Normal values and within-subject variability of cardiac I-123 MIBG scintigraphy in healthy individuals: Implications for clinical studies

Background: Although several myocardial iodine 123 metaiodobenzylguanidine (MIBG) indices are increasingly used to detect alterations in myocardial sympathetic activity in various forms of cardiac pathology, published measurements of normal values and within-subject variability are lacking. Methods and Results: Twenty-five healthy volunteers underwent planar and single photon emission computed tomography (SPECT) imaging. Heart-mediastinum ratio (H/M) and myocardial washout were calculated from planar images comparing three different methods for the assessment of myocardial activity: (1) global region over the myocardium (cavity included), (2) global region over the myocardium (cavity excluded), and (3) fixed small myocardial region. Segmental (relative) uptake and washout were assessed by SPECT. For all MIBG indices, the interindividual variation was the lowest for methods 1 and 2. In SPECT this variation was low for relative segmental uptake compared with washout. In 9 subjects a second MIBG scintigraphy was performed after 3 months. The within-subject variability of H/M and washout assessed by planar methods 1 and 2 was 5%, whereas it was approximately 9% for planar method 3. For relative segmental uptake from SPECT, this variability was 5%. Conclusion: MIBG H/M (planar) and relative segmental uptake (SPECT) show a low interindividual and within-subject variability. This enables the detection of small (regional) variations in myocardial sympathetic nervous function, especially to monitor the effect of therapeutic interventions in patients with various cardiac diseases. (J Nucl Cardiol 2004;11: 126-33.

The relation between cardiac 123I-mIBG scintigraphy and functional response 1 year after CRT implantation

Cardiac resynchronization therapy (CRT) is a disease-modifying therapy in patients with chronic heart failure (CHF). Current guidelines ascribe CRT eligibility on three parameters only: left ventricular ejection fraction (LVEF), QRS duration, and New York Heart Association (NYHA) functional class. However, one-third of CHF patients does not benefit from CRT. This study evaluated whether 123I-meta-iodobenzylguanidine (123I-mIBG) assessed cardiac sympathetic activity could optimize CRT patient selection

Citation Metrics for Legal Information Retrieval Systems

This paper examines citations in legal information retrieval. Citation metrics can be a factor of relevance in the ranking algorithms of legal information retrieval systems. We provide an overview of the Dutch legal publishing culture. To analyze citations in legal publications, we manually analyze a set of documents and register by what (type of) documents they are cited: document type, intended audience of documents, actual audience of documents and author affiliations. An analysis of 9 cited documents and 217 citing documents shows no strict separation in citations between documents aimed at scholars and documents aimed at practitioners. Our results suggest that citations in legal documents do not measure the impact on scholarly publications and scholars, but measure a broader scope of impact, or relevance, for the legal field.Computer Science

Vascular time-activity variation in patients undergoing 123I-MIBG myocardial scintigraphy: implications for quantification of cardiac and mediastinal uptake

For the quantification of cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake, the mediastinum is commonly used as a reference region reflecting nonspecific background activity. However, variations in the quantity of vascular structures in the mediastinum and the rate of renal clearance of (123)I-MIBG from the blood pool may contribute to increased interindividual variation in uptake. This study examined the relationship between changes in heart (H) and mediastinal (M) counts and the change in vascular (123)I-MIBG activity, including the effect of renal function. Fifty-one subjects with ischemic heart disease underwent early (15 min) and late (4 h) anterior planar images of the chest following injection of (123)I-MIBG. Vascular (123)I-MIBG activity was determined from venous blood samples obtained at 2 min, 15 min, 35 min, and 4 h post-injection. From the vascular clearance curve of each subject, the mean blood counts/min per ml at the time of each acquisition and the slope of the clearance curve were determined. Renal function was expressed as the estimated creatinine clearance (e-CC) and the estimated glomerular filtration rate (e-GFR). Relations between H and M region of interest (ROI) counts/pixel, vascular activity, and renal function were then examined using linear regression. Changes in ROI activity ratios between early and late planar images could not be explained by blood activity, the slope of the vascular clearance curves, or estimates of renal function. At most 3% of the variation in image counts could be explained by changes in vascular activity (p = 0.104). The e-CC and e-GFR could at best explain approximately 1.5% of the variation in the slopes of the vascular clearance curve (p = 0.194). The change in measured H and M counts between early and late planar (123)I-MIBG images is unrelated to intravascular levels of the radiopharmaceutical. This suggests that changes in M counts are primarily due to decrease in soft tissue activity and scatter from the adjacent lung

Citation metrics for legal information retrieval: scholars and practitioners intertwined?

This paper examines citations in legal documents in the context of bibliometric-enhanced legal information retrieval. It is suggested that users of legal information retrieval systems wish to see both scholarly and non-scholarly information, and legal information retrieval systems are developed to be used by both scholarly and non-scholarly users. Since the use of citations in building arguments plays an important role in the legal domain, bibliometric information (such as citations) is an instrument to enhance legal information retrieval systems. This paper examines, through literature and data analysis, whether a bibliometric-enhanced ranking for legal information retrieval should consider both scholarly and non-scholarly publications, and whether this ranking could serve both user groups, or whether a distinction needs to be made.Our literature analysis suggests that for legal documents, there is no strict separation between scholarly and non-scholarly documents. There is no clear mark by which the two groups can be separated, and in as far as a distinction can be made, literature shows that both scholars and practitioners (non-scholars) use both types.We perform a data analysis to analyze this finding for legal information retrieval in practice, using citation and usage data from a legal search engine in the Netherlands. We first create a method to classify legal documents as either scholarly or non-scholarly based on criteria found in the literature. We then semi-automatically analyze a set of seed documents and register by what (type of) documents they are cited. This resulted in a set of 52 cited (seed) documents and 3086 citing documents. Based on the affiliation of users of the search engine, we analyzed the relation between user group and document type.Our data analysis confirms the literature analysis and shows much cross-citations between scholarly and non-scholarly documents. In addition, we find that scholarly users often open non-scholarly documents and vice versa. Our results suggest that for use in legal information retrieval systems citations in legal documents measure part of a broad scope of impact, or relevance, on the entire legal field. This means that for bibliometric-enhanced ranking in legal information retrieval, both scholarly and non-scholarly documents should be considered. The disregard by both scholarly and non-scholarly users of the distinction between scholarly and non-scholarly publications also suggests that the affiliation of the user is not likely a suitable factor to differentiate rankings on. The data in combination with literature suggests that a differentiation on user intent might be more suitable.Algorithms and the Foundations of Software technolog

Renal Function in Relation to Cardiac 123I-MIBG Scintigraphy in Patients with Chronic Heart Failure

The aim of this study was to explore if estimates of renal function could explain variability of 123I-metaiodobenzylguanidine (123I-MIBG) assessed myocardial sympathetic activity. Furthermore estimates of renal function were compared to 123I-MIBG as predictors of cardiac death in chronic heart failure (CHF). Semi-quantitative parameters of 123I-MIBG myocardial uptake and washout were calculated using early heart/mediastinum ratio (H/M), late H/M and washout. Renal function was calculated as estimated Creatinine Clearance (e-CC) and as estimated Glomerular Filtration Rate (e-GFR). Thirty-nine patients with CHF (24 males; age: 64.4 ± 10.5 years; NYHA II/III/IV: 17/20/2; LVEF: 24.0 ± 11.5%) were studied. Variability in any of the semi-quantitative 123I-MIBG myocardial parameters could not be explained by e-CC or e-GFR. During follow-up (60 ± 37 months) there were 6 cardiac deaths. Cox proportional hazard regression analysis showed that late H/M was the only independent predictor for cardiac death (Chi-square 3.2, regression coefficient: −4.095; standard error: 2.063; hazard ratio: 0.17 [95% CI: 0.000–0.950]). Addition of estimates of renal function did not significantly change the Chi-square of the model. Semi-quantitative 123I-MIBG myocardial parameters are independent of estimates of renal function. In addition, cardiac sympathetic innervation assessed by 123I-MIBG scintigraphy seems to be superior to renal function in the prediction of cardiac death in CHF patients

Report on the 11th bibliometric-enhanced information retrieval workshop (BIR 2021)

Algorithms and the Foundations of Software technolog

Exploration of Domain Relevance by Legal Professionals in Information Retrieval Systems

This paper addresses relevance in legal information retrieval (IR). We investigate whether the conceptual framework of relevance in legal IR, as described by Van Opijnen (2017), can be confirmed in practice. The research is conducted with a user questionnaire in which users of a legal IR system had to choose which of two results they would like to see ranked higher for a query and were asked to provide a reasoning for their choice. To avoid questions with an obvious answer and extract as much information as possible about the reasoning process, the search results were chosen to differ on relevance factors from the literature, where one result scores high on one factor, and the other on another factor. The questionnaire had eleven pairs of search results. A total of 43 legal professionals participated: 14 legal information specialists, 6 legal scholars and 23 legal practitioners.The results confirms the existence of domain relevance as described in the theoretical framework by Van Opijnen (2017). Based on the factors mentioned by the respondents, we can conclude that document type, recency, level of depth, legal hierarchy, authority, usability and whether a document is annotated are factors of domain relevance that are largely independent of the task context.We also investigated whether different sub-groups of users of legal IR systems (legal information specialists who are searching for others, legal scholars, and legal practitioners) differ in terms of the factors they consider in judging the relevance of legal documents outside of a task context. Using a PERMANOVA we found no significant difference in the factors reported by these groups. At this moment there is no reason to treat these sub-groups differently in legal IR systems.Multivariate analysis of psychological dat