube-current modulation combined with hybriditerative algorithm allows radiation dose reduction of 28.9% without loss of diagnostic quality, being useful in reducing dose exposure in oncologic patients.

A machine learning-based strategy for predicting the mechanical strength of coral reef limestone using X-ray computed tomography

Different sedimentary zones in coral reefs lead to significant anisotropy in the pore structure of coral reef limestone(CRL),making it difficult to study mechanical behaviors.With X-ray computed tomography(CT),112 CRL samples were utilized for training the support vector machine(SVM)-,random forest(RF)-,and back propagation neural network(BPNN)-based models,respectively.Simultaneously,the machine learning model was embedded into genetic algorithm(GA)for parameter optimization to effectively predict uniaxial compressive strength(UCS)of CRL.Results indicate that the BPNN model with five hidden layers presents the best training effect in the data set of CRL.The SVM-based model shows a tendency to overfitting in the training set and poor generalization ability in the testing set.The RF-based model is suitable for training CRL samples with large data.Analysis of Pearson correlation coefficient matrix and the percentage increment method of performance metrics shows that the dry density,pore structure,and porosity of CRL are strongly correlated to UCS.However,the P-wave velocity is almost uncorrelated to the UCS,which is significantly distinct from the law for homogenous geomaterials.In addition,the pore tensor proposed in this paper can effectively reflect the pore structure of coral framework limestone(CFL)and coral boulder limestone(CBL),realizing the quantitative characterization of the heterogeneity and anisotropy of pore.The pore tensor provides a feasible idea to establish the relationship between pore structure and mechanical behavior of CRL.

Quantitative evaluation of deep convolutional neural network-based image denoising for low-dose computed tomography

To minimize radiation risk,dose reduction is important in the diagnostic and therapeutic applications of computed tomography(CT).However,image noise degrades image quality owing to the reduced X-ray dose and a possible unacceptably reduced diagnostic performance.Deep learning approaches with convolutional neural networks(CNNs)have been proposed for natural image denoising;however,these approaches might introduce image blurring or loss of original gradients.The aim of this study was to compare the dose-dependent properties of a CNN-based denoising method for low-dose CT with those of other noise-reduction methods on unique CT noise-simulation images.To simulate a low-dose CT image,a Poisson noise distribution was introduced to normal-dose images while convoluting the CT unit-specific modulation transfer function.An abdominal CT of 100 images obtained from a public database was adopted,and simulated dose-reduction images were created from the original dose at equal 10-step dose-reduction intervals with a final dose of 1/100.These images were denoised using the denoising network structure of CNN(DnCNN)as the general CNN model and for transfer learning.To evaluate the image quality,image similarities determined by the structural similarity index(SSIM)and peak signal-to-noise ratio(PSNR)were calculated for the denoised images.Significantly better denoising,in terms of SSIM and PSNR,was achieved by the DnCNN than by other image denoising methods,especially at the ultra-low-dose levels used to generate the 10%and 5%dose-equivalent images.Moreover,the developed CNN model can eliminate noise and maintain image sharpness at these dose levels and improve SSIM by approximately 10%from that of the original method.In contrast,under small dose-reduction conditions,this model also led to excessive smoothing of the images.In quantitative evaluations,the CNN denoising method improved the low-dose CT and prevented over-smoothing by tailoring the CNN model.

Hybrid reconstruction algorithm for computed tomography based on diagonal total variation

Inspired by total variation(TV), this paper represents a new iterative algorithm based on diagonal total variation(DTV) to address the computed tomography image reconstruction problem. To improve the quality of a reconstructed image, we used DTV to sparsely represent images when iterative convergence of the reconstructed algorithm with TV-constraint had no effect during the reconstruction process. To investigate our proposed algorithm, the numerical and experimental studies were performed, and rootmean-square error(RMSE) and structure similarity(SSIM)were used to evaluate the reconstructed image quality. The results demonstrated that the proposed method could effectively reduce noise, suppress artifacts, and reconstruct highquality image from incomplete projection data.

Relation between Epicardial Adipose Tissue Thickness Assessed by Multidetector Computed Tomography and Significance of Coronary Artery Disease

Objective: To evaluate the relation between epicardial adipose tissue (EAT) thickness and also pericoronary fat assessed by Multidetector Computed Tomography (MDCT) with both calcium score and significance of coronary artery disease. Background: Epicardial adipose tissue (the visceral fat of the heart present under the visceral layer of the pericardium) has the same origin of abdominal visceral fat, which is known to be strongly related to the development of coronary artery atherosclerosis. Multidetector CT (MDCT) provides an accurate and reproducible quantification of EAT due to its high spatial and temporal resolution. Patients and Methods: The current study included 70 patients with low-intermediate probability of coronary artery disease. All patients were subjected to 256 Multidetectors CT to assess EAT thickness, the mean thickness of the pericoronary fat surrounding the three coronary arteries and coronary calcium score. Also coronary CT angiography was done and patients were then divided into 3 groups according to significance of coronary atherosclerosis: Group 1: No atherosclerosis (20 patients), Group 2: Non obstructive atherosclerosis (luminal narrowing less than 50% in diameter) (25 patients), Group3: Obstructive atherosclerosis (luminal narrowing ≥ 50%) (25 patients). Results: The mean EAT thickness and the mean pericoronary fat thickness were significantly higher in patients with obstructive coronary artery disease (CAD) with stenosis > 50% (group 3) compared to other groups with normal coronaries or non obstructive (CAD). ROC curve was used to define the best cut off value of the thickness of both EAT and pericoronary fat in predicting the obstructive CAD group which was ≥7.2 and 12.6 mm for epicardial and pericoronary fat respectively. Also there is a positive correlation between both epicardial adipose tissue and pericoronary fat thickness and the coronary calcium score. Conclusion: EAT thickness and pericoronary fat thickness can be used in predicting the significance of coronary artery disease.

Acute coronary syndrome on non-electrocardiogram-gated contrastenhanced computed tomography

It is not rare for acute coronary syndrome(ACS)patients to present with symptoms that are atypical,rather than chest pain.It is sometimes difficult to achieve a definitive diagnosis of ACS for such patients who present with atypical symptoms,normal initial biomarkers of myocardial necrosis,and normal or nondiagnostic electrocardiograms(ECGs).Although cardiac CT allows for assessments of coronary artery stenosis as well as myocardial perfusion defect in patients with suspected ACS,it requires ECG gating and is usually performed with high-performance multislice CT for highly probable ACS patients.However,several recent reports have stated that ACS is detectable by myocardial perfusion defects even on routine non-ECG-gated contrast-enhanced CT.A growing number of contrast-enhanced CT scans are now being performed in emergency departments in search of pathologies responsible for a patient’s presenting symptoms.In order to avoid inappropriate management for this life-threatening event,clinicians should be aware that myocardial perfusion defect is more commonly detectable even on routine non-ECG-gated contrast-enhanced CT performed in search of other pathologies.

Comparison of computed tomography and magnetic resonance imaging for the detection of mandibular condylar osteochondroma

Objective The purpose of this study was to compare computed tomography(CT) and magnetic resonance imaging(MRI) for the detection of mandibular condylar osteochondroma.Methods Preoperative CT and MRI of 33 patients with unilateral condylar osteochondroma were reviewed. The morphology, location, continuity with the parent bone, cartilage cap, perichondrium of tumors, and changes in soft and hard tissues adjacent to the lesions were investigated by two reviewers. Data were analyzed using Mc Nemar test. A P value < 0.05 was considered significant.Results Among the 33 condylar osteochondromas, 11 were of the diffuse type, 10 were of the sessile type, and 12 were of the pedunculated type. Continuity with the cortex and marrow of the host condyle was observed on both CT and MRI. Both modalities had identical detection rates of surface reconstruction of the temporal bone joint, condylar dislocation, and pseudarthrosis formation. However, MRI showed significantly higher detection rates of the cartilage cap and perichondrium than CT(P < 0.05). Furthermore, MRI showed ipsilateral and contralateral temporo-mandibular joint(TMJ) disc displacement in 4 cases and 6 cases, respectively, and ipsilateral and contralateral TMJ effusion in 20 cases and 14 cases, respectively.Conclusion CT can intuitively display the morphology and spatial location of condylar osteochondromas through three-dimensional reconstruction. MRI may be superior to CT in the detection of cartilage cap, perichondrium of the condylar osteochondroma, and changes in the TMJ and adjacent soft tissues.

Qualitative visual trichotomous assessment improves the value of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography in predicting the prognosis of diffuse large B-cell lymphoma

Introduction:Fluorine-18 fluorodeoxyglucose(18F-FDG)positron emission tomography/computed tomography(PET/CT)is a powerful tool for monitoring the response of diffuse large B-cell lymphoma(DLBCL)to therapy,but the criteria to interpret PET/CT results remain under debate.We investigated the value of post-treatment PET/CT in predicting the prognosis of DLBCL patients when interpreted according to qualitative visual trichotomous assessment(QVTA)criteria compared with the Deauvil e criteria.Methods:In this retrospective study,final PET/CT scans of DLBCL patients treated with rituximab-based regimens between October 2005 and November 2010 were interpreted using the Deauvil e and QVTA criteria.Survival curves were estimated using Kaplan-Meier analysis and compared using the log-rank test.Results:A total of 253 patients were enrol ed.The interpretation according to the Deauvil e criteria revealed that 181patients had negative PET/CT scan results and 72 had positive results.The 3 year overal survival(OS)rate was significantly higher in patients with negative scan results than in those with positive results(91.6%vs.57.5%,P<0.001).The72 patients with positive scan results according to the Deauville criteria were divided into two groups by the interpretation according to the QVTA criteria:29 had indeterminate results,and 43 had positive results.The 3 year OS rate was significantly higher in patients with indeterminate scan results than in those with positive results(91.2%vs.33.5%,P<0.001)but was similar between patients with negative and indeterminate scan results(91.6%vs.91.2%,P=0.921).Conclusions:Compared with the Deauvil e criteria,using the QVTA criteria for interpreting post-treatment PET/CT scans of DLBCL patients is likely to reduce the number of false positive results.The QVTA criteria are feasible for therapeutic outcome evaluation and can be used to guide risk-adapted therapy.

Assessment of Organ Dose by Direct and Indirect Measurements for a Wide Bore X-Ray Computed Tomography Unit That Used in Radiotherapy

The aim of this study was to investigate the organ doses of patients undergoing computed tomography (CT) examination using the wide bore General Electric (GE) “Light Speed RT” unit. The head, chest and pelvic regions of the Rando-phantom were scanned with 120 kV, 200 mA, and 2.5 mm slice thickness for helical and axial modes. Thermoluminescent Dosimeter (TLD) pairs were used for the dosimetry of 10 organs. TL-counts were converted to dose by using CTDIcenter dose on CT-phantom. For the calculation of the organ doses, the ImPACT software was utilized by entering CTDIair (100 mAs) in small and large field of view (26.43 and 21.17 mGy respectively). The in-field dose ranges in helical and axial modes were 64.3 - 38 mGy and 47.6 - 19.7 mGy in head, 48.3 - 14.1 mGy and 34.1 - 10 mGy in chest, 28.4 - 10.2 mGy and 21 - 8.5 mGy in pelvic, respectively. The organ doses from software and TLD were compared and tailored as the in-field and the out-field radiation. First results showed that the organ dose was relatively higher in the helical mode on both direct and indirect measurement. The in-field organ dose differences between TLD and software were seen. In helical and axial modes, the dose differences ranged from +1 to +13.3 and -8.3 to +9.6 mGy for head exam, +1.1 to +15.3 and +0.3 to +9.1 mGy for chest, and -21.7 to +1.9 and -15.5 to +1.8 mGy for pelvic. The availability of this program for organ dose calculations by measuring CTDIair value for CT device used in the radiotherapy would be considered valuable.

Impact of random and scattered coincidences from outside of field of view on positron emission tomography/computed tomography imaging with different reconstruction protocols

Image quality in positron emission tomography(PET)is affected by random and scattered coincidences and reconstruction protocols.In this study,we investigated the effects of scattered and random coincidences from outside the field of view(FOV)on PET image quality for different reconstruction protocols.Imaging was performed on the Discovery 690 PET/CT scanner,using experimental configurations including the NEMA phantom(a body phantom,with six spheres of different sizes)with a signal background ratio of 4:1.The NEMA phantom(phantom I)was scanned separately in a one-bed position.To simulate the effect of random and scatter coincidences from outside the FOV,six cylindrical phantoms with various diameters were added to the NEMA phantom(phantom II).The 18 emission datasets with mean intervals of 15 min were acquired(3 min/scan).The emission data were reconstructed using different techniques.The image quality parameters were evaluated by both phantoms.Variations in the signal-to-noise ratio(SNR)in a 28-mm(10-mm)sphere of phantom II were 37.9%(86.5%)for ordered-subset expectation maximization(OSEM-only),36.8%(81.5%)for point spread function(PSF),32.7%(80.7%)for time of flight(TOF),and 31.5%(77.8%)for OSEM+PSF+TOF,respectively,indicating that OSEM+PSF+TOF reconstruction had the lowest noise levels and lowest coefficient of variation(COV)values.Random and scatter coincidences from outside the FOV induced lower SNR,lower contrast,and higher COV values,indicating image deterioration and significantly impacting smaller sphere sizes.Amongst reconstruction protocols,OSEM+PSF+TOF and OSEM+PSF showed higher contrast values for sphere sizes of 22,28,and 37 mm and higher contrast recovery coefficient values for smaller sphere sizes of 10 and 13 mm.

Conception the Fluid Flow Behavior within Oil Reservoir Rock by Using Computed Tomography(CT)Scan

The behavior of fluid flow has been studied during the different flow media over the past decades.In addition,the behavior of the flow of fluid through porous media has garnered much research interest.This paper sheds light on fissured rocks of oil reservoir media(as one of the porous media domain),and the effect of these fissured on fluid flow.In this article,the Finite Volume Method(FVM)has been used to visualize the behavior of single-phase fluid flow in an actual core according to the dual-porosity dual permeability model.The study was conducted in two parts,the first was the image processing for one of the real oil reservoir fractured rock images,where the image was processed and simulated by ANSYS-CFX software,and the results showed a complete visualizing of the fluid behavior during this domain.As for the other side,a simulation of a real reservoir rock belonging to the Al-Nour field in Iraq/Misan was made.The X-ray Computed Tomography(CT)scan has been used to convert the real fractured core to a dynamic domain.ANSYS-CFX program has been used and the results illustrated the pressure counter,the velocity counter,the velocity streamline,and the velocity vectors for the studied model in three dimensions.A comparison was made between the productivity index for fractured and non-fractured rock and the results explained that the presence of fracture can improve the productivity index to about 5.74%.

Ultrasonic Computed Tomography Imaging Method of Concrete Materials Based on Simulated Annealing Genetic Algorithm

Stability and accuracy of the imaging results are still unmet practical demands for ultrasonic computed tomography(CT)of concrete material.To address these issues,a CT technique based on simulated annealing genetic algorithm(SAGA)is presented in this work.Firstly,a natural weight matrix with clear physical meaning is introduced in the inverse algorithm and then a quadric broadening objective function is formed according to the propagation characteristics of ultrasound in concrete.After that,the simulated annealing(SA)searching is added to speed up the inverse process and to improve the convergence and stability of the algorithm.Finally,the optimal inverse imaging results have been achieved by variable ectopic adaptive genetic algorithm.The numerical simulation experiments have shown that the usage of the correct priori information and the excellent characteristic of SAGA in searching the global minimum value of the function have produced accurate and effective results with stable numerical values.The imaging resolution is improved and the imagining results reflecting the inner defections of the tested objects are more reliable and accurate.

Numerical analysis of the failure process of soil-rock mixtures through computed tomography and PFC3D models

Soil-rock mixture （SRM） is a unique type of geomaterial characterized by a heterogeneous composition and a complicated structure. It is intractable for the continuum-based soil and rock mechanics theories to accurately characterize and predict the SRM＇s mechanical properties. This study reports a novel numerical method incorporating microfocus computed tomography and PFC3D codes to probe the deformation and failure processes of SRM. The three-dimensional （3D） PFC models that represent the SRM＇s complex structures were built. By simulating the entire failure process in PFC3D, the SRM＇s strength, elastic modulus and crack growth were obtained. The influence of rock ratios on the SRM＇s strength, deformation and failure processes, as well as its internal mesoscale mechanism, were analyzed. By comparing simulation results with experimental data, it was verified that the 3D PFC models were in good agreement with SRM＇s real structure and the SRM＇s compression process, deformation and failure patterns; its intrinsic mesomechanism can be effectively analyzed based on such 3D PFC models.

双能量CT新虚拟单能量成像技术在头颈部动脉支架评估中的应用价值

目的:探讨基于双能量CT的新虚拟单能量成像(VMI+)技术应用于头颈部动脉支架成像的图像质量及最佳单能级水平。方法:对21例头颈部动脉支架植入术后复查的患者行双能量CT头颈部血管成像,经后处理获得M_0.6融合图像(M_0.6图像)和40~150 keV(10 keV间隔)VMI+图像。计算正常血管管腔及支架内管腔的信噪比(SNR)和对比噪声比(CNR),并采用5分法对图像质量进行主观评分。测量支架直径,计算支架内、外管腔的CT值差值△CT(内-外)以及支架直径低估率。结果:21例患者共植入23枚支架。80 keV VMI+图像支架血管段的SNR、CNR与M_0.6图像比较,差异无统计学意义(P>0.05)。80 keV时VMI+图像的支架直径测量值增大趋势开始减缓。与其他单能级图像相比,80 keV和90 keV图像的△CT_((内-外))绝对值较小。与M_0.6图像相比,80 keV图像的主观评分明显提高,差异有统计学意义(分别为4.93±0.23和4.61±0.37,P<0.05)。结论:80 keV VMI+可以提高头颈部动脉支架的图像质量,减少支架产生的射线束硬化伪影,推荐其作为头颈部动脉支架成像的最佳单能级水平。

18F-FCH PET/CT在原发与继发性甲状旁腺功能亢进中的对比研究

目的:对比18F-FCH PET/CT在原发性甲状旁腺功能亢进(PHPT)与继发性甲状旁腺功能亢进(SHPT)中的应用价值,并比较18F-FCH PET/CT影像参数在两者间的差异。方法:回顾性搜集行18F-FCH PET/CT显像的甲状旁腺亢进症患者50例(PHPT 28例,SHPT 22例)。通过t检验或非参数检验、Spearman相关性分析比较其临床生化指标、18F-FCH PET/CT显像参数及其诊断效能等方面的差异,比较18F-FCH PET/CT相关参数在PHPT与SHPT间的差异,同时探讨临床生化指标与PET参数间的相关性。结果:血钙、血磷、甲状旁腺激素、降钙素、MTV总和、TLFM总和在PHPT与SHPT两组间差异有统计学意义(P均<0.05),而SUV_(max)差异无统计学意义(P=0.072)。18F-FCH PET/CT检测PHPT更具优势,其诊断敏感度(分别为96.8%和74.6%)和阳性预测值(分别为96.8%和89.8%)均高于SHPT。血磷水平、SUV_(mean)总和鉴别诊断PHPT与SPHT的效能优于其他指标,其截断值分别为1.175(AUC=0.918)、3.4(AUC=0.8417)。PTH与SUV_(max)、MTV总和、TLFM总和等PET参数存在正相关性,其余临床指标与PET参数无明显相关性。结论:部分18F-FCH PET/CT影像参数及临床生化指标在PHPT与SHPT间差异有统计学意义,且PET/CT影像参数对PHPT的检测效能明显高于SHPT。在甲状旁腺功能亢进患者中,甲状旁腺激素与SUV_(max)、MTV总和、TLFM总和具有正相关性。

Imaging Findings in Chest Computed Tomography: Initial Experience in a Developing Country

Background:?High resolution chest computed tomography (HRCT) is an established imaging modality that accurately assesses disease processes that are non-specific on conventional chest radiography. Chest Computed Tomography (CT) has proven invaluable in the evaluation of various diseases of the chest providing precise diagnosis that have great impact on the course of management. In this study, our aim is to evaluate the spectrum of radiological findings in all patients that had chest CTs at a tertiary health Institution in a developing Country. Method: This is a 6-year retrospective study of all patients that had Chest CT from 2009 till 2015. All patient data were retrieved and their Chest CT images reviewed and radiological findings and diagnosis documented. Results: Age range of patients was 1 - 84 years with a mean of 52.36 ± 22.9 years. Ten patients were children (12%). There were more males 53 (63.1%) than females 31 (36.9%) in the study. Referral for imaging was predominantly from internal medicine 33 (47.1%) and Surgery 27 (38.6%) departments. Most of the patients, 53 (63.1%) did not have previous chest radiographs. Consolidative changes were the most common parenchymal finding (77.4%). Few mediastinal masses were found in the study population. CT angiography constituted only 10.7% of all chest CTs done in adults. Conclusion: Few chest CT evaluations are performed compared to CTs of other parts of the body done in the same period. Chest CT is generally under-utilized even in a tertiary institution. There is a need to educate chest physicians on the role and advantages of CT use for the management of their patients.

深度渐进重建算法对肥胖患者^(18)F-脱氧葡萄糖PET/CT图像质量和标准化摄取值的影响

目的:探讨深度渐进式重建(DPR)算法对肥胖患者氟-18脱氧葡萄糖正电子发射计算机断层扫描(^(18)F-FDG PET)图像质量和标准化摄取值(SUV)的提升作用。方法:回顾性收集2023年9月至2024年5月在南京医科大学附属南京医院行^(18)F-FDG PET/CT检查的27例肥胖患者图像,所有患者均采用uMI 780型PET/CT采集图像。采用有序子集最大期望值(OSEM)迭代算法和DPR算法进行PET图像重建,测量PET/CT图像散射符合计数率、真符合计数率、噪声等效计数率(NECR)和散射分数(SF)。评价肝脏^(18)F-FDG PET/CT图像信噪比(SNR),病灶最大SUV(SUVmax)、背景比(TBR)、对比度(CNR)和视觉评分的PET图像质量指标。分析DPR与OSEM两种重建算法各评价指标的差异性及一致性。结果:27例患者平均^(18)F-FDG注射活度为(0.12±0.01)mCi(1 mCi=37 MBq)/kg,PET图像真符合计数率、NECR和SF分别为(153.73±25.09)、(44.81±8.47)kcps和(36.77±1.91)%。DPR算法所得肝脏SNR为15.83±3.60,显著高于OSEM算法9.06±1.87,差异有统计学意义(t=20.6,P<0.05),且两种算法所得的肝脏SNR存在显著相关性(R2=0.91,P<0.0001)。在27个摄取^(18)F-FDG病灶中,OSEM算法所得病灶SUV_(max)、TBR和CNR分别为(5.86±1.49)、(1.95±0.49)和(17.74±4.77),均低于DPR算法的相应值,差异有统计学意义(t=9.03、8.79、15.49,P<0.05),且两种算法所得的病灶SUV_(max)、TBR和CNR存在显著相关性(R2=0.71、0.70、0.76,P<0.05)。DPR算法所得PET图像视觉评分为4(3,5)分,显著高于OSEM算法[3(2,4)]分,差异有统计学意义(U=396,P<0.05)。结论:肥胖患者^(18)F-FDG PET/CT显像散射效应较强,噪声等效计数率较低。DPR重建算法较OSEM算法能显著提高PET图像信噪比和病灶对比度,对病灶SUVmax有显著增益作用,能显著提升肥胖患者^(18)F-FDG PET/CT图像质量。

基于迭代重建算法的IDream重建技术对低剂量上腹部CT图像质量及肝囊肿显示的影响

目的:通过对迭代重建算法的IDream重建技术中不同重建等级肝囊肿CT图像显示的主观评估和上腹部图像质量的客观评价,探讨IDream重建技术降低图像噪声、优化图像质量及显示肝囊肿的最佳重建等级。方法:回顾性收集2021年8月至9月在北京协和医院就诊的53例肝囊肿患者上腹CT平扫影像资料,所有患者图像均行滤波反射投影(FBP)、IDream重建1、2、3、4和5级6种方法重建标准窗图像,共获得FBP组、IDream 1~5级组的6组图像。分别测量并记录每组图像肝脏、腹主动脉、竖脊肌、脂肪、脾脏的CT值及标准差(SD)值,计算图像的信噪比(SNR)、对比噪声比(CNR)。由两名8年以上工作经验的CT诊断医师对各组图像肝囊肿的显示进行主观评分。对比不同等级重建图像的客观参数及肝囊肿主观评分。采用单因素方差分析图像的客观参数,肝囊肿显示主观评分行Kruskal-Wallis H检验。结果:6组图像不同重建等级肝脏、腹主动脉、脂肪、竖脊肌、脾脏的CT值差异均无统计学意义(P>0.05)。在FBP组和IDream 1~5级6组图像中,随着重建等级增加,图像SD值逐渐降低,分别为(18.11±5.03)、(15.37±4.97)、(13.26±4.83)、(11.68±4.56)、(10.99±4.36)和(10.60±4.21)Hu。肝脏SNR、CNR随重建等级升高逐渐升高,6组图像SD值、SNR和CNR比较,差异均有统计学意义(F=20.75、17.72、3.15,P<0.05)。FBP组和IDream1~4级组图像肝囊肿主观评分分别为(3.12±0.35)、(3.63±0.46)、(4.02±0.42)、(4.61±0.48)和(4.63±0.48)分,逐渐升高,而IDream5级组图像评分略有降低,为(4.53±0.47)分,IDream 3级组和IDream 4级组图像评分最高。6组重建等级肝囊肿图像的平均主观评分比较,差异有统计学意义(H=192.17,P<0.05);结论:在上腹部CT平扫中,随着IDream重建等级的增加,图像噪声逐渐降低,图像客观参数逐渐提升;IDream3级和4级重建可得到肝囊肿客观评分最优的上腹部图像质量。

增强CT联合MRI检查对肾透明细胞癌的预后预测价值分析及与临床特征的相关性

目的:探讨增强CT联合MRI检查对肾透明细胞癌的预后预测价值及与临床特征的相关性。方法:回顾性选取2019年3月至2023年5月亳州市人民医院收治的80例疑似肾透明细胞癌(ccRCC)患者的增强CT和MRI术后随访资料,依据疾病进展情况将其分为病情进展组(24例)和无进展组(56例)。通过病史采集和体检、增强CT、MRI、实验室检查、病理检查等相关检查诊断病情进展,根据患者临床和影像图像信息将年龄、性别、肿瘤直径、有无癌栓、肿瘤位置以及手术方式进行单因素logistic回归分析,确定独立预测因子。采用受试者工作特征(ROC)曲线分析增强CT联合MRI检查对ccRCC的预后预测价值。采用Pearson线性相关性分析增强CT联合MRI检查结果与预后的相关性。结果:根据随访结果,病情进展组患者皮质期CT值、髓质期CT值及表观弥散系数(ADC)均明显小于无进展组,差异有统计学意义(t=10.610、4.697、2.901,P<0.05),弥散系数(K)明显大于无进展组,差异有统计学意义(t=6.375,P<0.05),两组扩散率(D)比较差异无统计学意义(P>0.05);增强CT、MRI单独检查及联合检查预测ccRCC预后的ROC曲线下面积(AUC)均>0.5,提示两种检查对预测ccRCC预后均具有一定的价值,且联合检查的AUC最高,为0.940,提示联合检查对预测ccRCC预后的价值最高;两组性别、手术方式、癌栓及肿瘤位置例数比较差异均无统计学意义(P>0.05),病情进展组年龄、肿瘤直径均明显大于无进展组,差异有统计学意义(t=4.292、3.219,P<0.05);logistic回归分析显示,患者年龄、肿瘤直径均是ccRCC预后的独立影响因素(HR=2.167、0.689,P<0.05);Pearson相关性分析结果显示,增强CT检查与预后均存在负相关性(r=-0.65,P<0.05),MRI检查与预后均存在正相关性(r=0.72,P<0.05),增强CT检查结果与MRI检查结果之间均存在负相关性(r=-0.58,P<0.05)。结论:增强CT联合MRI检查对肾透明细胞癌的预后预测高于单项检查,且与临床特征存在一定的相关性,但临床还需结合其他影响因素进行综合判断。