Dong Jin Im

Myocardial Extracellular Volume Fraction with Dual-Energy Equilibrium Contrast-enhanced Cardiac CT in Nonischemic Cardiomyopathy: A Prospective Comparison with Cardiac MR Imaging.

Purpose To evaluate the feasibility of equilibrium contrast material-enhanced dual-energy cardiac computed tomography (CT) to determine extracellular volume fraction (ECV) in nonischemic cardiomyopathy (CMP) compared with magnetic resonance (MR) imaging. Materials and Methods This study was approved by the institutional review board; informed consent was obtained. Seven healthy subjects and 23 patients (six with hypertrophic CMP, nine with dilated CMP, four with amyloidosis, and four with sarcoidosis) (mean age ± standard deviation, 57.33 years ± 14.82; 19 male participants [63.3%]) were prospectively enrolled. Twelve minutes after contrast material injection (1.8 mL/kg at 3 mL/sec), dual-energy cardiac CT was performed. ECV was measured by two observers independently. Hematocrit levels were compared between healthy subjects and patients with the Mann-Whitney U test. In per-subject analysis, interobserver agreement for CT was assessed with the intraclass correlation coefficient (ICC), and intertest agreement between MR imaging and CT was assessed with Bland-Altman analysis. In per-segment analysis, Student t tests in the linear mixed model were used to compare ECV on CT images between healthy subjects and patients. Results Hematocrit level was 43.44% ± 1.80 for healthy subjects and 41.23% ± 5.61 for patients with MR imaging (P = .16) and 43.50% ± 1.92 for healthy subjects and 41.35% ± 5.92 for patients with CT (P = .15). For observer 1 in per-subject analysis, ECV was 34.18% ± 8.98 for MR imaging and 34.48% ± 8.97 for CT. For observer 2, myocardial ECV was 34.42% ± 9.03 for MR imaging and 33.98% ± 9.05 for CT. Interobserver agreement for ECV at CT was excellent (ICC = 0.987). Bland-Altman analysis between MR imaging and CT showed a small bias (-0.06%), with 95% limits of agreement of -1.19 and 1.79. Compared with healthy subjects, patients with hypertrophic CMP, dilated CMP, amyloidosis, and sarcoidosis had significantly higher myocardial ECV at dual-energy equilibrium contrast-enhanced cardiac CT (all P < .01) in per-segment analysis. Conclusion Myocardial ECV with dual-energy equilibrium contrast-enhanced CT showed good agreement with MR imaging findings, suggesting the potential of myocardial tissue characterization with CT. (©) RSNA, 2016.

Myocardial T1 and T2 Mapping: Techniques and Clinical Applications

Cardiac magnetic resonance (CMR) imaging is widely used in various medical fields related to cardiovascular diseases. Rapid technological innovations in magnetic resonance imaging in recent times have resulted in the development of new techniques for CMR imaging. T1 and T2 image mapping sequences enable the direct quantification of T1, T2, and extracellular volume fraction (ECV) values of the myocardium, leading to the progressive integration of these sequences into routine CMR settings. Currently, T1, T2, and ECV values are being recognized as not only robust biomarkers for diagnosis of cardiomyopathies, but also predictive factors for treatment monitoring and prognosis. In this study, we have reviewed various T1 and T2 mapping sequence techniques and their clinical applications.

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.

Added value of cardiac computed tomography for evaluation of mechanical aortic valve: Emphasis on evaluation of pannus with surgical findings as standard reference

BACKGROUND The added value of cardiac computed tomography (CT) with transesophageal echocardiography (TEE) for evaluating mechanical aortic valve (AV) dysfunction has not yet been investigated. The purposes of this study were to investigate the added value of cardiac CT for evaluation of mechanical AVs and diagnoses of pannus compared to TEE, with surgical findings of redo-aortic valve replacement (AVR) used as a standard reference. METHODS 25 patients who underwent redo-AVR due to mechanical AV dysfunction and cardiac CT before redo-AVR were included. The presence of pannus, encroachment ratio by pannus, and limitation of motion (LOM) were evaluated on CT. The diagnostic performance of pannus detection was compared using TEE, CT, and CT+TEE, with surgical findings as a standard reference. The added value of CT for diagnosing the cause of mechanical AV dysfunction was assessed compared to TTE+TEE. RESULTS In two patients, CT analysis was not feasible due to severe metallic artifacts. On CT, pannus and LOM were found in 100% (23/23) and 60.9% (14/23). TEE identified pannus in 48.0% of patients (12/25). CT, TEE, and CT+TEE correctly identified pannus with sensitivity of 92.0%, 48.0%, and 92.0%, respectively (P=0.002 for CT vs. TEE). In 11 of 13 cases (84.6%) with inconclusive or negative TEE results for pannus, CT detected the pannus. Among 13 inconclusive cases of TTE+TEE for the cause of mechanical AV dysfunction, CT suggested 6 prosthetic valve obstruction (PVO) by pannus, 4 low-flow low-gradient PVO, and one LOM without significant PVO. CONCLUSIONS Cardiac CT showed added diagnostic value with TEE in the detection of pannus as the cause of mechanical AV dysfunction.

Assessment of Mitral Paravalvular Leakage After Mitral Valve Replacement Using Cardiac Computed Tomography: Comparison With Surgical Findings.

Background—The diagnostic performance of cardiac computed tomography (CT) for detection of paravalvular leakage (PVL) after mitral valve replacement has not been investigated in a large population. We aimed to investigate the diagnostic accuracy of CT for diagnosis of mitral PVL using surgical findings as the standard reference and to compare the diagnostic performance of CT with those of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE). Methods and Results—A total of 204 patients with previous mitral valve replacement who underwent cardiac CT were retrospectively included. The presence of mitral PVL was analyzed on CT, TTE, and TEE. In 78 patients who underwent redo-surgery, diagnostic performance for the detection of PVL for CT, TTE, and TEE were compared with surgical findings as the standard reference. The location of mitral PVL on CT and TEE was compared with surgical findings. Mitral PVL was present in 18.1% (37/204) on CT, in 16.2% (32/198) on TTE, and in 42.6% (29/68) on TEE. On the surgical field, PVL was identified in 41.0% (32/78). The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for detection of PVL were 96.9%, 97.8%, 96.9%, 97.8%, and 97.4% for CT; 81.3%, 95.6%, 92.9%, 87.8%, and 89.6% for TTE; and 96.2%, 95.8%, 96.2%, 95.8%, and 96.0% for TEE. CT and TEE identified the correct location of PVL in 75.9% (22/29) and 85.6% (19/23). Conclusions—Cardiac CT may have better diagnostic accuracy compared with TTE for the detection of mitral PVL and may be comparable to TEE for the detection and localization of PVL.

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.

Acute Pulmonary Embolism: Retrospective Cohort Study of the Predictive Value of Perfusion Defect Volume Measured With Dual-Energy CT

OBJECTIVE The purposes of this study were to investigate dual-energy CT findings predictive of clinical outcome and to determine the incremental risk stratification benefit of dual-energy CT findings compared with CT ventricular diameter ratio in patients with acute pulmonary embolism. MATERIALS AND METHODS A retrospective evaluation was conducted of the cases of 172 patients with acute pulmonary embolism who underwent dual-energy CT. Ventricular diameter ratio and relative perfusion defect volume were measured. The primary endpoints were death within 30 days and pulmonary embolism-related death. RESULTS A ventricular diameter ratio of 1 or greater was associated with increased risk of death within 30 days (hazard ratio, 3.822; p = 0.002) and pulmonary embolism-related death (hazard ratio, 18.051; p < 0.001). Relative perfusion defect volume was also associated with increased risk of death of any cause within 30 days (hazard ratio, 1.044; p = 0.014) and pulmonary embolism-related death (hazard ratio, 1.046; p = 0.017). However, the addition of relative perfusion defect volume to ventricular diameter ratio had no added benefit for prediction of death of any cause within 30 days (concordance statistic, 0.833 vs 0.815; p = 0.187) or pulmonary embolism-related death (concordance statistic, 0.873 vs 0.874; p = 0.866). CONCLUSION Compared with ventricular diameter ratio alone, lung perfusion defect volume had no statistically significant added benefit for prediction of death of any cause within 30 days or of pulmonary embolism-related death among patients with acute PE.

Utility of Dual-Energy CT-based Monochromatic Imaging in the Assessment of Myocardial Delayed Enhancement in Patients with Cardiomyopathy

Purpose To investigate the diagnostic utility of dual-energy computed tomography (CT)-based monochromatic imaging for myocardial delayed enhancement (MDE) assessment in patients with cardiomyopathy. Materials and Methods The institutional review board approved this prospective study, and informed consent was obtained from all participants who were enrolled in the study. Forty patients (27 men and 13 women; mean age, 56 years ± 15 [standard deviation]; age range, 22-81 years) with cardiomyopathy underwent cardiac magnetic resonance (MR) imaging and dual-energy CT. Conventional (120-kV) and monochromatic (60-, 70-, and 80-keV) images were reconstructed from the dual-energy CT acquisition. Subjective quality score, contrast-to-noise ratio (CNR), and beam-hardening artifacts were compared pairwise with the Friedman test at post hoc analysis. With cardiac MR imaging as the reference standard, diagnostic performance of dual-energy CT in MDE detection and its predictive ability for pattern classification were compared pairwise by using logistic regression analysis with the generalized estimating equation in a per-segment analysis. The Bland-Altman method was used to find agreement between cardiac MR imaging and CT in MDE quantification. Results Among the monochromatic images, 70-keV CT images resulted in higher subjective quality (mean score, 3.38 ± 0.54 vs 3.15 ± 0.43; P = .0067), higher CNR (mean, 4.26 ± 1.38 vs 3.93 ± 1.33; P = .0047), and a lower value for beam-hardening artifacts (mean, 3.47 ± 1.56 vs 4.15 ± 1.67; P < .0001) when compared with conventional CT. When compared with conventional CT, 70-keV CT showed improved diagnostic performance for MDE detection (sensitivity, 94.6% vs 90.4% [P = .0032]; specificity, 96.0% vs 94.0% [P = .0031]; and accuracy, 95.6% vs 92.7% [P < .0001]) and improved predictive ability for pattern classification (subendocardial, 91.5% vs 84.3% [P = .0111]; epicardial, 94.3% vs 73.5% [P = .0001]; transmural, 93.0% vs 77.7% [P = .0018]; mesocardial, 85.4% vs 69.2% [P = .0047]; and patchy. 84.4% vs 78.4% [P = .1514]). For MDE quantification, 70-keV CT showed a small bias 0.1534% (95% limits of agreement: -4.7013, 5.0080). Conclusion Dual-energy CT-based 70-keV monochromatic images improve MDE assessment in patients with cardiomyopathy via improved image quality and CNR and reduced beam-hardening artifacts when compared with conventional CT images.

Absolute-Delay Multiphase Reconstruction Reduces Prosthetic Valve–Related and Atrial Fibrillation–Related Artifacts at Cardiac CT

OBJECTIVE The objective of our study was to compare the image quality of cardiac CT images of mechanical valves in patients with irregular heart rates (HRs) using absolute-delay multiphase reconstruction versus relative-delay multiphase reconstruction. MATERIALS AND METHODS A total of 26 patients with 40 mechanical valves who had atrial fibrillation during CT were included. The image quality of the CT scans was assessed for the subvalvular and valvular regions on a 4-point scale. The paired t test or Wilcoxon signed rank test was used to compare image quality scores between the relative-delay and absolute-delay reconstruction techniques. The overall image quality score was determined as the mean of the valvular and subvalvular region scores. RESULTS For valvular regions, the image quality scores were 2.93 ± 0.73 (mean ± SD) for the relative-delay reconstruction technique and 3.55 ± 0.60 for the absolute-delay reconstruction technique (p < 0.0001). For subvalvular regions, the image quality scores were 2.8 ± 2.80 ± 0.79 and 3.35 ± 0.66 for the relative- and absolute-delay reconstructions (p < 0.0001), respectively. The nondiagnostic image quality group consisted of relative-delay reconstruction images of three valves (7.5%); the image quality scores for the absolute-delay reconstruction images of all three valves were improved, and the absolute-delay reconstruction images of the three valves were of diagnostic quality (p < 0.0001). CONCLUSION Absolute-delay multiphase reconstruction can improve CT image quality of mechanical valves in patients with an irregular HR compared with relative-delay reconstruction.

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.