Yoonjung Choi

Galvanically Replaced Hollow Au–Ag Nanospheres: Study of Their Surface Plasmon Resonance

We synthesized hollow Au-Ag nanospheres (NSs) by employing a galvanic replacement reaction between HAuCl4 and Ag NSs. Uniform Ag NSs with controllable sizes were synthesized as sacrificial templates by a seed-mediated strategy. The atomic ratio of Au to Ag in Au-Ag NSs was tunable by controlling the reagent concentration. UV-vis extinction spectra acquired from well-dispersed colloidal NS solutions were used to investigate the optical properties of the solutions. In addition to a common dipole mode exhibited on most transition metal nanoparticles, we observed a quadrupole plasmon resonance mode when the diameters of the Ag and Au-Ag NSs were larger than 100 nm. The quadrupole and dipole peaks both shifted to longer wavelengths with increased Au content in Au-Ag NSs. The experimental observation of optical properties of hollow Au-Ag NSs was compared with the theoretical simulation using DDA calculation, showing a good agreement.

Validation of intra- and interobserver reproducibility of shearwave elastography: Phantom study

PURPOSE To assess intra- and interobserver reproducibility of quantitative ultrasound (US) elastography for breast masses using shearwave elastography (SWE). MATERIALS AND METHODS The US elastography phantom was used. This training phantom contained 12 masses with dimensions from 6 to 11mm and varying B-mode (hypo- iso- and hyperechoic) characteristics and viscoelastic properties varying from about 50 to 250kPa. Four attending radiologists participated as operators and used Supersonic Imaging 15-4 MHz array to acquire images. In each session, B-mode US features were assessed once and US elastography values were assessed twice in a consecutive and distinct manner. A total of three identical sessions of data acquisition were performed at 2-week intervals. For categorical variables such as BI-RADS features of mass on B-mode image and qualitative SWE features, kappa (k) values were calculated by the generalized linear mixed model. For continuous variables, kPa, and ratio, intraclass correlation coefficients (ICCs) were calculated. RESULTS Interobserver agreement for SWE image similarity was moderate (k=0.57). With respect to quantitative SWE values, intraobserver ICCs were 0.65, 0.77, 0.92, and 0.91 for maximum elasticity; 0.70, 0.83, 0.94, and 0.94 for mean elasticity; and 0.67, 0.83, 0.92, and 0.92 for elasticity ratio for operators 1, 2, 3, and 4, respectively. Interobserver reproducibility showed good agreement with ICC values of 0.77 for maximum elasticity, 0.82 for mean elasticity, and 0.79 for elasticity ratio. CONCLUSION Quantitative US elastography for breast masses was highly reproducible with good agreement across operators. With respect to intraobserver reproducibility, ICC values varied but three out of four operators showed good agreement.

A practical MRI grading system for osteoarthritis of the knee: Association with Kellgren–Lawrence radiographic scores

PURPOSE To propose a reproducible and constant MR grading system for osteoarthritis of the knee joint that provides high interobserver and intraoberver agreement and that does not require complicated calculation procedures. MATERIALS AND METHODS This retrospective study sample included 44 men and 65 women who underwent both MRI and plain radiography of the knee at our institution. All patients were older than 50 years of age (mean 57.7) and had clinically suspected osteoarthritis of the knee. The standard of 4 grades on the MR grade scale was based mainly on cartilage injury and additional findings. Kellgren-Lawrence grades were assessed for the same patient group. The relationship between the results was determined. Statistical analyses were performed including kappa statistics, categorical regression analysis and nonparametric correlation analysis. RESULTS The interobserver and intraoberver agreements between the two readers in the grading of osteoarthritis were found to be almost perfect. Interobserver and intraobserver agreements were slightly lower for the MR grading system than for the Kellgren-Lawrence grading scale. The correlation between the MR grade and Kellgren-Lawrence grade was very high and did not differ with patient age. The MR grades were highly correlated with the Kellgren-Lawrence grades and showed excellent interobserver and intraobserver agreements. CONCLUSION This new MR grading system for osteoarthritis of the knee joint is reproducible and may be helpful for the grading of osteoarthritis of the knee without requiring reference to plain radiography.

Partially Cystic Thyroid Nodules: Ultrasound Findings of Malignancy

Objective To seek for the ultrasound (US) findings of partially cystic thyroid nodules that are associated with malignancy. Materials and Methods We reviewed the US characteristics of 22 surgically confirmed partially cystic papillary carcinomas, and compared them with those of 80 benign partially cystic nodules. The review cases were selected in a random order from a total of 1029 partially cystic nodules that were diagnosed with an US-guided fine needle aspiration biopsy over a period of 8 years (June 2003 to October 2010) at our institution. Results In partially cystic thyroid nodules, a taller-than-wide shape (100%, p < 0.001) and spiculated or microlobulated margin (58.3%, p = 0.003) were significantly associated with malignancy. In terms of internal solid portion of the nodule, eccentric configuration (68.0%, p < 0.001), non-smooth margin (81.3%, p < 0.001), hypoechogenecity (30.0%, p < 0.042), and microcalcification (89.5%, p < 0.001) were more frequently demonstrated in malignant nodules than benign ones. Conclusion In partially cystic thyroid nodules, understanding the characteristics of US findings is important to make a precise diagnosis of malignant nodules.

Influence of iodide ions on morphology of silver growth on gold hexagonal nanoplates.

Different morphologies of Au@Ag nanocrystals have been successfully synthesized using iodide ions in growth solutions consisting of ascorbic acid, NaOH, and CTAB. Without I(-) ions in growth solution, there were unnoticeable changes in morphology. On the other hand, with addition of I(-) ions, remarkable changes were observed including formation of hexagonal bipyramidal nanocrystals. Ag(+) ions were reduced and deposited on {111} facets of gold hexagonal nanoplates (GHNs), and hexagonal bipyramidal nanoparticles were formed more quickly in the presence of I(-) ions than without I(-) ions. Our studies reveal that I(-) ion affects the selective growth of Ag onto GHNs. This can be explained by the decrease in the surface redox potential of nanocrystals that occurs by combining with the AgI complex on the metallic surface. These results were confirmed by FESEM images, UV-vis-NIR spectra, and TEM images.

Sonographic Appearances of Soft Tissue Angioleiomyomas Differences From Other Circumscribed Soft Tissue Hypervascular Tumors

The purpose of this study was to evaluate the sonographic features of angioleiomyomas with priority given to the vascular pattern to help in the differential diagnosis from other hypervascular soft tissue tumors.

The management of software processes with software process improvement tool based on ISO 15504

Software processes are slowly penetrating the software development industry. The fact that software process has to be applied throughout the whole lifecycle of software development is particularly true for successful projects. Therefore, SPI (Software Process Improvement) is an ongoing activity throughout project duration. In this paper, we suggest process management system which is needed to assist SPI activities. To enhance the quality of software product, the proposed system supports internal assessors to conduct the gap analysis compliant with ISO IS 15504. Later, it has evolved as a process mentoring tool for developers, as well as SPI tool for software development organizations

Diagnostic performance of shear wave elastography of the breast according to scanning orientation.

To evaluate the influence of the scanning orientation on diagnostic performance measured by the mean elasticity, maximum elasticity, and fat‐to‐lesion elasticity ratio on ultrasound‐based shear wave elastography in differentiating breast cancers from benign lesions.

A new assessment of patellar instability using coronal magnetic resonance images of the patella superimposed on the femur and its clinical utility.

Objective This study aimed to evaluate the clinical utility of a new assessment for patellar subluxation using magnetic resonance (MR) images of the patella superimposed on the femur and to determine its correlation with the tibial tuberosity–trochlear groove (TT-TG) distance. Materials and Methods This retrospective study included 81 men and 44 women who underwent MR imaging at our institution. There were 19 cases of patellar dislocation. The control group consisted of 116 patients. An assessment of the distance of subluxation was carried out using coronal superimposed MR images. The results were correlated with the TT-TG distance calculated using the axial combined MR images. The sensitivity and specificity of various distances of subluxation were evaluated as diagnostic thresholds for patellar dislocation, where the clinical diagnosis was used as the standard of reference. Results The use of the distance of subluxation on coronal superimposed MR images showed discrete difference between patellar dislocation and controls. The mean distance of subluxation was approximately 3 times larger for patients with patellar dislocation compared with controls (P < 0.001). Likewise, the mean TT-TG distance was approximately 50% greater for patients with patellar dislocation compared with controls (P < 0.001). However, there was no correlation between the distance of subluxation and the TT-TG distance. The best diagnostic discrimination was achieved at the 7-mm threshold of subluxation. Conclusions The use of the distance of subluxation on coronal superimposed MR images can be a useful method to evaluate patellar dislocation. The best diagnostic discrimination was achieved at a threshold of 7 mm.

Clinical and imaging characteristics of papillary neoplasms of the breast associated with malignancy: a retrospective cohort study.

Papillary neoplasms of the breast comprise a broad range of pathologies ranging from papillomas to papillary carcinomas and have been associated with breast cancers. In this study, we evaluated the clinical, mammographic and sonographic features of papillary breast neoplasms from benign papillary breast lesions to malignancy-associated papillary lesions. A total of 194 lesions in 179 patients were analyzed, including 117 benign papillomas, 24 atypical papillomas, 41 benign papillomas with malignancies and 12 papillary carcinomas found between January 2003 and August 2011 in our institution. Statistically significant clinical factors included patient age (p = 0.001), lesion multiplicity (p = 0.009) and peripheral location (p = 0.003). Among these factors, the odds ratio for malignancy was 8.9 for bilateral multiple lesions. Visibility (p = 0.001) and density (p = 0.039) were significant factors for malignancy in mammograms, and echo patterns (p = 0.006), boundary (p = 0.001) and vascularity (p = 0.005) were significant features on ultrasound that differentiated malignancies from benign lesions. Overall, when papillary breast lesions are located bilaterally and peripherally in older patients, they are correlated with breast cancers. Additionally, for papillary breast lesions that appear highly dense on mammograms and/or exhibit positive vascularity on ultrasound, the probability of malignancy is relatively high.