Reduction In Detection Rate Research Articles

Wide Real-Life Data Support Reduced Sensitivity of Antigen Tests for Omicron SARS-CoV-2 Infections.

With the continuous spread of new SARS-CoV-2 variants of concern (VOCs), the monitoring of diagnostic test performances is mandatory. We evaluated the changes in antigen diagnostic tests' (ADTs) accuracy along the Delta to Omicron VOCs transition, exploring the N protein mutations possibly affecting ADT sensitivity and assessing the best sampling site for the diagnosis of Omicron infections. In total, 5175 subjects were enrolled from 1 October 2021 to 15 July 2022. The inclusion criteria were SARS-CoV-2 ADT combined with a same-day RT-PCR swab test. For the sampling site analysis, 61 patients were prospectively recruited during the Omicron period for nasal and oral swab analyses by RT-PCR. Next-Generation Sequencing data were obtained to evaluate the different sublineages. Using RT-PCR as a reference, 387 subjects resulted in becoming infected and the overall sensitivity of the ADT decreased from 63% in the Delta period to 33% in the Omicron period. This decrease was highly statistically significant (p < 0.001), and no decrease in viral load was detected at the RNA level. The nasal site presented a significantly higher viral load than the oral site during the Omicron wave. The reduced detection rate of Omicron infections by ADT should be considered in the global testing strategy to preserve accurate diagnoses across the changing SARS-CoV-2 variants.

Influence of COVID-19 over seasonal influenza activity in southern India

Basic epidemiological data is urgently needed in order to ascertain the changes brought about by COVID-19 pandemic, and help researchers, clinicians, and policy makers in addressing these issues. Data on influenza positivity from 2009 to 2019 was collected from Regional Influenza laboratory, JIPMER. Being COVID testing centre we tested samples (2020–2023) from Tamilnadu and Pondicherry. All SARI samples which were negative for COVID-19 were subjected to Influenza testing as regular surveillance activity was suspended. On comparison we found significant reduction in detection rates of influenza A H1N1, H3N2 and influenza B (p value = <0.01).

Quantification of impact of COVID-19 pandemic on cancer screening programmes - a case study from Argentina, Bangladesh, Colombia, Morocco, Sri Lanka, and Thailand.

It is quite well documented that the COVID-19 pandemic disrupted cancer screening services in all countries, irrespective of their resources and healthcare settings. While quantitative estimates on reduction in volume of screening tests or diagnostic evaluation are readily available from the high-income countries, very little data are available from the low- and middle-income countries (LMICs). From the CanScreen5 global cancer screening data repository we identified six LMICs through purposive sampling based on the availability of cancer screening data at least for the years 2019 and 2020. These countries represented those in high human development index (HDI) categories (Argentina, Colombia, Sri Lanka, and Thailand) and medium HDI categories (Bangladesh and Morocco). No data were available from low HDI countries to perform similar analysis. The reduction in the volume of tests in 2020 compared to the previous year ranged from 14.1% in Bangladesh to 72.9% in Argentina (regional programme) for cervical screening, from 14.2% in Bangladesh to 49.4% in Morocco for breast cancer screening and 30.7% in Thailand for colorectal cancer screening. Number of colposcopies was reduced in 2020 compared to previous year by 88.9% in Argentina, 38.2% in Colombia, 27.4% in Bangladesh, and 52.2% in Morocco. The reduction in detection rates of CIN 2 or worse lesions ranged from 20.7% in Morocco to 45.4% in Argentina. Reduction of breast cancer detection by 19.1% was reported from Morocco. No association of the impact of pandemic could be seen with HDI categories. Quantifying the impact of service disruptions in screening and diagnostic tests will allow the programmes to strategize how to ramp up services to clear the backlogs in screening and more crucially in further evaluation of screen positives. The data can be used to estimate the impact on stage distribution and avoidable mortality from these common cancers.

Variable detection of Omicron-BA.1 and -BA.2 by SARS-CoV-2 rapid antigen tests

During 2022, the COVID-19 pandemic has been dominated by the variant of concern (VoC) Omicron (B.1.1.529) and its rapidly emerging subvariants, including Omicron-BA.1 and -BA.2. Rapid antigen tests (RATs) are part of national testing strategies to identify SARS-CoV-2 infections on site in a community setting or to support layman’s diagnostics at home. We and others have recently demonstrated an impaired RAT detection of infections caused by Omicron-BA.1 compared to Delta. Here, we evaluated the performance of five SARS-CoV-2 RATs in a single-centre laboratory study examining a total of 140 SARS-CoV-2 PCR-positive respiratory swab samples, 70 Omicron-BA.1 and 70 Omicron-BA.2, as well as 52 SARS-CoV-2 PCR-negative swabs collected from March 8th until April 10th, 2022. One test did not meet minimal criteria for specificity. In an assessment of the analytical sensitivity in clinical specimen, the 50% limit of detection (LoD50) ranged from 4.2 × 104 to 9.2 × 105 RNA copies subjected to the RAT for Omicron-BA.1 compared to 1.3 × 105 to 1.5 × 106 for Omicron-BA.2. Overall, intra-assay differences for the detection of Omicron-BA.1-containing and Omicron-BA.2-containing samples were non-significant, while a marked overall heterogeneity among the five RATs was observed. To score positive in these point-of-care tests, up to 22-fold (LoD50) or 68-fold (LoD95) higher viral loads were required for the worst performing compared to the best performing RAT. The rates of true-positive test results for these Omicron subvariant-containing samples in the highest viral load category (Ct values < 25) ranged between 44.7 and 91.1%, while they dropped to 8.7 to 22.7% for samples with intermediate Ct values (25–30). In light of recent reports on the emergence of two novel Omicron-BA.2 subvariants, Omicron-BA.2.75 and BJ.1, awareness must be increased for the overall reduced detection rate and marked differences in RAT performance for these Omicron subvariants.

Reduced detection rate of artificial intelligence in images obtained from untrained endoscope models and improvement using domain adaptation algorithm.

A training dataset that is limited to a specific endoscope model can overfit artificial intelligence (AI) to its unique image characteristics. The performance of the AI may degrade in images of different endoscope model. The domain adaptation algorithm, i.e., the cycle-consistent adversarial network (cycleGAN), can transform the image characteristics into AI-friendly styles. We attempted to confirm the performance degradation of AIs in images of various endoscope models and aimed to improve them using cycleGAN transformation. Two AI models were developed from data of esophagogastroduodenoscopies collected retrospectively over 5 years: one for identifying the endoscope models, Olympus CV-260SL, CV-290 (Olympus, Tokyo, Japan), and PENTAX EPK-i (PENTAX Medical, Tokyo, Japan), and the other for recognizing the esophagogastric junction (EGJ). The AIs were trained using 45,683 standardized images from 1,498 cases and validated on 624 separate cases. Between the two endoscope manufacturers, there was a difference in image characteristics that could be distinguished without error by AI. The accuracy of the AI in recognizing gastroesophageal junction was >0.979 in the same endoscope-examined validation dataset as the training dataset. However, they deteriorated in datasets from different endoscopes. Cycle-consistent adversarial network can successfully convert image characteristics to ameliorate the AI performance. The improvements were statistically significant and greater in datasets from different endoscope manufacturers [original → AI-trained style, increased area under the receiver operating characteristic (ROC) curve, P-value: CV-260SL → CV-290, 0.0056, P = 0.0106; CV-260SL → EPK-i, 0.0182, P = 0.0158; CV-290 → CV-260SL, 0.0134, P < 0.0001; CV-290 → EPK-i, 0.0299, P = 0.0001; EPK-i → CV-260SL, 0.0215, P = 0.0024; and EPK-i → CV-290, 0.0616, P < 0.0001]. In conclusion, cycleGAN can transform the diverse image characteristics of endoscope models into an AI-trained style to improve the detection performance of AI.

Population structure of Mycobacterium tuberculosis from referral clinics in Western Siberia, Russia: Before and during the Covid-19 pandemic.

The dramatic change in global health imposed by the Covid-19 pandemic has also impacted TB control. The TB incidence decreased dramatically not because of the improved situation but due to undertesting, reduced resources, and ultimately, substantially reduced detection rate. We hypothesized that multiple and partly counteracting factors could influence changes in the local Mycobacterium tuberculosis population. To test this hypothesis, we analyzed M. tuberculosis isolates collected in Western Siberia, Russia, before and during the Covid-19 pandemic. A total of 269 M. tuberculosis isolates from patients admitted at referral clinics were studied. The pre-pandemic and pandemic collections included 179 and 90 isolates, respectively. Based on genotyping, both pre-pandemic and pandemic samples are heavily dominated by the Beijing genotype isolates (95% and 88%) that were mostly MDR (80 and 68%). The high proportion of MDR isolates is due to the specific features of the studied collections biased towards patients with severe TB admitted at the National referral center in Novosibirsk. While no dramatic change was observed in the M. tuberculosis population structure in the survey area in Western Siberia during the Covid-19 pandemic in 2020–2021 compared to the pre-pandemic collection, still we note a certain decrease of the Beijing genotype and an increase in the proportion and diversity of the non-Beijing isolates. However, the transmissible and MDR Beijing B0/W148 did not increase its prevalence rate during the pandemic. More generally, the high prevalence rate of the Beijing genotype and its strong association with MDR both before and during the pandemic are alarming features of this region in Western Siberia, Russia.

Impaired detection of omicron by SARS-CoV-2 rapid antigen tests

Since autumn 2020, rapid antigen tests (RATs) have been implemented in several countries as an important pillar of the national testing strategy to rapidly screen for infections on site during the SARS-CoV-2 pandemic. The current surge in infection rates around the globe is driven by the variant of concern (VoC) omicron (B.1.1.529). Here, we evaluated the performance of nine SARS-CoV-2 RATs in a single-centre laboratory study. We examined a total of 115 SARS-CoV-2 PCR-negative and 166 SARS-CoV-2 PCR-positive respiratory swab samples (101 omicron, 65 delta (B.1.617.2)) collected from October 2021 until January 2022 as well as cell culture-expanded clinical isolates of both VoCs. In an assessment of the analytical sensitivity in clinical specimen, the 50% limit of detection (LoD50) ranged from 1.77 × 106 to 7.03 × 107 RNA copies subjected to the RAT for omicron compared to 1.32 × 105 to 2.05 × 106 for delta. To score positive in these point-of-care tests, up to 10-fold (LoD50) or 101-fold (LoD95) higher virus loads were required for omicron- compared to delta-containing samples. The rates of true positive test results for omicron samples in the highest virus load category (Ct values < 25) ranged between 31.4 and 77.8%, while they dropped to 0–8.3% for samples with intermediate Ct values (25–30). Of note, testing of expanded virus stocks suggested a comparable RAT sensitivity of both VoCs, questioning the predictive value of this type of in vitro-studies for clinical performance. Given their importance for national test strategies in the current omicron wave, awareness must be increased for the reduced detection rate of omicron infections by RATs and a short list of suitable RATs that fulfill the minimal requirements of performance should be rapidly disclosed.

Feasibility study of using virtual non-contrast images derived from dual-energy CT to replace true non-contrast images in patients diagnosed with papillary thyroid carcinoma.

To assess the feasibility of using virtual non-contrast (VNC) images derived from dual-energy computed tomography (DECT) to replace true non-contrast (TNC) images of papillary thyroid carcinoma (PTC) patients. Images of 96 PTC patients were retrospectively analyzed. TNC images were acquired under the single-energy mode of DECT after the plain scanning. The arterial and venous phase VNC (VNC-a and VNC-v) images were generated by the post-processing algorithm from the arterial phase and venous phase of contrast-enhanced CT images, respectively. Mean attenuation values, image noise, number and length of calcification were measured. Radiation dose was also calculated. Last, subjective score of image quality was evaluated by a 5-point scale. Signal-to-noise ratio (SNR) of each tissue in TNC images is significantly higher than that of VNC images (p<0.050). Contrast-to-noise ratio (CNR) of fat, muscle, thyroid nodules and internal carotid artery in TNC images is significantly higher than that of VNC images, while CNR in TNC images is lower for cervical vertebra (p<0.001). Calcification is detected on TNC images of 44 patients, while it is omitted on VNC images of 14 patients (31.8%). The subjective score of TNC images is higher than VNC images (p<0.001). The effective dose reduction is 47.6% by avoiding plain scanning. Considering the different attenuation value, SNR, CNR and especially reduced detection rate of calcification, we deem that VNC images cannot be directly used to replace TNC images in PTC patients, despite the reduced radiation dose.

Irish National Diabetic RetinaScreen Programme: report on five rounds of retinopathy screening and screen-positive referrals. (INDEAR study report no. 1)

ObjectiveTo study the uptake of annual diabetic retinopathy screening and study the 5-year trends in the detection of screen-positive diabetic retinopathy and non-diabetes-related eye disease in a cohort of annually...

Improving the Shilling Attack Detection in Recommender Systems Using an SVM Gaussian Mixture Model

With recent advances in e-commerce platforms, the information overload has grown due to increasing number of users, rapid generation of data and items in the recommender system. This tends to create serious problems in such recommender systems. The increasing features in recommender systems pose some new challenges due to poor resilience to mitigate against vulnerable attacks. In particular, the recommender systems are more prone to be attacked by shilling attacks, which creates more vulnerability. A recommender system with poor detection of attacks leads to a reduced detection rate. The performance of the recommender system is thus affected with poor detection ability. Hence, in this paper, we improve the resilience against shilling attacks using a modified Support Vector Machine (SVM) and a machine learning algorithm. The Gaussian Mixture Model is used as a machine learning algorithm to increase the detection rate and it further reduces the dimensionality of data in recommender systems. The proposed method is evaluated against several result metrics, such as the recall rate, precision rate and false positive rate between different attacks. The results of the proposed system are evaluated against probabilistic recommender approaches to demonstrate the efficacy of machine learning language in recommender systems.

Divergent Long-Term Detection Rates of Proximal and Distal Advanced Neoplasia in Fecal Immunochemical Test Screening Programs: A Retrospective Cohort Study.

Short-term studies have reported that the fecal immunochemical test (FIT) is less accurate in detecting proximal than distal colorectal neoplasia. To assess the long-term detection rates for advanced adenoma and colorectal cancer (CRC), according to anatomical location. Retrospective study. Population-based, organized screening program in the Veneto region of Italy. Persons aged 50 to 69 years who completed 6 rounds of FIT screening. At each screening round, the detection rates for advanced adenoma and cancer, as well as the proportional interval cancer rate (PICR), were calculated by anatomical location (proximal colon, distal colon, or rectum). Between 2002 and 2014, a total of 123347 participants had 441647 FITs. The numbers of advanced adenomas and cancer cases detected, respectively, were 1704 and 200 in the proximal colon, 3703 and 324 in the distal colon, and 1220 and 209 in the rectum. Although the detection rate for proximal colon cancer declined only from the first to the second screening round (0.63 to 0.36 per 1000 screenees), the rate for both distal colon and rectal cancer steadily decreased across 6 rounds (distal colon, 1.65 in the first round to 0.17 in the sixth; rectum, 0.82 in the first round to 0.17 in the sixth). Similar trends were found for advanced adenoma (proximal colon, 5.32 in the first round to 4.22 in the sixth; distal colon, 15.2 in the first round to 5.02 in the sixth). Overall, 150 cases of interval cancer were diagnosed. The PICR was higher in the proximal colon (25.2% [95% CI, 19.9% to 31.5%]) than the distal colon (6.0% [CI, 3.9% to 8.9%]) or rectum (9.9% [CI, 6.9% to 13.7%]). Participants with irregular attendance were censored. Those who had a false-positive result on a previous FIT but negative colonoscopy results were included in subsequent rounds. This FIT-based, multiple-round, long-term screening program had a negligible reduction in detection rates for neoplastic lesions in the proximal versus the distal colon after the first round. This was related to a higher PICR in the proximal colon and suboptimal efficacy in preventing the age-related proximal shifting of CRC. None.

Fewer women aged 35 and older choose serum screening for Down's syndrome: Impact and implications.

To quantify changes in the proportion of women aged 35 and older choosing serum screening for Down's syndrome over time and the effect on false positive and detection rates. From Rhode Island hospital-based laboratory prenatal screening records (2013-2017) we extracted the test performed (Integrated, Combined, Quadruple), maternal age, and Down's syndrome risk; documented observed changes in maternal age distributions and false positive rates, and modelled the impact of varying proportions of older women choosing screening on each test's performance using the 2015 United States birth cohort as baseline. Over five years, observed false positive rates for Integrated testing declined from 1.9 to 1.3% (-32%). The proportion of older women tested declined from 14.9 to 8.5%, from which modelling predicts a 16% decline in the false positive rate. This is lower than our observed change but consistent with a reduction driven by declining participation by older women. Modelling predicted a detection rate reduction from 89 to 87%. Larger detection rate impacts were predicted for Combined and Quadruple testing. This study documents, for the first time, the declining proportion of older women choosing Down's syndrome serum screening and subsequent impact on screening performance. The American College of Obstetrics and Gynecology recommends offering cell-free DNA screening for these 'high risk' pregnancies and uptake may increase further. Screening programmes could consider increasing use of Integrated testing over other serum screening tests or lowering risk cut-offs so false positive rates approach those of 2012 to regain lost detection.

STUDY OF THE PLATELET-RICH PLASMA CLINICAL EFFICACY IN THE TREATMENT OF KNEE OSTEOARTHRITIS

The study of platelet-rich plasma efficacy in the treatment of patients with knee osteoarthritis (OA) was performed. 188 patients were included and divided into three groups. Group 1 - 82 patients with OA, where hyaluronic acid was used for treatment, Group 2 - 36 patients, and Platelet Rich Plasma (PRP) and hyaluronic acid were used, Group 3 - 70 patients, only PRP was used. It`s been found that the use of PRP for treatment is characterized by a pronounced clinical efficacy compared with use of hyaluronic acid, which manifests in reduced detection rate of edema, hyperthermia and hyperemia. The use of PRP leads to pain reduction in the knee joint and increase the functionality of patients, that confirmed by more pronounced declining of visual analog scale indicators, Leken index and the WOMAC index values increase. The presented results of study are consistent with authors who believe that the lack of side effects and complications when using PRP indicates the safety of its use in clinical practice.

Effect of Using the Same vs Different Order for Second Readings of Screening Mammograms on Rates of Breast Cancer Detection: A Randomized Clinical Trial.

Interpreting screening mammograms is a difficult repetitive task that can result in missed cancers and false-positive recalls. In the United Kingdom, 2 film readers independently evaluate each mammogram to search for signs of cancer and examine digital mammograms in batches. However, a vigilance decrement (reduced detection rate with time on task) has been observed in similar settings. To determine the effect of changing the order for the second film reader of batches of screening mammograms on rates of breast cancer detection. A multicenter, double-blind, cluster randomized clinical trial conducted at 46 specialized breast screening centers from the National Health Service Breast Screening Program in England for 1 year (all between December 20, 2012, and November 3, 2014). Three hundred sixty readers participated (mean, 7.8 readers per center)-186 radiologists, 143 radiography advanced practitioners, and 31 breast clinicians, all fully qualified to report mammograms in the NHS breast screening program. The 2 readers examined each batch of digital mammograms in the same order in the control group and in the opposite order to one another in the intervention group. The primary outcome was cancer detection rate; secondary outcomes were rates of recall and disagreements between readers. Among 1,194,147 women (mean age, 59.3; SD, 7.49) who had screening mammograms (596,642 in the intervention group; 597,505 in the control group), the images were interpreted in 37,688 batches (median batch size, 35; interquartile range [IQR]; 16-46), with each reader interpreting a median of 176 batches (IQR, 96-278). After completion of all subsequent diagnostic tests, a total of 10,484 cases (0.88%) of breast cancer were detected. There was no significant difference in cancer detection rate with 5272 cancers (0.88%) detected in the intervention group vs 5212 cancers (0.87%) detected in the control group (difference, 0.01% points; 95% CI, -0.02% to 0.04% points; recall rate, 24,681 [4.14%] vs 24,894 [4.17%]; difference, -0.03% points; 95% CI, -0.10% to 0.04% points; or rate of reader disagreements, 20,471 [3.43%] vs 20,793 [3.48%]; difference, -0.05% points; 95% CI, -0.11% to 0.02% points). Interpretation of batches of mammograms by qualified screening mammography readers using a different order vs the same order for the second reading resulted in no significant difference in rates of detection of breast cancer. isrctn.org Identifier: ISRCTN46603370.

Contingent screening for preterm pre-eclampsia.

Effective screening for pre-eclampsia resulting in delivery < 37 weeks' gestation (preterm PE) is provided by assessment of a combination of maternal factors, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF) at 11-13 or 19-24 weeks' gestation. This study explores the possibility of carrying out routine screening for preterm PE by maternal factors and MAP in all pregnancies and reserving measurements of UtA-PI and PlGF for a subgroup of the population, selected on the basis of the risk derived from screening by maternal factors and MAP alone. Study data were derived from prospective screening for adverse obstetric outcomes in women attending their routine hospital visit at 11-13 and/or 19-24 weeks' gestation. Bayes' theorem was used to derive the a-priori risk for preterm PE from maternal factors and MAP. The posterior risk was obtained by the addition of UtA-PI and PlGF. We estimated the detection rate (DR) of preterm PE, at an overall false-positive rate (FPR) of 10%, from a policy in which first-stage screening by a combination of maternal factors and MAP defines screen-positive, screen-negative and intermediate-risk groups, with the latter undergoing second-stage screening by UtA-PI and PlGF. At 11-13 weeks' gestation, the model-based DR of preterm PE, at a 10% FPR, when screening the whole population by maternal factors, MAP, UtA-PI and PlGF was 74%. A similar DR was achieved by two-stage screening, with screening by maternal factors and MAP in the first stage and reserving measurement of UtA-PI and PlGF for the second stage and for only 50% of the population. If second-stage screening was offered to 30% of the population, there would be only a small reduction in DR from 74% to 71%. At 19-24 weeks, the model-based DR of preterm PE, at a 10% FPR, when screening the whole population by maternal factors, MAP, UtA-PI and PlGF was 84%. A similar DR was achieved by two-stage screening with measurements of UtA-PI and PlGF in only 70% of the population; if second-stage screening was offered to 40% of the population, the DR would be reduced from 84% to 81%. High DR of preterm PE can be achieved by two-stage screening in the first and second trimesters with maternal factors and MAP in the whole population and measurements of UtA-PI and PlGF in only some of the pregnancies. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Early Fetal Echocardiography

ABSTRACTWithin the last decade, two significant events have contributed to the increasing interest in early fetal echocardiography. First, the introduction of high-frequency vaginal ultrasound probes allows detailed visualization of cardiac structures at early stage of gestation, making early detection of fetal malformations possible. Second, the close relationship observed between some first trimester sonographic and Doppler markers and congenital heart defects allows an early identification of a high-risk group at 11 to 14 weeks of gestation. In this context, from the early 1990s, many authors have examined the potential role of the transvaginal (TV) approach to obtain earlier diagnosis of fetal cardiac malformations. Further studies have appeared in the literature showing that early TV echocardiography in experienced hands is a fairly sensitive investigative tool. Although some malformations are detected as early as 11 weeks gestation, the optimal gestational age to perform the early scan is at least 13 weeks gestation. Transvaginal ultrasound is the preferred approach, although most of the authors agree that results can be improved if transabdominal ultrasound is also incorporated. The further application of color Doppler enhances visualization. The sensitivity and specificity of early fetal echocardiography for the detection of heart anomalies is acceptable compared with the ones obtained by midgestational echocardiography, showing a slight reduction in detection rates and an increase in false-positive and false-negative rates. The cardiac anomalies detected at this early stage of pregnancy are mainly defects involving the four-chamber view, indicating that defects solely affecting the outflow tracts are difficult to diagnose in the first trimester of pregnancy. Heart defects diagnosed early in pregnancy tend to be more complex than those detected later, with a higher incidence of associated structural malformations, chromosomal abnormalities, and spontaneous abortions. The neonate follow-up or postmortem examination in case of termination of pregnancy is essential to assess the actual role of early fetal echocardiography. At present, early fetal echocardiography is a promising technique, which can be of considerable value for patients at high risk. This technique is, however, currently limited to a few specialized centers.The aim of this review is to explore the possibilities of examining the fetal heart at this early stage of pregnancy. This article also presents our experience in the first multicenter trial in early fetal echocardiography performed in Spain. In accordance with other studies, this experience stresses the usefulness of early echocardiography when performed by expert operators on fetus specifically at risk for cardiac defects. Our review of these additional 48 cases contributes to the expanding literature on the ability of TV ultrasonography to detect fetal heart defects in early pregnancy.How to cite this articleComas C, Prats P. Early Fetal Echocardiography. Donald School J Ultrasound Obstet Gynecol 2017;11(1):29-43.

SU‐D‐207‐05: Real‐Time Intrafractional Motion Tracking During VMAT Delivery Using a Conventional Elekta CBCT System

Purpose:Real‐time kV projection streaming capability has become recently available for Elekta XVI version 5.0. This study aims to investigate the feasibility and accuracy of real‐time fiducial marker tracking during CBCT acquisition with or without simultaneous VMAT delivery using a conventional Elekta linear accelerator.Methods:A client computer was connected to an on‐board kV imaging system computer, and receives and processes projection images immediately after image acquisition. In‐house marker tracking software based on FFT normalized cross‐correlation was developed and installed in the client computer. Three gold fiducial markers with 3 mm length were implanted in a pelvis‐shaped phantom with 36 cm width. The phantom was placed on a programmable motion platform oscillating in anterior‐posterior and superior‐inferior directions simultaneously. The marker motion was tracked in real‐time for (1) a kV‐only CBCT scan with treatment beam off and (2) a kV CBCT scan during a 6‐MV VMAT delivery. The exposure parameters per projection were 120 kVp and 1.6 mAs. Tracking accuracy was assessed by comparing superior‐inferior positions between the programmed and tracked trajectories.Results:The projection images were successfully transferred to the client computer at a frequency of about 5 Hz. In the kV‐only scan, highly accurate marker tracking was achieved over the entire range of cone‐beam projection angles (detection rate / tracking error were 100.0% / 0.6±0.5 mm). In the kV‐VMAT scan, MV‐scatter degraded image quality, particularly for lateral projections passing through the thickest part of the phantom (kV source angle ranging 70°‐110° and 250°‐290°), resulting in a reduced detection rate (90.5%). If the lateral projections are excluded, tracking performance was comparable to the kV‐only case (detection rate / tracking error were 100.0% / 0.8±0.5 mm).Conclusion:Our phantom study demonstrated a promising Result for real‐time motion tracking using a conventional Elekta linear accelerator. MV‐scatter suppression is needed to improve tracking accuracy during MV delivery.This research is funded by Motion Management Research Grant from Elekta.

Tuberculosis control and economic recession: longitudinal study of data from 21 European countries, 1991-2012.

ObjectiveTo investigate whether the economic recession affected the control of tuberculosis in the European Union.MethodsMultivariate regression models were used to quantify the association between gross domestic product, public health expenditure and tuberculosis case detection rates, using data from 21 European Union member states (1991–2012). The estimated changes in case detection attributable to the recession were combined with mathematical models of tuberculosis transmission, to project the potential influence of the recession on tuberculosis epidemiology until 2030.FindingsBetween 1991 and 2007, detection rates for sputum-smear-positive tuberculosis in the European Union were stable at approximately 85%. During the economic recession (2008–2011) detection rates declined by a mean of 5.22% (95% confidence interval, CI: 2.54–7.90) but treatment success rates showed no significant change (P = 0.62). A fall in economic output of 100 United States dollars per capita was associated with a 0.22% (95% CI: 0.05–0.39) mean reduction in the tuberculosis case detection rate. An equivalent fall in spending on public health services was associated with a 2.74% (95% CI: 0.31–5.16) mean reduction in the detection rate. Mathematical models suggest that the recession and consequent austerity policies will lead to increases in tuberculosis prevalence and tuberculosis-attributable mortality that are projected to persist for over a decade.ConclusionAcross the European Union, reductions in spending on public health services appear to have reduced tuberculosis case detection and to have increased the long-term risk of a resurgence in the disease.

Freehand SPECT‐guided sentinel lymph node biopsy in early oral squamous cell carcinoma

In oral squamous cell carcinoma (OSCC), cervical lymph node status is the most important prognostic factor. Compared to elective neck dissection, reduced morbidity and better quality of life was demonstrated for sentinel lymph node biopsy, which is controversial because of the reduced detection rate of sentinel lymph nodes in close proximity to the injection site (also known as the shine-through phenomenon). We report the case of a 44-year-old woman with a biopsy-proven early OSCC of the anterior floor of the mouth, who received SLNB guided with freehand single-photon emission CT (fhSPECT), a system for the 3D visualization of radioactivity in the body. One level III sentinel lymph node and 1 level I sentinel lymph node, in close proximity to the injection site, were detected and dissected. The level I sentinel lymph node contained a metastasis. Using fhSPECT, the issue outlined was overcome, and the precise histopathological lymph node status (pN1; 1 of 49) was determined.

Echocardiography in Early Pregnancy

ABSTRACT Within the last decade, two significant events have contributed to the increasing interest in early fetal echocardiography. First, the introduction of high frequency vaginal ultrasound probes allows detailed visualization of cardiac structures at early stage of gestation, making early detection of fetal malformations possible. Second, the close relationship observed between some first trimester sonographic and Doppler markers and congenital heart defects allows an early identification of a high-risk group at 11 to 14 weeks of gestation. In this context, from the early 1990s, many authors have examined the potential role of the transvaginal approach to obtain earlier diagnosis of fetal cardiac malformations. Further studies have appeared in the literature showing that early transvaginal echocardiography in experienced hand is a fairly sensitive investigative tool. Although some malformations are detected as early as 11 weeks’ gestation, the optimal gestational age to perform the early scan is at least 13 weeks’ gestation. Transvaginal ultrasound is the preferred approach, although most of the authors agree that results can be improved if transabdominal ultrasound is also incorporated. The further application of color Doppler enhances visualization. The sensitivity and specificity of early fetal echocardiography for the detection of heart anomalies is acceptable compared to the ones obtained by mid-gestational echocardiography, showing a slight reduction in detection rates and an increase in false positive and negative rates. The cardiac anomalies detected at this early stage of pregnancy are mainly defects involving the four-chamber view, indicating that defects solely affecting the outflow tracts are difficult to diagnose in the first trimester of pregnancy. Heart defects diagnosed early in pregnancy tend to be more complex than those detected later, with a higher incidence of associated structural malformations, chromosomal abnormalities and spontaneous abortions. The neonate follow-up or postmortem examination in case of termination of pregnancy (TOP) is essential to assess the actual role of early fetal echocardiography. At present, early fetal echocardiography is a promising technique, which can be of considerable value for patients at high-risk. This technique is, however, currently limited to a few specialized centers. The aim of this review is to explore the possibilities of examining the fetal heart at this early stage of pregnancy. This article also present our experience in the first multicenter trial in early fetal echocardiography performed in Spain. In accordance with other studies, this experience stresses the usefulness of early echocardiography when performed by expert operators on fetus specifically at risk for cardiac defects. Our review of these additional 48 cases contributes to the expanding literature on the ability of transvaginal ultrasonography to detect fetal heart defects in early pregnancy. How to cite this article Gabriel CC, Rodriguez PP. Echocardiography in Early Pregnancy. Donald School J Ultrasound Obstet Gynecol 2013;7(2):168-181.