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.

Application of an Advanced Image-Based Virtual Monoenergetic Reconstruction of Dual Source Dual-Energy CT Data at Low keV Increases Image Quality for Esophageal Cancer Patients Imaging

Purpose: To explore the significance of dual-source computed tomography (DECT) virtual monoenergetic reconstructions technology in improving the imaging quality of esophageal cancer patients. Materials and methods: 68 patients with clinically suspected esophageal cancer (all confirmed by pathology) were collected. Routine plain scan was performed with SIEMENS Force dual-energy CT and then dual-phase scans were performed. The venous phase images were respectively subjected to traditional virtual monoenergetic reconstructions (Mono_E) and new generation virtual monoenergetic reconstructions (Mono+). Mono_E 55 keV and Mono+ 55 keV virtual single-energy images were obtained respectively. The signal-to-noise ratio (SNR) of normal esophageal tissue and esophageal cancer lesions, noise and contrast noise ratio (CNR tumor) of normal esophageal tissue and esophageal cancer lesions were compared among 100 kV images, Mono_E images and Mono+ images. At the same time, two imaging physicians read the films and scored the images of each group by using a 5-point scoring method. Results: Mono+ 55 keV images, SNR, SNRtumor, noise and CNRtumor were statistically different from those of 100 kV images and Mono_E images (P < 0.05). And Mono+ 55 keV images also had the highest subjective score, with statistical significance (P 55 keV images had the best quality. Conclusion: The new generation of virtual monoenergetic reconstructions post-processing (Mono+) could reduce image noise and improve the contrast between esophageal cancer lesions and normal esophageal tissues, which was of great significance to improve the imaging quality of esophageal cancer patients and improve the early detection rate of esophageal cancer.

Correlation between Low Tube Voltage in Dual Source CT Coronary Artery Imaging with Image Quality and Radiation Dose

The influence of low tube voltage in dual source CT（DSCT） coronary artery imaging on image quality and radiation dose and its application value in clinical practice were investigated. Totally, 300 cases of chest pain with low body mass index（BMI 〈18.5 kg/m2） subjected to DSCT coronary artery imaging were prospectively enrolled. The heart rate in all patients were greater than 65/min. The retrospective ECG gated scanning mode and simple random sampling method were used to assign the patients into groups A, B and C（n=100 each）. The patients in groups A, B and C experienced 120-, 100-, and 80-kV tube voltage imaging respectively, and the image quality was evaluated. The CT volume dose index（CTDIvol） and dose length product（DLP） were recorded, and the effective dose（ED） was calculated in each group. The image quality scores and radiation doses in groups were compared, and the influence of tube voltage on image quality and radiation dose was analyzed. The results showed that the excellent rate of image quality in groups A, B and C was 95.69%, 94.72% and 96.33% respectively with the difference being not statistically significant among the three groups（P〉0.05）. The CTDIvol values in groups A, B and C were 51.35±12.21, 21.28±7.13 and 6.34±3.34 mGy, respectively, with the difference being statistically significant（P〈0.05）. The ED values in groups A, B and C were 9.27±1.63, 4.56±2.29 and 2.29±1.69 mSv, respectively, with the difference being statistically significant（P〈0.05）. It was suggested that for the patients with low BMI, the application of DSCT coronary artery imaging with low tube voltage can obtain satisfactory image quality, and simultaneously, significantly reduce the radiation dose.

An experimental study of dual-energy CT imaging using synchrotron radiation

The measurement of electron density is important for medical diagnosis and charged particle radiotherapy treatment planning.Traditionally,electron density is obtained by CT imaging using the relationship between CT-number and electron densities established beforehand.However,the measurement is not accurate due to the beam hardening effect.In this paper,we propose a simple and practical electron density acquisition method based on dual-energy CT technique.For each sample,the CT imaging is conducted using two selected X-ray energy from synchrotron radiation.A post-processing dual-energy reconstruction method is used.Linear attenuation coefficients of the scanned samples are obtained by FBP reconstruction.The effective atomic number and electron density are got by solving the dual-energy simultaneous equations.Different phantoms and breast tissues were scanned in this experimental study under 10 keV and 30 keV monochromatic X-rays.The distribution of effective atomic numbers and electron densities of the scanned phantoms were obtained by Dual-energy CT image reconstruction,which agrees well with the theoretical values.Compared with conventional methods,the measurement accuracy is greatly improved, and the measurement error is reduced to about 1%.This experimental study demonstrates that DECT imaging based on synchrotron radiation source is applicable to medical diagnosis for quantitative measurement with high accuracy.

Exploration the Method of Low Dose Coronary Artery Imaging with Dual-Source CT

Objective: On the premise that the image quality meets the requirements of clinical diagnosis, we explored the methods to reduce the radiation dose of coronary artery imaging with Dual-Source CT (DSCT). Methods: We randomly selected 200 patients with coronary heat disease (BIM 0.05). The average image noise in group A is (41.76 ± 7.98) HU, in group B the average image noise is (43.97 ± 3.88) HU, the dif- ference between the two groups was not statistically significant (P>0.05). The average CTDIvol of group A and B were (20.63 ± 2.24) mGy, (38.11 ± 10.69) mGy, respectively, then P <0.01. The average DLP of group A and B are (235.75 ± 28.64) mGycm and (492.59 ± 125.49) mGycm respectively, then P <0.01, the dif- ference of radiation dose had statistical significance (P<0.05). Conclusions: For coronary artery imaging with DSCT the heart electric pulse (AUTO) regulation technology can meet the diagnostic requirements and effectively reduce the radiation dose.

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.

Application of Dual-Source CT TurboFlash Coarse Pitch Scanning in Coronary Artery Imaging

Objective: To compare and analyze the image quality and radiation dose of three scanning modes of dual-source CT coronary artery retrospectively, and to discuss the application value of TurboFlash coarse pitch scanning mode. Methods: The imaging data of 100 patients who underwent CT coronary angiography (CCTA) using Siemens force CT retrospective gated triggering spiral scan (RES-SPIRAL), adaptive prospective gated triggering sequence scan (SEQ) and prospective coarse pitch scan (TurboFlash) retrospectively was collected. The image quality was evaluated by objective and subjective methods. The effective radiation dose of patients was compared and analyzed, and the indications of the three scanning modes were analyzed. The application value of dual-source CT TurboFlash coarse pitch scanning in coronary artery imaging was evaluated. Results: The results showed that the left main coronary artery, the right coronary artery and their tertiary branches could be clearly displayed in the three groups of images: the left anterior descending branch, the left circumflex branch, and their three-level branches. There was no statistical difference in subjective image quality among the three groups of pictures (P > 0.05). There was no statistical difference in objective evaluation indexes, such as CT value, SNR, CNR and Noise among the three groups (P > 0.05). The patient radiation dose results showed that the effective radiation dose ED of RES-SPIRA scan was (9.22 ± 1.33) mSv. The dose of SEQ was (2.88 ± 2.47) mSv, and the dose of TurboFlash was (0.51 ± 0.16) mSv. There was significant difference in comparison of the three groups (P 0.05). RES-spiral scanning had the highest radiation dose and TurboFlash coarse pitch scanning (TurboFlash) had the lowest radiation dose. Conclusion: TurboFlash coarse pitch scanning is low in dosage, fast in speed and wide in adaptability. It is especially suitable for the elderly, children, coma and other patients who cannot cooperate with breath-holding examination, as well as for the screening and examination of coronary artery diseases in asymptomatic population. Undoubtedly, it is a worthy method of heart coronary artery examination.

Correlation analysis of dual-energy CT iodine maps with quantitative pulmonary perfusion MRI

AIM:To correlate dual-energy computed tomography(DECT) pulmonary angiography derived iodine maps with parameter maps of quantitative pulmonary perfusion magnetic resonance imaging(MRI).METHODS:Eighteen patients with pulmonary perfusion defects detected on DECT derived iodine maps were included in this prospective study and additionally underwent time-resolved contrast-enhanced pulmonary MRI [dynamic contrast enhanced(DCE)-MRI].DCE-MRI data were quantitatively analyzed using a pixel-by-pixel deconvolution analysis calculating regional pulmonary blood flow(PBF),pulmonary blood volume(PBV) and mean transit time(MTT) in visually normal lung parenchyma and perfusion defects.Perfusion parameterswere correlated to mean attenuation values of normal lung and perfusion defects on DECT iodine maps.Two readers rated the concordance of perfusion defects in a visual analysis using a 5-point Likert-scale(1 = no correlation,5 = excellent correlation).RESULTS:In visually normal pulmonary tissue mean DECT and MRI values were:22.6 ± 8.3 Hounsfield units(HU);PBF:58.8 ± 36.0 mL/100 mL per minute;PBV:16.6 ± 8.5 mL;MTT:17.1 ± 10.3 s.In areas with restricted perfusion mean DECT and MRI values were:4.0 ± 3.9 HU;PBF:10.3 ± 5.5 mL/100 mL per minute,PBV:5 ± 4 mL,MTT:21.6 ± 14.0 s.The differences between visually normal parenchyma and areas of restricted perfusion were statistically significant for PBF,PBV and DECT(P < 0.0001).No linear correlation was found between MRI perfusion parameters and attenuation values of DECT iodine maps(PBF:r = 0.35,P = 0.15;PBV:r = 0.34,P = 0.16;MTT:r = 0.41,P = 0.08).Visual analysis revealed a moderate correlation between perfusion defects on DECT iodine maps and the parameter maps of DCE-MRI(mean score 3.6,k 0.45).CONCLUSION:There is a moderate visual but not statistically significant correlation between DECT iodine maps and perfusion parameter maps of DCE-MRI.

Non-enhanced Low-tube-voltage High-pitch Dual-source Computed Tomography with Sinogram Affirmed Iterative Reconstruction Algorithm of the Abdomen and Pelvis

Objective To investigate the image quality, radiation dose and diagnostic value of the low-tube-voltage high-pitch dual-source computed tomography(DSCT) with sinogram affirmed iterative reconstruction(SAFIRE) for non-enhanced abdominal and pelvic scans. Methods This institutional review board-approved prospective study included 64 patients who gave written informed consent for additional abdominal and pelvic scan with DSCT in the period from November to December 2012. The patients underwent standard non-enhanced CT scans(protocol 1) [tube voltage of 120 k Vp/pitch of 0.9/filtered back-projection(FBP) reconstruction] followed by high-pitch non-enhanced CT scans(protocol 2)(100 k Vp/3.0/SAFIRE). The total scan time, mean CT number, signal-to-noise ratio(SNR), image quality, lesion detectability and radiation dose were compared between the two protocols. Results The total scan time of protocol 2 was significantly shorter than that of protocol 1(1.4±0.1 seconds vs. 7.6±0.6 seconds, P<0.001). There was no significant difference between protocol 1 and protocol 2 in mean CT number of all organs(liver, 55.4±6.3 HU vs. 56.1±6.8 HU, P=0.214; pancreas, 43.6±5.9 HU vs. 43.7±5.8 HU, P=0.785; spleen, 47.9±3.9 HU vs. 49.4±4.3 HU, P=0.128; kidney, 32.2±2.3 HU vs. 33.1±2.3 HU, P=0.367; abdominal aorta, 44.8±5.6 HU vs. 45.0±5.5 HU, P=0.499; psoas muscle, 50.7±4.1 HU vs. 50.3±4.5 HU, P=0.279). SNR on images of protocol 2 was higher than that of protocol 1(liver, 5.0±1.2 vs. 4.5±1.1, P<0.001; pancreas, 4.0±1.0 vs. 3.6±0.8, P<0.001; spleen, 4.7±1.0 vs. 4.1±0.9, P<0.001; kidney, 3.1±0.6 vs. 2.8±0.6, P<0.001; abdominal aorta, 4.1±1.0 vs. 3.8±1.0, P<0.001; psoas muscle, 4.5±1.1 vs. 4.3±1.2, P=0.012). The overall image noise of protocol 2 was lower than that of protocol1(9.8±3.1 HU vs. 11.1±3.0 HU, P<0.001). Image quality of protocol 2 was good but lower than that of protocol 1(4.1±0.7 vs. 4.6±0.5, P<0.001). Protocol 2 perceived 229 of 234 lesions(97.9%) that were detected in protocol 1 in the abdomen and pelvis. Radiation dose of protocol 2 was lower than that of protocol 1(4.4±0.4 m Sv vs. 7.3±2.4 m Sv, P<0.001) and the mean dose reduction was 41.4%. Conclusion The high-pitch DSCT with SAFIRE can shorten scan time and reduce radiation dose while preserving image quality in non-enhanced abdominal and pelvic scans.

Diagnostic Value of Dual-Energy CT in Differentiating Malignant and Benign Thyroid Nodules: A Systematic Review and Meta-Analysis

Objectives: To evaluate the diagnostic performance of the quantitative iodine parameters, including Iodine Concentration (IC), Normalized Iodine Concentration (NIC), and λHU, in distinguishing malignant and benign thyroid nodules. Methods: Relevant studies were searched from Web of Science, PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure database and other complementary sources from inception to May 20, 2020. Study selection, data extraction, quality assessment, and data analyses were performed following the Cochrane standards and the PRISMA-DTA guideline. Results: Eight studies were included (595 patients with 737 thyroid nodules). The pooled sensitivity, specificity and summary diagnostic odds ratio of IC were 79% (95% CI: 69% - 86%), 76% (95% CI: 65% - 84%) and 11 (95% CI: 5 - 27) respectively;those of NIC were 78% (95% CI: 70% - 85%), 80% (95% CI: 74% - 85%) and 15 (95% CI: 9 - 24) respectively;those of λHU were 80% (95% CI: 71% - 87%), 77% (95% CI: 70% - 83%) and 14 (95% CI: 8 - 24) respectively. Conclusion: DECT can be a potential evaluation tool for thyroid nodules. The NIC may be the most sensitive iodine parameter and could be comparable between different DECT machines in thyroid nodule assessment.

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.

STUDY OF MATCHING PROBLEM IN DUAL ENERGY SUBSTRACTION

After discussing the principle of dual energy substraction,this paper dealswith the matching problem in dual energy substraction in detail.In order to obtain bettermatching feature of images,the probability enhancement is used to process the originalimages.Several matching methods are presented,among these methods,the segment chos-en matching is specially useful for applications.Several experimental results are presented.

Theory and method of dual-energy x-ray grating phase-contrast imaging

The principle of dual-energy x-ray grating phase-contrast imaging(DEPCI) is clarified by using the theory of x-ray interference and Fresnel diffraction. A new method of retrieving phase from the two interferograms is proposed for DEPCI,and its feasibility is verified via simulation. Finally, the proposed method applied to DEPCI experiment demonstrates the effectiveness of the method. This paper lays the theoretical foundation for performance optimization of DEPCI and the further integration of DEPCI and computed tomography.

Head dual energy-computed tomography angiography versus neuro-digital subtraction angiography

Dual-energy X-ray absorptiometry provides two modes of head computed tomography （CT） angiography scanning： neuro-digital subtraction angiography and dual-energy CT angiography （DE-CTA）. Previous studies have compared image quality, radiation exposure, and bone removal between neuro-digital subtraction angiography and DE-CTA. However, the number of cases was relatively small. The present study examined 300 suspected cases of cerebrovascular disease and observed the methods and duration of post-processing, examination time, and data volume. Results demonstrated similar image quality between the two methods, but lower radiation doses and shorter examination time in DE-CTA. DE-CTA allowed for faster and more stable scanning performance and post-processing methods, facilitating accurate and direct diagnosis of cerebrovascular disease.

Dual-Energy X-Ray Computed Tomography Scanner Using Two Different Energy-Selection Electronics and a Lutetium-Oxyorthosilicate Photomultiplier Detector

To obtain two kinds of tomograms at two different X-ray energy ranges simultaneously, we have constructed a dual-energy X-ray photon counter with a lutetium-oxyorthosilicate photomultiplier detector system, three comparators, two microcomputers, and two frequency-voltage converters. X-ray photons are detected using the detector system, and the event pulses are input to three comparators simultaneously to determine threshold energies. At a tube voltage of 100 kV, the three threshold energies are 16, 35 and 52 keV, and two energy ranges are 16 - 35 and 52 - 100 keV. X-ray photons in the two ranges are counted using microcomputers, and the logical pulses from the two microcomputers are input to two frequency-voltage converters. In dual-energy computed tomography (CT), the tube voltage and current were 100 kV and 0.29 mA, respectively. Two tomograms were obtained simultaneously at two energy ranges. The energy ranges for gadolinium-L-edge and K-edge CT were 16 - 35 and 52 - 100 keV, respectively. The maximum count rate of dual-energy CT was 105 kilocounts per second with energies ranging from 16 to 100 keV, and the exposure time for tomography was 19.6 min.

Feasibility of Improved Attenuation Correction for SPECT Reconstruction in the Presence of Dense Materials Using Dual-Energy Virtual Monochromatic CT: A Phantom Study

Objective: Computed tomography (CT)-based attenuation correction (CTAC) offers the clear benefit of reliable reconstruction of single-photon emission computed tomography (SPECT) images through its ability to achieve object-specific attenuation maps, but artifacts from dense materials often deteriorate CTAC performance. Therefore, we investigate the feasibility of CTAC in the presence of dense materials using dual-energy virtual monochromatic CT data. Methods: A sodium pertechnetate-filled cylindrical uniform phantom, with a pair of undiluted iodine syringes attached, is scanned with a dual-source CT scanner to obtain both single-energy (120 kVp) polychromatic and dual-energy (80 kVp/140 kVp with tin filtering) virtual monochromatic CT images. The single-energy and the dual-energy CT images are then converted to attenuation maps at 141 keV. SPECT images are reconstructed from 99mTc emission data of the phantom using each single-energy and dual-energy attenuation map and incorporating CTAC procedure. A region-of-in- terest analysis is performed to quantitatively compare the attenuation maps between the single-energy and the dual-energy techniques, each at an iodine-free position and a position adjacent to the iodine solutions. Results: At the iodine-free position, the phantom provides a uniform distribution of attenuation maps in both the single-energy and the dual-energy techniques. In the presence of adjacent iodine solutions, however, severe artifacts appeare in the single-energy CT images. These artifacts make attenuation values fluctuate, resulting in erroneous pixel values in the CTAC SPECT images. In contrast, dual-energy CT strongly suppresses the artifacts and hence improves the uniformity of the attenuation maps and the resultant SPECT images. Conclusions: Dual-energy CT with virtual monochromatic reconstruction has the potential to substantially reduce artifacts arising from dense materials. It has the potential to improve the accuracy of attenuation maps and the resultant CTAC SPECT images.

基于双源CT的影像学模型对儿童上尿路结石的诊断价值

目的 探讨基于双源CT(dual-source CT,DSCT)的影像学模型用于儿童上尿路不同成分结石分析的诊断价值。方法 收集2021年1月至2022年12月间上尿路结石的53例患儿作为研究对象。其中体内的结石分析应用双能量方式进行扫描,而体外结石则将其放置于新鲜的猪肾内并全部浸于生理盐水中再扫描,体内和体外结石的扫描条件一致。在其软组织窗分别采用80kV、120kV和140kV电压下测定患儿结石的CT值,并采用双能量结石分析的相关软件对其主要成分进行判断。同时应用前期文献构建的影像组学预测模型和红外光谱分析结石样品的主要成分。结果 影像组学预测模型和采用红外光谱法分析发现29例纯结石,5例为混合结石。24例术前采用DSCT扫描发现21例纯结石, 2例混合结石。经统计分析,草酸钙结石、尿酸结石、羟基磷灰石、胱氨酸结石这四种纯结石年龄之间经统计分析,不具有显著性差异,男女患儿发病情况经统计分析,具有显著性差异。对比体内、外草酸钙结石、羟基磷灰石、尿酸结石、胱氨酸结石的扫描CT值在80kV、120kV和40kV下经统计分析,不具有显著性差异。不同的结石采用DSCT法(80kV和140kV)时CT值的差值和DEI值经统计学分析,具有显著性差异;采用常规扫描方法和DSCT法测定的ED值、CTDIvol值和DLP值经统计分析,均具有显著性差异(P<0.05),其中DSCT法均高于常规扫描法。结论 四种纯结石在不同电压下进行体内或体外扫描其CT值均无显著性差异,可见CT可作为临床上分析儿童上尿路结石成分的准确方法之一。结合CT值测量及DSCT分析软件可显著提高诊断的准确性,可在临床上推广应用。

Particle Image Velocimetry Study of Turbulence Characteristics in a Vessel Agitated by a Dual Rushton Impeller

Particle Image Velocimetry （PIV） has been used to investigate turbulence characteristics in a 0.48 m diameter stirred vessel filled to a liquid height （ H = 1.4T ） of 0.67 m. The agitator had dual Rushton impellers of 0.19 m diameter （ D = 0.4T ）. The developed flow patterns depend on the clearance of the lower impeller above the base of the vessel, the spacing between the two impellers, and the submergence of the upper impeller below the liq- uid surface. Their combinations can generate three basic flow patterns, named, parallel, merging and diverging flows. The results of velocity measurement show that the flow characteristics in the impeller jet flow region changes very little for different positions. Average velocity, trailing vortices and shear strain rate distributions for three flow patterns were measured by using PIV technique. The characteristics of trailing vortex and its trajectory were described in detail for those three flow patterns. Since the space-resolution of PIV can only reach the sub-grid rather than the Kolmogorov scale, a large-eddy PIV analysis has been used to estimate the distribution of the turbulent kinetic energy dissipation. Comparison of the distributions of turbulent kinetic energy and dissipation rate in merging flow shows that the highest turbulent kinetic energy and dissipation are both located in the vortex regions, but the maxima are at somewhat different lo- cations behind the blade. About 37% of the total energy is dissipated in dual impeller jet flow regions. The obtained distribution of shear strain rate for merging flow is similar to that of turbulence dissipation, with the shear strain rate around the trailing vortices much higher than in other areas.

双能CT定量参数联合临床特征对结直肠癌T2期与T3期分期的诊断价值

目的探讨双能CT定量参数联合临床特征构建的回归模型对结直肠癌T2期与T3期分期的诊断价值。方法该研究为横断面研究,收集2022年1月至2023年11月在重庆医科大学附属第二医院经术后病理证实,术前在本院放射科行双能CT检查的结直肠癌患者,共91例,根据中国结直肠癌诊疗规范(2020年版)病理T分期标准分为T2组(n=43)和T3(n=48)组。采用单因素分析比较2组间CT定量参数和临床特征的差异性,将差异具有统计学意义的变量采用单因素或多因素Logistic回归分析构建模型,并比较CT参数模型和联合模型的AUC,评估诊断T2期及T3期的效能。结果单因素分析发现癌胚抗原、N分期、肿瘤位置、肿瘤长径、虚拟平扫CT值、脂肪分数、电子密度及双能指数在T2组与T3组间差异具有统计学意义(P<0.05)。多因素Logistic分析发现N分期、肿瘤位置、肿瘤长径、脂肪分数和双能指数是诊断T3期的独立危险因素,将以上变量分别构建CT参数模型和CT参数+临床特征联合模型,其中CT参数模型诊断结直肠癌T3期的AUC为0.671(95%CI:0.558~0.783),联合模型的AUC为0.886(95%CI:0.815~0.957),且联合模型AUC值与CT参数模型AUC值间差异具有统计学意义(P<0.01)。结论双能CT定量参数联合临床特征构建的回归模型对术前诊断结直肠癌T2期与T3期分期具有较高价值。

双能量CT虚拟去钙技术在强直性脊柱炎骶髂关节炎骨髓水肿中的应用

目的 探究在强直性脊柱炎骶髂关节炎骨髓水肿中应用双能量CT虚拟去钙技术的临床价值。方法于2023年6月至2024年5月,选取我院50例强直性脊柱炎骶髂关节炎患者,依据BASDAI评分进行分组,分为早期急性期(平均分≥6.0分)、慢性活动期(平均分在4.0-6.0分之间)各25例,均进行双能量CT虚拟去钙技术预测,对比其预测价值,并进行分析。结果 两组在年龄、病程及SPARCC评分中无差异(P>0.05),且早期急性期ESR、CRP低于慢性活动期(P<0.05)。骨髓水肿SPARCC评分与病情活动性BASDAI评分呈正相关(rs=0.682,P<0.05)。早期急性期VNCa CT、有效原子序数、能谱曲线斜率及rCT值高于慢性活动期(P<0.05)。本次研究以MRI图像显示骨髓水肿区域为“金标准”发现,使用双能量CT虚拟去钙技术检测的阳性检出率较低(P<0.05)。双能量CT虚拟去钙技术灵敏度、特异度和准确度、AUC值均较高(P<0.05)。结论双能量CT虚拟去钙技术应用于强直性脊柱炎骶髂关节炎骨髓水肿具有较高的准确率,且诊断效能较高。