Dual-energy Spectral Computed Tomography Imaging Research Articles

Correlation Between Quantitative Parameters Obtained by Dual Energy Spectral CT and Prognostic Histopathological Factors and Biomarkers in Breast Cancer

Rationale and ObjectivesTo investigate the correlation between quantitative parameters obtained by dual energy spectral computed tomography (DESCT) and various histopathological factors and biomarkers associated with the prognosis of breast cancer. Materials and MethodsQuantitative parameters such as iodine content (IC), normalized IC (nIC), iodine enhancement (IE) and normalized IE (nIE) were measured on virtual monochromatic images and iodine mapping images obtained from DESCT in 116 female breast cancer patients. The relationship between these parameters and prognostic biomarkers such as estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) status and Ki67 levels, as well as the correlation with histological grade (HG), lymphovascular invasion (LVI), and metastatic axillary lymphadenopathy (LAP) were evaluated. ResultsER-negative tumors had significantly higher values of IC, nIC, IE, and nIE compared to ER-positive tumors. PR-negative tumors had significantly higher values of IE and nIEc compared to PR-positive tumors. HER2 overexpressed and Ki-67 high proliferation tumors showed significantly higher values of all quantitative parameters compared to HER2 negative and Ki-67 low proliferation tumors. All quantitative parameters were significantly higher in HG 3 tumors, tumors with detected LVI, and tumors with metastatic axillary LAP compared to low-grade tumors, LVI-negative tumors and tumors without metastatic axillary lymph nodes, respectively. ConclusionQuantitative parameters of IC and IE obtained from DESCT have shown potential for predicting prognosis in breast cancer patients. Higher values of these parameters have been found to correlate with poor prognostic biomarkers and histopathological features. These results suggest that quantitative DESCT imaging may offer an additional benefit in the noninvasive prediction of breast cancer prognosis.

A comparison study of dual-energy spectral CT and 18F-FDG PET/CT in primary tumors and lymph nodes of lung cancer.

We aimed to investigate whether there is a correlation between dual-energy spectral computed tomography (DESCT) and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) parameters in primary tumor and metastatic lymph nodes in patients with newly diagnosed lung cancer. Primary tumor and metastatic lymph nodes of 68 patients diagnosed with lung cancer were evaluated retrospectively with 18F-FDG PET/CT and DESCT imaging. The histologic subtypes were adenocarcinoma (n=29), squamous cell carcinoma (SCC) (n=26), small cell lung cancer (SCLC) (n=11), and large cell neuroendocrine cancer (LCNEC) (n=2). In terms of PET parameters, SUVmax, SUVmean, SULmax, SULmean, SULpeak, and normalized SUL values were obtained for primary tumors and metastatic lymph nodes. In terms of DESCT parameters, maximum and mean iodine content (IC), normalized IC values, iodine enhancement (IE) and normalized IE values were calculated. We found no correlation between DESCT and 18F-FDG PET/CT parameters in primary tumors and metastatic lymph nodes. In addition, no correlation was found in the analysis performed in any of the histologic subgroups. In patients with a primary tumor <3 cm, there was a moderate negative correlation between the parameters SUVmax-ICmax (r= -0.456, p = 0.043), SUVmean-ICmax (r= -0.464, p = 0.039) SULmean-ICmax (r= -0.497, p = 0.026), SUVmax-ICmean (r= -0.527, p = 0.020), SULmean-ICmean (r= -0.499, p = 0.025), and SULpeak-ICmean (r= -0.488, p = 0.029). We consider that DESCT and 18F-FDG PET/CT indicate different characteristics of the tumors and should not supersede each other.

A phantom study using dual-energy spectral computed tomography imaging: Comparison of image quality between two adaptive statistical iterative reconstruction (ASiR, ASiR-V) algorithms for evaluating ground-glass nodules of the lung.

To assess the image quality of the two adaptive statistical iterative reconstruction (ASiR and ASiR-V) algorithms for evaluating ground-glass nodules (GGNs) of the lung. The chest phantom with ground-glass simulated pulmonary nodules was scanned by dual-energy spectral computed tomography (CT) using gemstone spectral imaging mode. The image was reconstructed with ASiR and ASiR-V from 0 (FBP) to 90% blending percentages, respectively. The average noise and signal-to-noise ratio (SNR) of reconstruction images were calculated. The data were statistically analyzed. Compared with FBP, as the percentage of ASiR and ASiR-V increased from 10 to 90%, image noise reduced by 3.7%-45.2% and 14.1%-73.8%, respectively, and the SNR increased accordingly. There was significantly higher SNR value of ASiR-V images as the percentages of IR increased to 50% or greater, compared to those of ASiR. Subjective image quality scores of ASiR and ASiR-V improved significantly as percentage increased from 10 to 80% for ASiR and ASiR-V (peaked at 60% for both of them). Both ASiR and ASiR-V can reduce the image noise and improve the objective image quality for presenting pulmonary nodules on dual-energy spectral CT imaging compared with FBP. ASiR-V provided further image quality improvement than ASiR, and both ASiR and ASiR-V 60% had the highest image quality score.

Optimize non-contrast head CT imaging tasks using multiple virtual monochromatic image sets in dual-energy spectral CT.

To demonstrate the value of optimizing non-contrast head imaging tasks by using the multiple virtual monochromatic spectral imaging (VMSI) sets in dual-energy spectral computed tomography (CT) and determine the optimal energy levels for various tasks in imaging head. This retrospective study includes 55 patients (29 women and 26 men, average age of 54.5±12.3years) who underwent non-contrast head CT in spectral imaging mode. For each patient, 21 VMSI sets from 40 to 140 keV at 5 keV intervals and 120 kVp-like image were reconstructed. Signal-to-noise ratio (SNR) for gray matter (GM) and white matter (WM), contrast-to-noise ratio (CNR) between GM and WM, subcalvarial artifact index (SAI) and posterior fossa artifact index (PFAI) were measured by placing regions-of-interest (ROIs) in nine areas of the brain. Two radiologists subjectively rated the image quality in terms of GM-WM differentiation, beam hardening artifacts in the subcalvarial space, and posterior fossa. The overall image noise was evaluated using a 5-point Likert scale. Measurement data were then statistically analyzed. The optimal energy level for viewing the supratentorial brain and reducing beam hardening artifacts in the subcalvarial space and posterior fossa was 65 keV and 75 keV, respectively. All corresponding measurements at these energy levels were significantly better than those measured at other energy levels (all P < 0.05). Dual-energy spectral CT imaging provides a set of virtual monochromatic spectral imaging and can be selected on-demand to optimize the imaging tasks in non-contrast head CT. VMSI reconstruction of dual-energy unenhanced head CT scans at 65-75 keV enables to maximize image quality.

Correlation between dual-energy spectral CT imaging parameters and pathological grades of non-small cell lung cancer

To investigate the correlation between pathological grades of non-small cell lung cancers (NSCLCs) and quantitative parameters generated in dual-energy spectral computed tomography (CT). Fifty-three patients with NSCLCs who underwent preoperative dual-energy spectral CT imaging and surgical resection were evaluated retrospectively. These patients were divided into a low-grade group and a high-grade group based on their histopathological differentiation. In the arterial phase (AP) and venous phase (VP), iodine concentration (IC) in cancers was measured in iodine-based material decomposition images, and normalised to the IC in the aorta to calculate the normalised iodine concentration (NIC), the spectral CT curve was generated from the monochromatic images to calculate the slope of the spectral curve (λHU). Differences in quantitative parameters (NIC and λHU) were compared using the two-sample t-test. The correlations between spectral CT parameters and tumour grades were evaluated using the Spearman rank correlation analysis. Receiver operating characteristic (ROC) curves were generated to calculate their diagnostic efficacies. The NIC and λHU in the low-grade NSCLC group were significantly higher than those in the high-grade NSCLC group both in AP and VP (all p<0.001). There was a significant negative correlation between spectral CT parameters and pathological grades by the Spearman rank correlation (all p<0.001). ROC analysis indicated that λHU in VP provided the best diagnostic performance in distinguishing high-grade cancers from low-grade cancers (area under the ROC curve [AUC], 0.914; sensitivity, 85.7%; specificity, 84.4%). The quantitative parameters in dual-energy spectral CT imaging provide useful information to differentiate the pathological grades of NSCLCs.

Differentiating malignant from benign gastric mucosal lesions with quantitative analysis in dual energy spectral computed tomography: Initial experience.

To investigate the value of quantitative analysis in dual energy spectral computed tomography (DESCT) for differentiating malignant gastric mucosal lesions from benign gastric mucosal lesions (including gastric inflammation [GI] and normal gastric mucosa [NGM]). This study was approved by the ethics committee, and all patients provided written informed consent. A total of 161 consecutive patients (63 with gastric cancer [GC], 48 with GI, and 50 with NGM) who underwent dual-phase contrast enhanced DESCT scans in the arterial phase (AP) and portal venous phase (PVP) were included in this study. Iodine concentration (IC) in lesions was derived from the iodine-based material-decomposition images and normalized to that in the aorta to obtain normalized IC (nIC). The ratios of IC and nIC between the AP and PVP were calculated. Diagnostic confidence for GC and GI was evaluated with reviewing the features including gastric wall thickness, focal, and eccentric on the conventional polychromatic images. All statistical analyses were performed by using statistical software SPSS 17.0 (SPSS, Chicago, IL). IC and nIC in GC differed significantly from those in GI and NGM, except for nICAP in comparing GC with GI. Mean nIC values of GC (0.18 ± 0.06 in AP and 0.62 ± 0.16 in PVP) were significantly higher than that of NGM (0.12 ± 0.03 in AP and 0.37 ± 0.08 in PVP) (all P < 0.05). There was also significant difference for IC values in GC, GI, and NGM (24.19 ± 8.27, 19.07 ± 5.82, and 13.61 ± 2.52 mg/mL, respectively, in AP and 28.00 ± 7.01, 24.66 ± 6.55, and 16.94 ± 3.06 mg/mL, respectively, in PVP). Based on Receiver Operating Characteristic Curve analysis, nIC and IC in PVP had high sensitivities of 88.89% and 90.48%, respectively, in differentiating GC from NGM, while the sensitivities were 71.43% and 88.89% during AP. Ratios IC and nIC ratios did not provide adequate diagnostic accuracy with their area under curves less than 0.65. With the conventional features, the diagnostic accuracies for GC and GI were 75.0% and 98.0%, respectively. Quantitative analysis of DESCT imaging parameters for gastric mucosa, such as nIC and IC, is useful for differentiating malignant from benign gastric mucosal lesions.

GSI Quantitative Parameters: Preoperative Diagnosis of Metastasis Lymph Nodes in Lung Cancer

背景与目的肺癌淋巴结转移是重要的生存预后因素，准确的纵隔淋巴结分期可以使患者最大程度地受益于手术。本研究旨在探讨宝石能谱计算机断层扫描（computed tomography, CT）定量参数在术前诊断非小细胞肺癌（non-small cell lung cancer, NSCLC）患者淋巴结转移的价值。方法收集48例NSCLC患者，连续进行宝石能谱CT成像（gemstone spectral imaging, GSI）模式肺增强扫描和手术治疗。重建GSI数据，测量淋巴结的大小、动脉期和静脉期的CT值、能谱曲线的斜率、标准化碘浓度以及水浓度。采用独立样本的t检验，并进行受试者工作特征曲线（receiver operating characteristic, ROC）分析，确定诊断的最佳阈值及效能。结果转移性淋巴结与非转移性淋巴结短轴直径、动脉期和静脉期的CT值、能谱曲线的斜率、标准化碘浓度均有统计学差异。当确定动脉期能谱曲线斜率的最佳临界值为2.75，其诊断的敏感性、特异性及总体的准确性分别为88.2%、88.4%、87.0%。结论能谱CT的GSI模式定量参数较传统CT在术前诊断转移性淋巴结方面有更高的诊断效能。

Differentiating malignant vertebral tumours from non-malignancies with CT spectral imaging: a preliminary study.

To investigate the value of dual-energy spectral computed tomography (DESCT) for differentiating malignant vertebral tumours from non-malignancies during venous phase. This study was institutional review board-approved, and written informed consent was obtained from all patients. Thirty-seven patients were examined by DESCT during venous phase. Twenty patients had malignant vertebral tumours, 17 had non-malignant vertebral tumours. The iodine/water densities for the lesion, the lesion-to-muscle ratio, and lesion-to-artery ratio for iodine density measurements were calculated and compared between the two groups with the two-tailed Student t test. A p-value < 0.05 was considered statistically significant. Sensitivity and specificity were compared between the qualitative and quantitative studies. The iodine density, lesion-to-muscle ratio, and lesion-to-artery ratio of the iodine density measurement for malignant vertebral tumours were significantly different from the respective values for non-malignancies (all p < 0.05). Using 0.52 as the threshold value for the lesion-to-artery iodine density ratio, one could obtain sensitivity of 85% and specificity of 100% for differentiating malignant vertebral tumours from non-malignancies, significantly higher than the qualitative diagnosis. DESCT imaging enables analysis of a number of additional quantitative CT parameters to improve the accuracy for differentiating malignant vertebral tumours from non-malignancies during venous phase. • Dual-energy CT provides a new quantitative method. • CT spectral imaging improves the accuracy of differential diagnosis. • Lesion-to-artery iodine density ratio for malignant vertebral tumours was higher than for non-malignancies.

Differentiation of Lung Cancers From Inflammatory Masses with Dual-Energy Spectral CT Imaging

To investigate the value of dual-energy spectral computed tomography (DESCT) in the quantitative differentiation between pulmonary malignant masses and inflammatory masses. This study was an institutional review board-approved study, and written informed consent was obtained from all patients. Sixty patients with 35 lung cancers and 25 inflammatory masses underwent DESCT scan during arterial phase (AP) and venous phase (VP). CT numbers of net enhancement in 70keV monochromatic images in central and peripheral regions of masses and their differences (dCT) were measured. Iodine concentrations in the two regions were measured and normalized to the aorta as normalized iodine concentrations (NICs). The slopes of spectral attenuation curves (λHU) in the two regions were also calculated. The two-sample t test was used to compare quantitative parameters. Receiver operating characteristic (ROC) curves were generated to calculate sensitivity and specificity. CT numbers of net enhancement and NICs in central regions, and λHU values both in the central and peripheral region of lung cancers were significantly lower than those of inflammatory masses during AP and VP. On the other hand, the dCT values of lung cancers were higher than that of inflammatory masses. NIC value in the central regions in VP had the highest sensitivity (86%) and specificity (100%) in differentiating malignant masses from inflammatory masses. DESCT imaging with quantitative parameters such as CT numbers of 70keV monochromatic images, NIC, and λHU may be a new method for differentiating lung cancers from inflammatory masses.

Computer-Aided Diagnosis for Preoperative Invasion Depth of Gastric Cancer with Dual-Energy Spectral CT Imaging

This study evaluates the accuracy of dual-energy spectral computed tomography (DEsCT) imaging with the aid of computer-aided diagnosis (CAD) system in assessing serosal invasion in patients with gastric cancer. Thirty patients with gastric cancer were enrolled in this study. Two types of features (information) were collected with the use of DEsCT imaging: conventional features including patient's clinical information (eg, age, gender) and descriptive characteristics on the CT images (eg, location of the lesion, wall thickness at the gastric cardia) and additional spectral CT features extracted from monochromatic images (eg, 60keV) and material-decomposition images (eg, iodine- and water-density images). The classification results of the CAD system were compared to pathologic findings. Important features can be found out using support vector machine classification method in combination with feature-selection technique thereby helping the radiologists diagnose better. Statistical analysis showed that for the collected cases, the feature "long axis" was significantly different between group A (serosa negative) and group B (serosa positive) (P < .05). By adding quantitative spectral features from several regions of interest (ROIs), the total classification accuracy was improved from 83.33% to 90.00%. Two feature ranking algorithms were used in the CAD scheme to derive the top-ranked features. The results demonstrated that low single-energy (approximately 60keV) CT values, tumor size (long axis and short axis), iodine (water) density, and Effective-Z values of ROIs were important for classification. These findings concurred with the experience of the radiologist. The CAD system designed using machine-learning algorithms may be used to improve the identification accuracy in the assessment of serosal invasion in patients of gastric cancer with DEsCT imaging and provide some indicators which may be useful in predicting prognosis.

Comparison of gastric vascular anatomy by monochromatic and polychromatic dual-energy spectral computed tomography imaging

To evaluate the use of monochromatic and polychromatic dual-energy spectral computed tomography (CT) imaging for preoperative assessment of gastric vascular anatomy. Patients with suspected gastric cancer underwent spectral CT to generate conventional 140 kVp polychromatic and monochromatic images with energy levels ranging from 40 to 140 keV during the late arterial and portal venous phases. Optimal monochromatic images were selected according to the contrast-to-noise ratio (CNR) for the gastric artery. Image quality was subjectively assessed. Display rates of the arteries were recorded. The study included 64 patients. Monochromatic images at 53 ± 3 keV provided the optimum CNR. At this energy level, subjective image scores were significantly higher for monochromatic images than polychromatic images. There were no significant differences in the display rates of arteries between polychromatic and optimal monochromatic images. Monochromatic images obtained with spectral CT can improve the visualization of gastric arteries.

Differentiation of neoplastic from bland macroscopic portal vein thrombi using dual-energy spectral CT imaging: a pilot study

To assess the feasibility and value of dual-energy spectral computed tomography (DESCT) imaging for differentiating neoplastic from bland macroscopic portal vein (PV) thrombi. Computed tomography (CT) images of 44 patients with macroscopic PV thrombus (bland group, n = 16; neoplastic group, n = 28) were reviewed. Iodine-based material decomposition images in the portal venous phase were reconstructed to compare the iodine indices between groups, including thrombus iodine density (I (T)), thrombus-aorta iodine density ratio (I (T)/I (A)), and thrombus-PV iodine density ratio (I (T)/I (P)). Differential diagnostic performances of DESCT were calculated in the subgroup of 21 patients with histopathological evidence (bland group, n = 12; neoplastic group, n = 9). The iodine indices of the neoplastic group were significantly higher than those in the bland group (P < 0.001). A threshold I (T) of 1.14mg/mL, I (T)/I (A) of 0.17, and I (T)/I (P) of 0.17 in the portal venous phase yielded 100%, 88.9%, and 100% sensitivity, and 91.7%, 91.7%, and 83.3% specificity, respectively, in differentiating neoplastic from bland PV thrombi. DESCT imaging with quantification of thrombus iodine density in the portal venous phase appears to be a promising new method for distinguishing neoplastic from bland macroscopic PV thrombi. • Differentiating the nature of portal vein thrombus is of great clinical significance. • Iodine-based material decomposition imaging reflects iodine distribution after contrast media administration. • Dual-energy CT with iodine quantification can distinguish bland from neoplastic PV thrombi.

Precision of the measurement of CT numbers: comparison of dual-energy CT spectral imaging with fast kVp switching and conventional CT with phantoms

To compare dual-energy computed tomography (CT) spectral imaging and conventional CT imaging in terms of precision of the measurement of CT numbers in phantoms. A circular phantom (CP) and an elliptical phantom (EP) were used. Capsules filled with iodine contrast media solutions at various concentration levels were placed in the phantoms. Conventional CT was performed at a tube voltage of 120 kVp. Simulated monochromatic images at 65 keV were obtained by dual-energy CT spectral imaging. The CT number of each iodine capsule was measured. A linear regression model was used to evaluate linearity, while analysis of covariance was used to investigate the degree of variability according to phantom shape for each imaging method. With conventional imaging, the slopes of the regression lines for CT numbers measured at the EP center and EP periphery were significantly lower than those measured for CP (P < 0.0001 for both EP center vs. CP and for EP periphery vs. CP). No significant difference in slope was found among phantom shapes in dual-energy spectral CT imaging. Computed tomography numbers varied considerably depending on the phantom shape in conventional CT, whereas dual-energy CT provided consistent CT numbers regardless of the phantom shape.