Dual-energy Perfusion CT Research Articles

Dual-energy CT perfusion and angiography in chronic thromboembolic pulmonary hypertension: diagnostic accuracy and concordance with radionuclide scintigraphy

To evaluate the diagnostic accuracy of dual-energy computed tomography (DECT) perfusion and angiography versus ventilation/perfusion (V/Q) scintigraphy in chronic thromboembolic pulmonary hypertension (CTEPH), and to assess the per-segment concordance rate of DECT and scintigraphy. Forty consecutive patients with proven pulmonary hypertension underwent V/Q scintigraphy and DECT perfusion and angiography. Each imaging technique was assessed for the location of segmental defects. Diagnosis of CTEPH was established when at least one segmental perfusion defect was detected by scintigraphy. Diagnostic accuracy of DECT perfusion and angiography was assessed and compared with scintigraphy. In CTEPH patients, the per-segment concordance between scintigraphy and DECT perfusion/angiography was calculated. Fourteen patients were diagnosed with CTEPH and 26 with other aetiologies. DECT perfusion and angiography correctly identified all CTEPH patients with sensitivity/specificity values of 1/0.92 and 1/0.93, respectively. At a segmental level, DECT perfusion showed moderate agreement (κ = 0.44) with scintigraphy. Agreement between CT angiography and scintigraphy ranged from fair (κ = 0.31) to slight (κ = 0.09) depending on whether completely or partially occlusive patterns were considered, respectively. Both DECT perfusion and angiography show satisfactory performance for the diagnosis of CTEPH. DECT perfusion is more accurate than angiography at identifying the segmental location of abnormalities. • Chronic thromboembolic pulmonary hypertension (CTEPH) is potentially treatable by surgery. • Dual-energy computed tomography (DECT) allows angiography and perfusion using a single acquisition. • Both DECT perfusion and angiography showed satisfactory diagnostic performance in CTEPH. • DECT perfusion was more accurate than angiography in identifying segmental abnormalities.

Volumetric evaluation of dual-energy perfusion CT by the presence of intrapulmonary clots using a 64-slice dual-source CT

Dual-energy perfusion CT (DEpCT) directly represents the iodine distribution in lung parenchyma and low perfusion areas caused by intrapulmonary clots (IPCs) are visualized as low attenuation areas. To evaluate if volumetric evaluation of DEpCT can be used as a predictor of right heart strain by the presence of IPCs. One hundred and ninety-six patients suspected of having acute pulmonary embolism (PE) underwent DEpCT using a 64-slice dual-source CT. DEpCT images were three-dimensionally reconstructed with four threshold ranges: 1-120 HU (V₁₂₀), 1-15 HU (V₁₅), 1-10 HU (V₁₀), and 1-5 HU (V₅). Each relative ratio per V₁₂₀ was expressed as the %V₁₅, %V₁₀, and %V₅. Volumetric data-sets were compared with D-dimer, pulmonary arterial (PA) pressure, right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio, PA diameter, and PA/aorta (PA/Ao) diameter ratio. The areas under the ROC curves (AUCs) were examined for their relationship to the presence of IPCs. This study was approved by the local ethics committee. PA pressure and D-dimer were significantly higher in the patients who had IPCs. In the patients with IPCs, V₁₅, V₁₀, V₅, %V₁₅, %V₁₀, and %V₅ were also significantly higher than those without IPC (P ≤ 0.001). %V₅ had a better correlation with D-dimer (r = 0.30, P < 0.001) and RV/LV diameter ratio (r = 0.27, P < 0.001), and showed a higher AUC (0.73) than the other CT measurements. The volumetric evaluation by DEpCT had a correlation with D-dimer and RV/LV diameter ratio, and the relative ratio of volumetric CT measurements with a lower attenuation threshold might be recommended for the analysis of acute PE.

Different Perfusion Pattern Between Acute and Chronic Pulmonary Thromboembolism: Evaluation With Two-Phase Dual-Energy Perfusion CT

The purpose of this study was to evaluate whether two-phase dual-energy CT can differentiate between lung perfusion patterns of patients with chronic pulmonary thromboembolism (PTE) and those of patients with acute PTE. A total of 114 patients clinically suspected to have PTE were prospectively enrolled. All patients underwent dual-energy CT at pulmonary artery (PA) and delayed phases. Of 68 patients diagnosed with PTE on CT, 42 were finally included. Iodine-related attenuation values (IRAs) were measured in PA and delayed phases for each lung segment, and IRA change ratios were calculated using the formula 100% × [(IRA of delayed phase) - (IRA of PA phase)]/(IRA of PA phase). Among the 42 patients (19 men and 23 women; mean age, 60.3 ± 13.2 years; range, 28-82 years), 24 had a diagnosis of acute PTE and 18 of chronic PTE. Those segments with both perfusion and filling defects (n = 143) in patients with acute PTE showed no significant changes of mean IRA between PA and delayed phases, whereas the segments from patients with chronic PTE (n = 94) showed significantly increased IRA on delayed phase as compared with PA phase. The mean IRA change ratios in acute and chronic PTE were -3.14% and 191.9%, respectively (p < 0.0001). Chronic PTE segments were significantly more enhanced on the delayed phase of two-phase dual-energy CT images than were acute PTE segments, possibly resulting from more extensive systemic collateral formation in chronic PTE. Two-phase dual-energy CT can be used to differentiate distinct regional perfusion patterns between acute and chronic PTE.

Dual-energy perfusion CT of non-diseased lung segments using dual-source CT: correlation with perfusion SPECT

To determine the utility of dual-energy perfusion CT (DEpCT) of non-diseased lung segments, using dual-source CT, in comparison with perfusion single-photon emission computed tomography (SPECT). 28 patients (18 male and 10 female; mean age 63 years; age range 18-86 years) underwent DEpCT and SPECT within a 3-day interval. The presence and location of perfusion defects in each segment of the lungs were evaluated. Perfusion defects were noted in 7 of 361 segments (1.9%) by DEpCT and in 19 of 361 segments (5.3%) by perfusion SPECT. DEpCT was in good agreement with perfusion SPECT for 338 of 361 segments (93.6%). Intraobserver agreement was also good, ranging from 93.4 to 93.6% (κ = 0.64-0.75, p < 0.01). For non-diseased lung segments, DEpCT correlated well with SPECT.

Dual-energy perfusion-CT of pancreatic adenocarcinoma

PurposeTo evaluate the feasibility of dual-energy CT (DECT)-perfusion of pancreatic carcinomas for assessing the differences in perfusion, permeability and blood volume of healthy pancreatic tissue and histopathologically confirmed solid pancreatic carcinoma. Materials and methods24 patients with histologically proven pancreatic carcinoma were examined prospectively with a 64-slice dual source CT using a dynamic sequence of 34 dual-energy (DE) acquisitions every 1.5s (80ml of iodinated contrast material, 370mg/ml, flow rate 5ml/s). 80kVp, 140kVp, and weighted average (linearly blended M0.3) 120kVp-equivalent dual-energy perfusion image data sets were evaluated with a body-perfusion CT tool (Body-PCT, Siemens Medical Solutions, Erlangen, Germany) for estimating perfusion, permeability, and blood volume values. Color-coded parameter maps were generated. ResultsIn all 24 patients dual-energy CT-perfusion was. All carcinomas could be identified in the color-coded perfusion maps. Calculated perfusion, permeability and blood volume values were significantly lower in pancreatic carcinomas compared to healthy pancreatic tissue. Weighted average 120kVp-equivalent perfusion-, permeability- and blood volume-values determined from DE image data were 0.27±0.04min−1 vs. 0.91±0.04min−1 (p<0.0001), 0.5±0.07 *0.5min−1 vs. 0.67±0.05 *0.5min−1 (p=0.06) and 0.49±0.07min−1 vs. 1.28±0.11min−1 (p<0.0001). Compared with 80 and 140kVp the standard deviations of the kVp120kVp-equivalent values were manifestly smaller. ConclusionDual-energy CT-perfusion of the pancreas is feasible. The use of DECT improves the accuracy of CT-perfusion of the pancreas by fully exploiting the advantages of enhanced iodine contrast at 80kVp in combination with the noise reduction at 140kVp. Therefore using dual-energy perfusion data could improve the delineation of pancreatic carcinomas.

Analysis of perfusion defects by causes other than acute pulmonary thromboembolism on contrast-enhanced dual-energy CT in consecutive 537 patients

To assess causes, incidence and patterns of perfusion defects (PDs) on dual-energy perfusion CT angiography (DECTA) in clinically suspected acute pulmonary thromboembolisms (PTE). Consecutive 537 patients who underwent DECTA for suspicion of PTE were retrospectively reviewed. After excluding patients with possible PTE or unsatisfactory perfusion map quality, 299 patients with 1697 lobes were included. The DECTA (Somatom Definition, Siemens) was performed at 140kV and 80kV. Color-coded perfusion images were obtained with a lung PBV application of the workstation software (Syngo Dual Energy). The presence, incidence, three patterns of PDs (wedge-shaped, heterogeneous, and regionally homogeneous), pulmonary diseases, and the matchedness between the PD and the disease extent were studied. 315 of 1697 lobes (18.6%) in 156 of 299 patients (81.3%) showed PDs. Among them, 51 (3%), 257 (15.1%), and 7 (0.4%) lobes had PDs due to vascular, nonvascular, and unidentifiable causes, respectively. Vascular causes include: pulmonary arterial (PA) hypertension (0.7%), extrinsic occlusion of PA by fibrosis (0.6%), PA hypoplasia (0.6%), vasculitis (0.5%), cancer mass compressing PA, venous occlusion, AVM, and pulmonary angiosarcoma. Most of PDs were wedge-shaped and well-matched. Nonvascular causes include: mosaic attenuation (4.1%), emphysema (3.2%), interstitial fibrosis (1.6%), bronchitis (1.4%), GGO (1.2%), cellular bronchiolitis (1%), bronchiectasis, airway obstruction, compensaroty lung hyperinflation, air trapping, cor-pulmonale, bronchopneumonia, physiologic decreased ventilation, and segmental bronchial atresia. Most of PDs showed heterogeneous pattern and were not matched. Various vascular and nonvascular diseases cause PDs on DECTA. Each disease shows different pattern of PD depending on pathophysiology and physiologic compensation.

The low attenuation area on dual-energy perfusion CT: Correlation with the pulmonary function tests and quantitative CT measurements

PurposeTo retrospectively investigate the distribution of the low attenuation area (LAA) on dual energy perfusion CT (DEpCT) in comparison with the results of pulmonary function tests (PFTs) and quantitative CT measurements. Materials and methodsTwenty-eight patients (15 male and 13 female; mean age: 62.21 years) underwent DEpCT and PFTs within a 1-month interval. The ranges of the LAA on DEpCT were classified into six groups with attenuation values of 0–3, 0–5, 0–8, 0–10, 0–13 and 0–15HU and the ratios of LAA in each group were compared with the percentage of forced expiratory volume in the 1st second (%FEV1.0), FEV1.0/forced vital capacity (FEV1.0/FVC) and the relative area of the lung with attenuation coefficients lower than −950HU (RA−950). ResultsThe LAAs on the DEpCT images were significantly correlated with the RA−950, %FEV1.0 and FEV1.0/FVC, and the regression analysis showed that the best values of LAA on DEpCT were 0–10HU with RA−950 (r=0.63), 0–8HU with %FEV1.0 (r=−0.52) and 0–8HU with FEV1.0/FVC (r=−0.61) per patient. ConclusionThe iodine disturbance on DEpCT had a moderate correlation with the results of the PFTs and RA−950, but further examination would be needed for evaluation of iodine distribution.

Incremental value of dual-energy CT to coronary CT angiography for the detection of significant coronary stenosis: comparison with quantitative coronary angiography and single photon emission computed tomography

To determine the value of dual-energy CT (DECT) and combined information of perfusion and angiography in diagnosing coronary artery disease (CAD), with single photon emission computed tomography (SPECT) and quantitative coronary angiography (QCA) as a reference standard. Thirty-four patients were enrolled in this study. DECT was used as a contrast-enhanced retrospectively ECG-gated scan protocol during the rest state and tubes were set at 140/100 kV. DECT angiography (DE-CTA) and DECT perfusion (DE-CTP) were calculated from two kV images. DE-CTP results were compared with SPECT and DE-CTA with QCA, respectively. The combined DE-CTP with DE-CTA data were compared to QCA in diagnosis of obstructive CAD (stenosis ≥ 50%). DECT showed diagnostic image quality in 31 patients. Using SPECT as a reference, DE-CTP had sensitivity of 68%, specificity of 93%, and sensitivity of 81%, and specificity of 92% for identifying any type of perfusion deficits on the segment- and territory-based analysis, respectively. Using QCA as a reference standard, DE-CTA showed sensitivity of 82%, specificity of 91% and accuracy of 86% for detecting ≥50% coronary stenosis on the vessel-based analysis, whereas the combination of DE-CTA and DE-CTP gave sensitivity of 90%, specificity of 86% and accuracy of 88% for detecting ≥50% coronary stenosis, respectively. Combination of DE-CTP and DE-CTA may improve diagnostic performance compared to CTA alone for the diagnosis of significant coronary stenosis.

Imaging of acute pulmonary embolism using a dual energy CT system with rapid kVp switching: Initial results

PurposeComputed tomography pulmonary angiography (CTPA) is considered as clinical gold standard for diagnosing pulmonary embolism (PE). Whereas conventional CTPA only offers anatomic information, dual energy CT (DECT) provides functional information on blood volume as surrogate of perfusion by assessing the pulmonary iodine distribution. The purpose of this study was to evaluate the feasibility of lung perfusion imaging using a single-tube DECT scanner with rapid kVp switching. Materials and methodsFourteen patients with suspicion of acute PE underwent DECT. Two experienced radiologists assessed the CTPA images and lung perfusion maps regarding the presence of PE. The image quality was rated using a semi-quantitative 5-point scale: 1 (=excellent) to 5 (=non-diagnostic). Iodine concentrations were quantified by a ROI analysis. ResultsSeventy perfusion defects were identified in 266 lung segments: 13 (19%) were rated as consistent with PE. Five patients had signs of PE at CTPA. All patients with occlusive clots were correctly identified by DECT perfusion maps. On a per patient basis the sensitivity and specificity were 80.0% and 88.9%, respectively, while on a per segment basis it was 40.0% and 97.6%, respectively. None of the patients with a homogeneous perfusion map had an abnormal CTPA. The overall image quality of the perfusion maps was rated with a mean score of 2.6±0.6. There was a significant ventrodorsal gradient of the median iodine concentrations (1.1mg/cm3 vs. 1.7mg/cm3). ConclusionLung perfusion imaging on a DE CT-system with fast kVp-switching is feasible. DECT might be a helpful adjunct to assess the clinical severity of PE.

Adenosine-stress dynamic real-time myocardial perfusion CT and adenosine-stress first-pass dual-energy myocardial perfusion CT for the assessment of acute chest pain: Initial results

PurposeRecent innovations in CT enable the evolution from mere morphologic imaging to dynamic and functional testing. We describe our initial experience performing myocardial stress perfusion CT in a clinical population with acute chest pain. Methods and materialsMyocardial stress perfusion CT was performed on twenty consecutive patients (15 men, 5 women; mean age 65±8 years) who presented with acute chest pain and were clinically referred for stress/rest SPECT and cardiac MRI. Prior to CT each patient was randomly assigned either to Group A or to Group B in a consecutive order (10 patients per group). Group A underwent adenosine-stress dynamic real-time myocardial perfusion CT using a novel “shuttle” mode on a 2nd generation dual-source CT. Group B underwent adenosine-stress first-pass dual-energy myocardial perfusion CT using the same CT scanner in dual-energy mode. Two experienced observers visually analyzed all CT perfusion studies. CT findings were compared with MRI and SPECT. ResultsIn Group A 149/170 myocardial segments (88%) could be evaluated. Real-time perfusion CT (versus SPECT) had 86% (84%) sensitivity, 98% (92%) specificity, 94% (88%) positive predictive value, and 96% (92%) negative predictive value in comparison with perfusion MRI for the detection of myocardial perfusion defects. In Group B all myocardial segments were available for analysis. Compared with MRI, dual-energy myocardial perfusion CT (versus SPECT) had 93% (94%) sensitivity, 99% (98%) specificity, 92% (88%) positive predictive value, and 96% (94%) negative predictive value for detecting hypoperfused myocardial segments. ConclusionOur results suggest the clinical feasibility of myocardial perfusion CT imaging in patients with acute chest pain. Compared to MRI and SPECT both, dynamic real-time perfusion CT and first-pass dual-energy perfusion CT showed good agreement for the detection of myocardial perfusion defects.

Dual Energy CT lung perfusion imaging—Correlation with SPECT/CT

Aims were (1) to determine the diagnostic accuracy of Dual Energy CT (DECT) in the detection of perfusion defects and (2) to evaluate the potential of DECT to improve the sensitivity for PE. 15 patients underwent Dual Energy pulmonary CT angiography (DE CTPA) and a combination of lung perfusion SPECT/CT and ventilation scintigraphy. CTPA and DE iodine distribution maps as well as perfusion SPECT/CT and inhalation scintigrams were reviewed for pulmonary embolism (PE) diagnosis. DECT and SPECT perfusion images were assessed regarding localization and extent of perfusion defects. Diagnostic accuracy of DE iodine (perfusion) maps was determined with reference to SPECT/CT. Diagnostic accuracies for PE detection of DECT and of SPECT/CT with ventilation scintigraphy were calculated with reference to the consensus reading of all modalities. DE CTPA had a sensitivity/specificity of 100%/100% for acute PE, while the combination of SPECT/CT and ventilation scintigraphy had a sensitivity/specificity of 85.7%/87.5%. For perfusion defects, DECT iodine maps had a sensitivity/specificity of 76.7% and 98.2%. DECT is able to identify pulmonary perfusion defects with good accuracy. This technique may potentially enhance the diagnostic accuracy in the assessment of PE.

Initial study of dual energy lung perfusion imaging using dual-source CT

Objective To evaluate the clinical values of dual energy lung perfusion using dual-source CT. Methods Fifty-four patients who underwent chest contrast-enhanced CT were included in this study from May to August in 2007. Dual energy CT scanning was performed in all patients. The patients were divided into four groups: normal group, exudation lesion group, mass lesion group, and pulmonary embolism group. Imaging appearances of dual energy CT perfusion in four groups were analyzed. Results Dual energy CT showed symmetrical homogeneous perfusion in healthy subjects (n = 14), exudation lesions (n =10) appeared as low perfusion, In mass lesions (n =27), peripheral masses presented as local perfusion defect, central masses appeared as segmental perfusion defect because of the involvement of hilar vessels,and pulmonary embolism (n = 3) appeared as perfusion defect in corresponding pulmonary segment.Conclusion Dual energy CT scanning can be used to show the pulmonary perfusion status and assess the pulmonary perfusion abnormalities in central lung cancer and pulmonary embolism. Key words: Lung; Tomography,X-ray computed; Perfusion; Diagnostic imaging

Dual energy CT for the assessment of lung perfusion—Correlation to scintigraphy

Purpose of this study was to determine the diagnostic value of dual energy CT in the assessment of pulmonary perfusion with reference to pulmonary perfusion scintigraphy. Thirteen patients received both dual energy CT (DECT) angiography (Somatom Definition, Siemens) and ventilation/perfusion scintigraphy. Median time between scans was 3 days (range, 0–90). DECT perfusion maps were generated based on the spectral properties of iodine. Two blinded observes assessed DECT angiograms, perfusion maps and scintigrams for presence and location of perfusion defects. The results were compared by patient and by segment, and diagnostic accuracy of DECT perfusion imaging was calculated regarding scintigraphy as standard of reference. Diagnostic accuracy per patient showed 75% sensitivity, 80% specificity and a negative predictive value of 66%. Sensitivity per segment amounted to 83% with 99% specificity, with 93% negative predictive value. Peripheral parts of the lungs were not completely covered by the 80 kVp detector in 85% of patients. CTA identified corresponding emboli in 66% of patients with concordant perfusion defects in DECT and scintigraphy. Dual energy CT perfusion imaging is able to display pulmonary perfusion defects with good agreement to scintigraphic findings. DECT can provide a pulmonary CT angiogram, high-resolution morphology of the lung parenchyma and perfusion information in one single exam.