Dae Young Yoon

Computer-Aided Diagnosis for the Differentiation of Malignant from Benign Thyroid Nodules on Ultrasonography

RATIONALE AND OBJECTIVESnWe sought to evaluate the diagnostic performance of an artificial neural network (ANN) and binary logistic regression (BLR) in differentiating malignant from benign thyroid nodules on ultrasonography.nnnMATERIALS AND METHODSnTwo experienced radiologists, who were unaware of the histopathological diagnosis, analyzed ultrasonographic (US) features of 109 pathologically proven thyroid lesions (49 malignant and 60 benign) in 96 patients. Each radiologist was asked to evaluate US findings and categorize nodules into one of the two groups (malignant vs. benign) in each case. The following 8 US parameters were assessed for each nodule: size, shape, margin, echogenicity, cystic change, microcalcification, macrocalcification, and halo sign. Statistically significant US findings were obtained with backward stepwise logistic regression and were used for training and testing of the ANN and the BLR. The performance of the ANN and BLR was compared to that of the radiologists using receiver-operating characteristic (ROC) analysis.nnnRESULTSnStatistically significant US findings were size, margin, echogenicity, cystic change, and macrocalcification of the nodules. The area under the ROC curve (Az) values of ANN and BLR were 0.9492 +/- 0.0195 and 0.9046 +/- 0.0289, respectively. The Az value was 0.8300 +/- 0.0359 for reader 1 and 0.7600 +/- 0.0409 for reader 2. The Az values for ANN and BLR were significantly higher than those for both radiologists (all p < .05).nnnCONCLUSIONnThe performance of the ANN and the BLR was better than that of the radiologists in the distinction of benign and malignant thyroid nodules.

Korea's contribution to radiological research included in Science Citation Index Expanded, 1986-2010.

Objective To evaluate scientific papers published by Korean radiologists in the Science Citation Index Expanded (SCIE) radiology journals, between 1986 and 2010. Materials and Methods The Institute for Scientific Information Web of Knowledge-Web of Science (SCIE) database was searched for all articles published by Korean radiologists, in SCIE radiology journals, between 1986 and 2010. We performed the analysis by typing Korea and radiol in the address section and selecting the subject area of Radiology, Nuclear Medicine, and Medical Imaging with the use of the general search function of the software. Analyzed parameters included the total number of publications, document types, journals, and institutions. In addition, we analyzed where Korea ranks, compared to other countries, in terms of the number of published articles. All these data were analyzed according to five time periods: 1986-1990, 1991-1995, 1996-2000, 2001-2005, and 2006-2010. Results Overall, 4974 papers were published by Korean radiologists, in 99 different SCIE journals, between 1986 and 2010, of which 4237 (85.2%) were article-type papers. Of the total 115395 articles, worldwide, published in radiology journals, Koreas share was 3.7%, with an upward trend over time (p < 0.005). The journal with the highest number of articles was the American Journal of Roentgenology (n = 565, 13.3%). The institution which produced the highest number of publications was Seoul National University (n = 932, 22.0%). Conclusion The number of scientific articles published by Korean radiologists in the SCIE radiology journals has increased significantly between 1986 and 2010. Korea was ranked 4th among countries contributing to radiology research during the last 5 years.

Calcified Carcinoma of the Gallbladder with Calcified Nodal Metastasis Presenting as a Porcelain Gallbladder: A Case Report

Porcelain gallbladder is regarded as a risk factor of gallbladder cancer. A porcelain gallbladder with calcified regional lymph nodes was found using computed tomography (CT) and magnetic resonance imaging (MRI) in a 43-year-old man who presented with nausea, vomiting, and abdominal pain. His cholecystectomy specimen showed diffuse wall thickening and contained small gallstones. Histological examination revealed diffuse infiltrative adenocarcinoma with extensive intratumoral calcification (calcified carcinoma). The majority of the calcified material was located within or replaced the tumor glands, and was not found in the stroma. A lymph node was totally replaced with a calcified metastatic adenocarcinoma. To the best of our knowledge, only one case of calcified lymph node metastasis from a calcified carcinoma of the gallbladder has been previously reported in the literature. We herein add a case of calcified carcinoma of the gallbladder with calcified lymph node metastasis, presenting as a porcelain gallbladder on CT and MRI.

Harmonic ultrasonography for the detection of microlithiasis in the gallbladder

Purpose: To validate the use of harmonic ultrasonography (US) in the detection of gallbladder microlithiasis. Methods: From November 30, 2012, to January 18, 2014, fundamental US (FUS) and harmonic US with a high background noise (HUS-N) were performed for evaluation of gallbladder during the routine abdomen US. During the US, a dot-like stone (or stones) with Brownian motion was regarded as a positive finding of microlithiasis. Fifty-five patients with microlithiasis in the gallbladder detected on US were enrolled as the subjects of a retrospective review. With respect to the obtained images, two abdominal radiologists independently scored the conspicuity of gallbladder microlithiasis on FUS and HUS-N by using a 4-grade scale. The statistical analysis employed a kappa test and a Wilcoxon rank-sum test. Results: For FUS, the conspicuity grades of gallbladder microlithiasis were G1 in 25 and 37, G2 in 21 and 9, G3 in 6 and 6, G4 in 3 and 3 patients, while HUS-N showed G1 in 0 and 0, G2 in 3 and 2, G3 in 12 and 15, and G4 in 40 and 38 patients, respectively, by each of the two radiologists. The kappa value was 0.633 for FUS between the two radiologists and 0.708 for HUS-N. HUS-N showed better conspicuity of gallbladder microlithiasis than FUS with significant P-values of less than 0.001 and 0.001 for the two radiologists, respectively. Conclusion: Compared with FUS, HUS-N enables better detection of microlithiasis in the gallbladder.

Value of the Post-Operative CT in Predicting Delayed Flap Failures Following Head and Neck Cancer Surgery

Objective To identify post-operative computed tomography (CT) findings associated with delayed flap failures following head and neck cancer surgery. Materials and Methods We retrospectively reviewed 60 patients who underwent flap reconstruction after head and neck cancer surgery and post-operative (3–14 days) contrast-enhanced CT scans for suspected complications. Patients were divided into two groups: delayed flap failure patients (patients required flap revision) (n = 18) and flap success patients (n = 42). Clinical data (age, sex, T-stage, type of flap, and time interval between reconstruction surgery and CT) and post-operative CT findings of flap status (maximum dimension of the flap, intra- or peri-flap fluid collection and intra- or peri-flap air collection, fat infiltration within the flap, fistula to adjacent aerodigestive tract or skin, and enhanced vascular pedicle) were assessed and compared between the two groups. Results CT findings showed that the following flap anomalies were observed more frequently in the delayed flap failure group than in the flap success group: intra- or peri-flap fluid collection > 4 cm (61.1% vs. 23.8%, p < 0.05), intra- or peri-flap air collection > 2 cm (61.1% vs. 2.4%, p < 0.001), and fistula to adjacent aerodigestive tract or skin (44.4% vs. 0%, p < 0.001). The maximum dimension of the flap, fat infiltration within the flap, and enhanced vascular pedicle were not associated with delayed flap failures. Conclusion A large amount of fluid or air collection and fistula are the CT findings that were associated with delayed flap failures in patients with suspected post-operative complications after head and neck cancer surgery.

Assessment of Blood-Brain Barrier Permeability by Dynamic Contrast-Enhanced MRI in Transient Middle Cerebral Artery Occlusion Model after Localized Brain Cooling in Rats

Objective The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Materials and Methods Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20℃) infusion group, and localized warm-saline (37℃) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Results Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min-1 vs. 0.07 ± 0.02 min-1, p = 0.661 for Ktrans; 0.30 ± 0.05 min-1 vs. 0.37 ± 0.11 min-1, p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Conclusion Localized brain cooling (20℃) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37℃) infusion group.

Immunoglobulin G4-Related Sclerosing Disease Manifesting as Bilateral Tonsillar Hypertrophy on MR Images: A Case Report.

Immunoglobulin G4-related sclerosing disease (IgG4-SD) is currently recognized as a distinct systemic disease involving various organs. We reported the imaging findings of a case of pathologically confirmed IgG4-SD involving bilateral palatine tonsils. CT and MRI showed diffuse enlargement of both palatine tonsils with homogeneous contrast enhancement. Focal contour bulging was noted in the right palatine tonsil. Lesions appeared as isointense on T1-weighted and slightly hyperintense on T2-weighted MRI images, as compared with muscle. The T2-weighted MRI image showed a striated pattern in both tonsils. Despite its rare occurrence, IgG4-SD should be included in the differential diagnoses of patients with symptomatic bilateral tonsillar hypertrophy that is non-responsive to medication.