Sae Rom Hong

Combined Use of Automatic Tube Potential Selection with Tube Current Modulation and Iterative Reconstruction Technique in Coronary CT Angiography

PURPOSE To analyze the effect of automatic tube potential selection with tube current modulation (APSCM) and iterative reconstruction on image quality, diagnostic accuracy, and radiation dose at computed tomographic (CT) angiography and compare it with APSCM-only and body mass index (BMI)-based examination protocols. MATERIALS AND METHODS This study was approved by the institutional review board, and informed consent was obtained from all patients. Images from 185 patients who underwent a BMI-based protocol and 197 patients who underwent an APSCM protocol with filtered back projection (FBP) and an APSCM protocol with sinogram-affirmed iterative reconstruction (SAFIRE) were retrospectively evaluated. Diagnostic performance was compared with that of conventional coronary angiography in a subgroup of 51 patients. Statistical analysis was performed by using the independent or paired t test, Mann-Whitney U test, Wilcoxon signed rank test, χ(2) statistics, linear weighted κ statistics, and generalized estimating equation. RESULTS The APSCM group with SAFIRE had a significant reduction in image noise and a significant increase in CT number, contrast enhancement, signal-to-noise ratio, and contrast-to-noise ratio compared with the APSCM group with FBP (P < .0001) and the BMI-based group (P < .001, except P = .002 for image noise). Image quality and diagnostic accuracy showed no significant difference between the three groups. The use of APSCM resulted in a significant reduction in radiation dose compared with the BMI-based protocol. CONCLUSION The combination of SAFIRE and APSCM at coronary CT angiography significantly improves objective image quality while maintaining diagnostic accuracy and reduced radiation dose. Online supplemental material is available for this article.

Prognostic value of SYNTAX score based on coronary computed tomography angiography

BACKGROUND The long-term prognostic value of the computed tomography (CT)-based SYNTAX score has not yet been investigated. The aim of our study was to investigate the prognostic value of the CT-SYNTAX score in predicting major adverse cardiac events (MACEs) in populations who underwent both coronary computed tomography (CCTA) and invasive coronary angiography (ICA), compared with prognostic values of coronary artery disease (CAD) findings on CCTA and the ICA-based SYNTAX score. METHODS We retrospectively included 339 patients (213 men, mean age of 63.8±9.45years) with suspected CAD who underwent CCTA and ICA. SYNTAX score was obtained based on both CCTA and ICA. Follow-up clinical outcome data regarding composite MACEs were obtained. Cox proportional hazard models were developed to predict MACEs based on clinical variables, number of CAD vessels, and SYNTAX scores based on CCTA and ICA. The time-dependent receiver operating characteristic curve method was used, and the integrated area under the curve (iAUC) was calculated to compare the predictive prognosis of the models. RESULTS During the median follow-up of 1374days, there were 30 MACEs. In multivariate Cox regression adjusted for clinical variables, SYNTAX score group 4 (≥33) on CCTA and SYNTAX score groups 3 (23-32) and 4 (≥33) on ICA showed increased hazard ratios for MACEs compared to SYNTAX score group 1 (0). CT-SYNTAX score demonstrated no significant difference in iAUC compared with ICA-SYNTAX score and the number of vessels of CAD on CCTA. CONCLUSIONS CT-SYNTAX score can be a useful method for non-invasively predicting MACEs, especially in patients with complex CAD.

Accuracy of CT for Selecting Candidates for Coronary Artery Bypass Graft Surgery: Combination with the SYNTAX Score

PURPOSE To investigate the diagnostic performance of coronary computed tomographic (CT) angiography for selecting candidates for coronary artery bypass graft (CABG) surgery according to the 2011 American College of Cardiology Foundation (ACCF) and American Heart Association (AHA) guidelines for CABG surgery and determine the added value of SYNTAX (Synergy between PCI with TAXUS and Cardiac Surgery) scoring for selecting CABG surgery candidates. MATERIALS AND METHODS Approval was obtained from the Institutional Review Board, and informed consent was waived for this retrospective study. A total of 399 patients (mean age, 63.8 years; 244 men and 155 women) who underwent both coronary CT angiography and invasive coronary angiography were included. Eligible criteria for CABG surgery were established on the basis of the 2011 ACCF/AHA guidelines. RESULTS from coronary CT angiography and invasive coronary angiography were retrospectively reviewed, and SYNTAX scores were determined. The diagnostic performance of coronary CT angiography for selecting CABG surgery candidates was calculated with invasive coronary angiography as the reference method. The diagnostic performance of coronary CT angiography alone, the CT-based SYNTAX score, and the combined coronary CT angiography with CT-based SYNTAX score were assessed by using a combination of invasive coronary angiography and invasive coronary angiography-based SYNTAX scores as a reference method. Statistical analyses were performed by using the generalized estimating equation, independent t test, Mann-Whitney U test, Wilcoxon signed rank test, Fisher exact test, and χ(2) statistics. RESULTS The overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value of coronary CT angiography for selecting CABG surgery candidates were 96.5%, 96.5%, 88.3%, and 99.0%, respectively. When a combination of invasive coronary angiography with an invasive coronary angiography-based SYNTAX score was used as a standard reference, combined coronary CT angiography with a CT-based SYNTAX score had higher specificity and PPV (98.3% and 86.0%, respectively) than did coronary CT angiography alone (84.5% and 40.4%, respectively; P < .0001). CONCLUSION Coronary CT angiography had diagnostic accuracy comparable to that of invasive coronary angiography for selecting CABG surgery candidates, and combining a CT-based SYNTAX score with coronary CT angiography can be a highly specific method for selecting CABG surgery candidates.

Predictors of Recurrent Stroke in Patients with Ischemic Stroke: Comparison Study between Transesophageal Echocardiography and Cardiac CT

PURPOSE To investigate cardiac computed tomographic (CT) findings predictive of recurrent stroke in patients with ischemic stroke and determine the incremental risk stratification benefit of cardiac CT findings compared with transesophageal echocardiography (TEE) findings in patients with ischemic stroke. MATERIALS AND METHODS This single-center prospective study protocol was approved by the institutional review boards, and written informed consent was obtained from all patients. Among 548 consecutive patients, 374 patients with ischemic stroke (254 men and 120 women, with a mean age of 63.1 years) who underwent TEE and cardiac CT were prospectively enrolled in this study. TEE and cardiac CT images were assessed for cardioembolic sources, including thrombus, tumor, spontaneous echo contrast, valvular vegetation, atrial septal aneurysm, patent foramen ovale, and aortic plaque. The primary end point was stroke recurrence. Prognostic factors were assessed with Cox univariate and multivariate analysis. The integrated area under the receiver operating characteristic curve was calculated to compare the prognostic abilities of CT and TEE parameters. RESULTS During a median follow-up period of 433 days, there were a total of 28 recurrent stroke events. The TEE parameter of plaque complexity (hazard ratio, 13.512; 95% confidence interval: 3.668, 49.778; P < .001) and CT parameter of plaque complexity (hazard ratio, 32.538; 95% confidence interval: 7.544, 140.347; P < .001) were predictors of recurrent stroke. The time-dependent receiver operating characteristic curve analysis demonstrated no significant differences in prediction of recurrent stroke between TEE and CT parameters (integrated area under the receiver operating characteristic curve, 0.812 vs 0.840, respectively). CONCLUSION Complex aortic plaque evaluated with cardiac CT and TEE was associated with an increased risk of stroke recurrence in patients with ischemic stroke.

Usefulness of thin‐section single‐shot turbo spin echo with half‐fourier acquisition in evaluation of local invasion of lung cancer

To evaluate the usefulness of thin‐section single‐shot turbo spin echo with half‐Fourier acquisition (SS‐TSE‐HF) alone for evaluation of local invasion of lung cancer.

Krypton-enhanced ventilation CT with dual energy technique: Experimental study for optimal krypton concentration

ABSTRACT Purpose/Aim of the study. To assess the feasibility of krypton-enhanced ventilation CT using dual energy (DE) technique for various krypton concentrations and to determine the appropriate krypton concentration for DE ventilation CT through an animal study. Materials and Methods. Baseline DECT was first performed on seven New Zealand white rabbits. The animals were then ventilated using 20%, 30%, 40%, 50%, 60%, to 70% krypton concentration, and DECT was performed for each concentration. Krypton extraction was performed through a workstation, and results were displayed on a color map. Overlay Hounsfield unit (HU) values were obtained by two observers in consensus readings. A linear mixed model was used to correlate overlay HU values and krypton concentrations. Visual assessments of the homogeneity of krypton maps were also performed. Results. Mean overlay HU values according to krypton concentration were as follows; 20% krypton, 1.68 ± 5.15; 30% krypton, 3.73 ± 5.93; 40% krypton, 6.92 ± 5.51; 50% krypton, 10.88 ± 5.17; 60% krypton, 14.54 ± 4.23; and 70% krypton, 18.79 ± 3.63. We observed a significant correlation between overlay HU values on krypton maps and krypton concentrations (P < .001). For the krypton color maps, all observers determined universal enhancement on the 70% krypton map for all animals. Conclusion. It is feasible to evaluate lung ventilation function using DECT with a krypton concentration of at least 70%.

Differentiation Between Mucus Secretion and Endoluminal Tumors in the Airway: Analysis and Comparison of CT Findings

OBJECTIVE The objective of our study was to suggest CT features that help differentiate transient mucus secretion from airway tumors in the evaluation of soft-tissue nodular lesions confined within the airway lumen. MATERIALS AND METHODS Forty-two patients with airway tumors (mean age, 57.6 ± 14.9 [SD] years) and 48 patients with secretion (mean age, 67.8 ± 13.4 years) were included. Two observers analyzed the following features on contrast-enhanced CT in consensus readings: shape (round, ovoid, lobulating, or complex); margin (circumscribed or uncircumscribed); size (including change in size between mediastinal and lung window images); location (anterior, posterior, or unclear); angle between the lesion and contacting airway wall (acute, obtuse, or unclear); attenuation (quantitative and qualitative analyses); and presence of air, fat, or calcification within the lesion. The positive predictive value (PPV) of each CT finding was calculated for secretion and tumor, respectively. RESULTS Round (90.0%) or lobulating (92.9%) shape, uncircumscribed margin (100.0%), unclear location (87.5%), unclear angle (87.5%), a CT number of 21.7 HU or more (91.7%), and internal features such as fat (100.0%) or calcification (100.0%) showed high PPVs for tumors. Complex shape (100.0%), change in size of more than 15.9% (96.8%), a CT number of less than 21.7 HU (83.3%), and internal air density (100.0%) showed high PPVs for secretion. CONCLUSION On contrast-enhanced CT, the evaluation of shape, change in size between mediastinal and lung window images, the measurement of CT number, and internal features such as air, fat, or calcification might help differentiate secretion from tumors.

Three-Dimensional Ground Glass Opacity Ratio in CT Images Can Predict Tumor Invasiveness of Stage IA Lung Cancer

Purpose We investigated the relationship between various parameters, including volumetric parameters, and tumor invasiveness according to the International Association for the Study of Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) classification. Materials and Methods We retrospectively reviewed 99 patients with completely resected stage IA lung adenocarcinoma. The correlation between several parameters [one-dimensional ground glass opacity (1D GGO) ratio, two-dimensional (2D) GGO ratio, three-dimensional (3D) GGO ratio, 1D solid size, 2D solid size, and 3D solid size] and tumor invasiveness according to IASLC/ATS/ERS classification was investigated using receiver operating characteristic (ROC) analysis. Adenocarcinoma in situ and minimally invasive adenocarcinoma were referred to as noninvasive adenocarcinoma. Results The areas under the curve (AUC) to predict invasive adenocarcinoma for the 1D, 2D, and 3D GGO ratios were 0.962, 0.967, and 0.971, respectively. The optimal cut-off values for the 1D, 2D, and 3D GGO ratios were 38%, 62%, and 74%, respectively. The AUC values for 1D, 2D, and 3D solid sizes to predict invasive adenocarcinoma were 0.933, 0.944, and 0.903, respectively. The optimal cut-off values for 1D, 2D, and 3D solid sizes were 1.2 cm, 1.5 cm2, and 0.7 cm3, respectively. The difference in the ROC curves for 3D GGO ratio and 3D solid size was significant (p=0.01). Conclusion Computed tomography image-related parameters based on GGO were well correlated with and predictive of invasiveness according to IASLC/ATS/ERS classification. 3D GGO ratio was more strongly correlated with pathologic invasiveness than 3D solid size.

Predictors of False-Negative Results from Percutaneous Transthoracic Fine-Needle Aspiration Biopsy: An Observational Study from a Retrospective Cohort

Purpose We investigated factors predictive of false-negative pulmonary lesions with nonspecific benign cytology results on percutaneous transthoracic fine-needle aspiration biopsy (FNAB). Materials and Methods We included 222 pulmonary lesions that had a nonspecific benign result from percutaneous transthoracic FNAB between March 2005 and December 2012, and were confirmed by subsequent pathologic results or adequate clinical follow up over at least 2 years. Clinical, imaging, and biopsy procedure-related findings were compared between lesions with a final diagnosis of malignancy (false-negative) and lesions with a benign diagnosis (true-negative). Multivariate logistic regression analysis was performed to identify significant predictors of false-negatives. Results Of 222 lesions, 115 lesions were proved to be false-negatives, and 107 were true-negatives. Compared with the true-negatives, false-negative lesions showed significantly older age (p=0.037), higher maximum standardized uptake value (SUVmax) on positron emission tomography (p=0.001), larger lesion size (p=0.007), and lesion characteristics of a subsolid nodule (p=0.007). On multivariate logistic regression analysis, SUVmax, lesion size, and lesion characteristics were significant predictors of false-negative results. Conclusion Among the clinical, radiologic, and procedure-related factors analyzed, high SUVmax, large lesion size, and subsolid lesions were useful for predicting malignancy in pulmonary lesions with nonspecific benign cytology results on FNAB.

Predictive factors for treatment response using dual-energy computed tomography in patients with advanced lung adenocarcinoma

PURPOSE This study aimed to investigate whether the quantitative parameters of dual-energy computed tomography (DECT) can predict the effects of chemotherapy in advanced adenocarcinoma based on the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines. MATERIALS AND METHODS A total of 90 patients (59 males, 31 females, age 61.4 ± 12.3 (23-85)) with unresectable lung adenocarcinoma (TNM stage IIIB or IV) who underwent DECT before chemotherapy were prospectively included in this study. By comparing baseline studies with the best response achieved during 1 st line chemotherapy, patients were divided into two groups according to RECIST (version 1.1) guidelines as follows; responders (CR or PR) and non-responders (SD or PD). Quantitative measurements were performed on baseline DECT, and a logistic regression model was used to evaluate predictive factors for a response to chemotherapy. RESULTS Among 90 patients, 38 were categorized as responders, while 52 patients were non-responders. The mean iodine concentration measurements were significantly higher in responders compared with non-responders (1.81 ± 0.51 vs 1.33 ± 0.76 mg/ml, p < 0.001). On multivariate analysis, EGFR mutation (odds ratio (OR): 3.116, 95% confidential interval (CI):1.182-8.213, p = .019) and iodine concentration (OR: 1.112, 95% CI:1.034-1.196, p = .006) were found to be significant for predicting a treatment response. CONCLUSIONS Dual-energy CT using a quantitative analytic method based on iodine concentration measurements can be used to predict the effects of chemotherapy in patients with advanced adenocarcinoma.