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.

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.

Assessment of sub-milli-sievert abdominal computed tomography with iterative reconstruction techniques of different vendors

AIM: To assess diagnostic image quality of reduced dose(RD) abdominal computed tomography(CT) with 9 iterative reconstruction techniques(IRTs) from 4 different vendors to the standard of care(SD) CT.METHODS: In an Institutional Review Board approved study, 66 patients(mean age 60 ± 13 years, 44 men, and 22 women) undergoing routine abdomen CT on multi-detector CT(MDCT) scanners from vendors A, B, and C(≥ 64 row CT scanners)(22 patients each) gave written informed consent for acquisition of an additional RD CT series. Sinogram data of RD CT was reconstructed with two vendor-specific and a vendor-neutral IRTs(A-1, A-2, A-3; B-1, B-2, B-3; and C-1, C-2, C-3) and SD CT series with filtered back projection. Subjective image evaluation was performed by two radiologists for each SD and RD CT series blinded and independently. All RD CT series(198) were assessed first followed by SD CT series(66). Objective image noise was measured for SD and RD CT series. Data were analyzed by Wilcoxon signed rank, kappa, and analysis of variance tests.RESULTS: There were 13/50, 18/57 and 9/40 missed lesions(size 2-7 mm) on RD CT for vendor A, B, and C, respectively. Missed lesions includes liver cysts, kidney cysts and stone, gall stone, fatty liver, and pancreatitis. There were also 5, 4, and 4 pseudo lesions(size 2-3 mm) on RD CT for vendor A, B, and C, respectively. Lesions conspicuity was sufficient for clinical diagnostic performance for 6/24(RD-A-1), 10/24(RD-A-2), and 7/24(RD-A-3) lesions for vendor A; 5/26(RD-B-1), 6/26(RD-B-2), and 7/26(RD-B-3) lesions for vendor B; and 4/20(RD-C-1) 6/20(RD-C-2), and 10/20(RD-C-3) lesions for vendor C(P = 0.9). Mean objective image noise in liver was significantly lower for RD A-1 compared to both RD A-2 and RD A-3 images(P < 0.001). Similarly, mean objective image noise lower for RD B-2(compared to RD B-1, RD B-3) and RD C-3(compared to RD C-1 and C-2)(P = 0.016).CONCLUSION: Regardless of IRTs and MDCT vendors, abdominal CT acquired at mean CT dose index volume 1.3 m Gy is not sufficient to retain clinical diagnostic performance.

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.

Effects of Saline Administration, Abdominal Compression, and Prolongation of Acquisition Delay on Image Quality Improvement of CT Urography

Objective To retrospectively evaluate the effects of saline administration following contrast material injection, abdominal compression and two delay phase acquisition on image quality improvement of computed tomographic urography (CTU). Methods Medical records and informed consents of patients were obtained. In totally 122 patients (50 men, 72 women), two delay phase images with CTU were performed. Scans began simultaneously with a contrast bolus injection of 100 mL (300 mgI/mL) followed by a saline bolus injection of 100 mL at a rate of 5 mL/s. Two delay phase images were taken at 400 and 550 seconds for each patient. Examinations were taken by using abdominal compression or not. The distention and opacification of the urinary tract were evaluated by two interpreters together on transverse images and post-processing images. Effects of four techniques (saline administration and abdominal compression, saline administration only, compression only, and neither saline administration nor compression) and two delay phase acquisition on image quality improvement were analysed by using ANOVA and Chi-square test. Results Saline administration improved opacification (P<0.05) and increased overall image quality (P<0.01) of the intrarenal collecting system and proximal ureter. Abdominal compression (P<0.05) and delayed phase image acquisition of 550 seconds (P<0.01) all improved distention of the intrarenal collecting system and proximal ureter but did not improve opacification. No statistically significant effects on the distal ureter were found. However, there were more visualized distal ureteral segments with the longer imaging delay. Conclusion Saline administration, abdominal compression and longer imaging delays are all effective in improving image quality of 64-detector row CTU.

Application of Dual-Energy CT Non-Linear Fusion Technology in Improving CTA Image Quality of Renal Cancer

Objective: To explore the significance of dual-energy CT non-linear fusion technique in improving the quality of CTA image of renal cancer. Methods: The CTA images of 100 patients who had been confirmed by pathology as renal cancer were collected and were randomly divided into experimental group and control group with 50 cases respectively. The two groups of patients were treated with iodine concentration of 300 mg/ml and 350 mg/ml non-ionic contrast agent, with a dosage of 1.5 ml/kg and an injection rate of 4 ml/s. The contrast agent intelligently tracking method was adopted bolus. The control group used the conventional CTA scanning, with a reference tube voltage/tube current of 100 kv/ref150 mas. The experimental group adopted the double energy scanning, with ball tube A and ball tube B. The reference tube voltage/tube current was 100 kv/ref250 mas and sn150 kv/ref125 mas respectively. The images of the experimental group were non-linear fused to obtain the Mono+ 55 kev single-energy images. The CT value, SNR contrast ratio of the abdominal aorta, renal artery and tumor tissue of the experimental group images and the 100 KV images and the Mono+ 55 kev images of the control group were compared. The objective evaluation and subjective evaluation of the image quality of the three groups of images was performed. Results: The results showed that the 100 kV images of the experimental group were statistically different from those of the control group (P05) in CT value, SNR and CNR (P 0.05). And there was no statistically significant difference between the non-linear fusion single-energy Mono+ 55 kev images and the control group images in CT value, SNR and CNR (P > 0.05). The subjective evaluation of image quality showed that there was no significant difference between Mono+ 55 kev images and control group images, and the quality of Mono+ 55 kev images was higher than that of experimental group 100 kV images. Conclusion: The dual-energy CT non-linear fusion technique can improve the quality of CTA image in patients with renal cancer, and it is possible to obtain high quality CTA images with low iodine concentration contrast agent.

Intelligent detection method for workpiece defect based on industrial CT image

In order to solve the problem of internal defect detection in industry, an intelligent detection method for workpiece defect based on industrial computed tomography (CT) images is proposed. The industrial CT slice image is preprocessed first with the combination of adaptive median filtering and adaptive weighted average filtering by analyzing the characteristics of the industrial CT slice images. Then an image segmentation algorithm based on gray change rate is used to segment low contrast information in industrial CT images, and the feature of workpiece defect is extracted by using Hu invariant moment. On this basis, the radial basis function (RBF) neural network model is established and the firefly algorithm is used for optimization, and the intelligent identification of the internal defects of the workpiece is completed. Simulation results show that this method can effectively improve the accuracy of defect identification and provide a theoretical basis for the detection of internal defects in industry.

Significance of an Advanced Image-Based Virtual Monoenergetic Reconstruction of Dual Source Dual-Energy CT Data at Low keV Increases Image Quality for Portal Vein System of Pancreatic Cancer Patients

Purpose: To explore the significance of dual-source computed tomography (DECT) virtual monoenergetic reconstructions technology in improving image quality for portal vein system of pancreatic cancer patients. Materials and methods: 47 patients with clinically suspected pancreatic cancer (all confirmed by pathology) were collected. Routine plain scan was performed with Siemens Force dual-source dual-energy CT followed by 3 scans respectively carried out in arterial phase, portal phase and delayed phase. Traditional virtual monoenergetic reconstructions (Mono_E) and new generation of virtual monoenergetic reconstructions (Mono+) were respectively performed on portal vein images to obtain virtual single energy images including Mono_ E70 keV, Mono_E 55 keV and Mono+ 70 keV and Mono+ 55 keV. The signal-to-noise ratio (SNR) and noise of portal vein, normal pancreatic tissues and pancreatic lesions of 100 kV, Mono_E and Mono+ images were compared. In addition, the contrast noise ratio of portal vein and lesions as well as pancreatic tissues and lesions (CNR PV, CNRtumor) were also compared. At the same time, two imaging physicians with rich clinical experiences read the films and scored the images of each group by using the 5-point scoring method. Results: Mono+ 55 keV images including SNRpv, SNRpanc, SNRtumor, Noise, CNRpv, CNRtumor were statistically different from 100 KV images and Mono_E images (P < 0.05). As for the subjective score, Mono+ 55 keV image score also had the highest score, which had statistical significance (P < 0.05). The results showed that Mono+ 55 keV images had the best quality. Conclusion: The new generation of virtual Mono+ post-treatment can reduce image noise. Low energy Mono+ images can improve the contrast between pancreatic cancer lesions and portal of pancreatic cancer patients.

Compressed sensing and Otsu's method based binary CT image reconstruction technique in non-destructive detection

This paper tries to address the problem of binary CT image reconstruction in non-destructive detection with an algorithm based on compressed sensing(CS) and Otsu's method, which could reconstruct binary CT image of test object from incomplete detection data. According to binary CT image characteristics, we employ Splitbregman method based on L1/2regularization to solve piecewise constant region reconstruction. To improve the reconstructed image quality from incomplete detection data, we utilize a priori knowledge and Otsu's method as the optimization constraint. In our study, we make numerical simulation to investigate our proposed method,and compare reconstructed results from different reconstruction methods. Finally, the experimental results demonstrate that the proposed method could effectively reduce noise and suppress artifacts, and reconstruct high-quality binary image from incomplete detection data.

Visualization of Three-dimensional Human Data Based on CT Image

Three-dimensional medical image visualization becomes an essential part for medical field, including computer aided diagnosis, surgery planning and simulation, artificial limb surgery, radiotherapy planning, and teaching etc. In this paper, marching cubes algorithm is adopted to reconstruct the 3-D images for the CT image sequence in DICOM format under theVC＋＋6.0 and the visual package VTK platform. The relatively simple interactive operations such as rotation and transfer can be realized on the platform. Moreover, the normal vector and interior point are calculated to form the virtual clipping plane, which is then used to incise the 3-D object. Information of the virtual slice can be obtained, in the mean while the virtual slice images are displayed on the screen. The technique can realize the real time interaction extraction of virtual slice on 3-D CT image. The cuboids structured can be zoomed, moved and eircumrotated by operating mouse to incise the 3-D reconstruction object. Real time interaction can be realized by clipping the reconstruction object. The coordinates can be acquired by the mouse clicking in the 3D space, to realize the point mouse pick-up as well angle and distance interactive measurement. We can get quantitative information about 3-D images through measurement.

基于改进残差和注意力的CT肺癌辅助诊断

为了提高结节检测和肺癌诊断的性能,本文提出一种改进的卷积神经网络(CNN)模型用于这2个步骤的结节特征提取。该模型以一种改进U-Net网络作为基础网络,并引入了ResNeXt模块和注意力机制,在保持模型复杂度的同时,提高网络学习多种形状和大小的结节特征的能力。实验结果表明:该模型在DSB数据集上表现良好,结节检测的灵敏度和特异性分别达到了99.15%和99.99%,肺癌诊断的准确率和AUC值分别达到了80.43%和0.86。可见,本文方法对于多种多样的结节特征具有高度敏感性,具有一定的临床价值。

脊椎骨内神经鞘瘤的CT、MRI表现(附11例报道及文献复习)

目的探讨脊椎骨内神经鞘瘤(Intraosseous Schwannoma,IOS)的特征性影像学表现,以与其他脊椎溶骨性病变区别开。方法回顾性分析上海交通大学医学院附属第九人民医院经手术病理证实的脊椎IOS的临床资料及CT、MRI等影像学资料。该文收集了11例脊椎IOS患者,其中男性7例,女性4例,年龄23~74岁[平均年龄(51±17)岁]。所有患者均行CT和MRI检查。由两名高年资骨关节系统放射科医师对所有影像学征象进行评估,并复习了近几年来文献报告的脊椎IOS影像学征象。结果病变累及部位包括颈椎3例(3/11,27.3%),胸椎1例(1/11,9.1%),腰椎5例(5/11,45.5%),腰骶椎2例(2/11,18.2%),最大径(5.8±2.85)cm,形态均为不规则形。CT显示偏心性膨胀性溶骨性骨质破坏,密度不均匀,平扫CT值为(43.0±11.55)HU。增强后不均匀轻度强化,CT值为(70.3±12.22)HU,病灶边界清晰,有硬化缘,未见骨膜反应,病灶易沿着椎间孔向椎管内外延伸。在MRI上,与肌肉组织相比,病灶在T1WI上呈等稍低信号,在T2WI上呈混杂稍高信号,压脂后呈混杂高信号,DWI未见弥散受限,ADC值为(1.25±0.176)×10-3mm2/s,增强后不均匀明显强化,时间-信号强度曲线为I型,7例患者病灶内发生囊性变。结论脊椎IOS是一种罕见的良性肿瘤,影像学表现具有一定的特征性,在鉴别诊断边界清晰的具有异质性的脊椎溶骨性病变时应予以考虑。

基于不同管电压的人工智能重建算法对胸部体模CT扫描图像质量和辐射剂量的影响研究

目的:基于成年男性仿真胸部体模(PH-N1)CT扫描,探究不同管电压结合人工智能(AI)重建(CI)算法对胸部体模CT扫描图像质量和辐射剂量的影响。方法:采用512层超高端CT分为4种管电压对体模进行扫描,分别为70 kV、80 kV、100 kV和120 kV,对不同管电压的CT扫描图像采用10%、30%、50%、70%和90%CI算法重建1 mm薄层图像,比较4组扫描的容积剂量指数(CTDIvol)和剂量-长度乘积(DLP)。测量图像主动脉、腹壁脂肪及竖棘肌的CT值、标准偏差(SD)值,由两名5年以上工作经验的高年资诊断医师独立双盲的对图像质量进行5分制评估,并行Kappa一致性检验。采用单因素方差分析比较图像目标组织的CT值、SD值差异。采用Friedman秩和检验比较组间主观图像质量的差异。结果:4种不同管电压的CTDIvol和DLP比较,差异有统计学意义(F=1855.617、3996.118,P<0.05)。在70 kV管电压下,10%、30%、50%、70%和90%CI算法重建的主动脉、腹壁脂肪及竖棘肌的CT值比较,差异均无统计学意义(P>0.05),而SD值差异均有统计学意义(F=32.267、53.327、14.873,P<0.05)。在90%权重的CI算法重建4种不同管电压下,主动脉、腹壁脂肪及竖棘肌的CT值随着管电压的降低,CT值逐渐降低,差异有统计学意义(F=139.899、2563.93、219.231,P<0.05)。两名诊断医师对各组图像的主观评分一致性较好(Kappa=0.712~0.869)。结论:CI算法在70 kV管电压下90%权重的CI算法重建图像与80 kV、90 kV、120 kV图像相比,可以明显降低辐射剂量,同时图像具有良好信噪比。

心脏双源CT与心脏磁共振成像计算细胞外容积用于评价慢性心力衰竭患者心肌弥漫性纤维化的对比研究

目的:探究心脏双源CT(DSCT)与心脏磁共振成像(MRI)计算细胞外容积(ECV),评价慢性心力衰竭(CHF)患者心肌纤维化(MF)的可行性和准确性。方法:选取2019年1月至2021年6月新疆维吾尔自治区人民医院收治的67例CHF患者,分别行DSCT和MRI扫描,计算ECV,比较两种方法对MF的诊断效能。结果:DSCT-ECV的分配系数(λ)为0.56±0.27,ECV为(33.04±10.68)%;而MRI-ECV的分配系数(λ)为0.51±0.32,ECV为(29.49±11.14)%。DSCT-ECV与MRI-ECV相比差异无统计学意义(P>0.05),DSCT-ECV与MRI-ECV诊断CHF患者MF均有较高的灵敏度、特异度和准确率(DSCT-ECV:100%、92.86%和98.51%,MRI-ECV:98.11%、100%和98.51%),两种方式的诊断可靠性比较差异均无统计学意义(P>0.05)。结论:ECV是心力衰竭的可量化技术,且预测心肌弥漫性纤维化能力强,DSCT-ECV和MRI-ECV评价CHF患者的MF准确性高,可用于相关疾病分级、进展监测和治疗指导,而DSCT-ECV较MRI-ECV应用更方便。

Fused monochromatic imaging acquired by single source dual energy CT in hepatocellular carcinoma during arterial phase: an initial experience

Objective： To explore whether single and fused monochromatic images can improve liver tumor detection and delineation by single source dual energy CT （ssDECT） in patients with hepatocellular carcinoma （HCC） during arterial phase. Methods： Fifty-seven patients with HCC who underwent ssDECT scanning at Beijing Cancer Hospital were enrolled retrospectively. Twenty-one sets of monochromatic images from 40 to 140 keV were reconstructed at 5 keV intervals in arterial phase. The optimal contrast-noise ratio （CNR） monochromatic images of the liver tumor and the lowest-noise monochromatic images were selected for image fusion. We evaluated the image quality of the optimal-CNR monochromatic images, the lowest-noise monochromatic images and the fused monochromatic images, respectively. The evaluation indicators included the spatial resolution of the anatomical structure, the noise level, the contrast and CNR of the tumor. Results： In arterial phase, the anatomical structure of the liver can be displayed most clearly in the 65-keV monochromatic images, with the lowest image noise. The optimal-CNR monochromatic images of HCC tumor were 50-keV monochromatic images in which the internal structural features of the liver tumors were displayed most clearly and meticulously. For tumor detection, the fused monochromatic images and the 50-keV monochromatic images had similar performances, and were more sensitive than 65-keV monochromatic images. Conclusions： We achieved good arterial phase images by fusing the optimal-CNR monochromatic images of the HCC tumor and the lowest-noise monochromatic images. The fused images displayed liver tumors and anatomical structures more clearly, which is potentially helpful for identifying more and smaller HCC tumors.

Clinical value of CT three-dimensional imaging in diagnosing gastrointestinal tract diseases

AIM： To discuss the clinical value of CT three-dimensional （3-D） imaging in diagnosing gastrointestinal tract diseases.METHODS： Three-D imaging findings of 52 patients were retrospectively analyzed. Three-D imaging methods included shaded surface display （SSD）, volume rendering （VR）, virtual endoscopy （VE） and multiplanar reformatting （MPR）. The diagnosis results of CT 3-D were evaluated by comparison with those of endoscopy and/or surgical finding.RESULTS： Fifty-two patients with gastrointestinal tract diseases were diagnosed by CT 3-D imaging, of whom 50 cases were correctly diagnosed and 2 were misdiagnosed. There were 33 cases of gastric diseases （27 with carcinoma, 5 with peptic ulcer and 1 with leiomyoma） and 19 large intestinal diseases （10 with colon carcinoma, 2 with carcinoma of the rectum, 5 with colon polypus and 2 with tuberculosis of the ileocecal junction）. Twenty-two cases with prominent lesions （9 with subsequent hollow lesions）, 20 with stenosis of cavity （8 with concomitant prominent lesions） and 10 with hollow lesions （5 with concomitant prominent lesions） were shown in 3-D images. The minimal lesion shown was 1.0 cm × 0.8 cm × 0.5 cm.CONCLUSION： CT 3-D imaging, a non-invasive examination without pain, can display clearly and directly the lesions of gastrointestinal tract with accurate location and high diagnosis accuracy. It is an important complementary technique to endoscopy.

Imaging characteristics of a rare case of monostotic fibrous dysplasia of the sacrum:A case report

BACKGROUND Fibrous dysplasia(FD)is a common benign intramedullary fibro-osseous lesion.Involvement of the spine is rare,with the literature including only case reports,and cases of monostotic FD(MFD)in the sacrum are extremely rare.A correct preoperative diagnosis of spinal MFD is important for clinicians to select proper treatment.CASE SUMMARY We retrospectively assessed a case report of MFD in the sacrum.This patient was examined by computed tomography(CT)and magnetic resonance imaging(MRI),and the diagnosis was confirmed by pathology.A review of the literature was performed to analyze the imaging characteristics and differential diagnoses of spinal MFD.For our patient,the CT scan showed the lesion to be expansile,with ground glass opacity and a sclerotic rim.On MRI,the lesion showed iso-low signal intensity on T1WI and iso-high signal intensity on T2WI.A low signal rim was found on T1WI and T2WI.Our patient was treated by posterior focal excision,decompression,bone grafting,fusion and pedicle screw fixation.A satisfactory result was achieved,with pain disappearance.No complications had occurred at the 1-year follow up.CONCLUSION MFD is an expansile osteolytic change.Ground glass opacity and a sclerotic margin are obvious characteristics.The lesion often involves the vertebral body and posterior element.Knowledge of these imaging characteristics of spinal FD could be helpful for diagnosis and prevent unnecessary procedures.

子宫肉瘤的CT及MRI影像学表现

目的 分析并总结子宫肉瘤的CT及MRI影像表现。方法 回顾性分析15例经病理及手术证实为子宫肉瘤患者的临床特征、CT及MRI表现,总结并探讨其特征性影像学表现。结果 15例子宫肉瘤患者中包括子宫平滑肌肉瘤患者8例,其中4例病灶局限于宫腔内,4例表现为盆腔巨大包块,8例病灶均呈囊实性包块;未分化子宫肉瘤1例,呈类圆形短T_(1)、长T_(2)信号,边界清,DWI呈边缘环形高信号;子宫腺肉瘤2例,表现结节状、团块状混杂密度病灶,增强扫描呈明显不均匀强化;低级别子宫内膜间质肉瘤3例,均呈T_(1)WI等或低信号、T_(2)WI高或稍高信号且DWI呈明显高信号;高级别子宫内膜间质肉瘤1例,表现为盆腔内巨大囊实性占位,病理证实病灶侵穿浆膜累及局部肠壁浆膜下组织。结论 子宫肉瘤常表现为盆腔内囊实性包块,体积较大,形态不规则,可侵犯邻近结构或发生远处转移。MRI表现较具有特征性,常表现为等或稍长T_(1)WI、混杂长T_(2)WI信号,DWI呈高或略高信号,增强扫描肿块呈明显不均匀强化。

各种能谱CT的性能及应用差异研究

能谱CT以其独特的能谱分析工具为临床疾病的影像学检查提供了更为丰富的信息。基于各种能谱CT的原理和性能存在差异,本文对各种能谱CT的辐射剂量、图像质量及两者之间的关系,及其在临床应用的差异,如碘基图定量分析、去金属及硬化伪影、物质成分的分离与鉴别、微细结构的显示和虚拟平扫等进行综述,以期为临床影像工作者针对不同的临床需求选择能谱CT提供参考,以求临床效益最大化。

面向急性缺血性脑卒中的CT生成MRI算法

急性缺血性脑卒中病灶在计算机断层扫描(CT)上表现不明显,但在核磁共振成像(MRI)上可以清晰显示。然而,当患者体内有金属植入物等特殊情况则无法进行MRI检测,使得患者的治疗受到延误。通过CT生成MRI可在急性缺血性脑卒中的诊断和治疗中起到至关重要的作用,但现有的医学影像跨模态生成方法从CT得到的MRI缺乏病灶信息且边界模糊。为了解决上述问题,提出一种基于影像组学和扩散生成对抗网络的急性缺血性脑卒中CT生成MRI算法,通过影像组学在CT上进行病灶特征增强,突出生成MRI的病灶信息,引入梯度损失为生成图像与真实图像增加边缘感知约束,提升生成MRI的质量。在ISLES2018挑战赛数据集上的实验结果表明,该算法生成的MRI在整体上的峰值信噪比为23.051 dB,结构相似度为0.798,皮尔逊相关系数为0.969,并且病灶区域的互信息为2.075,与现有的生成模型相比,该算法的各项指标均达到最优。此外,经3名经验丰富的放射科医生在生成的MRI上确定病灶并进行阳性/阴性分类,其中生成的MRI中无错误病灶,且分类准确率可达到86.61%,可作为一种辅助工具协助医生进行诊断。