Doo Kyoung Kang

CT Signs of Right Ventricular Dysfunction: Prognostic Role in Acute Pulmonary Embolism

OBJECTIVES The purpose of this study was to compare the prognostic role of various computed tomography (CT) signs of right ventricular (RV) dysfunction, including 3-dimensional ventricular volume measurements, to predict adverse outcomes in patients with acute pulmonary embolism (PE). BACKGROUND Three-dimensional ventricular volume measurements based on chest CT have become feasible for routine clinical application; however, their prognostic role in patients with acute PE has not been assessed. METHODS We evaluated 260 patients with acute PE for the following CT signs of RV dysfunction obtained on routine chest CT: abnormal position of the interventricular septum, inferior vena cava contrast reflux, right ventricle diameter (RVD) to left ventricle diameter (LVD) ratio on axial sections and 4-chamber (4-CH) views, and 3-dimensional right ventricle volume (RVV) to left ventricle volume (LVV) ratio. Comorbidities and fatal and nonfatal adverse outcomes according to the MAPPET-3 (Management Strategies and Prognosis in Pulmonary Embolism Trial-3) criteria within 30 days were recorded. RESULTS Fifty-seven patients (21.9%) had adverse outcomes, including 20 patients (7.7%) who died within 30 days. An RVD(axial)/LVD(axial) ratio >1.0 was not predictive for adverse outcomes. On multivariate analysis (adjusting for comorbidities), abnormal position of the interventricular septum (hazard ratio [HR]: 2.07; p = 0.007), inferior vena cava contrast reflux (HR: 2.57; p = 0.001), RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 2.51; p = 0.009), and RVV/LVV ratio >1.2 (HR: 4.04; p < 0.001) were predictive of adverse outcomes, whereas RVD(4-CH)/LVD(4-CH) ratio >1.0 (HR: 3.68; p = 0.039) and RVV/LVV ratio >1.2 (HR: 6.49; p = 0.005) were predictive of 30-day death. CONCLUSIONS Three-dimensional ventricular volume measurement on chest CT is a predictor of early death in patients with acute PE, independent of clinical risk factors and comorbidities. Abnormal position of the interventricular septum, inferior vena cava contrast reflux, and RVD(4-CH)/LVD(4-CH) ratio are predictive of adverse outcomes, whereas RVD(axial)/LVD(axial) ratio >1.0 is not.

Adenosine-stress dynamic myocardial CT perfusion imaging: initial clinical experience.

Objective:To evaluate the feasibility of adenosine-stress dynamic myocardial volume perfusion imaging with second generation dual source computed tomography (CT) for the qualitative and quantitative assessment of myocardial blood flow (MBF) compared with stress perfusion and viability magnetic resonance imaging (MRI). Material and Methods:Ten patients (8 male, 2 female, mean age 62.7 ± 7.1 years) underwent stress/rest perfusion and delayed-enhancement MRI, and a cardiac CT protocol comprising prospectively electrocardiogram -triggered coronary CT angiography, dynamic adenosine-stress myocardial perfusion imaging using a “shuttle” mode, and delayed enhancement acquisitions. Two independent observers visually assessed myocardial perfusion defects. For semi-quantitative evaluation, CT- and MRI-derived myocardial-to-left ventricular upslope indices were compared. Additionally, absolute MBF was quantified based on dynamic perfusion CT and correlated with semi quantitative CT measurements. Myocardial perfusion analysis was performed on a segmental basis. Analysis used paired t tests, Wilcoxon signed-rank test, linear correlation, and Bland-Altman statistics. Results:A total of 149 segments (93.1%) were suitable for analysis. Sensitivity, specificity, positive and negative predictive values for detection of myocardial perfusion defects at CT compared with MRI were 86.1%, 98.2%, 93.9%, and 95.7%, respectively. Semiquantitative analysis of CT data showed significant differences between ischemic and nonischemic myocardium with a signal intensity upslope that was comparable with MRI-derived values (CT: 5.2 ± 2 SI/s, MRI: 4.8 ± 2.3 SI/s, P > 0.05). Moderate correlation was observed between absolute CT quantification of MBF and semi-quantitative CT measurements. Mean total dose length product for the entire cardiac CT protocol was 1290.4 ± 233.3 mGy cm. Conclusion:Adenosine-stress volumetric first pass CT perfusion imaging is feasible and may enable the evaluation of qualitative and semi quantitative parameters of myocardial perfusion in a comparable fashion as MRI.

Reproducibility of CT Signs of Right Ventricular Dysfunction in Acute Pulmonary Embolism

OBJECTIVE The purpose of our study was to determine the interobserver reproducibility of CT findings of right ventricular (RV) dysfunction in pulmonary embolism (PE). MATERIALS AND METHODS Two experienced observers independently and retrospectively evaluated pulmonary CT angiography (CTA) studies of 50 patients with acute PE for the following signs: bowing of the interventricular septum, inferior vena cava (IVC) contrast medium reflux, RV diameter (RVD)/left ventricular diameter (LVD) ratio on axial sections and four-chamber (4-CH) views, and RV volume (RVV)/left ventricular volume (LVV) ratio. Analysis used kappa statistics, Spearmans rank correlation, and Bland-Altman statistics. RESULTS The two observers had fair to moderate agreement (kappa = 0.32-0.44) for septal bowing and moderate to good agreement (kappa = 0.57-0.68) for diagnosing IVC reflux. The Spearmans rank correlation coefficients for RVD(axial)/LVD(axial) ratio and RVD(4-CH)/LVD(4-CH) ratio between the two observers were 0.88 (p < 0.001) and 0.85 (p < 0.001), respectively. On Bland-Altman analysis, the mean differences for RVD(axial)/LVD(axial) ratio and RVD(4-CH)/LVD(4-CH) ratio were 0.014 (+/- 0.195) and 0.001 (+/- 0.242), respectively. The correlation coefficient for RVV/LVV ratio was 0.93 (p < 0.001), and the mean difference was 0.033 (+/- 0.229). CONCLUSION Considerable differences exist in the interobserver reproducibility of CT findings of RV dysfunction on pulmonary CTA in patients with acute PE. Cardiac chamber measurements are more reproducible than septal bowing and IVC reflux. Volumetric determination of the RVV/LVV ratio is the least user dependent and most reproducible.

Dual-Energy Computed Tomography for Integrative Imaging of Coronary Artery Disease: Principles and Clinical Applications

The introduction of coronary CT angiography (cCTA) has reinvigorated the debate whether management of patients with suspected coronary artery disease (CAD) should be primarily based on physiological, functional versus anatomical testing. Anatomical testing (i.e., cCTA or invasive catheterization) enables direct visualization and grading of coronary artery stenoses but has shortcomings for gauging the hemodynamic significance of lesions for myocardial perfusion. Rest/stress myocardial perfusion imaging (MPI) has been extensively validated for assessing the clinical significance of CAD by demonstrating fixed or reversible perfusion defects but has only limited anatomical information. There is growing evidence that contrast medium enhanced dual-energy cCTA (DECT) has potential for the comprehensive analysis of coronary artery morphology as well as changes in myocardial perfusion. DECT exploits the fact that tissues in the human body and iodine-based contrast media have unique absorption characteristics when penetrated with different X-ray energy levels, which enables mapping the iodine (and thus blood) distribution within the myocardium. The purpose of this communication is to describe the practical application of this technology for the comprehensive diagnosis of ischemic heart disease. We examine recent scientific findings in the context of current pivotal transitions in cardiovascular disease management and demonstrate the potential of cardiac DECT for the integrative assessment of patients with known or suspected CAD within a single CT-based protocol.

Cost-effectiveness of substituting dual-energy CT for SPECT in the assessment of myocardial perfusion for the workup of coronary artery disease

PURPOSE We compared cost-effectiveness and potential lifetime benefits of using dual-energy computed tomography (DECT) for myocardial perfusion assessment instead of single photon emission computed tomography (SPECT) for the workup of coronary artery disease (CAD). MATERIALS AND METHODS A decision and simulation model was developed to estimate cost and health effects of using DECT myocardial perfusion imaging instead of SPECT for identifying patients in need of invasive imaging and possible revascularization. The model was based on the performance indices of stress/rest DECT compared with stress/rest SPECT for detecting myocardial perfusion deficits in 50 patients (mean age 61±10 years) with CAD. Stress/rest perfusion and delayed enhancement cardiac MRI served as reference standard. For DECT a reimbursement of US

High-temporal resolution dual-energy computed tomography of the heart using a novel hybrid image reconstruction algorithm: initial experience.

1700 was assumed but costs of cardiac MRI were not included in the model. All other actual healthcare costs in these patients were derived from MUSCs hospital billing system. RESULTS Compared with cardiac MRI, DECT (versus SPECT) had 90% (85%) sensitivity and 71% (58%) specificity for identifying patients with obstructive CAD. Compared with the no imaging and no treatment strategy, routine SPECT gained 13.49 quality-adjusted life-years (QALYs) with an incremental cost-effectiveness ratio (ICER) of US

Magnetic resonance imaging patterns of tumor regression after neoadjuvant chemotherapy in breast cancer patients: correlation with pathological response grading system based on tumor cellularity

3557 (in 2010) per QALY. In comparison, DECT ICER was lower (US

CT Findings in Patients With Pericardial Effusion: Differentiation of Malignant and Benign Disease

3.191 per QALY, p=0.0002) and an additional 0.64 QALYs was obtained (total of 14.13 QALYs) if compared with the SPECT strategy as well as the no imaging and no treatment strategy. CONCLUSION Using DECT as the first-line imaging test for myocardial perfusion for the workup of patients with CAD has the potential to provide gains in QALYs, while lowering costs if compared to routine myocardial perfusion SPECT.

Prognostic role of MRI enhancement features in patients with breast cancer: value of adjacent vessel sign and increased ipsilateral whole-breast vascularity.

Objectives: Dual-energy computed tomography (DECT) has been proposed for the comprehensive assessment of coronary artery stenosis and myocardial perfusion yet traditionally required reducing the temporal resolution of cardiac studies. We evaluated a reconstruction algorithm that preserves high temporal resolution at cardiac DECT. Methods: Twelve consecutive patients (3 women; mean [SD] age, 64 [10] years) with an abnormal single photon emission CT result underwent invasive coronary angiography and cardiac DECT. Dual-energy CT studies were reconstructed using the standard algorithm with 165-millisecond temporal resolution and a hybrid algorithm providing 83-millisecond temporal resolution. These studies were rated for coronary image quality and motion artifacts and compared with invasive coronary angiographic studies. Results: One hundred sixty-eight coronary artery segments (82%) were evaluated. The standard 165-millisecond reconstruction provided 95% diagnostic segments compared with 100% using the 83-millisecond hybrid reconstruction. Image quality was rated significantly (P < 0.05) better with hybrid reconstruction and had 91.4% sensitivity, 94.7% specificity, 82.1% positive predictive value, and 97.7% negative predictive value for detecting significant stenosis versus 85.7%, 93.2%, 76.9%, and 96.1% with standard reconstruction, respectively. Conclusions: Hybrid image reconstruction mitigates the former limitations in temporal resolution of cardiac DECT.

Coronary Atherosclerosis in African American and White Patients with Acute Chest Pain: Characterization with Coronary CT Angiography

Purpose The objectives of the study were to analyze the tumor shrinkage pattern on magnetic resonance imaging (MRI) after neoadjuvant chemotherapy and to evaluate whether there is any difference in shrinkage pattern between pathological responder and nonresponder groups. In addition, we wanted to compare tumor diameter obtained from MRI with histological diameter according to the tumor shrinkage pattern. Methods Between July 2008 and December 2010, 55 consecutive patients (56 lesions) with pathologically proven breast cancer who underwent neoadjuvant chemotherapy followed by surgery were retrospectively enrolled. The shrinkage pattern was classified into 4 categories: I (concentric shrinkage without surrounding lesion), II (concentric shrinkage with surrounding lesions), III (shrinkage with residual multinodular lesions, and IV (diffuse contrast enhancement in whole quadrants). Histological regression was scored on a 5-point scale regarding tumor cellularity reduction (Miller-Payne grading system). Patients with Miller-Payne grade 1 or 2 were classified into the nonresponder group, and patients with grade 3, 4, or 5 were in the responder group. Results Of 56 lesions, pattern I was seen in 29 lesions, pattern II in 13 lesions, pattern III in 5 lesions, and pattern IV in 4 lesions. Three lesions were not visualized on MRI after neoadjuvant chemotherapy, and 2 lesions were increased in size. There was a statistically significant difference in the tumor shrinkage pattern between responder and nonresponder groups (P = 0.017). All 5 lesions with type III shrinkage pattern were found in the responder group, and all 4 lesions with pattern IV were in the nonresponder group. Magnetic resonance imaging diameter of lesions with types I, II, and IV patterns showed significant correlation with the histological diameter. Among them, the correlation factor was highest in pattern IV (&rgr; = 0.94, P < 0.001) followed by pattern I (&rgr; = 0.67, P < 0.01) and pattern II (&rgr; = 0.502, P = 0.08). However, in type III shrinkage pattern, tumor size measured on MRI was not significantly correlated with histological size (P = 0.87). Conclusions Types III and I shrinkage patterns were more frequently observed in the pathological responder group, and type IV was more frequently noted in the nonresponder group. Tumor diameter measured on MRI showed strong correlation with histological diameter in lesions with types I and IV shrinkage patterns, whereas lesions with type III did not show significant correlation. Type II pattern showed similar frequencies between the 2 groups and moderate correlation between sizes obtained from MRI and histology.