Dual-energy computed tomography: Survey results on current uses and barriers to further implementation.

OBJECTIVE: To gauge the current availability of dual-energy computed tomography (DECT) scanners in the UK, establish available technologies, look broadly at current clinical uses in adults and paediatrics, and identify barriers to implementation and potential ways to increase use. METHODS: A survey was distributed amongst 10 radiology departments and shared on two national professional co-operation mail bases; the survey ran from 20th July to 9th December 2020. It explored current DECT utilisation in adults and paediatrics as well as barriers to use and suggestions to overcome those barriers. RESULTS: The survey demonstrated DECT availability on 39 (40%) of the 98 CT scanners, but there was limited clinical use in adults and paediatrics. Eighteen (72%) of the 25 respondents had access to at least one DECT scanner, with 14 (56%) having adult DECT protocols in clinical use; <10% head examinations and <50% for other anatomical areas. Only two (8%) respondents had DECT paediatric protocols in clinical use; <10% examinations for all anatomical areas.The main barriers to implementation identified were lack of experience with DECT (8 (44%) users (adult) and 10 (56%) users (paediatric)) and no clinical protocols available (6 (33%) users (adult and paediatric)).Understanding DECT benefits and establishing suitable protocols were the most popular suggestions for increased implementation (10 (40%) of 25 respondents). CONCLUSION: DECT scanners are available, but clinical use is limited for both adults and paediatrics. The main barriers identified were lack of experience with DECT and the availability of suitable protocols. Further work identified to help implementation included better education on the benefits of DECT, provision of clinical protocols and ensuring a multidisciplinary approach. ADVANCES IN KNOWLEDGE: Barriers to implementation of clinical DECT protocols were identified, together with potential solutions to overcome these and enable further implementation.

Clinical and Payer-Based Analysis of Value of Dual-Energy Computed Tomography for Workup of Incidental Abdominal Findings.

OBJECTIVE: To perform a clinical and payer-based analysis of the value of dual-energy computed tomography (DECT) for workup of incidental abdominal findings. METHODS: This was a single-center, retrospectively designed, Health Insurance Portability and Accountability Act-compliant study approved by our institutional review board. Sixty-nine examinations in 69 patients (45 men, 24 women; mean age, 57.7 years) who underwent single-phase postcontrast abdominal DECT studies between January 1, 2011, and December 31, 2017, were included. Two radiologists, blinded to study objective and design, reviewed all cases and identified incidental abdominal findings needing further imaging. All incidental findings were reviewed by 2 other investigators, who determined whether an imaging-based diagnosis could be made using DECT virtual noncontrast images and iodine maps. Additional studies and associated payer-reimbursement amounts avoided by use of DECT were estimated. All imaging costs were estimated based on the US Centers for Medicare & Medicaid Services reimbursement amounts. RESULTS: Thirty-four incidental findings (renal mass, n = 20; adrenal nodule, n = 8; pancreatic cystic lesions, n = 3; others, n = 3) were identified in 19 (27.5%) of 69 patients. Dual-energy computed tomography characterized 27 incidental findings in 15 patients and accounted for cost savings of 15 additional imaging examinations (abdominal magnetic resonance imaging, n = 11; abdominal computed tomography, n = 4). Based on Centers for Medicare & Medicaid Services reimbursement amounts, we estimated that, by abolishing the need for additional imaging use, DECT saved US $84.95 per patient. CONCLUSIONS: Dual-energy computed tomography can provide an imaging-based diagnosis of incidental abdominal findings, otherwise incompletely characterized on routine abdominal computed tomography, in approximately 21% of patients. In select patients, the monetary savings from abolishing additional imaging may reduce payer costs associated with use of DECT.

How to Incorporate Dual-Energy Computed Tomography Into Your Neuroradiology Practice: Questions and Answers.

Dual-energy computed tomography (DECT) has many current and evolving applications in neuroradiology including material decomposition, improving conspicuity of iodinated contrast enhancement, and artifact reduction. However, there are multiple challenges in incorporating DECT into practice including hardware selection, postprocessing software requirements, technologist and physician training, and numerous workflow issues. This article reviews in a question-and-answer format common issues that arise when incorporating DECT into a busy neuroradiology practice.

Dual-Energy Computed Tomography: Dose Reduction, Series Reduction, and Contrast Load Reduction in Dual-Energy Computed Tomography.

Evolution in computed tomography technology and image reconstruction have significantly changed practice. Dual energy computed tomography is being increasingly adopted owing to benefits of material separation, quantification, and improved contrast-to-noise ratio. The radiation dose can match that from single energy computed tomography. Spectral information derived from a polychromatic x-ray beam at different energies yields in image reconstructions that reduce the number of phases in a multiphasic examination and decrease the absolute amount of contrast media. This increased analytical and image processing capability provides new avenues for addressing radiation dose and iodine exposure concerns.

Comparison of the effect of radiation exposure from dual-energy CT versus single-energy CT on double-strand breaks at CT pulmonary angiography.

PURPOSE: To compare the effect of dual-source dual-energy CT versus single-energy CT on DNA double-strand breaks (DSBs) in blood lymphocytes at CT pulmonary angiography (CTPA). METHODS AND MATERIALS: Sixty-two patients underwent either dual-energy CTPA (Group 1: n = 21, 80/Sn140 kVp, 89/38 mAs; Group 2: n = 20, 100/Sn140 kVp, 89/76 mAs) or single-energy CTPA (Group 3: n = 21, 120 kVp, 110 mAs). Blood samples were obtained before and 5 min after CTPA. DSBs were assessed with fluorescence microscopy and Kruskal-Walls tests were used to compare DSBs levels among groups. Volume CT dose index (CTDIvol), dose length product (DLP) and organ radiation dose were compared using ANOVA. RESULTS: There were increased excess DSB foci per lymphocyte 5 min after CTPA examinations in three groups (Group 1: P = .001; Group 2: P = .001; Group 3: P = .006). There were no differences among groups regarding excess DSB foci/cell and percentage of excess DSBs (Group 1, 23%; Group 2, 24%; Group 3, 20%; P = .932). CTDIvol, DLP and organ radiation dose in Group 1 were the lowest among the groups (all P < .001). CONCLUSION: DSB is increased following dual-source and single-source CTPA, while dual-source dual-energy CT protocols do not increase the estimated radiation dose and also do not result in a higher incidence of DNA DSBs in patients undergoing CTPA.

Dual Energy CT - a Novel Technique for Diagnostic Testing of Fragility Fractures of the Pelvis.

Background The incidence of fragility fractures of the pelvis is increasing. Established methods to diagnose this condition include X-rays, computed tomography (CT) and magnetic resonance imaging (MRI). Dual energy CT (DECT) is a modern technology for the imaging of bone oedema/bruises and has been used in injuries of the extremities and spine. It is unclear whether this technique can also be used in fragility fractures of the pelvis. The aim of this study was to perform a literature research and survey of the "AG Becken III" members of the German Society of Trauma Surgery (DGU) on the usefulness of DECT in fractures of the pelvis. Material and Methods A PubMed-based literature search on DECT comprised the key words "Dual Energy CT", "Pelvis/Pelvic", "Insufficiency" and "Fractures" and their combinations. Thirty-two publications were reviewed completely (full text). Finally, 15 articles were chosen and included in the current study. The survey of the members of the "AG Becken III" was based on a questionnaire and aimed to determine the popularity and potential benefits of DECT in comparison to established diagnostic options. Results No studies on the use of DECT in fragility fractures of the pelvis were identified; the few articles found referred to fractures of the extremities and spine. The response rate to the questionnaire was 25/83 (30.1 %). The participants had a mean personal experience of 8.4 years/151.6 interventions in pelvic surgery. Although some respondents had heard of DECT, this technique - if available - was only used in other indications. However, the potential benefit of DECT was recognised, especially in the acute diagnostic testing of fragility fractures. There is limited consensus on the optimal diagnostic test (CT vs. MRI) of pelvic fractures. Conclusion Although DECT is already established for other indications and is regarded as a promising method by all respondents of the "AG Becken III", DECT is not yet routinely used for diagnostic testing of fragility fractures of the pelvis. Potential advantages of DECT include its greater sensitivity than CT in detecting bone oedema with equal radiation exposure. Unlike MRI, it is available 24 hours/7 days.

Optimal Adaptive Statistical Iterative Reconstruction Percentage in Dual-energy Monochromatic CT Portal Venography.

RATIONALE AND OBJECTIVES: The aim of this article was to study the influence of different adaptive statistical iterative reconstruction (ASIR) percentages on the image quality of dual-energy computed tomography (DECT) portal venography in portal hypertension patients. MATERIALS AND METHODS: DECT scans of 40 patients with cirrhosis (mean age, 56 years) at the portal venous phase were retrospectively analyzed. Monochromatic images at 60 and 70 keV were reconstructed with four ASIR percentages: 0%, 30%, 50%, and 70%. Computed tomography (CT) numbers of the portal veins (PVs), liver parenchyma, and subcutaneous fat tissue in the abdomen were measured. The standard deviation from the region of interest of the liver parenchyma was interpreted as the objective image noise (IN). The contrast-noise ratio (CNR) between PV and liver parenchyma was calculated. The diagnostic acceptability (DA) and sharpness of PV margins were obtained using a 5-point score. The IN, CNR, DA, and sharpness of PV were compared among the eight groups with different keV + ASIR level combinations. RESULTS: The IN, CNR, DA, and sharpness of PV of different keV + ASIR groups were all statistically different (P < 0.05). In the eight groups, the best and worst CNR were obtained in the 60 keV + 70% ASIR and 70 keV + 0% ASIR (filtered back-projection [FBP]) combination, respectively, whereas the largest and smallest objective IN were obtained in the 60 keV + 0% ASIR (FBP) and 70 keV + 70% combination. The highest DA and sharpness values of PV were obtained at 50% ASIR for 60 keV. CONCLUSIONS: An optimal ASIR percentage (50%) combined with an appropriate monochromatic energy level (60 keV) provides the highest DA in portal venography imaging, whereas for the higher monochromatic energy (70 keV) images, 30% ASIR provides the highest image quality, with less IN than 60 keV with 50% ASIR.

Model-Based Iterative Reconstruction for Dual-Energy X-Ray CT Using a Joint Quadratic Likelihood Model.

Dual-energy X-ray CT (DECT) has the potential to improve contrast and reduce artifacts as compared to traditional CT. Moreover, by applying model-based iterative reconstruction (MBIR) to dual-energy data, one might also expect to reduce noise and improve resolution. However, the direct implementation of dual-energy MBIR requires the use of a nonlinear forward model, which increases both complexity and computation. Alternatively, simplified forward models have been used which treat the material-decomposed channels separately, but these approaches do not fully account for the statistical dependencies in the channels. In this paper, we present a method for joint dual-energy MBIR (JDE-MBIR), which simplifies the forward model while still accounting for the complete statistical dependency in the material-decomposed sinogram components. The JDE-MBIR approach works by using a quadratic approximation to the polychromatic log-likelihood and a simple but exact nonnegativity constraint in the image domain. We demonstrate that our method is particularly effective when the DECT system uses fast kVp switching, since in this case the model accounts for the inaccuracy of interpolated sinogram entries. Both phantom and clinical results show that the proposed model produces images that compare favorably in quality to previous decomposition-based methods, including FBP and other statistical iterative approaches.

Congenital anomalies of coronary arteries in complex congenital heart disease: diagnosis and analysis with dual-source CT.

BACKGROUND: Congenital heart diseases (CHDs) are sometimes associated with coronary artery anomalies (CAAs). Accurate preoperative evaluation of coronary artery anatomy is essential for successful surgical repair of complex CHD. OBJECTIVE: The aim of this study was to evaluate the incidence of congenital CAAs in patients with complex CHD at dual-source CT. METHODS: Four hundred seventeen consecutive patients with complex CHD underwent contrast-enhanced cardiac CT angiography. The results were retrospectively analyzed, including the types and incidences of CAAs in various forms of complex CHD. Each patient was analyzed independently by 2 experienced cardiovascular radiologists. Image quality of coronary arteries was assessed on a 5-point scale with 2 or less being nondiagnostic. RESULTS: Thirty-five of 417 studies were nondiagnostic (8.39%). Sixty-three cases of CAA (15.11%) were detected by anomalous ostia and coronary arteries. CAA was involved in 6 of 108 patients with tetralogy of Fallot (5.56%), 18 of 84 patients with double outlet right ventricle (21.43%), 11 of 97 patients with pulmonary artery atresia (11.34%), 7 of 36 patients with transposition of the great arteries (22.22%), 15 of 41 patients with single ventricle (36.59%), 4 of 12 patients with truncus arteriosus/aortopulmonary window (33.33%), and 2 of 39 patients with interruption of the aortic arch/coarctation of the aorta (5.13%). Twenty of these were accompanied with an anomalous coronary course (31.74%). CONCLUSION: Patients with complex CHD have a higher prevalence of CAAs, which should be considered before surgery. Dual-source CT is an effective technique to visualize and evaluate complex CHD.

Utility of dual phase liver CT for metastatic melanoma staging and surveillance.

RATIONALE AND OBJECTIVES: To evaluate the clinical utility of dual phase computed tomography (CT) for assessment of hepatic metastases in patients with metastatic melanoma. MATERIALS AND METHODS: A retrospective case-control study of dual phase CT examinations consisting of late hepatic arterial and portal venous phases performed on patients with melanoma was undertaken. In 2010, 420 dual phase CT examinations were performed on 188 patients. Of these, 46 CT examinations on 24 patients with hepatic metastases were combined with 52 control studies for evaluation. Two blinded reviewers independently evaluated single portal venous phase alone and dual phase imaging on separate occasions. The presence of hepatic lesions, the conspicuity of the lesions, and the likelihood that the detected lesions were metastases was recorded. Agreement between readers, sensitivity and specificity was calculated. RESULTS: In no case was hepatic metastatic disease only apparent on arterial phase imaging. Arterially enhancing hepatic lesions only visible on the arterial phase or much more conspicuous on the arterial phase were present in 10 studies (10%), all of which were benign. Liver metastases were rated as being more accurately assessed on the portal venous phase in up to 100%. In a per scan analysis dual phase and venous phase imaging had similar sensitivities of 96% (95%, CI: 86-100) and 98% (95%, CI: 89-100), respectively. CONCLUSION: Single portal venous phase imaging is adequate for staging and surveillance in patients with metastatic melanoma.

Estimated radiation dose and image quality comparison of the scan protocols in dual-source computed tomography coronary angiography.

INTRODUCTION: Radiation exposure from computed tomography coronary angiography (CTCA) is of particular concern and several techniques have been introduced to lower the radiation dose. In this study, we aimed to compare the diagnostic image quality and estimated radiation dose of the three CTCA acquisition protocols in a recently introduced second generation dual-source computed tomography. METHODS: Two hundred consecutive subjects underwent dual-source CTCA by using high-pitch spiral, sequential and retrospective spiral protocols. Effective radiation dose, expressed in millisieverts, was calculated as the product of the dose-length product times a conversion factor of 0.014. Image quality was evaluated on a per-segment basis, with a four-point scale. RESULTS: For the high-pitch spiral, sequential and retrospective spiral protocols, mean effective radiation doses were 1.41 ± 0.56, 5.50 ± 2.06 and 7.79 ± 2.25 mSv and mean per-subject image scores were 2.8 ± 0.7, 2.2 ± 0.8 and 2.5 ± 0.8, respectively. Radiation dose of the high-pitch mode was significantly lower (P < 0.001) than the sequential and retrospective spiral modes, and statistical analysis for image quality revealed a significant difference between the high-pitch spiral and the sequential modes (P < 0.05). CONCLUSION: Dual-source CTCA using high-pitch acquisition considerably lowers radiation exposure in subjects with a low and stable heart rate and maintains good image quality, especially when the subjects have a body mass index ≤25 and a tube voltage of 80 or 100 kV is used. However, when sequential and retrospective spiral modes are used in the same device, mean radiation doses can increase roughly three and five times more, respectively.

Second-generation dual-energy computed tomography of the abdomen: radiation dose comparison with 64- and 128-row single-energy acquisition.

PURPOSE: This study was designed to compare the radiation dose in abdominal dual-energy (DE) and single-energy (SE) acquisitions obtained in clinical practice with a second-generation DE computed tomography (DECT) and to analyze the dose variation in comparison with an SE acquisition performed with a 64-row SECT (SECT). METHODS: A total of 130 patients divided into 2 groups underwent precontrast and portal abdominal 128-row CT examination. In group A, DE portal acquisition was performed using a detector configuration of 2 × 40 × 0.6 mm, tube A at 80 kVp and a reference value of 559 mAs, tube B at 140 kVp and a reference value of 216 mAs, pitch 0.6, and online dose modulation; group B underwent SE portal acquisition using a detector configuration of 64 × 0.6 mm, 120 kVp and a reference value of 180 mAs, pitch 0.75, and online dose modulation. Group C consisted of 32 subjects from group A previously studied with 64-row SECT using the following parameters: detector configuration 64 × 0.6 mm, 120 kVp and a reference value of 180 mAs, pitch 0.75, and online dose modulation. In each group, the portal phase dose-length product and radiation dose (mSv) were calculated and normalized for a typical abdominal acquisition of 40 cm. RESULTS: After normalization to standard 40-cm acquisition, a dose-length product of 599.0 ± 133.5 mGy · cm (range, 367.5 ± 1231.2 mGy · cm) in group A, 525.9 ± 139.2 mGy · cm (range, 215.7-882.8 mGy · cm) in group B, and 515.9 ± 111.3 mGy · cm (range, 305.5-687.2 mGy · cm) in group C was calculated for portal phase acquisition.A significant radiation dose increase (P < 0.05) was observed in group A (10.2 ± 2.3 mSv) compared with group B (8.9 ± 2.4) and group C (8.8 ± 1.9 mSv). No significant difference (P > 0.05) was reported between SE 64- and 128-row acquisitions. A significant positive correlation between radiation dose and body mass index was observed in each group (group A, r = 0.59, P < 0.0001; group B, r = 0.35, P < 0.0001; group C, r = 0.20, P = 0.0098). CONCLUSIONS: In clinical practice, abdominal DECT acquisition shows a significant but minimal radiation dose increase, on the order of 1 mSv, compared with 64- and 128-row SE acquisition. The slightly increased radiation dose can be justified if the additional information obtained using a spectral imaging approach directly impacts on patient management or reduce the overall radiation dose with the generation of virtual unenhanced images, which can replace the precontrast acquisition.

Diagnostic accuracy of dual-source CT coronary angiography in patients with atrial fibrillation: meta analysis.

RATIONALE AND OBJECTIVE: To synthesize the available data to underscore the diagnostic accuracy of dual-source CT (DSCT) coronary angiography in patients with atrial fibrillation (AF). MATERIALS AND METHODS: We searched in the electronic databases of PubMed for all published studies that examined patients with AF using DSCT. We used an exact binomial rendition of the bivariate mixed-effects regression model to synthesize the diagnostic data. RESULTS: The positive and negative likelihood ratios (LRs) at the patient level were 6.0 (CI, 3.6-10.1) and 0.03(CI, 0.004-0.2), respectively. The negative predictive values higher than 90% were available for a CAD prevalence <78%. The pooled vessel- and segment-level estimates showed higher positive and negative LRs than the patient-level estimates (15.3 [CI, 9.8-23.9] and 0.1 [CI, 0.07-0.3]; 25.1 [CI, 10.8-58.5] and 0.2 [CI, 0.2-0.3], respectively). No statistically significant heterogeneity between studies and publication bias were found at the patient level estimate. A sensitivity analysis showed that no study influenced the pooled results larger than 0.02. CONCLUSIONS: Cardiac angiography with DSCT can be applied as an imaging test for ruling out CAD in patient with AF. However, DSCT angiography may be not an effective tool for risk stratification for the high negative LR at the artery and segment levels.

Clinical utility of ultra high pitch dual source thoracic CT imaging of acute pulmonary embolism in the emergency department: are we one step closer towards a non-gated triple rule out?

OBJECTIVES/PURPOSE: Aim of this study was to retrospectively compare the image quality and the radiation dose of an ultra high pitch CT scan for the evaluation of pulmonary embolism and visualization of cardiac structures in comparison to our institution's standard pulmonary embolism protocol. METHOD AND MATERIALS: The study cohort consisted of 115 consecutive patients, 57 underwent CT pulmonary angiography on a dual source 128 slice scanner (Siemens Somatom Definition FLASH) via an ultra high pitch mode (Pitch 2.8) while 58 were scanned on a dual source 64 slice scanner (Siemens Somatom Definition Dual Source) with standard pitch (Pitch 0.9). Qualitative image assessment was determined by two blinded radiologists with 3 and 15 years' experience in chest and cardiac CT. Quantitative image assessment was determined by the signal to noise ratio (SNR) and contrast to noise ratio (CNR). Effective radiation dose was calculated via the product of the dose length product. RESULTS: For the ultra high pitch protocol, 14% (8/57) were positive for pulmonary embolus compared to 13.7% (8/58) for the standard pitch group. 98.2% of the ultra high pitch scans were diagnostic for pulmonary embolus vs. 94.8% of the standard protocol. Visualization of cardiac structures was significantly improved with the ultra high pitch protocol (p<0.0001). Significantly more lung parenchymal motion was observed on the standard protocol (p<0.0001). The mean pulmonary vessel attenuation, SNR, and CNR were not significantly different. The mean effective dose was lower for the ultra high pitch studies (4.09mSv±0.78 vs. 7.72mSv±2.60, p<0.0001). CONCLUSION: Ultra high pitch CT imaging for pulmonary embolus is a technique which has potential to assess motion free evaluation of most cardiac structures and proximal coronary arteries at lower radiation doses.

Influence of vascular enhancement, age and gender on pulmonary perfused blood volume quantified by dual-energy-CTPA.

OBJECTIVES: To determine the influence of technical and demographic parameters on quantification of pulmonary perfused blood volume (PBV) in dual energy computed tomography pulmonary angiography (DE-CTPA). MATERIALS AND METHODS: Pulmonary PBV was quantified in 142 patients who underwent DE-CTPA for suspected pulmonary embolism but in whom no thoracic pathologies were detected. Multivariate linear regression analysis was performed to calculate the influence of age, gender, enhancement of pulmonary trunk and enhancement difference between pulmonary trunk and left atrium (as a measure of timing) on PBV values. The resulting regression coefficients were used to calculate age-specific ranges of normal for PBV values adjusted for vascular enhancement and timing. RESULTS: Enhancement of the pulmonary trunk (ß=-0.29, p=0.001) and enhancement difference between pulmonary trunk and left atrium (ß=-0.24, p=0.003) were found to significantly influence PBV values. Age (ß=-0.33, p<0.001) but not gender (ß=0.14, p=0.05) had a significant negative influence on pulmonary PBV values. There was a 20% relative decrease of pulmonary PBV from patients aged <30 to patients over 80 years of age. CONCLUSIONS: DE-CTPA derived PBV values need to be corrected for age, vascular enhancement and timing but not for gender. The age-specific ranges of normal derived from this study can be used as a reference in future studies of PBV in pulmonary pathologies.

Comparison of dual-energy subtraction and electronic bone suppression combined with computer-aided detection on chest radiographs: effect on human observers' performance in nodule detection.

OBJECTIVE: The objective of our study was to compare the effect of dual-energy subtraction and bone suppression software alone and in combination with computer-aided detection (CAD) on the performance of human observers in lung nodule detection. MATERIALS AND METHODS: One hundred one patients with from one to five lung nodules measuring 5-29 mm and 42 subjects with no nodules were retrospectively selected and randomized. Three independent radiologists marked suspicious-appearing lesions on the original chest radiographs, dual-energy subtraction images, and bone-suppressed images before and after postprocessing with CAD. Marks of the observers and CAD marks were compared with CT as the reference standard. Data were analyzed using nonparametric tests and the jackknife alternative free-response receiver operating characteristic (JAFROC) method. RESULTS: Using dual-energy subtraction alone (p = 0.0198) or CAD alone (p = 0.0095) improved the detection rate compared with using the original conventional chest radiograph. The combination of bone suppression and CAD provided the highest sensitivity (51.6%) and the original nonenhanced conventional chest radiograph alone provided the lowest (46.9%; p = 0.0049). Dual-energy subtraction and bone suppression provided the same false-positive (p = 0.2702) and true-positive (p = 0.8451) rates. Up to 22.9% of lesions were found only by the CAD program and were missed by the readers. JAFROC showed no difference in the performance between modalities (p = 0.2742-0.5442). CONCLUSION: Dual-energy subtraction and the electronic bone suppression program used in this study provided similar detection rates for pulmonary nodules. Additionally, CAD alone or combined with bone suppression can significantly improve the sensitivity of human observers for pulmonary nodule detection.

Effectiveness of automated quantification of pulmonary perfused blood volume using dual-energy CTPA for the severity assessment of acute pulmonary embolism.

PURPOSE: The purpose of this study was to determine whether automated quantification of pulmonary perfused blood volume (PBV) in dual-energy computed tomography pulmonary angiography is of diagnostic value in assessing the severity of acute pulmonary embolism (PE). MATERIALS AND METHODS: Ethical approval and informed consent were waived by the responsible institutional review board for this retrospective study. Of 224 consecutive patients with dual-energy computed tomography pulmonary angiographic findings positive for acute PE, we excluded 153 patients because of thoracic comorbidities (n = 130), missing data (n = 11), severe artifacts (n = 11), or inadequate enhancement (n = 1). Automated quantification of PBV was performed in the remaining 71 patients (mean [SD] age, 62 [16] years) with acute PE and no cardiopulmonary comorbidities. Perfused blood volume values adjusted for age and sex were correlated with the Qanadli obstruction score, morphological computed tomographic signs of right heart dysfunction, serum levels of troponin, and the necessity for intensive care unit (ICU) admission. RESULTS: Dual-energy computed tomography pulmonary angiography-derived PBV values inversely correlated with the Qanadli score (r = -0.46; P < 0.001), the right and left ventricle (RV/LV) ratio (r = -0.52; P < 0.001), and troponin I (r = -0.45; P = 0.001). The patients with global PBV values lower than 60% were significantly more likely to require admission to an ICU than did the patients with global pulmonary PBV of 60% or higher (47% vs 11%; P = 0.003; positive predictive value, 47%; negative predictive value, 89%). On the univariate analysis, a significant negative correlation was found between the global PBV values and the Qanadli obstruction score (r = -0.46; P < 0.001), the RV/LV diameter ratio (r = -0.52; P < 0.001), and the necessity for ICU admission (r = -0.39; P = 0.001). On the retrospective multivariate regression analysis, the areas under the receiver operating characteristic curve for the prediction of ICU admission were 0.75 for the pulmonary PBV, 0.83 for the Qanadli obstruction score, 0.68 for the computed tomographic signs of right heart dysfunction (interventricular septal bowing and/or contrast reflux), and 0.76 for the RV/LV diameter ratio. CONCLUSIONS: Dual-energy computed tomography pulmonary angiography can be used for an immediate, reader-independent estimation of global pulmonary PBV in acute PE, which inversely correlates with thrombus load, laboratory parameters of PE severity, and the necessity for ICU admission.

Impact of coronary calcium score on the prevalence of coronary artery stenosis on dual source CT coronary angiography in caucasian patients with an intermediate risk.

PURPOSE: To investigate the prevalence of significant coronary artery stenosis on coronary computed tomography angiography (cCTA) in symptomatic Caucasian patients with an intermediate risk score at different levels of coronary artery calcification (CAC). METHOD: In total, 383 consecutive symptomatic Caucasian patients (147 females, 60 ± 13 years) with an intermediate risk score underwent nonenhanced CT for CAC scoring immediately before contrast-enhanced cCTA on a dual-source CT scanner. Additionally clinically indicated invasive coronary angiography (ICA) was performed in 90 patients. The prevalence of significant coronary artery stenosis (>50%) on cCTA and ICA was correlated at different CAC score levels. RESULTS: Of 121 patients with a zero CAC score, none had significant coronary artery stenosis on cCTA or ICA. Coronary CTA diagnosed in 54 of 70 patients with high CAC score (>400), a significant stenosis. Subsequent ICA confirmed significant stenosis in 30 of 32 patients. Sensitivity and a negative predictive value of CAC score ruling out significant stenosis on cCTA were 100% and 100%, respectively, using cutoff value of zero and specificity and positive predictive value to predict significant stenosis on cCTA were 79% and 51%, respectively, using a cutoff value of >400. CONCLUSION: Significant coronary artery stenosis is extremely unlikely, with an estimated risk of 4 in 1000 patients in symptomatic Caucasian patients with an intermediate risk score and negative CAC score. To reduce radiation exposure, radiation-free tests should be considered for differential diagnosis of chest pain in these patients.

Prognostic value of perfusion defect volume at dual energy CTA in patients with pulmonary embolism: correlation with CTA obstruction scores, CT parameters of right ventricular dysfunction and adverse clinical outcome.

PURPOSE: To investigate the prognostic value of perfusion defect volume (PDvol) at dual-energy-CT-angiography (DE-CTA) in patients with acute pulmonary embolism (PE) by correlating PDvol with CTA-obstruction-scores (OS), CT parameters of right-ventricular-dysfunction (RVD), and adverse-clinical-outcome. MATERIALS AND METHODS: DE-CTA of 60 patients (mean age: 65±14.4 years) with PE were analyzed. Iodine maps were generated, and normalized PDvol--defined as volume of perfusion defects/total lung volume--was quantified. Furthermore, established prognostic parameters (Qanadli and Mastora-OS, and CT parameters of RVD) were obtained. CT parameters of RVD--namely the right ventricle/left ventricle (RV/LV) diameter ratio measured on transverse sections (RV/LVtrans), four-chamber views (RV/LV4ch), and RV/LV volume ratios (RV/LVvol)--were assessed. PDvol was correlated with OS, CT parameters of RVD and adverse clinical outcome (defined as the need for intensive care treatment or death). RESULTS: 10 of 60 patients with PE experienced adverse clinical outcome. Patients with adverse clinical outcome showed significantly higher PDvol (35±11% vs. 23±10%, p=0.002), RV/LV ratios (RV/LV4ch 1.46±0.32 vs. 1.18±0.26, p=0.005; RV/LVvol 2.25±1.33 vs. 1.19±0.56, p=0.002) and higher Mastora global scores (52 vs. 13, p=0.02) compared to those without adverse clinical outcome. A weak correlation was observed between PDvol and the Mastora global score (r=0.5; p=0.0003), as well as between PDvol and RV/LV4Ch (r=0.432, p=0.0006). No correlation was found between PDvol and the Qanadli score or the remainder of the RVD-CT parameters. CONCLUSION: The extent of perfusion defects as assessed by DE-CTA correlates with adverse clinical outcome in patients with PE. Therefore, volumetric quantification of perfusion defects at DE-CTA allows the identification of low-risk patients who do not require intensified monitoring and treatment.