Application value of dual-energy CT perfusion imaging in acute pulmonary embolism examination / 中国辐射卫生

Objective To analyze the pulmonary perfusion defect index (PPDI) of dual-energy computed tomography (CT) and pulmonary artery obstruction index (PAOI) of conventional CT angiography, and to investigate the clinical application value of dual-energy CT perfusion imaging in the examination of patients with acute pulmonary embolism. Methods A retrospective study was conducted on 21 patients diagnosed with acute pulmonary embolism in Weifang People's Hospital from January 1, 2022 to December 31, 2022. PPDI, PAOI, and maximum plasma D-dimer concentration (mg/L) were calculated. According to the 2019 ESC Guidelines, the patients were divided into low-risk group (n = 8) and medium-risk group (n = 12). The Mann-Whitney U test was used for between-group comparisons. The Spearman’s rank correlation coefficient was used to analyze the correlations between PAOI, PPDI, and plasma D-dimer concentration. Results The PPDI, PAOI, and D-dimer values in the low-risk group were 3.33 (2.09, 4.58), 5.00 (3.13, 5.00), and 0.67 (0.52, 0.79), respectively. The PPDI, PAOI, and D-dimer values in the middle-risk group were 8.34 (5.42, 12.50), 12.50 (8.13, 15.00), and 1.18 (0.86, 2.87), respectively. The Z-values of comparison between the two groups were −3.092, −3.650, and −3.318, respectively (all P < 0.05). There were significant differences in PPDI, PAOI, and D-dimer between the low-risk and middle-risk groups (P < 0.05). Positive correlations were observed between PPDI and PAOI, between PPDI and D-dimer, and between PAOI and D-dimer (rs = 0.869, 0.918, 0.909, all P < 0.05). Conclusion Both PPDI and PAOI can be used for the clinical examination of patients with acute pulmonary embolism and evaluation of the severity of the disease. Compared with conventional CT, dual-energy CT perfusion imaging is more efficient in the diagnosis of acute pulmonary embolism, and facilitates accurate clinical treatment.

The progress of preoperative and intraoperative urinary calculi analysis / 中华泌尿外科杂志

The incidence and recurrence rates of urinary stone diseases have remained high recently, and stone analysis is of great significance for further understanding of the pathophysiological processes of urinary stones and to develop effective prevention strategies and precise treatment. Imaging evaluation is the main method of preoperative stone analysis, and dual-energy CT has shown its potential in identifying common main components of stones. The emergence of photon counting spectral CT is expected to achieve accurate analysis of stone components at the pixel level. The intraoperative stone analysis mainly relies on the automatic recognition of endoscopic images, and using machine learning algorithms can more reliably predict common stone composition. It is of great significance for stone analysis and assessment of metabolic causes by introducing morpho-constitutional classification (MCC)and observing and describing the papillary renal lesions during operation. This article reviews the progress of preoperative and intraoperative stone analysis, in order to improve clinicians' understanding of the importance of stone analysis, and provide a direction for further clinical research.

Feasibility of improving the quality of children′s abdominal images using split-filter dual-energy CT / 中华放射医学与防护杂志

Objective:To evaluate the effects of split-filter dual-energy CT (SF-DECT) in improving image quality at low doses in the process of abdominal examinations for children.Methods:A preliminary study was conducted using child phantoms. Furthermore, 20 children aged 4-6 years were recruited prospectively for clinical validation from June 2020 to December 2020. Conventional single-energy CT (SECT) and SF-DECT were employed to scan the abdominal areas of the phantoms and children. Then, the CT values, image noise, contrast to noise ratios (CNRs), and image subjective scores of SF-DECT and SECT were compared under various doses (1, 2, 3, and 4 mGy).Results:For the phantoms under doses of 3 and 4 mGy, SF-DECT decreased the image noise by 18.9% and 23.6%, respectively, and increased the liver and kidney CNRs (CNR liv and CNR kid) by 12.8% and 31.9% at most, respectively, compared to SECT ( Z = 3.00, 5.17, P < 0.001). For children, SF-DECT decreased image noise ( Z = 4.64, P < 0.001) and increased CNR liv and CNR kid ( Z = 3.78, 3.39, P < 0.001). For both the phantoms and the children, the subjective scores of images scanned using the SF-DECT were higher than those scanned using the SECT ( Z = 1.96-3.80, P < 0.05). Conclusions:Compared with SECT, SF-DECT can improve the quality of children′s abdominal images. This technique has a certain prospect of optimizing abdominal CT for children. However, it is necessary to conduct in-depth clinical research to verify the result.

Application of dual-energy CT in differential diagnosis of lung metastases and benign nodules in breast cancer / 中华放射学杂志

Objective:To investigate the application value of dual-energy CT in the differential diagnosis of lung metastases and benign nodules in breast cancer.Methods:The data of 96 patients with pathology-confirmed breast cancer at the Fifth Affiliated Hospital of Wenzhou Medical University from March 2017 to June 2021 were analyzed retrospectively. All patients received dual-energy chest CT scans within 2 weeks before surgery. All 96 patients were female, aged 31-84 (56±12) years. A total of 207 pulmonary nodules from 96 patients were classified into 81 lung metastases and 126 benign nodules according to pathological findings. Conventional CT features [longest diameter, boundary, location and CT value difference between arterial and venous phases (ΔCT) of nodules] and dual-energy CT parameters [standardized iodine concentration (NIC), slope of energy spectrum (λ HU) and normalized effective atomic number (nZ eff) in arterial and venous phases] were analyzed and measured. The χ 2 test, independent samples t test and Kruskal-Wallis rank-sum test were used to analyze the differences of conventional CT features and dual-energy CT parameters between lung metastases and benign nodules. First, the least shrinkage and selection operator (LASSO) regression method was used to screen conventional CT features and dual-energy CT parameters, and then logistic regression analysis was performed to screen out independent risk factors for lung metastases. Receiver operating characteristic (ROC) curves were used to evaluate the efficacy of CT parameters alone and logistic model in differentiating lung metastases from benign lung nodules. Results:There were statistically significant differences between lung metastases and benign nodules in longest diameter, ?CT, NIC, λ HU and nZ eff in arterial and venous phases (all P<0.05). LASSO regression and binary logistic regression analysis showed that the venous phase λ HU (OR=59.413, 95%CI 14.233-248.002, P<0.001) and the venous phase nZ eff (OR=4.508, 95%CI 2.787-7.290, P<0.001) were independent risk factors for predicting lung metastases. Among them, the venous phase λ HU had the highest diagnostic efficiency, with an area under curve (AUC) of 0.794 and an accuracy of 74.88%. The AUC of the logistic model constructed by combining the venous phase λ HU and the venous phase nZ eff could reach 0.958, and the accuracy was improved to 92.27%, which was significantly higher than the efficacy of the two alone ( Z=6.02, 9.54, all P<0.001). Conclusion:Dual-energy CT has great application value in the identification of lung metastases and benign nodules in patients with breast cancer, especially when combined with venous phase λ HU and venous phase nZ eff, the diagnostic efficiency is further improved.

A feasibility study of predictive values of lateral cervical lymph node metastasis from cN1-stage papillary thyroid carcinoma based on dual-energy CT nomogram / 中华放射学杂志

Objective:To investigate the feasibility of predicting lateral cervical lymph node metastasis (LLNM) in patients with papillary thyroid carcinoma (PTC) based on the nomogram constructed by dual-energy CT data.Methods:In total 417 patients with PTC confirmed by pathology in Tianjin First Central Hospital from January 2015 to December 2018 were retrospectively analyzed as a training group. Internal validation was conducted, including 139 patients in the LLNM group and 278 patients in the non-LLNM group. A total of 169 PTC patients from January 2019 to June 2020 were included as an external validation group, including 58 patients in the LLNM group and 111 patients in the non-LLNM group. The morphological characteristics of the primary thyroid lesions on dual-energy CT iodine maps were analyzed, including tumor location, maximum diameter, calcification, and extrathyroidal extension (ETE). Iodine concentration (IC) of the PTC parenchyma and the internal carotid artery on the same level in the arterial and venous phases were measured, and normalized iodine concentration (NIC) was calculated. The independent risk factors for LLNM were obtained by univariate and multivariate logistic regression analysis. Base on the results, a prediction model was constructed and expressed in the form of a nomogram. The internal and external validation of the model was carried out using ROC curve.Results:Multivariate binary logistic regression analysis showed that the lesion location in the upper polar of the thyroid, the presence of ETE, IC in arterial phase>2.9 mg/ml, IC in the venous phase>3.2 mg/ml, and NIC in the arterial phase>0.21 were independent risk factors for LLNM prediction. The nomogram based on the above factors was constructed with an area under the ROC curve (AUC) of 0.895 (95%CI 0.862-0.923). With a cut-off value of 0.79, the sensitivity and specificity were 86.3% and 75.2%, respectively. As for the external validation group, the AUC of the model was 0.887 (95%CI 0.830-0.931), with the sensitivity of 82.8%, and the specificity of 81.1%.Conclusion:The application values of the nomogram model based on dual-energy CT data in preoperative evaluation of the possibility of LLNM of PTC patients has been verified. The model constructed in this study might be helpful with the individualized treatment in a certain degree.

Application of Virtual Monochromatic Images Reconstructed by Dual-energy Computed Tomography in Radiotherapy Treatment Planning System / 中国医疗器械杂志

Virtual monochromatic images (VMI) that reconstructed on dual-energy computed tomography (DECT) have further application prospects in radiotherapy, and there is still a lack of clinical dose verification. In this study, GE Revolution CT scanner was used to perform conventional imaging and gemstone spectral imaging on the simulated head and body phantom. The CT images were imported to radiotherapy treatment planning system (TPS), and the same treatment plans were transplanted to compare the CT value and the dose distribution. The results show that the VMI can be imported into TPS for CT value-relative electron density conversion and dose calculation. Compared to conventional images, the VMI varies from 70 to 140 keV, has little difference in dose distribution of 6 MV photon treatment plan.

Analysis of risk factors influencing the detection rate of urate crystal by dual energy computed tomography / 北京大学学报(医学版)

OBJECTIVE@#To explore the risk factors of detection of uric acid crystals by dual energy CT (DECT) in patients with gout diagnosed by gold standard.@*METHODS@#From June 2011 to December 2018, clinical data of 29 patients were collected who were diagnosed with acute or chronic gout by positive polarized light analysis of joint synovial fluid in First Hospital of Peking University. Chi-square test, Logistic regression and t-test were used. The relationship between DECT and the clinical data, laboratory examination and drug treatment were analyzed.@*RESULTS@#In this study, 29 patients were included, of whom, 22 patients were detected with uric acid crystals by DECT, and 7 patients were not. According to whether the uric acid crystals were detected or not by DECT, the patients were divided into two groups. Compared with the negative group, the patients were older in positive group [(47±12) vs. (39±11) years, P=0.15], had higher body bass index (BMI) [(27.9±3.7) vs. (22.8±2.1) kg/m2, P=0.002], longer gout disease duration [(135±102) vs.(45±53) months, P=0.035], higher in the highest serum uric acid in history [(643±121) vs. (543±103) μmol/L, P=0.043]. Although uric acid near DECT in positive group was higher than in negative group, there was no statistical difference [(558±150) vs. (513±89) μmol/L, P=0.497]. Comparing positive group with negative group, the percentage of the patients in acute phase was higher than in chronic phase [18(81.8%) vs. 4(57%), P=0.311];the percentage of the patients taking uric-acid-lowering drugs was higher than the other group [22(100%) vs. 5 (71%), P=0.052];the percentage of the patients with recurrent typical attacks was higher than that of those without typical attacks [22 (100%) vs.6 (85%), P=0.241]. The consistency of symptoms and the finding of uric acid crystals by DECT had been compared between the joints. The right knee joint had the highest consistency (Kappa=0.627), followed by the left MTP1 (Kappa=0.58), the right metatarsophalangeal 1(MTP1, Kappa=0.551) and the left knee (Kappa=0.494), all of which had statistical significance. The consistency of the ankle joint was lower (the right ankle joint: Kappa=0.19, the left ankle joint: Kappa=0.256), showing no statistical significance. BMI (kg/m2) [2.307 (1.139-4.670), P=0.02], gout duration (years) [0.306 (0.906-4.881), P=0.186], and the highest uric acid level in history (mg/dL) [0.023 (0.981-2.764), P=0.137] had relationship to the positive result of urate crystals in DECT.@*CONCLUSION@#Gout patients with larger BMI, higher previous highest uric acid value and longer gout duration had higher sensitivity of the positive result in DECT.

Electronic cleaning of intestinal contents tagging by diatrizoate meglumine for single-source dual-energy CT colonography with sequential acquisitions and volume scanning / 重庆医学

Objective To study the feasibility of applying electronic cleaning to intestinal contents tagging by diatrizoate meglumine for single-source dual-energy CT colonography with sequential acquisitions and volume scanning.Methods Twenty-four volunteers had fine effect of intestinal contents tagging by diatrizoate meglumine,good colorectal distension effect,fine image quality of dual-energy fusion colorectal images,and with informed consents were enrolled in this study.The single-source dual-energy CT colonography with sequential acquisitions and volume scanning was performed with an Acquilion ONE 320 row CT scanner,tube voltage 135 kVp/80 kVp.The intestinal contents conducted the dual-energy electronic cleaned based on decomposition of intestinal contents tagging by diatrizoate meglumine,soft tissue and air.The intestinal contents in one segment of intestinal lumen being 100％ electronically cleaned served as the basic standard,the electronic cleaning effects were divided into the 5 grades:excellent,good,moderate,fair and poor;and grade 1-3 were effective fecal electronic cleaning.Results The grade 1,2,3,4,5 of electronic cleaning effect for solid as the main intestinal contents were 22.2％,53.3％,17.8％,6.7％ and 0％ respectively;and which of electronic cleaning effect for liquid as the main intestinal contents were 47.5％,47.5％,5.0％,0％ and 0％ respectively.The together total effective electronic cleaning of intestinal contents was 97.9％ and the electronic cleaning effect was good.Conclusion Electronic cleaning could be used in the intestinal contents tagging by diatrizoate meglumine for single-source dual-energy CT colonography with sequential acquisitions and volume scanning.

Value of dual-source dual-energy CT in differentiating extravasation of iodine contrast agents from secondary hemorrhage after revascularization in acute ischemic stroke / 实用医学杂志

Objective To explore the value of dual-source dual-energy CT (DSDE-CT) in differentiating extravasation of iodine contrast agents from secondary hemorrhage after revascularization in acute ischemic stroke. Methods 46 acute ischemic stroke patients following intra-arterial thrombolysis were examined with DSDE-CT within 2 hours after the procedure. Simultaneous imaging at 80 kV/392 mA and 140 kV/196 mA was employed, and then mixed images, virtual unenhanced non-contrast images and iodine overlay maps were calculated. Mixed images alone, as conventional CT, and DUDE-CT interpretations were assessed separately by two radiologists and compared with follow-up CT. Results 6 of 34 patients were negative cases proven by CT without high density, and another 28 cases were proven positive cases with 3 cases of cerebral hemorrhage, 21 cases of contrast agent extravasation, and the remaining 4 cases of combined cerebral hemorrhage and contrast agent extravasation. The sensibility, specificity, positive predictive value, negative predictive value and accuracy of mixed imaging alone in diagnosing hemorrhage was 66.67%, 100%, 1005, 96.15% and 96.43%, while the sensibility, specificity, positive predictive value, negative predictive value and accuracy of hemorrhage with DUDE-CT was 100%, 96%, 75%, 100% and 96.43% . The diagnostic accuracy of superimposed fusion images for intracranial hemorrhage, extravasation of contrast agent and hemorrhage with extravasation of contrast agent was relatively high, and the difference was statistically significant (P < 0.05). The diagnostic accuracy of superimposed fusion images consistent with clinical follow-up was significantly higher (Kappa=0.815),as compared with that of mixed imaging alone (Kappa=0.0.564). Conclusion DUDE-CT has great value in differentiating hemorrhage from iodinated contrast after intra-arterial thrombolysis in acute ischemic stroke.

Study on colorectal distension with partially automated and individualized insufflation of air for dual-energy CT colonography / 重庆医学

Objective To study the compliance of examinees,and effectiveness of colorectal distension with partially automated and individualized insufflation of air for dual-energy CT colonography.Methods Forty-six healthy adult volunteers without history of conditions affecting gastrointestinal motor function were enrolled in this study.One day before CT examination,volunteers were asked to orally administered 60 mL 4% diatrizoate meglumine five times for fecal tagging.Air was insufflated by using an inflator in a partially automated and individualized manner.The volunteers were initially asked to assume the right lateral decubitus position,then slowly turn to the supine position.Insufflation rate began at 1.5 L/min,and decreased to 0.5 L/min at later stage.The necessity and volume of air insufflation were decided according to effectiveness of colorectal distension on CT scout images,self-reported sensation of volunteers,and intestinal pressure.Dual-energy CT scanning was performed,and dual-energy blended images were acquired.Compliance of volunteers was statistically analyzed.The effectiveness of colorectal segments distension was statistically analyzed by using Kruskal-Wallis H test.Results No abdominal pain,bloating,nausea or vomiting were noted in the 46 volunteers.All volunteers easily accepted colorectal insufflation of air,with grade 1 compliance.The effectiveness of colorectal distension of grades 1,2,3 and 4 were 0%,2.1%,5.1% and 92.8%,respectively.The difference of effectiveness of colorectal segments distension had no statistical significance(χ2=6.19,P=0.288).The effectiveness of insufflation was poor in 6 colorectal segments,including 2 in sigmoid colon and 2 in rectum.Effectiveness of insufflation was suboptimal in 14 colorectal segments,including 4 in descending colon,4 in sigmoid colon,and 3 in rectum.Conclusion Compliance of examinees with partially automated and individualized insufflation of air for dual-energy CT colonography is excellent,with good effectiveness of colorectal distension.

Analysis of dual energy CT imaging in the diagnosis of gouty tophus deposition value / 重庆医学

Objective To explore the value of dual energy CT imaging in the diagnosis of gouty tophus deposition.Methods Sixty-five cases of patients with gout treated in this hospital between December 2012 to December 2015 were selected.Another 65 cases of patients(rheumatoid arthritis,degenerative osteoarthritis and unexplained leg pain) were selected as control group.The re sults of dual energy CT imaging between two group were compared.Three experienced clinicians who didn't understand the imaging results were selected.They had a medical history and physical examination in patients with gout.The differences between clinical evaluation and imaging results were compared.Results Dual energy CT imaging showed that there were no tophi deposition in con trol group;the topi deposition in wrist joint,knee joint and ankle joint were 6.06％oo (33/34),100.00％ (22/22) and 96.49％ (55/57) in gout group.Dual energy CT imaging detected a total of 545 parts of tophus deposition.It was 4.36 times of the result of clinical evaluation(125 parts).Conclusion Dual energy CT imaging shows the advantages of simple noninvasive,high accuracy and low rate of misdiagnosis in diagnosing gout nodules.

Dual-Energy CT: New Horizon in Medical Imaging

Dual-energy CT has remained underutilized over the past decade probably due to a cumbersome workflow issue and current technical limitations. Clinical radiologists should be made aware of the potential clinical benefits of dual-energy CT over single-energy CT. To accomplish this aim, the basic principle, current acquisition methods with advantages and disadvantages, and various material-specific imaging methods as clinical applications of dual-energy CT should be addressed in detail. Current dual-energy CT acquisition methods include dual tubes with or without beam filtration, rapid voltage switching, dual-layer detector, split filter technique, and sequential scanning. Dual-energy material-specific imaging methods include virtual monoenergetic or monochromatic imaging, effective atomic number map, virtual non-contrast or unenhanced imaging, virtual non-calcium imaging, iodine map, inhaled xenon map, uric acid imaging, automatic bone removal, and lung vessels analysis. In this review, we focus on dual-energy CT imaging including related issues of radiation exposure to patients, scanning and post-processing options, and potential clinical benefits mainly to improve the understanding of clinical radiologists and thus, expand the clinical use of dual-energy CT; in addition, we briefly describe the current technical limitations of dual-energy CT and the current developments of photon-counting detector.

Diagnostic Performance of Coronary CT Angiography, Stress Dual-Energy CT Perfusion, and Stress Perfusion Single-Photon Emission Computed Tomography for Coronary Artery Disease: Comparison with Combined Invasive Coronary Angiography and Stress Perfusion Ca

OBJECTIVE: To investigate the diagnostic performance of coronary computed tomography angiography (CCTA), stress dual-energy computed tomography perfusion (DE-CTP), stress perfusion single-photon emission computed tomography (SPECT), and the combinations of CCTA with myocardial perfusion imaging (CCTA + DE-CTP and CCTA + SPECT) for identifying coronary artery stenosis that causes myocardial hypoperfusion. Combined invasive coronary angiography (ICA) and stress perfusion cardiac magnetic resonance (SP-CMR) imaging are used as the reference standard. MATERIALS AND METHODS: We retrospectively reviewed the records of 25 patients with suspected coronary artery disease, who underwent CCTA, DE-CTP, SPECT, SP-CMR, and ICA. The reference standard was defined as ≥ 50% stenosis by ICA, with a corresponding myocardial hypoperfusion on SP-CMR. RESULTS: For per-vascular territory analysis, the sensitivities of CCTA, DE-CTP, SPECT, CCTA + DE-CTP, and CCTA + SPECT were 96, 96, 68, 93, and 68%, respectively, and specificities were 72, 75, 89, 85, and 94%, respectively. The areas under the receiver operating characteristic curve (AUCs) were 0.84 ± 0.05, 0.85 ± 0.05, 0.79 ± 0.06, 0.89 ± 0.04, and 0.81 ± 0.06, respectively. For per-patient analysis, the sensitivities of CCTA, DE-CTP, SPECT, CCTA + DE-CTP, and CCTA + SPECT were 100, 100, 89, 100, and 83%, respectively; the specificities were 14, 43, 57, 43, and 57%, respectively; and the AUCs were 0.57 ± 0.13, 0.71 ± 0.11, 0.73 ± 0.11, 0.71 ± 0.11, and 0.70 ± 0.11, respectively. CONCLUSION: The combination of CCTA and DE-CTP enhances specificity without a loss of sensitivity for detecting hemodynamically significant coronary artery stenosis, as defined by combined ICA and SP-CMR.

Comparative Study for Diagnostic Value Between Dual Energy CT Lung Perfusion Imaging and CT Pulmonary Angiography in Patients With Pulmonary Embolism / 中国循环杂志

Objective: To explore the value of dual energy CT lung perfusion imaging (DEPI) for diagnosing pulmonary embolism (PE) in comparison with CT pulmonary angiography (CTPA). Methods: There were 49 patients with suspected PE received DEPI scanning and 19 with CTPA conifrmed diagnosis were enrolled in this study. CTPA image was obtained by 80 kv data, and DEPI image was obtained by PBV software. The location, type of PE in CTPA image, and the location, shape of perfusion defect in DEPI were observed and compared by segment basis. The correlation and agreement of CTPA and DEPI for diagnosing PE were calculated and the un-agreement was analyzed. Results: A total of 380 segments were included for analysis. CTPA detected 162 segments of PE and DEPI detected 155 segments of perfusion defect or reduction, partial PE were mainly presented by perfusion defects as speckles, patches or without perfusion defect, and complete PE were mainly showed segmental or sub-segmental perfusion defects. CTPA and DEPI were correlated for PE diagnosis (χ2=305.5,P=0.000), the diagnostic agreement was 83.42% and KAPPA value was 0.659. Conclusion: The perfusion defect in DEPI is related to the degree and type of PE presented in CTPA, their combination is helpful for diagnosing PE.

Research progress and clinical applications of computed tomographic colonography in coloretal cancer / 中国癌症杂志

Computed tomography colonography (CTC) is a well-established technique for evaluation of colorectal cancer (CRC). Signiifcant advances have been made in the technique of CTC since its inception. Besides being an excellent tool for detection of CRC, it is minimally invasive, less time-consuming and well tolerated by patients. Furthermore, it has fewer complications than conventional colonoscopy (CC) or barium enema (BE). The application of new technologies, such as electronic cleansing (EC) and dual-energy CT (DECT), enriches the examination of CTC. In 2005, a standardized reporting scheme, CT colonography reporting and data system (C-RADS), was put forward by the working group on virtual colonoscopy. They proposed that the report should include lesion size, number, morphology, location, attenuation and recommendations for lesion surveillance. New research progress and clinical applications of CTC in CRC are reviewed in this article. In addition, the paper also brielfy touches upon technique, indications, contraindications, safety and risk of CTC.

Collateral Ventilation Quantification Using Xenon-Enhanced Dynamic Dual-Energy CT: Differences between Canine and Swine Models of Bronchial Occlusion

OBJECTIVE: The aim of this study was to evaluate whether the difference in the degree of collateral ventilation between canine and swine models of bronchial obstruction could be detected by using xenon-enhanced dynamic dual-energy CT. MATERIALS AND METHODS: Eight mongrel dogs and six pigs underwent dynamic dual-energy scanning of 64-slice dual-source CT at 12-second interval for 2-minute wash-in period (60% xenon) and at 24-second interval for 3-minute wash-out period with segmental bronchus occluded. Ventilation parameters of magnitude (A value), maximal slope, velocity (K value), and time-to-peak (TTP) enhancement were calculated from dynamic xenon maps using exponential function of Kety model. RESULTS: A larger difference in A value between parenchyma was observed in pigs than in dogs (absolute difference, -33.0 +/- 5.0 Hounsfield units [HU] vs. -2.8 +/- 7.1 HU, p = 0.001; normalized percentage difference, -79.8 +/- 1.8% vs. -5.4 +/- 16.4%, p = 0.0007). Mean maximal slopes in both periods in the occluded parenchyma only decreased in pigs (all p < 0.05). K values of both periods were not different (p = 0.892) in dogs. However, a significant (p = 0.027) difference was found in pigs in the wash-in period. TTP was delayed in the occluded parenchyma in pigs (p = 0.013) but not in dogs (p = 0.892). CONCLUSION: Xenon-ventilation CT allows the quantification of collateral ventilation and detection of differences between canine and swine models of bronchial obstruction.

Effects of Dual-Energy CT with Non-Linear Blending on Abdominal CT Angiography

OBJECTIVE: To determine whether non-linear blending technique for arterial-phase dual-energy abdominal CT angiography (CTA) could improve image quality compared to the linear blending technique and conventional 120 kVp imaging. MATERIALS AND METHODS: This study included 118 patients who had accepted dual-energy abdominal CTA in the arterial phase. They were assigned to Sn140/80 kVp protocol (protocol A, n = 40) if body mass index (BMI) or = 25. Non-linear blending images and linear blending images with a weighting factor of 0.5 in each protocol were generated and compared with the conventional 120 kVp images (protocol C, n = 37). The abdominal vascular enhancements, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and radiation dose were assessed. Statistical analysis was performed using one-way analysis of variance test, independent t test, Mann-Whitney U test, and Kruskal-Wallis test. RESULTS: Mean vascular attenuation, CNR, SNR and subjective image quality score for the non-linear blending images in each protocol were all higher compared to the corresponding linear blending images and 120 kVp images (p values ranging from < 0.001 to 0.007) except for when compared to non-linear blending images for protocol B and 120 kVp images in CNR and SNR. No significant differences were found in image noise among the three kinds of images and the same kind of images in different protocols, but the lowest radiation dose was shown in protocol A. CONCLUSION: Non-linear blending technique of dual-energy CT can improve the image quality of arterial-phase abdominal CTA, especially with the Sn140/80 kVp scanning.

Pulmonary Bone Cement Embolism: CT Angiographic Evaluation with Material Decomposition Using Gemstone Spectral Imaging

We report a case of pulmonary bone cement embolism in a female who presented with dyspnea following multiple sessions of vertebroplasty. She underwent spectral CT pulmonary angiography and the diagnosis was made based on enhanced visualization of radiopaque cement material in the pulmonary arteries and a corresponding decrease in the parenchymal iodine content. Here, we describe the CT angiography findings of bone cement embolism with special emphasis on the potential benefits of spectral imaging, providing additional information on the material composition.

Assessment of Perfusion Pattern and Extent of Perfusion Defect on Dual-Energy CT Angiography: Correlations between the Causes of Pulmonary Hypertension and Vascular Parameters

OBJECTIVE: To assess perfusion patterns on a dual-energy pulmonary CT angiography (DECTA) of pulmonary hypertension (PHT) with variable causes and to assess whether the extent of perfusion defect can be used in the severity assessment of PHT. MATERIALS AND METHODS: Between March 2007 and February 2011, DECTA scans of 62 consecutive patients (24 men, 38 women; mean age, 58.5 +/- 17.3 [standard deviation] years; range, 19-87 years) with PHT were retrospectively included with following inclusion criteria; 1) absence of acute pulmonary thromboembolism, 2) maximal velocity of tricuspid regurgitation jet (TR Vmax) above 3 m/s on echocardiography performed within one week of the DECTA study. Perfusion patterns of iodine map were divided into normal (NL), diffuse heterogeneously decreased (DH), multifocal geographic and multiple peripheral wedging patterns. The extent of perfusion defects (PD), the diameter of main pulmonary artery (MPA) and the ratio of ascending aorta diameter/MPA (aortopulmonary ratio, APR) were measured. Pearson correlation analysis was performed between TR Vmax on echocardiography and CT imaging parameters. RESULTS: Common perfusion patterns of primary PHT were DH (n = 15) and NL (n = 12). The perfusion patterns of secondary PHT were variable. On the correlation analysis, in primary PHT, TR Vmax significantly correlated with PD, MPA and APR (r = 0.52, r = 0.40, r = -0.50, respectively, all p < 0.05). In secondary PHT, TR Vmax significantly correlated with PD and MPA (r = 0.38, r = 0.53, respectively, all p < 0.05). CONCLUSION: Different perfusion patterns are observed on DECTA of PHT according to the causes. PD and MPA are significantly correlated with the TR Vmax.

Dual-Energy CT in the Assessment of Mediastinal Lymph Nodes: Comparative Study of Virtual Non-Contrast and True Non-Contrast Images

OBJECTIVE: To evaluate the reliability of virtual non-contrast (VNC) images reconstructed from contrast-enhanced, dual-energy scans compared with true non-contrast (TNC) images in the assessment of high CT attenuation or calcification of mediastinal lymph nodes. MATERIALS AND METHODS: A total of 112 mediastinal nodes from 45 patients who underwent non-contrast and dual-energy contrast-enhanced scans were analyzed. Node attenuation in TNC and VNC images was compared both objectively, using computed tomography (CT) attenuation, and subjectively, via visual scoring (0, attenuation the aorta; 2, calcification). The relationship among attenuation difference between TNC and VNC images, CT attenuation in TNC images, and net contrast enhancement (NCE) was analyzed. RESULTS: CT attenuation in TNC and VNC images showed moderate agreement (intraclass correlation coefficient, 0.612). The mean absolute difference was 7.8 +/- 7.6 Hounsfield unit (HU) (range, 0-36 HU), and the absolute difference was equal to or less than 10 HU in 65.2% of cases (73/112). Visual scores in TNC and VNC images showed fair agreement (kappa value, 0.335). Five of 16 nodes (31.3%) which showed score 1 (n = 15) or 2 (n = 1) in TNC images demonstrated score 1 in VNC images. The TNC-VNC attenuation difference showed a moderate positive correlation with CT attenuation in TNC images (partial correlation coefficient [PCC] adjusted by NCE: 0.455) and a weak negative correlation with NCE (PCC adjusted by CT attenuation in TNC: -0.245). CONCLUSION: VNC images may be useful in the evaluation of mediastinal lymph nodes by providing additional information of high CT attenuation of nodes, although it is underestimated compared with TNC images.