Young Lan Seo

The Prevalence and Significance of Incidental Thyroid Nodules Identified on Computed Tomography

Purpose: The purpose of this study was to assess the prevalence of incidental thyroid nodules (ITN) found on computed tomography (CT) of the neck and to determine whether CT characteristics could distinguish malignant from benign thyroid lesions. Materials and Methods: We retrospectively reviewed CT scans in 734 patients without known thyroid disease (384 men and 350 women; mean age, 49.8 ± 13.7 years). The CT findings of ITN such as size, shape (anteroposterior-transverse diameter ratio [AP/T ratio]), margin, peripheral enhancing rim, intralesional calcification, and attenuation characteristics were analyzed and correlated with ultrasonographic (US) findings. Results: One hundred sixty ITNs were noted in 123 (16.8%) patients. Of 120 ITNs whose histological diagnoses were available, 15 (12.5%) were malignant. Malignant nodules more frequently showed nodular or rim calcifications (46.7% vs 13.3%; P < 0.0005), AP/T ratio of greater than 1.0 (33.3% vs 9.5%; P < 0.05), and mean attenuation value on contrast-enhanced scan of greater than 130 Hounsfield units (86.7% vs 49.5%; P < 0.05) than benign nodules. Conclusions: We found at least a 9.4% (15/160) prevalence of malignancy among ITN detected on CT. The further evaluation with US or biopsy should be performed, if an ITN shows CT features suggesting malignancy (calcification; AP/T ratio, >1.0; or mean attenuation value, >130 HU).

Peripheral Calcification in Thyroid Nodules Ultrasonographic Features and Prediction of Malignancy

The purpose of this study was to investigate the association between peripheral calcification in thyroid nodules detected on ultrasonography and thyroid malignancy.

Citation Classics in Radiology Journals: The 100 Top-Cited Articles, 1945–2012

OBJECTIVE The number of citations an article receives after its publication reflects its impact in the scientific community. The aim of this study was to identify and characterize the 100 top-cited articles published in radiology journals. MATERIALS AND METHODS The top-cited articles published in 12 radiology journals were identified using the database of Science Citation Index Expanded (1945-2012). The 100 top-cited articles were selected and analyzed with regard to the number of citations, year of publication, publishing journal, authorship, institution and country of origin, type of article, radiologic subspecialty, main topic, and radiologic technique. RESULTS The 100 top-cited articles were published in eight radiology journals, led by Radiology (n=67) and followed by the American Journal of Roentgenology (n=11). These articles were published between 1939 and 2006 with a mean of 664.3 citations per article (range, 371-6931). Seventy-eight articles were published after 1979, 57 originated from the United States, and 69 were original articles. The most common subspecialties of study were interventional radiology (n=19), neuroradiology (n=15), and breast imaging (n=11). The main topics of articles were radiofrequency ablation of hepatic tumors (n=9), followed by receiver operating characteristic curves (n=6). CONCLUSION Our study presents a detailed list and analysis of the 100 top-cited articles published in radiology journals, which provides insight into historical developments in the field of radiology.

Characteristics and Trends of Radiology Research: A Survey of Original Articles Published in AJR and Radiology between 2001 and 2010

PURPOSE To determine the characteristics and trends of the original articles published in two major American radiology journals, AJR American Journal of Roentgenology (AJR) and Radiology, between 2001 and 2010. MATERIALS AND METHODS This was a retrospective bibliometric analysis that did not involve human subjects and was exempt from institutional review board approval. All 6542 original articles published in AJR and Radiology between 2001 and 2010 were evaluated. The following information was abstracted from each article: radiologic subspecialty, radiologic technique used, type of research, sample size, study design, statistical analysis, study outcome, declared funding, number of authors, affiliation of the first author, and country of the first author. In addition, all the variables examined were presented along with the trend over time. RESULTS The most common subspecialty of study was abdominal (1219 of 6542, 18.6%), followed by vascular/interventional (804 of 6542, 12.3%). A total of 3744 (57.2%) original articles used magnetic resonance (MR) imaging or computed tomography (CT), 5495 (84.1%) were clinical research articles, 3060 (46.8%) had sample size of more than 50, 4087 (62.5%) were retrospective, 4714 (72.1%) performed statistical analysis, 6225 (95.2%) showed positive study outcome, 4784 (73.1%) were not funded, 3942 (60.3%) had four to seven authors, and 5731 (87.6%) were written by the primary author who was from a department of radiology or radiology-related specialties. The United States published 45.5% (2975 of 6542) of the articles, followed by Japan (n = 525, 8.0%), Germany (n = 485, 7.4%), and South Korea (n = 455, 7.0%). In the time trend analysis, the following variables showed a significantly positive trend: cardiac subspecialty, CT and MR imaging as the radiologic techniques, type of research as other (nonbasic, nonclinical), sample size of more than 50, four to seven as the number of authors, medicine-related department of the first author, and South Korea and Italy as countries of the first author. On the other hand, pediatric subspecialty, combined (basic and clinical) type of research, and number of authors fewer than four showed a significantly negative trend. CONCLUSION The bibliometric analysis of the AJR and Radiology journals with articles published between 2001 and 2010 revealed characteristics and trends of the current radiology research that may provide useful information to researchers and editorial staff in radiology.

CT, MR, 18F-FDG PET/CT, and their combined use for the assessment of mandibular invasion by squamous cell carcinomas of the oral cavity

Background: A reliable assessment of mandibular invasion is crucial for treatment planning to obtain both radical tumor resection and good functional results. Purpose: To retrospectively compare the diagnostic value of three different imaging methods – computed tomography (CT), magnetic resonance (MR) imaging, 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT – and their combined use for detection of mandibular invasion by squamous cell carcinoma (SCC) of the oral cavity. Material and Methods: Forty-six patients (39 men and 7 women; mean age, 59.4 years) suspected of having mandibular invasion by SCC of the oral cavity underwent CT, MR, and PET/CT within 2 weeks before surgery. First, each study was reviewed separately for the presence of mandibular invasion by tumors. Then, the value of combined images was assessed based on a confidence rating score for each modality assigned by observers. These results were verified with histopathologic findings. Results: Histopathologic examination revealed mandibular invasion in 12 of 46 SCCs. The sensitivity, specificity, and accuracy were 41.7%, 100%, and 84.8% for CT; 58.3%, 97.1%, and 87.0% for MR; and 58.3%, 97.1%, and 87.0% for PET/CT, respectively. The comparison of these modalities showed no statistically significant difference among them (P > 0.05). The combination of CT, MR, and PET/CT improved sensitivity (83.3%), without loss of specificity (100%) and accuracy (95.7%), although the difference failed to reach statistical significance (P > 0.05). Conclusion: The combined analysis of CT, MR, and PET/CT can improve sensitivity in the detection of mandibular invasion by SCC of the oral cavity.

Publication Rates for Abstracts Presented by Korean Investigators at Major Radiology Meetings

Objective To determine the publication rate of abstracts presented by Korean investigators at national and international radiological meetings, and to identify predictive factors of publication. Materials and Methods Abstracts presented at the annual meetings of the Korean Radiological Society (KRS), and abstracts presented by Korean investigators at the annual meetings of the Radiological Society of North America (RSNA) and European Congress of Radiology (ECR) from 2001 to 2002 were searched for subsequent publication, using PubMed and the Korean Medical Database. The following variables were evaluated. 1) The overall publication rate; 2) the publication rates according to the radiological subspecialty, presentation type (oral or poster), sample size (≤ 20, 21-50, or > 50), study design (prospective or retrospective), statistical analysis (present or absent), and study outcome (positive or negative); 3) the time to publication; 4) the journal where the study was published; 5) consistency between the abstract and the final publication. Results Of 1,097 abstracts, 301 (27.4%) were subsequently published, at an average of 15.8 ± 13.8 months after presentation in 48 journals. The publication rates for studies presented at the RSNA (35.4%) and ECR (50.5%) conferences were significantly higher than that for the KRS conference (23.6%, p < 0.05). Vascular/interventional radiology studies had the highest publication rate (33.1%), whereas musculoskeletal radiology studies had the lowest publication rate (17.1%). Other factors associated with subsequent publication were prospective design, use of statistical testing, and a positive study outcome. Conclusion The publication rate is significantly lower for the KRS (23.6%) meeting abstracts as compared to those of the RSNA (35.4%) and ECR (50.5%). Prospective design, use of statistical testing, and positive study outcome have a statistically significant effect on the publication rate.

Effects of right- versus left-arm injections of contrast material on computed tomography of the head and neck.

Objective: To investigate the effects of the right- and left-arm injections of contrast material on image quality in computed tomography of the head and neck. Methods: Sixty patients were prospectively and randomly assigned into 2 groups. Eighty milliliters of contrast material (iodine concentration, 300 mg/mL) was administered into the right (n = 30) or the left (n = 30) antecubital vein at a 2-mL/s injection rate. The attenuation of the carotid artery (CA) and the internal jugular vein (IJV) was measured at 1.5-second intervals in each patient. The mean attenuation values for CA and IJV, the time to reach peak attenuation, the duration of diagnostic window (both CA and IJV enhancement were greater than 150 HU), the perivenous artifacts, and the retrograde flow of contrast material column from the subclavian or brachiocephalic vein were statistically compared between patients with right-arm injection and those with left-arm injection. Results: The mean attenuation values in CA and IJV were slightly higher in patients with right-arm injection than in those with left-arm injection, although no significant difference was reached (P = 0.06 for CA and 0.07 for IJV). The right-arm injection resulted in significantly reduced perivenous artifacts and retrograde flow of contrast material column. There were no significant differences in the time to reach the peak attenuation and in the duration of the diagnostic window between the 2 groups. Conclusions: The right-arm injection of contrast material may provide better image quality in the computed tomography of the head and neck when compared with the left-arm injection.

Locally Advanced Thyroid Cancer: Can CT Help in Prediction of Extrathyroidal Invasion to Adjacent Structures?

OBJECTIVE The purpose of this study was to determine the diagnostic accuracy of CT for detecting extrathyroidal invasion of thyroid cancer to adjacent structures. MATERIALS AND METHODS Eighty-four patients (19 men, 65 women; age range, 19-84 years; mean, 54.2 +/- 15.4 years) with 86 malignant tumors of the thyroid with extracapsular extension (37 T3, 49 T4) were retrospectively enrolled in this study. Two radiologists independently evaluated the CT findings of invasion of thyroid cancer into the trachea, esophagus, common carotid artery, internal jugular vein, and recurrent laryngeal nerve. These results were compared with the surgical and histopathologic findings. RESULTS The mean sensitivity, specificity, and accuracy of CT were as follows: 59.1%, 91.4%, and 83.2% for tracheal invasion; 28.6%, 96.2%, and 90.7% for esophageal invasion; 75.0%, 99.4%, and 98.8% for invasion of the common carotid artery; 33.3%, 98.8%, and 97.1% for invasion of the internal jugular vein; and 78.2%, 89.8%, and 85.5% for invasion to the recurrent laryngeal nerve. Interobserver agreement was moderate to good in the five categories of extrathyroidal invasion with a mean kappa value of 0.65 (range, 0.49-0.77). CONCLUSION Although the effectiveness is limited by low sensitivity, CT may be a valuable tool for evaluation of extrathyroidal invasion of thyroid cancer to adjacent structures.

Combination of magnetic resonance cholangiopancreatography and computed tomography for preoperative diagnosis of the Mirizzi syndrome.

Objective: To determine the diagnostic accuracy of combined magnetic resonance cholangiopancreatography (MRCP) and computed tomography (CT) for preoperative diagnosis of Mirizzi syndrome. Materials and Methods: Fifty-two patients with surgically proven Mirizzi syndrome (n = 13) and cholecystitis without evidence for Mirizzi syndrome (n = 39) underwent both MRCP using single-shot turbo spin echo and 3-dimensional turbo spin echo sequences and CT. Two blinded observers independently and retrospectively reviewed the combination of MRCP and CT images and CT images alone. Diagnostic accuracy for a combined protocol and CT was evaluated. Results: The overall sensitivity, specificity, positive and negative predictive values, and accuracy of the combination of MRCP and CT were 96.0%, 93.5%, 83.5%, 98.5%, and 94.0%, respectively. Corresponding values of CT were 42.0%, 98.5%, 93.0%, 83.5%, and 85.0%, respectively. The sensitivity, negative predictive value, and accuracy of combined protocol were significantly higher than those of CT alone (P = 0.000, 0.001, and 0.042, respectively). Interobserver agreement was better for combined images (&kgr; = 0.906) than for CT images alone (&kgr; = 0.812). Conclusions: A combination of MRCP and CT is useful for preoperative diagnosis of Mirizzi syndrome.

Trend Toward an Increase in Authorship for Leading Radiology Journals

OBJECTIVE The purpose of this study was to determine authorship trends in two leading radiology journals over the past 2 decades. MATERIALS AND METHODS All original articles (n = 5195) published in AJR and Radiology for the periods 1991-1993, 2001-2003, and 2011-2013 were reviewed. The following variables were extrapolated from each article: number of authors, radiologic subspecialty, and country of origin. The number of authors listed per article was correlated with the publication period, journal, radiologic subspecialty, and country of origin. RESULTS The mean number of authors per article increased from 5.1 in 1991-1993 to 6.2 in 2001-2003 and to 7.1 in 2011-2013 across both journals (p < 0.0001). Both AJR and Radiology had statistically significant increases in the number of authors per article over time, but the number of authors per article in Radiology was significantly higher than that in AJR (p < 0.0001 for all study periods). The number of authors per article significantly increased for all radiologic subspecialties. The mean numbers of authors per article by country of origin are as follows: Italy, 8.3; Japan, 7.6; France, 7.5; Germany, 7.4; China, 7.3; Austria, 7.2; and South Korea, 6.8. These were significantly higher than the mean number of authors from Switzerland, which was 6.3. CONCLUSION The number of authors significantly and consistently increased in two leading radiology journals over the past 2 decades.