Yoo Jin Hong

Dual-Enhanced Cardiac CT for Detection of Left Atrial Appendage Thrombus in Patients With Stroke A Prospective Comparison Study With Transesophageal Echocardiography

Background and Purpose— A noninvasive method with high reliability and accuracy comparable to transesophageal echocardiography for identification of left atrial appendage thrombus would be of significant clinical value. The aim of this study was to assess the diagnostic performance of a dual-enhanced cardiac CT protocol for detection of left atrial appendage thrombi and for differentiation between thrombus and circulatory stasis in patients with stroke. Methods— We studied 83 consecutive patients with stroke (56 men and 27 women; mean age, 62.6 years) who had high risk factors for thrombus formation and had undergone both dual-source CT and transesophageal echocardiography within a 3-day period. CT was performed with prospective electrocardiographic gating, and scanning began 180 seconds after the test bolus. Results— Among the 83 patients, a total of 13 thrombi combined with spontaneous echo contrast and 14 spontaneous echo contrasts were detected by transesophageal echocardiography. All 13 thrombi combined with spontaneous echo contrast were correctly diagnosed on CT. Using transesophageal echocardiography as the reference standard, the overall sensitivity and specificity of CT for the detection of thrombi and circulatory stasis in the left atrial appendage were 96% (95% CI, 78% to 99%), and 100% (95% CI, 92% to 100%), respectively. On CT, the mean left atrial appendage/ascending aorta Hounsfield unit ratios were significantly different between thrombus and circulatory stasis (0.15 Hounsfield unit versus 0.27 Hounsfield unit, P=0.001). The mean effective radiation dose was 3.11 mSv. Conclusions— Dual-enhanced cardiac CT with prospective electrocardiographic gating is a noninvasive and sensitive modality for detecting left atrial appendage thrombus with an acceptable radiation dose.

Cardioembolic Stroke: Dual-Energy Cardiac CT for Differentiation of Left Atrial Appendage Thrombus and Circulatory Stasis

PURPOSE To assess the diagnostic performance of dual-energy cardiac computed tomography (CT) in the detection of left atrial appendage (LAA) thrombi and differentiation between thrombus and circulatory stasis in patients with stroke, by using transesophageal echocardiography (TEE) as the reference standard. MATERIALS AND METHODS The institutional review board approved this study, and patients provided informed consent. Thirty-two patients with stroke who had atrial fibrillation (AF) and either thrombus or the spontaneous echo contrast (SEC) echo pattern at TEE were prospectively enrolled. For the control group, 31 patients who were planning to undergo AF ablation and who had no abnormalities at TEE were enrolled. All patients underwent dual-energy cardiac CT that was not electrocardiographically gated. For quantitative analysis, iodine concentration was measured on CT images. The statistical significance of differences in mean iodine concentration between thrombus and SEC as measured at CT was assessed by using the Student t test. RESULTS Among the 63 patients, a total of 13 thrombi and 19 instances of SEC were detected at TEE. Using TEE as the reference standard, the overall sensitivity, specificity, positive predictive value, and negative predictive value of dual-energy cardiac CT in the detection of thrombi and SEC in the LAA were 97% (95% confidence interval [CI]: 82%, 100%), 100% (95% CI: 86%, 100%), 100%, and 97%, respectively. At CT, the mean iodine concentration was 1.23 mg/mL ± 0.34 (standard deviation) for thrombus and 3.61 mg/mL ± 1.01 for SEC (P = .001). CONCLUSION Dual-energy cardiac CT is a highly sensitive modality for detecting LAA thrombus and for differentiating thrombus from SEC in patients with stroke.

Diagnostic accuracy of multidetector row computed tomography in T- and N staging of gastric cancer with histopathologic correlation.

Purpose: To evaluate the diagnostic accuracy of multidetector row computed tomography (MDCT) for the preoperative T- and N staging of gastric cancer. Materials and Methods: Eighty-four consecutive patients with gastric cancer underwent preoperative MDCT. Except for 15 patients who did not undergo surgery, 69 patients were included in our study. Two radiologists independently evaluated the T- and N staging on the axial CT images alone and in combination with the MPR images. For N staging, the new TNM and Japanese classifications were independently used. Differences in staging accuracy for T- and N staging were assessed using the McNemar test. Results: The overall T staging accuracy of the axial and combined axial and MPR images was as follows: 67% (47 of 70 cancers) versus 77% (54 of 70 cancers) (P = 0.039). The overall N staging accuracy of the axial and combined axial and MPR images was as follows: 59% (41 of 69 cancers) versus 67% (46 of 69 cancers) (P = 0.180, Japanese classification) and 54% (37 of 69 cancers) versus 59% (41 of 69 cancers) (P = 0.109, TNM classification). Conclusions: Using MPR images enables more accurate preoperative T staging of gastric cancer, but not for N staging in either classification system.

Tumor perfusion‐related parameter of diffusion‐weighted magnetic resonance imaging: Correlation with histological microvessel density

We obtained intravoxel incoherent motion (IVIM) parameters through biexponential analysis on diffusion‐weighted MR imaging (DWI) using multiple b values. Correlation was evaluated between these parameters and histological microvessel density (MVD) for the possibility of noninvasive evaluation of MVD with DWI.

Anomalous origin of the right coronary artery from the left coronary sinus with an interarterial course: subtypes and clinical importance.

PURPOSE To classify anomalous origins of the right coronary artery (RCA) from the left coronary sinus (AORL) with an interarterial course into two subtypes and to evaluate the clinical importance of each. MATERIALS AND METHODS Institutional review board approval was obtained for this retrospective study, and informed consent was waived. Through a retrospective review of 22,925 consecutive cardiac computed tomographic (CT) scans, 124 cases of AORL with an interarterial course were identified. These anomalies were classified into two subtypes according to the location of the anomalous RCA ostium: high interarterial course (between the aorta and the pulmonary artery) and low interarterial course (between the aorta and the right ventricular outflow tract). The clinical records were evaluated, and differences in prevalence of typical angina and major adverse cardiac events (MACEs) between the subtypes were analyzed through the χ(2) contingency tables or Fisher exact test. RESULTS After excluding patients with combined cardiac disease, 87 patients (51 [59%] men, 36 [41%] women; mean age, 56.0 years) were enrolled. Of the 87 patients, 53 had a high interarterial course and 34 had a low interarterial course. A significant difference in the prevalence of typical angina (high [43%] vs low [6%], P = .001) and MACE (high [28%] vs low [6%], P = .012) was observed between the two subtypes. For patients with a high interarterial course, the odds ratio for typical angina was 12.3 (95% confidence interval: 2.7, 56.6), and the odds ratio for MACE was 6.3 (95% confidence interval: 1.3, 29.7). CONCLUSION The prevalence of typical angina and that of MACE were significantly higher in patients with a high interarterial course than in those with a low interarterial course.

Positive predictive values of sonographic features of solid thyroid nodule.

AIM The purpose of this study was to assess the positive predictive value of the suspicious sonographic features of solid nodules of the thyroid. MATERIALS AND METHODS After approval by our institutional review board, we evaluated 594 sonographically detected nodules on which fine needle aspiration biopsy had been performed from January to December 2005. Among these, pure cystic lesions and inadequate pathologic results were excluded. The remaining 530 solid thyroid nodules were analyzed by two radiologists. Each lesion was classified based on four sonographic features that suggested malignancy: microcalcifications; an irregular or microlobulated margin; marked hypoechogenicity; and a shape that was taller than wide. The sensitivity, specificity, positive predictive value, and negative predictive value of the each sonographic feature were calculated. RESULTS Final pathologic results showed that 97 (18.3%) of 530 nodules were malignant. The positive predictive values for malignancy in each sonographic feature were microcalcifications, 38.6% (39/101); an irregular or microlobulated margin, 28.2% (70/248); marked hypoechogenecity, 49.4% (38/77); taller than wide shape, 59.8% (49/82). In terms of relative risk, microcalcification [P<.01, relative risk (RR)=3.115, 95% CI: 1.724-5.628], hypoechogenecity (P<.01, RR=2.510, 95% CI: 1.290-4.881). The shape of nodule which was taller than wide (P<.01, RR=7.624, 95% CI: 4.156-13.986) revealed the highest predictive sonographic finding suggesting malignancy. However, margin is the least significant feature of detection of thyroid malignancy (P=.27, RR=1.395, 95% CI: 0.777-2.505). CONCLUSION The three sonographic features of solid thyroid nodule, that is, microcalcifications, marked hypoechogenecity, and a taller than wide shape are meaningful findings in the diagnosis of thyroid malignancy. The shape that was taller than wide was the most reliable sonographic feature for predicting malignancy.

Korean Guidelines for the Appropriate Use of Cardiac CT

The development of cardiac CT has provided a non-invasive alternative to echocardiography, exercise electrocardiogram, and invasive angiography and cardiac CT continues to develop at an exponential speed even now. The appropriate use of cardiac CT may lead to improvements in the medical performances of physicians and can reduce medical costs which eventually contribute to better public health. However, until now, there has been no guideline regarding the appropriate use of cardiac CT in Korea. We intend to provide guidelines for the appropriate use of cardiac CT in heart diseases based on scientific data. The purpose of this guideline is to assist clinicians and other health professionals in the use of cardiac CT for diagnosis and treatment of heart diseases, especially in patients at high risk or suspected of heart disease.

Automatic Tube Potential Selection with Tube Current Modulation (APSCM) in coronary CT angiography: Comparison of image quality and radiation dose with conventional body mass index-based protocol

BACKGROUND The use of Automatic Tube Potential Selection with Tube Current Modulation (APSCM) may lower radiation dose, but it is unknown whether image quality is maintained. OBJECTIVE The aim of this study was to evaluate the radiation dose and image quality of APSCM application compared with conventional body mass index (BMI)-based examination protocol for coronary computed tomography angiography (CTA). METHODS Consecutive patients (n = 487) were retrospectively enrolled: 239 patients who underwent coronary CTA with APSCM (APSCM group) and 248 patients who underwent coronary CTA with a BMI-based tube potential (in kV) and tube current-time product (in mAs) protocol (BMI-based group). Comparison of quantitative and qualitative image quality and radiation dose was performed. RESULTS The use of APSCM found significant reduction in radiation dose compared with the BMI-based protocol, with a significantly more frequent use of 80 kV (P < 0.0001). Diagnostic image quality was maintained, with no significant difference between the 2 groups (P = 0.887). CONCLUSION The use of APSCM for coronary CTA significantly reduced radiation dose while maintaining image quality; therefore, it is feasible in daily practice which covers patients with various BMI values.

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.

Meaning of zero coronary calcium score in symptomatic patients referred for coronary computed tomographic angiography

AIMS The clinical implication of a zero coronary calcium score (CCS) in patients with chest pain syndrome has been under debate. This study was undertaken to determine the meaning of a CCS of zero in a large sample of symptomatic patients referred for coronary computed tomographic (CT) angiography. METHODS AND RESULTS We consecutively enrolled 2088 patients (age 58 ± 10 years, 1028 men) who had undergone 64-slice cardiac CT due to chest pain syndrome. A CCS of zero was detected in 1114 patients (471 men and 643 women). Of these 1114 patients, obstructive coronary artery disease (CAD) was found in a total of 48 patients (4.3%); 35 men (7.4%) and 13 women (2.0%). Among the zero CCS patients with obstructive CAD, men had a higher prevalence of both premature CAD (49 vs. 0%) and multivessel disease (20 vs. 8%) than women. During the follow-up period (1033 ± 136 days), early revascularization was done in 25 patients (2.2%, 18 men and 7 women) and there were 14 major adverse cardiac events (1.3%, 8 men and 7 women) among the zero CCS patients. CAD severity was a strong prognostic indicator in the zero CCS patients. CONCLUSION A CCS of zero cannot be used by itself to exclude obstructive CAD in symptomatic patients referred for coronary CT angiography (CCTA). The prevalence of obstructive CAD and adverse cardiac events are not negligible in symptomatic patients with a CCS of zero, and CAD severity by CCTA is associated with higher rates of adverse cardiac event.