Machine learning based ischemia-specific stenosis prediction: A Chinese multicenter coronary CT angiography study.

OBJECTIVES: To evaluate the performance of coronary computed tomography angiography (CCTA) derived characteristics including CT derived fractional flow reserve (CT-FFR) with FFR as a reference standard in identifying the lesion-specific ischemia by machine learning (ML) algorithms. METHODS: The retrospective analysis enrolled 596 vessels in 462 patients (mean age, 61 years ± 11 [SD]; 71.4 % men) with suspected coronary artery disease who underwent CCTA and invasive FFR. The data were divided into training cohort, internal validation cohort, external validation cohorts 1 and 2 according to participating centers. All CCTA-derived parameters, which contained 10 qualitative and 33 quantitative plaque parameters, were collected to establish ML model. The Boruta and unsupervised clustering algorithm were implemented to select important and non-redundant parameters. Finally, the eight features with the highest mean importance were included for further ML model establishment and decision tree building. Five models were built to predict lesion-specific ischemia: stenosis degree from CCTA, CT-FFR, ΔCT-FFR, ML model and nested model. RESULTS: Low-attenuation plaque, bend and lesion length were the main predictors of ischemia-specific lesions. Of 5 models, the ML model showed favorable discrimination for ischemia-specific lesions in the training and three validation sets (area under the curve [95 % confidence interval], 0.93 [0.90-0.96], 0.86 [0.79-0.94], 0.88 [0.83-0.94], and 0.90 [0.84-0.96], respectively). The nested model which combined the ML model and CT-FFR showed better diagnostic efficacy (AUC [95 %CI], 0.96 [0.94-0.99], 0.92 [0.86-0.99], 0.92 [0.86-0.99] and 0.94 [0.91-0.98], respectively; all P < 0.05), and net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were significantly higher than CT-FFR alone. CONCLUSIONS: Comprehensive CCTA-derived multiparameter model could better predict the ischemia-specific lesions by ML algorithms compared to stenosis degree from CTA, CT-FFR and ΔCT-FFR. Decision tree can be used to predict myocardial ischemia effectively.

Optimal Measurement Sites of Coronary-Computed Tomography Angiography-derived Fractional Flow Reserve: The Insight From China CT-FFR Study.

OBJECTIVES: To investigate the optimal measurement site of coronary-computed tomography angiography-derived fractional flow reserve (FFR CT ) for the assessment of coronary artery disease (CAD) in the whole clinical routine practice. MATERIALS AND METHODS: This retrospective multicenter study included 396 CAD patients who underwent coronary-computed tomography angiography, FFR CT , and invasive FFR. FFR CT was measured at 1 cm (FFR CT -1 cm), 2 cm (FFR CT -2 cm), 3 cm (FFR CT -3 cm), and 4 cm (FFR CT -4 cm) distal to coronary stenosis, respectively. FFR CT and invasive FFR ≤0.80 were defined as lesion-specific ischemia. The diagnostic performance of FFR CT to detect ischemia was obtained using invasive FFR as the reference standard. Reduced invasive coronary angiography rate and revascularization efficiency were calculated. After a median follow-up of 35 months in 267 patients for major adverse cardiovascular events (MACE), Cox hazard proportional models were performed with FFR CT values at each measurement site. RESULTS: For discriminating lesion-specific ischemia, the areas under the curve of FFR CT -1 cm (0.91) as well as FFR CT -2 cm (0.91) were higher than those of FFR CT -3 cm (0.89) and FFR CT -4 cm (0.88), respectively (all P <0.05). The higher reduced invasive coronary angiography rate (81.6%) was found at FFR CT -1 cm than FFR CT -2 cm (81.6% vs. 62.6%, P <0.05). Revascularization efficiency did not differ between FFR CT -1 cm and FFR CT -2 cm (80.8% vs. 65.5%, P =0.019). In 12.4% (33/267) MACE occurred and only values of FFR CT -2 cm were independently predictive of MACE (hazard ratio: 0.957 [95% CI: 0.925-0.989]; P =0.010). CONCLUSIONS: This study indicates FFR CT -2 cm is the optimal measurement site with superior diagnostic performance and independent prognostic role.

Functional CAD-RADS using FFRCT on therapeutic management and prognosis in patients with coronary artery disease.

OBJECTIVES: To propose a novel functional Coronary Artery Disease-Reporting and Data System (CAD-RADS) category system integrated with coronary CT angiography (CCTA)-derived fractional flow reserve (FFRCT) and to validate its effect on therapeutic decision and prognosis in patients with coronary artery disease (CAD). METHODS: Firstly, we proposed a novel functional CAD-RADS and evaluated the performance of functional CAD-RADS for guiding treatment strategies with actual clinical treatment as a reference standard in a retrospective multicenter cohort with CCTA and invasive FFR performed in all patients (n = 466). Net reclassification improvement (NRI) of functional CAD-RADS over anatomical CAD-RADS was calculated. Secondly, the prognostic value of functional CAD-RADS in a prospective two-arm cohort (566 [FFRCT arm] vs. 567 [CCTA arm]) was calculated, after a 1-year follow-up, functional CAD-RADS in FFRCT arm (n = 513) and anatomical CAD-RADS in CCTA arm (n = 511) to determine patients at risk of adverse outcomes were compared with a Cox hazard proportional model. RESULTS: Functional CAD-RADS demonstrated superior value over anatomical CAD-RADS (AUC: 0.828 vs. 0.681, p < 0.001) and comparable performance to FFR (AUC: 0.828 vs. 0.848, p = 0.253) in guiding therapeutic decisions. Functional CAD-RADS resulted in the revision of management plan as determined by anatomical CAD-RADS in 30.0% of patients (n = 140) (NRI = 0.369, p < 0.001). Functional CAD-RADS was an independent predictor for 1-year outcomes with indexes of concordance of 0.795 and the corresponding value was 0.751 in anatomical CAD-RADS. CONCLUSION: The novel functional CAD-RADS gained incremental value in guiding therapeutic decision-making compared with anatomical CAD-RADS and comparable power in 1-year prognosis with anatomical CAD-RADS in a real-world scenario. KEY POINTS: • The novel functional CAD-RADS category system with FFRCT integrated into the anatomical CAD-RADS categories was originally proposed. • The novel functional CAD-RADS category system was validated superior value over anatomical CAD-RADS (AUC: 0.828 vs. 0.681, p < 0.001) in guiding therapeutic decisions and revised management plan in 30.0% of patients as determined by anatomical CAD-RADS (net reclassification improvement index = 0.369, p < 0.001). • Functional CAD-RADS was an independent predictor with an index of concordance of 0.795 and 0.751 in anatomical CAD-RADS for 1-year prognosis of adverse outcomes.

Influence of diabetes mellitus on the diagnostic performance of machine learning-based coronary CT angiography-derived fractional flow reserve: a multicenter study.

OBJECTIVES: To examine the diagnostic accuracy of machine learning-based coronary CT angiography-derived fractional flow reserve (FFRCT) in diabetes mellitus (DM) patients. METHODS: In total, 484 patients with suspected or known coronary artery disease from 11 Chinese medical centers were retrospectively analyzed. All patients underwent CCTA, FFRCT, and invasive FFR. The patients were further grouped into mild (25~49 %), moderate (50~69 %), and severe (≥ 70 %) according to CCTA stenosis degree and Agatston score < 400 and Agatston score ≥ 400 groups according to coronary artery calcium severity. Propensity score matching (PSM) was used to match DM (n  = 112) and non-DM (n  = 214) groups. Sensitivity, specificity, accuracy, and area under the curve (AUC) with 95 % confidence interval (CI) were calculated and compared. RESULTS: Sensitivity, specificity, accuracy, and AUC of FFRCT were 0.79, 0.96, 0.87, and 0.91 in DM patients and 0.82, 0.93, 0.89, and 0.89 in non-DM patients without significant difference (all p > 0.05) on a per-patient level. The accuracies of FFRCT had no significant difference among different coronary stenosis subgroups and between two coronary calcium subgroups (all p > 0.05) in the DM and non-DM groups. After PSM grouping, the accuracies of FFRCT were 0.88 in the DM group and 0.87 in the non-DM group without a statistical difference (p > 0.05). CONCLUSIONS: DM has no negative impact on the diagnostic accuracy of machine learning-based FFRCT. KEY POINTS: • ML-based FFRCT has a high discriminative accuracy of hemodynamic ischemia, which is not affected by DM. • FFRCT was superior to the CCTA alone for the detection of ischemia relevance of coronary artery stenosis in both DM and non-DM patients. • Coronary calcification had no significant effect on the diagnostic accuracy of FFRCT to detect ischemia in DM patients.

Role of contrast-enhanced ultrasonography in MR-guided focused ultrasound ablation on uterus fibroids: lesion selection and assessment of ablative effects.

OBJECTIVES: To determine whether contrast-enhanced ultrasonography (CEUS) can be used for selecting lesions and assessing the ablative effects of MRgFUS ablation on uterus fibroids, compared with MR imaging. METHODS: This retrospective study was approved by the institutional review board of our hospital. From April 2018 to November 2019, a total of 44 symptomatic fibroids in 38 patients who underwent MRgFUS ablation were included. The association between pre-ablation characteristics on CEUS/MR imaging and the non-perfusion volume (NPV) after ablation was analyzed using multivariable linear regression analysis. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve values was compared between the CEUS and MR imaging regression models. NPV after ablation was compared between CEUS and enhanced MR imaging. RESULTS: On CEUS, entangled branch vessels, fast-in, and fast-out patterns were significantly associated with NPV, with an AUC of 0.95 (95% CI; 0.88, 1.00). On MR imaging, hyper-intensity on T2-weighted images (T2WI), hyper-intense ring-like signal on T2WI images, and hyper-enhancement on contrast-enhanced T1WI images were correlated with NPV, with an AUC of 0.86 (95% CI; 0.70, 1.00). After ablation, no differences in NPV were noted between contrast-enhanced T1WI (84.13 ± 75.42 cm3) and CEUS (80.22 ± 76.49 cm3). CONCLUSIONS: Some pre-ablation characteristics of uterine fibroids on CEUS were associated with NPV after MRgFUS. CEUS may contribute to the evaluation of ablative outcomes and patient selection, similar to MR imaging. KEY POINTS: • Contrast-enhanced ultrasonography (CEUS) is effective for selecting the appropriate uterine fibroids before MR-guided focused ultrasound (MRgFUS) ablation and evaluating non-perfusion volumes (NPV) after ablation, as a potential alternative to MR imaging. • Before ablation, entangled branch vessels, fast-in, and fast-out patterns on CEUS were significantly associated with NPV after MRgFUS. • No significant differences in NPV were detected between contrast-enhanced T1WI and CEUS after ablation.

The effect of coronary calcification on diagnostic performance of machine learning-based CT-FFR: a Chinese multicenter study.

OBJECTIVE: To investigate the effect of coronary calcification morphology and severity on the diagnostic performance of machine learning (ML)-based coronary CT angiography (CCTA)-derived fractional flow reserve (CT-FFR) with FFR as a reference standard. METHODS: A total of 442 patients (61.2 ± 9.1 years, 70% men) with 544 vessels who underwent CCTA, ML-based CT-FFR, and invasive FFR from China multicenter CT-FFR study were enrolled. The effect of calcification arc, calcification remodeling index (CRI), and Agatston score (AS) on the diagnostic performance of CT-FFR was investigated. CT-FFR ≤ 0.80 and lumen reduction ≥ 50% determined by CCTA were identified as vessel-specific ischemia with invasive FFR as a reference standard. RESULTS: Compared with invasive FFR, ML-based CT-FFR yielded an overall sensitivity of 0.84, specificity of 0.94, and accuracy of 0.90 in a total of 344 calcification lesions. There was no statistical difference in diagnostic accuracy, sensitivity, or specificity of CT-FFR across different calcification arc, CRI, or AS levels. CT-FFR exhibited improved discrimination of ischemia compared with CCTA alone in lesions with mild-to-moderate calcification (AUC, 0.89 vs. 0.69, p < 0.001) and lesions with CRI ≥ 1 (AUC, 0.89 vs. 0.71, p < 0.001). The diagnostic accuracy and specificity of CT-FFR were higher than CCTA alone in patients and vessels with mid (100 to 299) or high (≥ 300) AS. CONCLUSION: Coronary calcification morphology and severity did not influence diagnostic performance of CT-FFR in ischemia detection, and CT-FFR showed marked improved discrimination of ischemia compared with CCTA alone in the setting of calcification. KEY POINTS: • CT-FFR provides superior diagnostic performance than CCTA alone regardless of coronary calcification. • No significant differences in the diagnostic performance of CT-FFR were observed in coronary arteries with different coronary calcification arcs and calcified remodeling indexes. • No significant differences in the diagnostic accuracy of CT-FFR were observed in coronary arteries with different coronary calcification score levels.

Predicting Disease-Free Survival With Multiparametric MRI-Derived Radiomic Signature in Cervical Cancer Patients Underwent CCRT.

Prognostic biomarkers that can reliably predict the disease-free survival (DFS) of locally advanced cervical cancer (LACC) are needed for identifying those patients at high risk for progression, who may benefit from a more aggressive treatment. In the present study, we aimed to construct a multiparametric MRI-derived radiomic signature for predicting DFS of LACC patients who underwent concurrent chemoradiotherapy (CCRT). METHODS: This multicenter retrospective study recruited 263 patients with International Federation of Gynecology and Obetrics (FIGO) stage IB-IVA treated with CCRT for whom pretreatment MRI scans were performed. They were randomly divided into two groups: primary cohort (n = 178) and validation cohort (n = 85). The LASSO regression and Cox proportional hazard regression were conducted to construct the radiomic signature (RS). According to the cutoff of the RS value, patients were dichotomized into low- and high-risk groups. Pearson's correlation and Kaplan-Meier analysis were conducted to evaluate the association between the RS and DFS. The RS, the clinical model incorporating FIGO stage and lymph node metastasis by the multivariate Cox proportional hazard model, and a combined model incorporating RS and clinical model were constructed to estimate DFS individually. RESULTS: The final radiomic signature consisted of four radiomic features: T2W_wavelet-LH_ glszm_Size Zone NonUniformity, ADC_wavelet-HL-first order_ Median, ADC_wavelet-HH-glrlm_Long Run Low Gray Level Emphasis, and ADC_wavelet _LL_gldm_Large Dependence High Gray Emphasis. Higher RS was significantly associated with worse DFS in the primary and validation cohorts (both p<0.001). The RS demonstrated better prognostic performance in predicting DFS than the clinical model in both cohorts (C-index, 0.736-0.758 for RS, and 0.603-0.649 for clinical model). However, the combined model showed no significant improvement (C-index, 0.648, 95% CI, 0.571-0.685). CONCLUSIONS: The present study indicated that the multiparametric MRI-derived radiomic signature could be used as a non-invasive prognostic tool for predicting DFS in LACC patients.

DCE-MRI Quantitative Parameters as Predictors of Treatment Response in Patients With Locally Advanced Cervical Squamous Cell Carcinoma Underwent CCRT.

PURPOSE: To evaluate the predictive value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) quantitative parameters in treatment response to concurrent chemoradiotherapy (CCRT) for locally advanced cervical squamous cell carcinoma (LACSC). METHODS AND MATERIALS: LACSC patients underwent CCRT had DCE-MRI before (e0) and after 3 days of treatment (e3). Extended Tofts Linear model with a user arterial input function was adopted to generate quantitative measurements. Endothelial transfer constant (Ktrans), reflux rate (Kep), fractional extravascular extracellular space volume (Ve), and fractional plasma volume (Vp) were calculated, and percentage changes ΔKtrans, ΔKep, ΔVe, and ΔVp were computed. The correlations of these measurements with the tumor regression rate were analyzed. The predictive value of these parameters on treatment outcome was generated by the receiver operating characteristic (ROC) curve. Univariate and multivariate logistic regression analyses were conducted to find the independent variables. RESULTS: Ktrans-e0, Kep -e0, ΔKtrans, and ΔVe were positively correlated with the tumor regression rate. Mean values of Ktrans-e0, Ktrans-e3, ΔKtrans, and ΔVe were higher in the non-residual tumor group than residual tumor group and were independent prognostic factors for predicting residual tumor occurrence. Ktrans-e3 showed the highest area under the curve (AUC) for treatment response prediction. CONCLUSIONS: Quantitative parameters at e0 and e3 from DCE-MRI could be used as potential indicators for predicting treatment response of LACSC.

The influence of image quality on diagnostic performance of a machine learning-based fractional flow reserve derived from coronary CT angiography.

OBJECTIVE: To investigate the effect of image quality of coronary CT angiography (CCTA) on the diagnostic performance of a machine learning-based CT-derived fractional flow reserve (FFRCT). METHODS: This nationwide retrospective study enrolled participants from 10 individual centers across China. FFRCT analysis was performed in 570 vessels in 437 patients. Invasive FFR and FFRCT values ≤ 0.80 were considered ischemia-specific. Four-score subjective assessment based on image quality and objective measurement of vessel enhancement was performed on a per-vessel basis. The effects of body mass index (BMI), sex, heart rate, and coronary calcium score on the diagnostic performance of FFRCT were studied. RESULTS: Among 570 vessels, 216 were considered ischemia-specific by invasive FFR and 198 by FFRCT. Sensitivity and specificity of FFRCT for detecting lesion-specific ischemia were 0.82 and 0.93, respectively. Area under the curve (AUC) of high-quality images (0.93, n = 159) was found to be superior to low-quality images (0.80, n = 92, p = 0.02). Objective image quality and heart rate were also associated with diagnostic performance of FFRCT, whereas there was no statistical difference in diagnostic performance among different BMI, sex, and calcium score groups (all p > 0.05, Bonferroni correction). CONCLUSIONS: This retrospective multicenter study supported the FFRCT as a noninvasive test in evaluating lesion-specific ischemia. Subjective image quality, vessel enhancement, and heart rate affect the diagnostic performance of FFRCT. KEY POINTS: • FFRCTcan be used to evaluate lesion-specific ischemia. • Poor image quality negatively affects the diagnostic performance of FFRCT. • CCTA with ≥ score 3, intracoronary enhancement degree of 300-400 HU, and heart rate below 70 bpm at scanning could be of great benefit to more accurate FFRCTanalysis.

CT FFR for Ischemia-Specific CAD With a New Computational Fluid Dynamics Algorithm: A Chinese Multicenter Study.

OBJECTIVES: The aim of this study was to validate the feasibility of a novel structural and computational fluid dynamics-based fractional flow reserve (FFR) algorithm for coronary computed tomography angiography (CTA), using alternative boundary conditions to detect lesion-specific ischemia. BACKGROUND: A new model of computed tomographic (CT) FFR relying on boundary conditions derived from structural deformation of the coronary lumen and aorta with transluminal attenuation gradient and assumptions regarding microvascular resistance has been developed, but its accuracy has not yet been validated. METHODS: A total of 338 consecutive patients with 422 vessels from 9 Chinese medical centers undergoing CTA and invasive FFR were retrospectively analyzed. CT FFR values were obtained on a novel on-site computational fluid dynamics-based CT FFR (uCT-FFR [version 1.5, United-Imaging Healthcare, Shanghai, China]). Performance characteristics of uCT-FFR and CTA in detecting lesion-specific ischemia in all lesions, intermediate lesions (luminal stenosis 30% to 70%), and "gray zone" lesions (FFR 0.75 to 0.80) were calculated with invasive FFR as the reference standard. The effect of coronary calcification on uCT-FFR measurements was also assessed. RESULTS: Per vessel sensitivities, specificities, and accuracies of 0.89, 0.91, and 0.91 with uCT-FFR, 0.92, 0.34, and 0.55 with CTA, and 0.94, 0.37, and 0.58 with invasive coronary angiography, respectively, were found. There was higher specificity, accuracy, and AUC for uCT-FFR compared with CTA and qualitative invasive coronary angiography in all lesions, including intermediate lesions (p < 0.001 for all). No significant difference in diagnostic accuracy was observed in the "gray zone" range versus the other 2 lesion groups (FFR ≤0.75 and >0.80; p = 0.397) and in patients with "gray zone" versus FFR ≤0.75 (p = 0.633) and versus FFR >0.80 (p = 0.364), respectively. No significant difference in the diagnostic performance of uCT-FFR was found between patients with calcium scores ≥400 and <400 (p = 0.393). CONCLUSIONS: This novel computational fluid dynamics-based CT FFR approach demonstrates good performance in detecting lesion-specific ischemia. Additionally, it outperforms CTA and qualitative invasive coronary angiography, most notably in intermediate lesions, and may potentially have diagnostic power in gray zone and highly calcified lesions.

Diagnostic Performance of Machine Learning Based CT-FFR in Detecting Ischemia in Myocardial Bridging and Concomitant Proximal Atherosclerotic Disease.

BACKGROUND: The diagnostic performance of coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) in detecting ischemia in myocardial bridging (MB) has not been investigated to date. METHODS: This retrospective multicentre study included 104 patients with left anterior descending MBs. MB was classified as either superficial or deep, short, or long, whereas all MB vessels were further divided into <50%, 50% to 69%, and ≥70% groups, according to proximal lumen stenosis on invasive coronary angiography. Diagnostic performance and receiver operating characteristics (ROC) of CT-FFR to detect lesion-specific ischemia was assessed on a per-vessel level, using invasive FFR as reference standard. Intraclass correlation coefficient (ICC) and Bland-Altman plots were used for agreement measurement. RESULTS: Forty-eight MB vessels (46.2%) showed ischemia by invasive FFR (≤0.80). Sensitivity, specificity, and accuracy of CT-FFR to detect functional ischemia were 0.96 (0.85 to 0.99), 0.84 (0.71 to 0.92), and 0.89 (0.81 to 0.94), respectively, in all MB vessels. There were no differences in diagnostic performance between superficial and deep MB or between short and long MB (all P > 0.05). The accuracy of CT-FFR was 0.96 (0.85 to 0.99) in ≥70% stenosis, 0.82 (0.67 to 0.91) in 50% to 69% stenosis, and 0.89 (0.51 to 0.99) in <50% stenosis (P = 0.081). Bland-Altman analysis showed a slight mean difference between CT-FFR and invasive FFR of 0.014 (95% limit of agreement, -0.117 to 0.145). The ICC was 0.775 (95% confidence interval, 0.685-0.842, P < 0.001). CONCLUSIONS: CT-FFR demonstrated high diagnostic performance for identifying functional ischemia in vessels with MB and concomitant proximal atherosclerotic disease when compared with invasive FFR. However, the clinical use of CT-FFR in patients with MB needs further study for stronger and more robust results.

Primary mediastinal giant liposarcoma with smooth muscle and neural differentiation: A case report.

Liposarcoma has previously been described in Western studies, however, such cases are rarely reported in the mediastinum. In addition, the presence of a liposarcoma with smooth muscle and neural differentiation has not been previously reported. Thus, the present study describes the rare case of a 28-year-old Chinese male admitted to our hospital with the symptoms of chest tightness and shortness of breath due to a recurrent fibrolipoma in the mediastinum. The resected tumor measured 23 cm at its largest diameter, with histopathological and immunohistochemical features indicating a well-differentiated liposarcoma accompanied by smooth muscle and neural differentiation. Following the resection, the patient underwent radiation treatment and remains alive with no evidence of disease recurrence at two months post-surgery. To the best of our knowledge, the present study is the first to report a case of liposarcoma with smooth muscle and neural differentiation, which indicates that liposarcomas could potentially originate from stem cells. The present study highlights the fact that pathologists must carefully investigate the histopathological characteristics of liposarcomas in order to obtain an accurate diagnosis.

Effect of reduced x-ray tube voltage, low iodine concentration contrast medium, and sinogram-affirmed iterative reconstruction on image quality and radiation dose at coronary CT angiography: results of the prospective multicenter REALISE trial.

BACKGROUND: Both low tube voltage and sinogram-affirmed iterative reconstruction (IR) techniques hold promise to decrease radiation dose at coronary CT angiography (CCTA). The increased iodine contrast at low tube voltage allows for minimizing iodine load. OBJECTIVE: To assess the effect of reduced x-ray tube voltage, low iodine concentration contrast medium and IR on image quality and radiation dose at CCTA. METHODS: Two hundred thirty-one consecutive patients with suspected coronary artery disease were enrolled in this prospective, multicenter trial and randomized to 1 of 2 dual-source CCTA protocols: 120-kVp with 370 mgI/mL iopromide or iopamidol (n = 116; 44 women; 55.3 ± 9.8 years) or 100 kVp with 270 mgI/mL iodixanol (n = 115; 48 women; 54.2 ± 10.4 years). Reconstruction was performed with filtered back projection and IR. Attenuation, image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured and image quality scored. Size-specific dose estimates and effective doses were calculated. RESULTS: There were no significant differences in mean arterial attenuation (406.6 ± 76.7 vs 409.7 ± 65.2 Hounsfield units; P = .739), image noise (18.7 ± 3.8 vs 17.9 ± 3.4 Hounsfield units; P = .138), signal-to-noise ratio (22.5 ± 5.4 vs 23.7 ± 6.1; P = .126), contrast-to-noise ratio (17.5 ± 5.5 vs 18.3 ± 6.1; P = .286), or image quality scores (4.1 ± 0.9 vs 4.0 ± 0.9; P > .05) between 120-kVp filtered back projection-reconstructed and 100-kVp IR-reconstructed series. Mean iodine dose was 26.5% lower (18.3 ± 0.5 vs 24.9 ± 0.9 g; P < .0001), mean size-specific dose estimate was 35.1% lower (17.9 ± 6.6 vs 27.5 ± 8.2 mGy; P < .0001), and effective dose was 34.9% lower (2.3 ± 1.0 vs 3.5 ± 1.1 mSv; P < .0001) with the 100 kVp compared with the 120-kVp protocol, respectively. CONCLUSION: Using low x-ray tube voltage and IR allows for decreasing the iodine load and effective radiation dose at CCTA while maintaining image quality.

Experimental study of endothelial progenitor cells labeled with superparamagnetic iron oxide in vitro.

Endothelial progenitor cells (EPCs) have an essential role in counteracting risk factor­induced endothelial injury and protecting against the development of vascular injury, such as myocardial infarction. Magnetic resonance imaging (MRI) was reported to be effective in tracking transplanted stem cells following cell­labeling with superparamagnetic iron oxide (SPIO) nanoparticles. SPIO has previously been used to label and track EPCs; however, the safest concentration of SPIO for labeling EPCs on a cellular level has remained to be elucidated. In addition, the optimum number of SPIO­labeled cells required to produce the highest quality magnetic resonance images has not yet been determined. In the present study, EPCs were isolated from the bone marrow of minipigs using density gradient centrifugation. Their biological activity was then studied using flow cytometric analysis. Cells were incubated at different concentrations of SPIO for different durations and then the growth curve, apoptosis, morphology and labeling efficiency of the EPCs were detected using optical and electron microscopy. T2­weighted fast spin­echo (T2WITSE) MRI of the different numbers of SPIO­labeled EPCs (35 µg/ml) were then obtained in axial and sagittal planes. The results of the present study demonstrated that EPCs were efficiently labeled with SPIO, with a labeling efficiency in each group of ~100% following incubation for 24 h. SPIO was found to be localized in the endosomal vesicles of EPCs, which was confirmed by electron microscopy. When the concentration of SPIO was <70 µg/ml, no significant differences were observed in cell viability, proliferative capability (P>0.05) and morphology between labeled and unlabeled EPCs. Furthermore, the T2WITSE signal intensity was significantly decreased in the groups of 5.0x105/ml and 1.0x105/ml compared with that of the control (P<0.05). In conclusion, the results of the present study indicated that 35 µg/ml was the most effective concentration of SPIO to label EPCs in vitro and acquire a high quality MRI. These findings may therefore contribute to the development of a promising novel therapeutic method for the treatment of myocardial infarction following autograft with SPIO­labeled EPCs in vivo.

Gorham-Stout syndrome presenting in a 5-year-old girl with a successful bisphosphonate therapeutic effect.

Gorham-Stout syndrome (GSS), also known as Gorham-Stout disease, massive osteolysis, disappearing bone disease or phantom bone, is a rare disorder of the musculo-skeletal system. It most commonly involves the skull, shoulder and pelvic girdle. Histological examination reveals a progressive osteolysis always associated with an angiomatosis of blood vessels and sometimes of lymphatics, which seemingly is responsible for the destruction of the bone. It is extremely rare that Gorham-Stout syndrome involves the bones of the entire body. A 5-year-old girl complaining of intermittent and dull back pain for 3 months was admitted to a local hospital. X-ray revealed left pleural effusion, and the patient was diagnosed with tuberculous pleurisy. Thus, anti-tuberculosis therapy was performed. However, it was not effective. A soft mass with significant tenderness was found in the upper segment of the right leg 50 days afterwards. X-ray revealed multiple osteolysis of the bilateral clavicle, scapula, rib, vertebral body, ilium, sacrum, femur and tibia. The biopsy from the right tibia disclosed that the lesion was composed of hyperplastic blood vessels and fibrous tissues similar to hemangioma. Based on the above clinical, radiological and histopathological findings, the clinical physician confirmed a diagnosis of Gorham-Stout disease, and prescribed oral anti-osteoclastic medications consisting of bisphosphonates. At present, the girl is alive and healthy, and new lesions have not been noted.

[Construction and expression of dual promoter lentiviral vector containing TFR and VEGF genes].

AIM: To construct a dual promoter lentivira vector containing TFR and VEGF gene, and detect the expression of TFR and VEGF genes in MSCs of Chinese mini-swine. METHODS: The TFR and VEGF gene were amplified by polymerase chain reaction and cloned into pLenti-GFP-Neo after the CMV and SV40 promoter respectively, to generate the lentivira vector pLenti-TG-VEGF. The four-plasmids lentiviral vector system(pRsv-REV, pMDlg-pRRE, pMD2G and pLenti-TG-VEGF)were cotransfected into human embryonic kidney 293 T cells with Lipofectin 2000 reagent. The packaged virus was harvested 72 h later. MSCs were infected by lentivirus carrying TFR and VEGF genes. Western blotting was used to detect the expression of TFR and VEGF genes in the viral infected MSCs. RESULTS: Restriction endonuclease digestion analysis and DNA sequencing demonstrated that the dual promoter lentivirus vector containing TFR and VEGF genes were constructed successfully. MSCs could be successfully infected by the recombinant lentivirus. Expression of TFR and VEGF protein could be detected in the infected MSCs by Western blotting. CONCLUSION: The dual promoter lentiviral vector containing TFR and VEGF genes are constructed successfully which provides basis for future research on Cardiac molecular imaging of cell transplantation.

[Imagings of coronary total occlusion using dual-source computed tomography].

OBJECTIVE: To analyze the imaging characteristics of coronary arteries with total occlusion (TO) lesions shown by dual-source computed tomography CT (DSCT) coronary angiography. METHOD: The clinical data of patients who were diagnosed as coronary heart disease together with total occlusion lesions between March 2008 and March 2010 were retrospectively analyzed. RESULTS: In a cohort of 140 patients with 152 TO lesions, TO vessels in right coronary artery, left anterior descending artery, left circumflex coronary artery, or left main coronary artery were 68, 48, 20, and 1, respectively. Side branch TO were found in 15 vessels, in which 13 cases were found to be with TO in two coronary arteries. The length of TO was 5-58 mm, mean (16.8 ± 3.9) mm. TO lesions with a length ≥ 1 cm accounted for 91.4%. The appearance of stump in TO were abrupt occlusion (n=68) , blunt occlusion (n=64) , and mouse-tail occlusion (n=20) . Among all the TO lesions, 73% were soft plaque or mainly soft plaque together with minimal calcification. Mixed plaque and calcified plaque were less seen. Ten TO segments presented with dilated lumens were thrombogenesis. There were 25 TO segments angulated or tortuosity, which were most frequently shown in right coronary artery. DSCT only presented 3 TO with clear collateral vessels and no TO with bridge collateral vessels was shown. CONCLUSIONS: DSCT can provide most necessary information of coronary TO lesions. Therefore, it can be used to guide surgeries on TO lesions and improve the success rates of surgeries.

Primary gastrointestinal stromal tumor of the liver: a case report.

We report a case of primary gastrointestinal stromal tumor (GIST) of the liver. A 17-year-old man with a solid mass in the anterior segment of the right liver was asymptomatic with negative laboratory examinations with the exception of positive HBV. Contrast-enhanced ultrasound (CEUS) revealed a hypervascular lesion in the arterial phase and hypoechoic features during the portal and late phases. However, enhanced spiral computed tomography (CT) showed hypoattenuation in all three phases. Following biopsy, immunohistochemical evaluation demonstrated positive CD117. Different imaging features of primary GISTs of the liver are due to pathological properties and different working systems between CEUS and enhanced spiral CT.

[Effects of 16-multi-detector row CT aortography with lower tube current].

OBJECTIVE: To study the effects of 16-multi-detector row CT (MDCT) aortography with lower tube current in diagnosis of aortic diseases. METHODS: The study was conducted in 2 steps. In the first step, 58 patients with suspicious aortic disease or after operation on the aorta underwent 16-MDCT aortography for 70 times. Ten of them underwent scanning with conventional tube current of 175 mAs and the other 60 patients were divided into 3 groups according to their bogy weights: <65 kg group (n=20) receiving the lowest tube current of 25 mAs, 65-75 kg group (n=20) receiving the lowest tube current of 50 mAs, and >75 kg group (n=20) receiving the lowest tube current of 75 mAs. In the second step 60 patients with dissecting aneurysm, underwent 16-MDST aortography and were divided into 3 groups according to their body weight too: <65 kg group (n=20) receiving the lowest tube current of 50 mAs, 65-75 kg group (n=20) receiving the lowest tube current of 75 mAs, and >75 kg group (n=20) receiving the lowest tube current of 100 mAs, all 25 mAs more compared with the corresponding groups in the first step. The weighted CT dose index (CTDI), scanning length, and dose length produce (DLP) were recorded. The diagnostic accuracy rates of the images from the low dose groups were compared with those of the higher dose groups. RESULTS: The data of the first step showed that the CTDI values of the patients who received 25 mAs, 50 mAs, and 75 mAs tube current were 11.3%, 29.0%, and 42.7% that of the conventional tube current group (all P < 0.001) and the DLP values of the 3 low dose groups were also significantly lower than that of the conventional tube current group (all P < 0.001). The diagnostic accuracy rate of the 25 mAs, 50 mAs, and 75 mAs groups were 60% , 85%, and 85% that of the conventional tube current group. The results of the second step showed that the CTDI values of the 50 mAs, 75 mAs, and 100 mAs groups were 29.0%, 42.7%, and 57.3% that of the conventional tube current group respectively, and the DLP values of the 3 low dose groups were also significantly lower than that of the conventional group ( all P < 0. 001); and the 50 mAs, 75 mAs, and 100 mAs groups all showed good three-dimensional reconstruction imaging qualities, all with the diagnostic accuracy rate of 100%. The crossing section and three-dimensional images all showed excellent diagnostic image quality. CONCLUSION: 16-MDCT aortography with the tube current at the doses 50 mAs to 100 mAs suffices to diagnose aortic diseases in patients with different body weights. Higher tube current should be used in dissecting aneurysm. The tube current at the dose of 100 mAs satisfies the imaging and diagnosing of all kinds of aortic diseases in the patients with any body weight.

[Diagnosis of aortic intramural hematoma by electron beam CT].

OBJECTIVE: To assess the value of electron beam CT (EBCT) in the diagnosis of aortic intramural hematoma (AIH). METHODS: Twenty-five patients who complained of acute chest and back pain were scanned with an EBCT scanner (Imatron C-150) using contrast-enhanced continuous volume scanning (CVS) for establish the diagnosis of AIH. RESULTS: Seven patients were diagnosed as having Stanford type A, and the others as type B AIH. The direct features of AIH in EBCT included crescent or circular thickening (>5 mm) of the aortic wall without signs of lumen formation resulting from intimal rupture. The indirect features included calcification ingression (7 cases), penetrating ulcer (12 cases), atherosclerosis (18 cases) and leakages (5 cases). The complicating features included pericardial effusion (5 cases), pleural effusion (14 cases), involvement of the large branches (5 cases), aortic dissection (3 cases) and aneurysms (4 cases). CONCLUSION: EBCT can provide important information for the diagnosis and treatment of AIH, and can be useful for follow-up observation of the patients.