Search

Background: Subtraction of single-photon emission computed tomography (SPECT) images has a number of clinical applications in e.g. foci localization in ictal/inter-ictal SPECT and defect detection in rest/stress cardiac SPECT. In this work, we investigated the technical performance of SPECT subtraction for the purpose of quantifying the effect of a vasoconstricting drug (angiotensin-II, or AT2) on the Tc-99m-MAA liver distribution in hepatic radioembolization using an innovative interventional hybrid C-arm scanner. Given that subtraction of SPECT images is challenging due to high noise levels and poor resolution, we compared four methods to obtain a difference image in terms of image quality and quantitative accuracy. These methods included (i) image subtraction: subtraction of independently reconstructed SPECT images, (ii) projection subtraction: reconstruction of a SPECT image from subtracted projections, (iii) projection addition: reconstruction by addition of projections as a background term during the iterative reconstruction, and (iv) image addition: simultaneous reconstruction of the difference image and the subtracted image. Results: Digital simulations (XCAT) and phantom studies (NEMA-IQ and anthropomorphic torso) showed that all four methods were able to generate difference images but their performance on specific metrics varied substantially. Image subtraction had the best quantitative performance (activity recovery coefficient) but had the worst visual quality (contrast-to-noise ratio) due to high noise levels. Projection subtraction showed a slightly better visual quality than image subtraction, but also a slightly worse quantitative accuracy. Projection addition had a substantial bias in its quantitative accuracy which increased with less counts in the projections. Image addition resulted in the best visual image quality but had a quantitative bias when the two images to subtract contained opposing features. Conclusion: All four investigated methods of SPECT subtraction demonstrated the capacity to generate a feasible difference image from two SPECT images. Image subtraction is recommended when the user is only interested in quantitative values, whereas image addition is recommended when the user requires the best visual image quality. Since quantitative accuracy is most important for the dosimetric investigation of AT2 in radioembolization, we recommend using the image subtraction method for this purpose. [ABSTRACT FROM AUTHOR]

The decomposition of numbers when solving subtraction tasks is regarded as more powerful than counting-based strategies. Still, many students fail to solve subtraction tasks despite using decomposition. To shed light upon this issue, we take a variation theoretical perspective (Marton, 2015) seeing learning as a function of discerning critical aspects and their relations of the object of learning. In this paper, we focus on what number relations students see in a three-digit subtraction task, and how they see them. We analyzed interview data from 55 second-grade students who used decomposition strategies to solve 204 − 193 =. The variation theory of learning was used to analyze what number relations the students experienced and how they experienced them, aiming to explain why they made errors even though they used presumably powerful strategies in their problem-solving. The findings show that students who simultaneously experienced within-number relations and between-number relations when solving the task succeeded in solving it, whereas those who did not do this failed. These findings have importance for understanding what students need to discern in order to be able to solve subtraction tasks in a proficient way. [ABSTRACT FROM AUTHOR]

Practical reasons can be aggregated to decide what one ought to do. This paper explores an operation that undoes aggregation: subtraction. I consider several distinctions concerning subtraction: subtracting content and subtracting strength; and subtracting one reason from one other reason or from a set of reasons. I put forward a precise understanding of subtracting the content of one reason from another, based on an operation of difference on a state-like, structured notion of content. Finally, I apply my approach to subtracting reasons to normative domains, and in particular to belief revision and norm change. [ABSTRACT FROM AUTHOR]

Learning to calculate with natural numbers by structuring seems promising but how this can be taught in a sustainable manner remains an open question. An eight-month-long intervention based on the idea of using a structural approach to addition and subtraction, and particularly bridging through ten, was implemented in four Swedish first-grade classes. One goal was that by the end of first grade, students would be able to solve tasks such as subtracting 8 from 15 by using part-whole number relations. In this paper, we report on learning outcomes from task-based interviews with intervention and control groups before, immediately after, and one year after the intervention, in order to investigate long-term effects and whether students used a structural approach when solving tasks in a higher number range in the second grade. In comparison to controls, students in the intervention group showed higher increases in their learning outcomes. Moreover, the intervention group used a structural approach to a larger extent when solving tasks in higher number ranges, whereas students in the control group more commonly used single-unit counting to solve such tasks. These findings have implications both for teaching and for research on students’ development of arithmetic skills. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate the usefulness of temporal subtraction CT (TSCT) of temporal bone CT for the detection of postoperative recurrent/residual cholesteatoma of the middle ear. Methods: Thirty-two consecutive patients with surgically proven postoperative recurrent/residual cholesteatoma and 14 consecutive patients without recurrent/residual lesion matched the selection criteria and were retrospectively evaluated. TSCT imaging was generated with the use of serial postoperative CT. Two experienced radiologists and two residents evaluated the presence of bone erosive change by comparison serial CT studies, and CT and TSCT. The detection rate of bone erosive change, sensitivity and specificity of the recurrence/residual lesions, and reading time for each reader were evaluated. Results: TSCT + CT significantly improved the detection of bone erosive changes compared to CT-only evaluation (17.4–41.3% vs. 37.0–58.7%, p = 0.008–0.046). The mean sensitivity and specificity of TSCT + CT for experienced radiologists were 0.77 and 1.00, and 0.52 and 0.97 without TSCT. The mean sensitivity and specificity of TSCT + CT for residents were 0.64 and 1.00, and 0.41 and 1.00 without TSCT. Sensitivity showed an increase in all readers. The use of TSCT significantly reduced the reading time per case in all readers (p < 0.001). Conclusion: TSCT improves the depiction of newly occurring progressive bone erosive changes, and detection sensitivity and reading time in postoperative recurrence/residual cholesteatoma of middle ear. [ABSTRACT FROM AUTHOR]

In this study, to investigate the influence of numerical surface forms on strategy execution in subtraction and addition, 25 college students were required to perform a mental arithmetic task. Behavioral and electroencephalography responses were recorded to explore the stages of strategy execution. Arithmetic problems were presented within 11–20 by Arabic, Chinese and English numerals, respectively. The results showed that, compared with Arabic and Chinese numerals, participants had longer RTs under the condition of English numerals. English numerals induced stronger N100, P200 and P300 amplitudes, and longer latency in P200 and P300 amplitudes than in other conditions. These findings indicated that numerical surface forms affected the execution of mental arithmetic strategies, with Chinese and English numerals being processed deeper in the brain. Especially, the English digital word form occupied more psychological resources, and it was activated more in the frontal area and the parietal area, which would obviously hinder the processing of arithmetic information. [ABSTRACT FROM AUTHOR]

Purpose: Tumor size and depth of invasion (DOI) are mandatory assessments for tumor classification in tongue cancer but are often non-assessable on CT due to dental artifacts. This study investigated whether subtraction iodine imaging (SII) would improve tumor delineation and measurability. Materials and methods: Fifty-seven consecutive patients with tongue cancer, who underwent scanning with a 320-row area detector CT with contrast administration and were treated with surgical resection, were retrospectively evaluated. CT was reconstructed with single-energy projection-based metallic artifact reduction (sCT). SII was generated by subtracting the pre-contrast volume scans from the post-contrast volume scans using a high-resolution deformable registration algorithm. MRI scans were also evaluated for comparing the ability of measurements. Two radiologists visually graded the tumor delineation using a 5-point scale. Tumor size and DOI were measured wherever possible. The tumor delineation score was compared using the Wilcoxon signed-rank method. Spearman's correlations between imaging and pathological measurements were calculated. Intraclass correlation coefficients of measurements between readers were estimated. Results: The tumor delineation score was greater on sCT-plus-SII than on sCT alone (medians: 3 and 1, respectively; p < 0.001), with higher number of detectable cases observed with sCT-plus-SII (36/57 [63.2%]) than sCT alone (21/57 [36.8%]). Tumor size and DOI measurability were higher with sCT-plus-SII (29/57 [50.9%]) than with sCT alone (17/57 [29.8%]). MRI had the highest detectability (52/57 [91.2%]) and measurability (46/57 [80.7%]). Correlation coefficients between radiological and pathological tumor size and DOI were similar for sCT (0.83–0.88), sCT-plus-SII (0.78–0.84), and MRI (0.78–0.90). Intraclass correlation coefficients were higher than 0.95 for each modality. Conclusions: SII improves detectability and measurability of tumor size and DOI in patients with oral tongue squamous cell carcinoma, thus increasing the diagnostic potential. SII may also be beneficial for cases unevaluable on MRI due to artifacts or for patients with contraindications to MRI. [ABSTRACT FROM AUTHOR]

A challenge for prospective teachers (PTs) is to determine what students know about a topic through asking appropriate questions and being thoughtful about the wording of these questions so as to capture and reframe students' spontaneous mathematical thinking and eventually unriddle the fuzzy boundary of students' complex thinking. This study examined four PTs' efforts to elicit kindergarteners' subtraction strategies and make conclusions about their subtraction understanding. Drawing on PTs' plans for interviewing kindergarteners on subtraction problems, interview transcripts, and reflection papers, the results suggest that PTs provided effective scaffolds, adding context to numerical problems or explaining mathematical terms and symbols as needed. However, they avoided asking problems with subtrahends greater than five, numbers above ten, and missing starts or missing subtrahends, limiting their ability to draw targeted conclusions about the students' strengths and needs. Using effective questions allowed one PT who posed a limited variety of problems to make stronger conclusions about her student's subtraction understanding, while asking a broader variety of problems helped another PT who used limited questions make conclusions about her student's subtraction understanding. Based on these results, mathematics teacher educators could leverage their PTs' strengths to either encourage multiple interviews, each targeting different problem types, or one interview with a broader variety of problem types. The results of this study further highlight the need for PTs to move beyond just asking students to explain their strategies and have them justify or represent their strategies as well. [ABSTRACT FROM AUTHOR]

In this study, we present a mathematical analysis distinguishing two conceptions of equivalence: proportional equivalence and unit equivalence. These two conceptions have distinct meanings in relation to equivalent fractions: one is grounded in proportionality, while the other is grounded in equal wholes. We argue that (a) the distinction of equivalence gives a unified framework of equal fractions that has not previously been described in the literature; (b) a conceptual understanding of both fraction equivalences is integral to understanding rational numbers; and (c) knowledge of both conceptions of equivalence is important for developing a conceptual understanding of fraction arithmetic. Past research has largely overlooked the distinction between the two types of equivalence. However, this may provide an important foundation for central topics that build on equivalence, and a better understanding of these two types of equivalence may support a more flexible understanding of fractions. Last, we propose future directions for teaching equivalence in mathematics. [ABSTRACT FROM AUTHOR]

Medical confidentiality is an essential duty in the medical profession. In this paper, we introduce a novel robust blind watermarking method for securing the medical report in a DICOM (Digital Imaging and Communications in Medicine) imaging. The insertion of each bit is done in the subtraction of adjacent DC coefficients of the FFT (fast Fourier transformation) using a key kw. Each bit of the watermark is eXORed with a bit generated by a proposed system which generates a bit sequence in function of the key kw. The proposed method has the features of having better security, invisibility, and robustness. Experimental results show that it is robust to single, double, and triple attacks and that it has better robustness than recently proposed watermarking schemes. Graphical abstract The proposed security system. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate how pictorial representations with different semiotic characteristics affect additive word problem solving by kindergartners. The focus of the study is on three categories of additive problems (change problems, combine problems and equalize problems) and on representational pictures with different semiotic characteristics: (a) pictures in which the problem quantities are represented in pictorial form, that is, as groups of illustrated objects (PP pictures), (b) pictures in which the quantities are represented partly in pictorial form and in symbolic form (PS pictures), and (c) pictures in which the quantities are represented in symbolic form (SS pictures). Data were collected from 63 kindergartners using a paper-and-pencil test. Results showed that the semiotic characteristics of representational pictures had a strong and significant effect on performance. Children's performance was higher in the problems with PP pictures but declined in the problems with PS and SS pictures. However, the differences in children's performance across the problems with different representational format varied between the problem categories and their mathematical structures. The semiotic characteristics of representational pictures had an important role in the establishment of close relations between children's solutions in problems in different categories. Detailed analysis of children's answers to the problems revealed a number of picture-related difficulties. Findings are discussed and directions for future research are drawn considering the methodological limitations of the study. [ABSTRACT FROM AUTHOR]

In this paper, we report how 5-year-olds' arithmetic skills developed through participation in an 8-month-long intervention. The intervention program aimed to enhance the children's ways of experiencing numbers' part-part-whole relations as a basis for arithmetic skills and was built on principles from the variation theory of learning. The report is based on an analysis of assessments with 103 children (intervention group n = 65 and control group n = 38) before and after the intervention and a follow-up assessment 1 year after the intervention. Our findings show that the learning outcomes of the intervention group were significantly higher compared to those of the control group after the intervention and that differences between the groups remained even 1 year after the intervention. In particular, the results show that children participating in the intervention group learned to recognize and use part-part-whole relations in novel arithmetic tasks. [ABSTRACT FROM AUTHOR]

Performance on word problems is influenced by linguistic and arithmetic factors, and by their interaction. To study these factors and interactions, we manipulated linguistic and arithmetic factors independently in a within-participant design that included complexity parameters (a) in the domain of arithmetic: carry/borrow (no-carry/borrow vs. carry/borrow), operation (addition vs. subtraction), (b) in the domain of linguistics: nominalization (nominalized vs. verbalized form), and (c) linking the two domains: lexical consistency (linguistic predicate locally consistent vs. inconsistent with mathematical operation). Response times of 25 students solving 320 one-step word problems were measured. All four factors showed a main effect on response times, and interactions between linguistic and arithmetic factors affected response times. These interactions were observed when the linguistic and arithmetic factors were conceptually linked. Our results highlight that not only the linguistic and arithmetic complexities of an item contribute to the difficulty of a word problem, but linguistic and arithmetic factors interact. We discuss the theoretical implications for the numerical and the linguistic domain as well as the possible impact of domain-general characteristics, such as working memory limitations as a potential reason for the observed interactions between numerical and linguistic attributes. [ABSTRACT FROM AUTHOR]

The question of teaching a standard written algorithm for the four arithmetical operations in the first years of elementary school is increasingly raised as a consequence of the possibility of using calculators, tablets, and computers. This article first presents arguments both against and for maintaining this teaching in the first school years. Then, it presents an analysis of the procedure—whether it implies the standard algorithm or not—used by second grade students to solve a subtraction verbal problem. The 4720 students involved in the research were divided in a control group (n = 2101) and an experimental group (n = 2619) in which the standard written algorithm (SWA) was taught, or not taught, respectively. The effectiveness of algorithm use was analyzed not only in terms of accuracy of the answers, but also for its influence on the choice of the correct arithmetical operation and for its choice by the students as a function of their ability. The SWA was strongly associated with the use of the false arithmetical operation (effect size ϕ = 0.79)—addition instead of subtraction—but was chosen by students of all levels of ability. The latter result suggests that the SWA is well suited for the most advanced students but far less for the others who use it mechanically and without reflection. [ABSTRACT FROM AUTHOR]

The idea of using fingers as a key component in arithmetic development has received a great deal of support, much of which is based on neuroscientific evidence. However, this body of work pays limited attention to how fingers are used and possible different outcomes in arithmetic problem solving. The aim of our paper, based on an analysis of 126 observations of 4–5-year-olds solving a simple subtraction task, is to discuss different ways of using fingers, with some of the ways appearing more, and others less, powerful. The analysis suggests there is much more complexity to children's finger-related strategies than prior research has indicated. Empirical findings in our study point to the decisive effects of different ways of using fingers, and in particular for either keeping track of counted units or for presenting a structured awareness of number. Three ways of using fingers emerge in the analysis, which are discussed in relation to their rate of success in solving the subtraction task and with attention to why the differences matter for the success rate. Through this discussion we suggest that the complexity of how fingers are used must be considered. [ABSTRACT FROM AUTHOR]

Purpose To evaluate role of quantitative assessment of chemical shift MR imaging and chemical shift subtraction technique in differentiating adenomatous from non-adenomatous adrenal lesions with comparison of accuracy level of each technique. Materials and methods A prospective study was carried out from 4-2014 to 5-2016 using 1.5T MRI. In-phase/opposed phase MRI sequences were applied for 52 patients having 58 adrenal lesions, 18 were hyper functioning and 40 were non-functioning. Lesions signal changes between in- and opposed phase sequences and post processing was done to calculate different quantitative chemical shift parameters using spleen, paraspinal muscle, and liver as a reference tissues. Additionally subtraction chemical shift MR technique on selected 16 cases was applied. Results Signal intensity index and the two formulas of adrenal to spleen ratio were more accurate than other quantitative chemical shift MRI parameters in discrimination between adenomatous and nonadenomatous adrenal lesions with selected cutoff value 23.4% for the signal intensity index, 0.72 and −27.82% for adrenal to spleen ratio% using the old and new formulas respectively. Chemical shift subtraction technique expressed significant difference between adenomas and non-adenomatous adrenal lesions where adenomas had ratio of 108.87 or more, and the non-adenomatous lesions had ratio of 47.74 or less with selected cutoff value 173.0475. Conclusion The signal intensity index and adrenal to spleen ratio are the most reliable quantitative chemical shift MRI methods in differentiation of adrenal adenomas from other non-adenomatous adrenal solid lesions. Chemical shift subtraction MRI is a recent technique that gives highly confident discrimination between two categories of pathology without using of any reference organ. [ABSTRACT FROM AUTHOR]

The present study aims to identify factors that may influence the dissociability of number magnitude processing and arithmetic fact retrieval at the behavioural level. To that end, we assessed both subtraction and multiplication performance in a within-subject approach and evaluated the interdependence of unit-decade integration measures on the one hand as well as sex differences in the interdependence of performance measures on the other hand. We found that subtraction items requiring borrowing (e.g. 53-29 = 24, 3 < 9) are more error prone than subtraction items not requiring borrowing (e.g. 59-23 = 34, 9 > 3), thereby demonstrating a borrowing effect, which has been suggested as a measure of unit-decade integration in subtraction. Furthermore, we observed that multiplication items with decade-consistent distractors (e.g. 6 × 4 = 28 instead of 24) are more error prone that multiplication items with decade-inconsistent distractors (e.g. 6 × 4 = 30 instead of 24), thereby demonstrating a decade-consistency effect, which has been suggested as a measure of unit-decade integration in simple multiplication. However, the borrowing effect in subtraction was not correlated with the effect of decade consistency in simple multiplication in either men or women. This indicates that unit-decade integration arises from different systems in subtraction and multiplication. Nevertheless, men outperformed women not only in subtraction, but also in multiplication. Furthermore, subtraction and multiplication performance on correct solution probes were correlated in women, but unrelated in men. Thus, the view of differential systems for number magnitude processing and arithmetic fact retrieval may not be universal across sexes. [ABSTRACT FROM AUTHOR]

In conventional coronary computed tomography angiography (CCTA), metal artifacts are frequently observed where stents are located, making it difficult to evaluate in-stent restenosis. This study was conducted to investigate whether subtraction CCTA can improve diagnostic accuracy in the evaluation of in-stent restenosis. Subtraction CCTA was performed using 320-row CT in 398 patients with previously placed stents who were able to hold their breath for 25 s and in whom mid-diastolic prospective one-beat scanning was possible. Among these patients, 126 patients (94 men and 32 women, age 74 ± 8 years) with 370 stents who also underwent invasive coronary angiography (ICA) were selected as the subjects of this study. With ICA findings considered the gold standard, conventional CCTA was compared against subtraction CCTA to determine whether subtraction can improve diagnostic accuracy in the evaluation of in-stent restenosis. When non-assessable stents were considered to be stenotic, the diagnostic accuracy in the evaluation of in-stent restenosis was 62.7 % for conventional CCTA and 89.5 % for subtraction CCTA. When the non-assessable stents were considered to be non-stenotic the diagnostic accuracy was 90.3 % for conventional CCTA and 94.31 % for subtraction CCTA. When subtraction CCTA was used to evaluate only the 138 stents that were judged to be non-assessable by conventional CCTA, 116 of these stents were judged to be assessable, and the findings for 109 of them agreed with those obtained by ICA. Even for stents with an internal diameter of 2.5-3 mm, the lumen can be evaluated in more than 80 % of patients. Subtraction CCTA provides significantly higher diagnostic accuracy than conventional CCTA in the evaluation of in-stent restenosis. [ABSTRACT FROM AUTHOR]

To investigate the clinical usefulness of subtraction coronary computed tomographic angiography (CCTA) in patients with severe calcification. A 320-row area detector CT system was used in this study. The subjects were 78 patients (47 men and 31 women, 739 years of age) with an Agatston score of >300 who were able to undergo prospective one-beat scanning during a single breath-hold. The CCTA findings were compared against invasive coronary angiography. The diagnostic capabilities of CCTA for the severely calcified segments with and without the additional information provided by subtraction CCTA were compared. Severe calcification was observed in 174 (31.9%) of the 546 segments, and non-assessable regions were observed in 74 (13.6%) of the segments. The addition of subtraction CCTA information improved the diagnostic accuracy for segments with severe calcification from 67.8 to 82.8% on a per-segment basis and from 70.1 to 82.1% on a per-patient basis, with non-assessable segments considered to be stenotic. When non-assessable segments were considered to be an incorrect diagnosis, the diagnostic accuracy was improved from 48.3 to 75.9% on a per-segment basis and from 43.3 to 79.1% on a per-patient basis. In addition, when evaluation was limited to non-assessable segments, subtraction CCTA provided a diagnostic accuracy of 81.1% when non-assessable segments were considered to be stenotic or 66.2% when non-assessable segments were considered to be an incorrect diagnosis. Subtraction CCTA improves the diagnostic capabilities of CCTA in patients with severe calcification. [ABSTRACT FROM AUTHOR]

For improvement of three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) image quality in the neck, fat-subtracted MRA by use of the two-point Dixon technique was compared with conventional fat-suppressed MRA techniques. Three different types of neck 3D-TOF-MRA were obtained [minimum echo time (TE) (1.9 ms), opposed-phase TE (3.4 ms), and chemical shift selective fat suppression (CHESS) (TE = 1.9 ms)] on five volunteers at 3.0 T. MRA was obtained with subtraction of fat-only images (produced by a two-point Dixon sequence) from minimum-TE MRA images, and compared with other fat-suppressed MRA images. Fat-subtracted MRA demonstrated uniform fat suppression compared with other techniques. The mean vessel-to-fat contrast in fat-subtracted MRA was significantly higher ( p < 0.01) than in other MRA images (minimum-TE: 0.137 ± 0.086, opposed-phase TE: 0.268 ± 0.102, CHESS: 0.307 ± 0.052, fat-subtracted: 0.965 ± 0.101). The mean vessel-to-muscle contrast in opposed-phase TE MRA was significantly lower ( p < 0.01) than in other MRA images (minimum-TE: 0.526 ± 0.036, opposed-phase TE: 0.419 ± 0.188, CHESS: 0.511 ± 0.023, fat-subtracted: 0.573 ± 0.016). Fat-subtracted MRA by use of the two-point Dixon technique improves the image quality of neck MRA. This technique would be a useful method for MRA, especially in areas with inhomogeneous magnetic fields, such as the neck. [ABSTRACT FROM AUTHOR]

The purpose of this study was to explore the feasibility of subtraction coronary computed tomography angiography (CCTA) by second-generation 320-detector row CT in patients with severe coronary artery calcification using invasive coronary angiography (ICA) as the gold standard. This study was approved by the institutional board, and all subjects provided written consent. Twenty patients with calcium scores of >400 underwent conventional CCTA and subtraction CCTA followed by ICA. A total of 82 segments were evaluated for image quality using a 4-point scale and the presence of significant (>50 %) luminal stenosis by two independent readers. The average image quality was 2.3 ± 0.8 with conventional CCTA and 3.2 ± 0.6 with subtraction CCTA ( P < 0.001). The percentage of segments with non-diagnostic image quality was 43.9 % on conventional CCTA versus 8.5 % on subtraction CCTA ( P = 0.004). The segment-based diagnostic accuracy for detecting significant stenosis according to ICA revealed an area under the receiver operating characteristics curve of 0.824 (95 % confidence interval [CI], 0.750-0.899) for conventional CCTA and 0.936 (95 % CI 0.889-0.936) for subtraction CCTA ( P = 0.001). The sensitivity, specificity, positive predictive value, and negative predictive value for conventional CCTA were 88.2, 62.5, 62.5, and 88.2 %, respectively, and for subtraction CCTA they were 94.1, 85.4, 82.1, and 95.3 %, respectively. As compared to conventional, subtraction CCTA using a second-generation 320-detector row CT showed improvement in diagnostic accuracy at segment base analysis in patients with severe calcifications. [ABSTRACT FROM AUTHOR]

Background Subtraction imaging is a technique whereby an unenhanced T1-weighted sequence is digitally subtracted from the identical sequence performed after gadolinium administration. Aim of the work This study will highlight the role of subtraction imaging for non-vascular MRI applications. Subjects and methods The study included 40 patients presenting with lesions in different parts of the body, that are initially hyperintense on T1W sequences. We used post-processing software (Osirix) to digitally subtract the pre-enhancement from the post enhancement sequences. Results Based on subtraction imaging findings 5 patients were diagnosed with intraocular melanomas, two patients were diagnosed with hemorrhagic cysts in the masseter muscle, two patients were diagnosed with hemorrhagic cysts in the parotid gland, two patients were diagnosed with dysplastic hepatic nodules, 5 patients were diagnosed with post-ablation necrosis following hepatocellular carcinoma (HCC) treatment, two patients showed recurrent HCC after chemoembolisation, 3 patients showed chemoembolised HCC without recurrence, 4 patients showed intraluminal gall bladder sludge, 4 patients showed hemorrhagic renal cysts, one patient showed solid papillary neoplasm of the pancreas, 6 patients showed chocolate ovarian cysts, two patient showed ovarian cystadenoma and two patients showed ovarian cystadenocarcinoma. Conclusion Subtraction MRI is very helpful tool in non-vascular MRI applications. [ABSTRACT FROM AUTHOR]

We explore the feasibility of coronary calcium subtraction computed tomography angiography (CCTA) in patients with high calcium scores using invasive coronary angiography as the gold standard. Eleven patients with calcium scores of >400 underwent CCTA using a subtraction protocol followed by invasive coronary angiography. In addition to standard reconstructions, subtracted images were obtained using a dedicated subtraction algorithm. A total of 55 calcified segments were evaluated for image quality [using a 4-point scale ranging from 1 (uninterpretable) to 4 (good)] and the presence of significant (≥50 %) luminal stenosis. Conventional and subtracted CCTA were compared using quantitative coronary angiography (QCA) as the gold standard. The average image quality of conventional CCTA was 2.5 ± 0.6 versus 3.1 ± 0.6 on subtraction CCTA ( P < 0.001). The percentage of segments with a score 1 or 2 was reduced from 41.8 to 12.7 % after coronary calcium subtraction ( P = 0.002). On QCA, significant stenosis was observed in 16 segments. The area under the receiver operating characteristics curve to detect ≥50 % stenosis on QCA increased from 0.741 [95 % confidence interval (CI) 0.598-0.885] for conventional CCTA to 0.905 (95 % CI 0.791-1.000) for subtraction CCTA ( P = 0.003). In patients with extensive calcifications undergoing CCTA, coronary calcium subtraction may improve the evaluation of calcified segments. [ABSTRACT FROM AUTHOR]

This study examined interventions for addition and subtraction that were implemented through single-case design (SCD) research studies. We attempted to extend prior SCD meta-analyses by examining differences in effect sizes across several moderating variables and by including a novel index of effect, improvement rate difference (IRD). We also examined the extent to which effect sizes differed by degree of experimental control achieved in the studies. Forty-seven effect sizes were obtained across 11 studies. IRD effect sizes ranged from .59 to .90 and suggested a moderate to large effect for the math interventions. Variables that appeared to moderate the effects were student age, time spent in intervention, and intervention type. We also identified a relationship between experimental control and the obtained effect sizes. Findings indicated that further SCD research in basic arithmetic and rigorous experiments are necessary to establish an evidence base that accurately characterizes intervention effectiveness. [ABSTRACT FROM AUTHOR]

The research study this article is based on aims to implement research knowledge to teaching, that is, the concept of critical aspects and dimensions of variation used in the variation theory. To do this, the researchers worked with willing teachers to explore how to make mathematics teaching more effective. This paper illustrates how teachers make use of a learning theory, the variation theory, as well as their own professional expertise and collaboration to help students improve their mathematical understanding of subtraction as well as their learning of it. The students' tests, examinations of students' mathematical work, the teachers' lessons plan and reports of the instructions for lessons form the data base for the article. The analysis indicates that one of the critical aspects in the process of implementation of the variation theory in the teachers' practice was to identify the critical aspects in students' learning. Another critical aspect in the implementation of the variation theory was to open up dimensions of variation in the identified critical aspects of the students. By giving teachers the possibility to develop the ability to identify critical aspects in students' learning, dimensions of variation are opened up in these aspects, and by applying this knowledge in the daily teaching, they have the possibility to improve students' learning. The findings suggest that developing an understanding of the students' critical aspects can be a productive basis in helping teachers make fundamental changes in their instructions and improve students' learning. [ABSTRACT FROM AUTHOR]

Novel architectures for designing modulo 2+1 subtractors and combined adders/subtractors are proposed in this manuscript. Both the normal and the diminished-one representations of the operands are considered. Unit gate estimates and CMOS VLSI implementations reveal that the proposed modulo 2+1 subtractors for operands in the normal representation are more efficient than those previously proposed. The proposed diminished-one modulo 2+1 subtractors have a complexity similar to that of the corresponding diminished-one adders. Modulo 2−1 subtractors and adders/subtractors are also considered for the sake of completeness and a comparison between alternative architectures is provided. [ABSTRACT FROM AUTHOR]

One of the major challenges in coronary computed tomography (CT) is the presence of severe calcification, which may interfere with the assessment of lesions and may reduce diagnostic accuracy. However, such calcifications may potentially be eliminated by subtracting precontrast CT image data from contrast-enhanced coronary CT angiography data. Such examinations require perfect alignment and can be performed in two ways: 1) the 'single breath-hold method,' in which both precontrast and postcontrast CT data are acquired during a breath-hold, and 2) the 'two breath-hold method,' in which the calcium scoring data are used as the precontrast CT data. Misregistration artifacts must be corrected manually based on visual assessment, which results in long image processing times. Although a number of challenges remain to be overcome, subtraction coronary CT angiography might improve the diagnostic accuracy of coronary CT angiography in patients with severe calcification in the future. [ABSTRACT FROM AUTHOR]

The main objective of this article is to implement and compare QRS subtraction techniques for intra-cardiac atrial electrograms based on using the surface ECG as a reference. A band-pass filter between 8 and 20 Hz followed by rectification, and then a low-pass filter at 6 Hz are used for QRS detection. QRS subtraction was performed using three different approaches: flat, linear and spline interpolations. QRS subtraction affects the power of the signals but it normally does not affect the dominant frequency. The average power of the atrial electrograms after QRS subtraction is significantly reduced for frequencies above 10 Hz. [ABSTRACT FROM AUTHOR]

This study was designed to investigate preservice elementary school teachers' (PSTs') responses to written standard place-value-operation tasks (addition and subtraction). Previous research established that PSTs can often perform but not explain algorithms and provided a four-category framework for PSTs' conceptions, two correct and two incorrect. Previous findings are replicated for PSTs toward the end of their college careers, and two conceptions are further analyzed to yield three categories of incorrect views of regrouped digits: (a) consistently as 1 value (all as 1 or all as 10), (b) consistently within but not across contexts (i.e., all as 10 in addition but all as 1 in subtraction), and (c) inconsistently (depending on the task). [ABSTRACT FROM AUTHOR]

The purpose of the current study was to investigate the effect of three procedures designed to promote the generalization of fluent responding of 12 addition facts to 12 related subtraction facts. The first procedure was completed to determine whether increases in the number of digits correct per minute computed on addition facts would generalize to related subtraction facts. If students were fluent in the targeted addition problems and no generalization was detected, a second procedure was implemented where students completed a conceptual lesson. If no generalization was observed during this phase, a third procedure was implemented where students completed addition problems presented in a cloze format. Results failed to demonstrate generalized fluency gains across any of the procedures. Discussion focuses on future directions of generalization research to further our understanding of the conditions needed for generalization to occur. [ABSTRACT FROM AUTHOR]

The general scale parameter, having the dimensions of mass squared, is dynamically generated in the QCD gluon sector. It is introduced through the difference between the regularized full gluon self-energy and its value at some finite point. It violates transversality of the full gluon self-energy. The Slavnov-Taylor identity for the full gluon propagator, when it is given by the corresponding equation of motion, is also violated by it. So in order to maintain both transversality and the identity it should be disregarded from the very beginning, i.e., put formally zero everywhere. However, we have shown how to preserve the above-mentioned identity at non-zero mass squared parameter. This allows one to establish the structure of the full gluon propagator when it is explicitly present. Its contribution does not survive in the perturbation theory regime, when the gluon momentum goes to infinity. At the same time, its contribution dominates the structure of the full gluon propagator when the gluon momentum goes to zero. We have also proposed a method how to restore transversality of the relevant gluon propagator in a gauge invariant way, while keeping the mass squared parameter “alive”. [ABSTRACT FROM AUTHOR]

An in-depth analysis of the major early numerical aspects (single-digit and multidigit addition and subtraction) in a representative Chinese textbook series and a US textbook series (Math Expressions) with major East Asian components illustrated how linguistic issues create different teaching and learning tasks for the same mathematical topic and how additional meaning-making supports may be needed in the US. Analyses of multidigit methods in several East Asian textbooks revealed a wide range of written-numeric support of the steps in these operations. Coherence and learning paths in both programs were identified. A framework that identifies elements of a coherent learning path of meaning-making supports is proposed to facilitate future cross-cultural analyses. [ABSTRACT FROM AUTHOR]

The crystallinity index of cellulose is an important parameter to establish because of the effect this property has on the utilization of cellulose as a material and as a feedstock for biofuels production. However, it has been found that the crystallinity index varies significantly depending on the choice of instrument and data analysis technique applied to the measurement. We introduce in this study a simple and straightforward method to evaluate the crystallinity index of cellulose. This novel method was developed using solid state 13C NMR and subtraction of the spectrum of a standard amorphous cellulose. The crystallinity indexes of twelve different celluloses were measured and the values from this method were compared with the values obtained by other existing methods, including methods based on X-ray diffraction. An interesting observation was that the hydration of the celluloses increased their crystallinity indexes by about 5%, suggesting that addition of water increased cellulose order for all the cellulose samples studied. [ABSTRACT FROM AUTHOR]

The article presents a research analyzing epigenetic abnormalities in cardiac hypertrophy and heart failure. It suggests that epigenetic changes play an important role in the development of cardiac hypertrophy and heart failure based on a study involving the coupling of chromatin immunoprecipitation to high-throughput profiling systems of cardiac myocytes in normal as well as affected hearts.

We conducted this study to determine the relationship between math preference and mastery for five middle school students with autism spectrum disorders. We randomly presented several math addition and subtraction problem formats to determine the students’ preferences. Results indicated that preference was idiosyncratic across students. In addition, preference was not related to mastery in some students. Results are discussed within a theoretical framework of matching law. Implications for practitioners are discussed. [ABSTRACT FROM AUTHOR]

We describe the use of a combination of fat-suppression SPIR (spectral inversion recovery) and subtraction FLAIR imaging to aid in detection of abnormal meningeal enhancement. [ABSTRACT FROM AUTHOR]

The objective of this paper is to develop a novel digital subtraction technique for serial intra-oral radiography, which would allow the detection of subtle variations in grey values. Digital images of the maxilla of a dried human skull and of a fresh pig mandible were acquired using intra-oral photostimulable phosphor plates (Digora FMX, Soredex, Helsinki) with an aluminium calibration stepwedge incorporated in the filmholder. Exposures were made with an X-ray tube for intra-oral radiography (Prostyle Intra, Planmeca, Helsinki). During pilot testing, parameter settings were adapted to reach an optimal contrast. Exposures were repeated within a 1-week interval to determine the test–retest reliability of the development. After in vitro and in vivo testing, the exposure technique and software development were used to evaluate its applicability in a pilot clinical case. Although parameter settings remained stable during the in vitro studies, the clinical exposures yielded non-linear digital images, thus, not readily suitable for data acquisition and comparison of the regions of interest. To allow further analysis, image processing was carried out using self-developed software for semi-automated linearisation and optimised contrast normalisation. This processing significantly increased the precise quantisation of jawbone density and the assessment of subtle bone density changes in arbitrarily selected regions of interest of in vivo exposures. The clinical applicability of the technique is demonstrated in a pilot case. It was demonstrated that minute densitometric deviations could be detected. The present technique and image processing may allow the quantification of jawbone density. [ABSTRACT FROM AUTHOR]

Pupils' mistakes, if suitably analysed, may give useful suggestions for improving the teaching/learning process of mathematics. We present here the main issues of an investigation on a population of 732 Italian pupils (9–12 years old), addressed to determine the typology of errors in performing written subtraction. We compared our results with those emerging from a study carried out in Brazil on pupils of the same age, concerning the errors in performing the usual algorithm of written subtraction. In our study, one group of Italian pupil utilized the usual algorithm and another group utilized an algorithm also called ‘Austrian subtraction', which was commonly taught in the primary schools of Trieste (Italy) up to the sixties and is still taught in Austria. We attempted to assess whether certain error patterns depend on different ethnic–cultural situations, teaching methods and algorithm used, and to what extent. We briefly present results from the experimental research and subsequent developments. [ABSTRACT FROM AUTHOR]

Chemokines are low-molecular weight-chemotactic cytokines, which are involved in lymphocyte trafficking and migration of leucocytes to sites of injury, in immune surveillance and in healing process. They also play a role in pathogenesis of inflammatory diseases. Three novel CC chemokines were identified from domestic duck ( Anas platyrhynchos) by screening of an enriched cDNA library constructed from mitogen-stimulated splenic mononuclear cells. Two of the clones (AB163 and AB330) had a very high nucleotide (both about 81%) and predicted amino acid level (71 and 76%, respectively) identity to the reported chicken macrophage inflammatory protein 1-β (MIP-1β; SCYA4) and regulated upon activation of normal T-cell expressed and secreted (RANTES; SCYA5) sequences. In phylogenetic analysis, these molecules clustered together with corresponding chemokines reported from other vertebrates. The third clone (AB187) had highest homology to chicken MIP-1β (36% amino acid identity) and showed closer relation to a number of chemokines belonging to monocyte chemoattractant proteins and MIP-1α chemokines. Expression of these molecules was upregulated upon mitogen stimulation of splenocytes as detected by semiquantitative RT-PCR. AB187 showed several fold increases (about 8.5 times) in the mRNA expression. Basal level expression of some of these chemokines was detected in both lymphoid and nonlymphoid tissues, including spleen, liver, lung, and bone marrow. Considering the importance of this animal species as a model for diseases such as chronic human hepatitis B, further studies will offer valuable insights into the role of these molecules in immunopathology of such diseases. [ABSTRACT FROM AUTHOR]

This study consists of a novel strategy for the identification of potential cancer exclusively expressed genes, which might lead to the development of valuable diagnostic molecular markers. Normal- and cancerpaired tissues from the same patient were collected and subjected to the construction of primary complementary deoxyribonucleic acid (cDNA) libraries. The cancer cDNA library was generated by subtracting normal cDNAs from the primary cancer library. The remaining clones in the subtracted cancer library were sequenced and Basic Local Alignment Search Tool (BLAST)-analyzed against current nonredundant and esthuman databases in the GenBank. The clones that had no matches with any known gene sequences except the human genomic sequences were identified as ideal candidates for potential molecular marker development. The candidate marker sequence and associated primer sequences were identified on the target clone sequence of the region with the least, or no, matched homologs. The specificity of the markers was measured by a polymerase chain reaction test experiment with the DNA templates from different human normal tissues, genomic DNA, and additional patients’ tissues. Results from bioinformatical and experimental approaches used suggest that the methodology has a high potential to identify cancer exclusive transcripts. Thus, it might result in the development of diagnostic markers. [ABSTRACT FROM AUTHOR]

Primitive hematopoietic progenitor cells such as severe combined immunodeficiency-repopulating cells and long-term culture-initiating cells are enriched in CD34+CD38- cells derived from various stem cell sources. In this study, to elucidate the features of such primitive cells at the molecular level, we tried to isolate genes that were preferentially expressed in umbilical cord blood (CB)-derived CD34+CD38- cells by subtractive hybridization. The gene for VPAC1 receptor, a receptor for the neuropeptide vasoactive intestinal peptide (VIP), was thereby isolated and it was shown that this gene was expressed in both CD34+CD38- and CD34+CD38+ CB cells and that the expression levels were higher in CD34+CD38- CB cells. Next, we assessed the effects of VIP on the proliferation of CD34+ CB cells using in vitro culture systems. In serum-free single-cell suspension culture, VIP enhanced clonal growth of CD34+ CB cells in synergy with FLT3 ligand (FL), stem cell factor (SCF), and thrombopoietin (TPO). In serum-free clonogenic assays, VIP promoted myeloid (colony-forming unit-granulocyte/macrophage (CFU-GM)) and mixed (CFU-Mix) colony formations. Furthermore, in Dexter-type long-term cultures, VIP increased colony-forming cells at week 5 of culture. These results suggest that VIP functions as a growth-promoting factor of CB-derived hematopoetic progenitor cells. [ABSTRACT FROM AUTHOR]

The first generation of digital subtraction MR angiography using thick-slab contrast-enhanced 2D projection techniques has confirmed the potential of MRI to produce noninvasive subsecond angiograms of the craniocervical circulation. As time-resolved techniques become more sophisticated and 3D acquisitions can be obtained with high isotropic spatial resolution we may start to see the demise of catheter angiography as a diagnostic procedure. [ABSTRACT FROM AUTHOR]

We report new subtraction algorithms for the detection of lesions in dynamic contrast-enhanced MR mammography(CE MRM). Twenty-five patients with suspicious breast lesions underwent dynamic CE MRM using 3D fast low-angle shot. After the acquisition of the T1-weighted scout images, dynamic images were acquired six times after the bolus injection of contrast media. Serial subtractions, step-by-step subtractions, and reverse subtractions, were performed. Two radiologists attempted to differentiate benign from malignant lesion in consensus. The sensitivity, specificity, and accuracy of the method leading to the differentiation of malignant tumor from benign lesions were 85.7, 100, and 96%, respectively. Subtraction images allowed for better visualization of the enhancement as well as its temporal pattern than visual inspection of dynamic images alone. Our findings suggest that the new subtraction algorithm is adequate for screening malignant breast lesions and can potentially replace the time-intensity profile analysis on user-selected regions of interest. [ABSTRACT FROM AUTHOR]

The aim of our study was to test the possibility of using image subtraction in detecting enhancing lesions in brain MR scans with and without magnetization transfer (MT) in multiple sclerosis (MS). Ten MS patients underwent 1.5-T MR imaging of the brain with spin-echo T1-weighted sequences with and without MT, repeated after 0.1 mmol/kg of an usual two-compartment paramagnetic contrast agent (Gadoteridol, Gd-HP-DO3A). Precontrast images were subtracted from postcontrast. Enhancing lesions were counted on the postcontrast images only (post-Gd), comparing pre- and postcontrast images by direct visual control (pre/post-Gd), and on the subtracted images (SI) only. Without MT, 36 enhancing lesions were counted on post-Gd, 36 on pre/post-Gd, and 59 on SI; using MT, 69, 52, and 50, respectively. Significant differences were found for pre/post-Gd without MT vs SI without MT ( p=0.028) and vs pre/post-Gd with MT ( p=0.012) as well as for pre/post-Gd with MT vs post-Gd with MT ( p=0.028). With pre/post-Gd, MT allowed the detection of 1.6 enhancing lesions per patient more than without MT. Whereas the SI without MT allow the detection of an increased number of enhancing lesions, SI with MT do not. An off-site final assessment allowed calculation of sensitivity and positive predictive value as follows: without MT were 63 and 94% (post-Gd), 67 and 100% (pre/post-Gd), 96 and 88% (SI); and with MT were 93 and 73% (post-Gd), 96 and 100% (pre/post-Gd), 91 and 98% (SI), respectively. Thus, SI seem to increase the sensitivity without MT; moreover, they could be used to correct the pseudoenhancement that impair post-Gd images with MT. [ABSTRACT FROM AUTHOR]

The present paper describes the success, the methods (mental, informal written, standard algorithm) and the strategies of informal written arithmetic to be observed when 300 elementary students worked on six addition and six subtraction problems with three-digit numbers. These twelve problems were administered repeatedly by means of a class test: in February (grade 3; nine-year-olds) before the standard algorithms were introduced, in June after they had been dealt with and in October at the beginning of grade 4. [ABSTRACT FROM AUTHOR]

We attempted to identify the genes involved in cellularsenescence, telomere maintenance and telomerase regulationthrough subtractive screening of cDNA libraries prepared froma human lung adenocarcinoma cell line A549 and its sublinesnamed A5DC7, CK and AST-9. Cell phenotypes of A5DC7, CK andAST-9 are normal cell-like, cancer cell-like and intermediate,respectively. These cell lines have different phenotypes interms of telomerase activity and telomere maintenance, andthus are thought to be useful for identifying the genesinvolved in cellular senescence and telomerase regulation. In this study, we identified 86 independent cDNA clones bysubtractive screening. Among these cDNA clones, subtractingA5DC7 cDNAs from A549 cDNAs and CK cDNAs gave 7 and 3 cDNAclones which highly and specifically expressed in tester celllines. Genes corresponding to these 10 cDNA clones mightparticipate in maintaining cancer-cell phenotypes. As aresult of database searching, each four of A549 specific cDNAclones are found to correspond to known cDNAs. Each two ofA549 specific and two of CK specific cDNA clones have highhomology to independent ESTs. Sequences having homology toeach one of A549 specific and one of CK specific cDNA cloneshave not been deposited in the Genbank database, indicatingthat these two cDNA clones are part of novel genes. Weanticipate that their involvement in telomerase regulationand/or senescence program can be clarified by functionalanalysis using each full-length cDNA. [ABSTRACT FROM AUTHOR]

We applied an improved representational difference analysis (RDA), efficiency-monitored RDA (EM-RDA), to analyze the genetic alterations of scirrhous gastric cancer. Clinical samples of this cancer are difficult to analyze genetically because of the large number of normal cells in the stroma. The entire 3rd difference product obtained from EM-RDA was subcloned. This is equivalent to the scirrhous gastric cancer DNA with the normal gastric tissue DNA subtracted from it. The difference clones, which were confirmed by Southern blot as being derived from the cancer, were sequenced. As a result, two difference clones were identified as DNA fragments of the Epstein-Barr virus (EBV). The existence of EBV in the scirrhous gastric cancer cells was proved by EBV-encoded small RNA 1 in situ hybridization. EM-RDA made it possible to detect the first case of EBV-related gastric cancer in a young woman. Copyright © 2000 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In this article, we develop a novel subtraction method using carbodiimide-bound microplates. This method utilizes the high affinity of carbodiimides for both single- and double-stranded nucleic acids. Carbodiimide-mediated end-attachment of driver RNA to microplates allows semisolid phase hybridization between driver RNA and target cDNA, and ensures easy removal of RNA/cDNA hybrids composed of the genes commonly expressed in driver and target. As a result, the target-specific genes are left unhybridized and enriched in the hybridization supernatant. We define the optimal conditions for the method as a target/driver RNA ratio of 1:10 and a period of hybridization of 24 h. There are at least three major advantages with the present method: (1) The entire procedure, which consists of two steps, is very simple; (2) hybridization efficiency can be monitored before further processing of the samples; and (3) rare transcripts can be effectively enriched. This method may be a powerful tool to isolate the genes specifically expressed in particular cell or tissue types, and is easily applicable to many studies in molecular biology and genetics. Isolation of polyploid megakaryocyte-specific genes is shown as an example. [ABSTRACT FROM AUTHOR]