Results of tuberculosis contact investigation in congregate settings in Korea, 2013

Objectives

This study aimed to check the status of the contact investigation in congregate settings to eradicate tuberculosis (TB) in the Republic of Korea.

Methods

The “Integrated System for Disease and Public Health Management” is used for care and follow-up for patients and contacts of TB. We downloaded data for contact investigations conducted from January to December 2013.

Results

A total of 1,200 contact investigations in congregate settings were carried out by 25 field investigators in 2013. We performed the status of contact investigation, TB, and LTBI rate by age, accept rate of LTBI treatment, and complete rate of LTBI treatment during 2013. A total of 1,547 index TB patients, 149,166 contacts, and 259 additional TB patients were found through the investigation. Kindergartens showed the highest LTBI rate, 19.8%, among educational facilities. The second highest was in elementary schools and the subtotal LTBI rate of educational facilities was 7.8%. Social welfare/correctional facilities and workplaces showed relatively high LTBI rates of 23.8% and 23.6%, respectively. By age, individuals >35 years showed the highest LTBI rate, followed by those aged 0–4 years, 30–34 years, and 5–9 years, with rates of 18.1%, 16.4%, and 15.4% respectively. When comparing the tuberculin skin test (TST) positive conversion ratio by facility, middle school and high school were relatively high compared to the others. The accept rate of LTBI treatment in the workplace was lowest at 63% and the complete rate in elementary schools was lowest at 76.5%.

Conclusion

TB contact investigation is considered as a meaningful strategy for preventing TB outbreaks in congregate settings and decreasing the prevalence of TB in young people. Results of this study could be used to establish the LTBI management policy.

Mapping the nonlinear dynamics of a laser diode via its terminal voltage

We show that the bifurcations between dynamical states originating in the nonlinear dynamics of an external-cavity semiconductor laser at constant current can be detected by its terminal voltage V. We experimentally vary the intensity fed back into the gain medium by the external cavity and show that the dc component V(dc) of V tracks the optical intensity-based bifurcation diagram. It is shown using computational results based upon the Lang-Kobayashi model that whereas optical intensity accesses the dynamical-state variable |E|, V is related to population-inversion carrier density N. The change in feedback strength affects N and thereby the quasi-Fermi energy level difference at the p-i-n junction band-gap of the gain medium. The change in the quasi-Fermi energy-level thereby changes the terminal voltage V. Thus V is shown to provide information on the change in the dynamical-state variable N, which complements the more conventionally probed optical intensity.

Upper abdominal gadoxetic acid-enhanced and diffusion-weighted MRI for the detection of gastric cancer: Comparison with two-dimensional multidetector row CT

AIM

To evaluate the diagnostic performance of abdominal magnetic resonance imaging (MRI) for the detection of gastric cancer in comparison with that of two-dimensional (2D) multidetector row computed tomography (CT).

MATERIALS AND METHODS

The study included 189 patients with 170 surgically confirmed gastric cancers and 19 patients without gastric cancer, all of whom underwent gadoxetic acid-enhanced MRI with diffusion-weighted (DW) imaging, and multidetector contrast-enhanced abdominal CT imaging. Two observers independently analysed three sets of images (CT set, conventional MRI set, and combined conventional and DW MRI set). A five-point scale for likelihood of gastric cancer was used. Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were evaluated. Quantitative [apparent diffusion coefficient (ADC) analyses with Mann-Whitney U-test were conducted for gastric cancers and the nearby normal gastric wall.

RESULTS

The diagnostic accuracy and sensitivity for detection of gastric cancer were significantly higher on combined conventional and DW MRI set (77.8-78.3%; 75.3-75.9%) than the CT imaging set (67.7-71.4%; 64.1-68.2%) or the conventional MRI set (72-73%; 68.8-70%; p < 0.01). In particular, for gastric cancers with pT2 and pT3, the combined conventional and DW MRI set (91.6-92.6%) yielded significantly higher sensitivity for detection of gastric cancer than did the CT imaging set (76.8-81.1%) by both observers (p < 0.01). The mean ADC of gastric cancer lesions (1 ± 0.23 × 10(-3) mm(2)/s) differed significantly from that of normal gastric wall (1.77 ± 0.25 × 10(-3) mm(2)/s; p < 0.01).

CONCLUSION

Abdominal MRI with DW imaging was more sensitive for the detection of gastric cancer than 2D-multidetector row CT or conventional MRI alone.

Pancreatic ductal adenocarcinoma: prevalence and diagnostic value of dark choledochal ring sign on T2-weighted MRI

AIM

To investigate the dark choledochal ring sign on T2-weighted imaging (T2WI) as an indicator for pancreatic ductal adenocarcinoma (PDAC) among periampullary carcinomas.

MATERIALS AND METHODS

Sixty patients with surgically confirmed periampullary cancers [30 PDACs, 15 distal common bile duct (CBD) cancers, 13 ampullary cancers, and two duodenal cancers] who underwent liver magnetic resonance imaging (MRI) were included in this study. Two reviewers independently evaluated unenhanced and gadoxetic acid-enhanced MRI (T1WI image set), and a combined T2WI and T1WI image set for differentiation between PDAC and other periampullary carcinomas using a rating scale, and the presence of the dark choledochal ring sign on T2WI, for all 60 tumours.

RESULTS

In PDAC, the dark choledochal ring sign on T2WI was considered positive in 23 cases by observer 1 and 24 cases by observer 2, but only in one or two CBD cancers, as determined by each observer, respectively. This resulted in sensitivities of 76.7% and 80% and specificities of 96.7% and 93.3% for observer 1 and 2, respectively, in the diagnosis of PDAC. Adding T2WI correctly led to a change of diagnosis in three and four cases of PDAC by each observer, respectively. Thus, there were significant differences between the two image sets for both observers in distinguishing between PDAC and other periampullary carcinomas (p = 0.02).

CONCLUSION

The presence of the dark choledochal ring sign on axial T2WI could be a complementary imaging feature indicative of PDAC to differentiate PDAC from other periampullary carcinomas at MRI.

Effects of heteroatom substitution in conjugated heterocyclic compounds on photovoltaic performance: from sulfur to tellurium

Band gaps of benzochalcogenophene-based organic semiconductors and the efficiencies of the corresponding photovoltaic devices can be tuned through heteroatom variation.

Gadoxetic acid-enhanced MRI for T-staging of gallbladder carcinoma: emphasis on liver invasion

OBJECTIVE

To evaluate the diagnostic performance of gadoxetic acid-enhanced MRI with an emphasis on the usefulness of the hepatobiliary phase (HBP) in T-staging of gallbladder carcinoma.

METHODS

66 patients with surgically confirmed gallbladder carcinoma underwent MRI. Two radiologists independently reviewed two sets of gadoxetic acid-enhanced MRI without and with the HBP. Local tumour spread was evaluated according to T-staging, and the results were compared with pathological findings. The diagnostic performance of two image sets to differentiate each T-stage was compared.

RESULTS

The sensitivities of MRI with the HBP to differentiate T1 vs ≥ T2 lesions, ≤ T2 vs ≥ T3 lesions and ≤ T3 vs T4 lesions were 96.3%, 85.7% and 100% for Observer 1 and 92.6%, 95.2% and 100% for Observer 2, respectively (p<0.0001). By adding the HBP, the sensitivities to differentiate ≤ T2 vs ≥ T3 lesions were increased from 66.7% to 85.7% for Observer 1 and from 81.0% to 95.2% for Observer 2, although there was no significant difference (p>0.05). The overall accuracies for T-staging were increased from 80.3% to 86.4% for Observer 1, a statistically significant degree (p=0.046), and from 83.8% to 87.9% for Observer 2 (p>0.05). The k-value for the two observers indicated excellent agreement.

CONCLUSION

Gadoxetic acid-enhanced MRI provided acceptable diagnostic performance for T-staging of gallbladder carcinoma. Addition of the HBP aids in the detection of liver invasion.

ADVANCES IN KNOWLEDGE

In the T-staging of gallbladder carcinoma, gadoxetic acid-enhanced MRI with the HBP may enhance detection of liver invasion.