Multiple Paired Samples Research Articles

The use of slice encoding for metal artifact correction (SEMAC) sequencing improves the diagnostic evaluation of graft integrity following anterior cruciate ligament reconstruction

ObjectivesTo determine whether magnetic resonance imaging (MRI) with metal artifact reduction sequencing is superior to conventional knee MRI in the evaluation of an injured anterior cruciate ligament (ACL) graft, where visualisation on conventional MRI can be limited by the metal artifact from fixation devices. MethodsEighteen patients underwent conventional MRI sequence (proton density fat saturated [PDFS]) and two types of metal artifact reduction sequencing MRI (WARP, slice encoding for metal artifact correction (SEMAC); Siemens) following a secondary injury to their ACL reconstructed knee. Six raters with experience in knee MRI evaluation reviewed sagittal PDFS, WARP, and SEMAC sequences, providing semi-quantitative grades for visualisation and diagnostic confidence assessing the ACL, posterior cruciate ligament , menisci, tibial and femoral tunnel margins, and articular cartilage. Intra-class correlation coefficients for inter-rater reliability were evaluated. The 6-rater mean scores for the visualisation and diagnostic confidence derived from each sequence were compared using the Friedman test for multiple paired samples. ResultsNo statistically significant difference in the ACL visualisation among the sequences was found (p ​= ​0.193). Further, a subgroup analysis was performed in cases evaluated as “moderately blurry” or “indistinct ACL visualisation” on PDFS (58% of cases). SEMAC significantly improved diagnostic confidence in ACL visualisation (p ​= ​0.041) and ACL graft rupture (p ​= ​0.044) compared to PDFS.There was no statistically significant difference in the inter-observer reliability between sequences. The WARP sequence added 2.84 ​± ​0.69 ​min, while SEMAC added 2.95 ​± ​0.40 ​min to the standard knee MRI scan time. Conclusionuse of the SEMAC metal reduction sequence significantly improved diagnostic accuracy and confidence in the detection of ACL graft rupture in cases where the ACL was moderately blurry or indistinct on the PDFS sequence. This sequence should be considered as an adjunct to conventional PDFS in cases where graft visualisation is limited by the metal artifact from fixation devices. Level of evidenceIII.

The feasibility of non-contrast-enhanced zero echo time magnetic resonance angiography for characterization of intracranial atherosclerotic disease.

Accurate and non-invasive assessment of intracranial atherosclerotic disease (ICAD) is important because of its effect on treatment planning. The aim of this study is to investigate if zero echo time (zTE) magnetic resonance angiography (zTE-MRA) is feasible in the characterization of ICAD. A total of 175 patients with ICAD were recruited. ZTE-MRA and time-of-flight (TOF)-MRA sequences were conducted for all participants using a 3T clinical MR system. Forty-one patients also underwent digital subtraction angiography (DSA), and were confirmed to have intracranial arterial stenosis (ICAS). Weighted kappa (κ) statistics were used to assess the inter-observer agreement and diagnostic consistency of both zTE- and TOF-MRA, using DSA as a reference. The Wilcoxon signed-rank test was used to evaluate differences in image quality between zTE- and TOF-MRA images. The nonparametric test of multiple paired samples was used to compare the results of vascular stenosis diagnosis between zTE-, TOF-MRA and DSA. Supported by high inter-observer agreement (weighted κ=0.78), zTE-MRA generated significantly higher scores than TOF-MRA for susceptibility artifact signal (mean: 3.03±0.98 vs. 2.72±1.09; P=0.017) and flow signal in parent artery (mean: 3.63±0.49 vs. 3.07±0.82; P<0.001). Additionally, zTE-MRA showed more robust diagnostic performance than TOF-MRA for patients with ICAD and degree of vascular stenosis (P<0.05), and was highly consistent with reference DSA images (weighted κ=0.80). ZTE-MRA has potential for use as a routine clinical method for patients with ICAD.

Quantitative assessment of condyle positional changes before and after orthognathic surgery based on fused 3D images from cone beam computed tomography.

To establish one method that can be used to quantitatively evaluate the condyle positional changes with 3D images in postoperative mandibular prognathism patients. This is a retrospective observational study. Twenty-one patients who underwent bilateral sagittal split ramus osteotomy (BSSRO) were scanned with cone beam computed tomography (CBCT) for temporomandibular joints (TMJs) at 1 week preoperatively (T0), 1 to 2 weeks (T1), 3 months (T2), 6 months (T3), and 12 months (T4) postoperatively. The data were then grouped into T0T1, T1T2, T2T3, T3T4 and T0T1, T0T2, T0T3, and T0T4. Semi-automatic registration was conducted, and the condyle positional changes were measured in segmented 3D models. Inter- and intra-observer variability and the repeatability of registration were analyzed with paired t test; the repeated measurement analysis of variance was used for analyzing the repeatability of the marked points; the consistency of segmentation was analyzed with nonparametric test of multiple paired samples (Friedman test) and the independent-sample t test was applied to comparing changes between different periods of time. Differences were considered to be statistically significant when P < 0.05. In T0T1 and T1T2, the condylar position was changed greatly. In T2T3, the mean condylar translations were less than 0.2 mm in all directions, the mean rotational changes of condyle were less than 0.2 mm; in the period of T3T4, the mean condylar translations in all directions were less than 0.02 mm. For series 2, the condyle translational changes in axial, coronal, and sagittal views were within 0.10 mm, and the rotation direction of condyle in all three views was the same within 1 year after operation. Fused three-dimensional images can be used to qualitatively and quantitatively evaluate condyle positional changes. The condylar position might be stable at 3 months postoperatively. The condyles of most of patients did not fully return to their preoperative position within 1 year after the operation. One method for fusing images has been established to detect the condylar positional changes. This method may be applied to estimate the bony changes of condyle, even bony changes in other part of dentomaxillofacial region. Meanwhile, the data of condyle positional changes from asymptomatic patients after the surgery within 1 year can be used as a reference for further exploration of the relationship between orthognathic surgery and the occurrence of osteoarthritis postoperatively in the future. • By fused 3D images, the change of condylar position after bilateral sagittal split ramus osteotomy can be observed intuitively. • For the patients with mandibular prognathism, the condylar position would be stable at 3 months postoperatively. • The condyles of most mandibular prognathism patients did not fully return to their preoperative position within 1 year after operation.

Correlation and temporal variability of urinary biomarkers of chemicals among couples: Implications for reproductive epidemiological studies

BackgroundExposure to some environmental chemicals is ubiquitous and linked to a variety of adverse outcomes, including children's health. While few studies have assessed the contribution of both male and female exposures to children's health, understanding the patterns of couple's exposure is needed to understand their joint effects. ObjectiveWe assessed the correlation patterns between male and female partners' concentrations of 37 environmental chemical biomarkers. We also assessed the temporal reliability of the biomarkers within couples. MethodsWe calculated Spearman pairwise correlations between specific gravity adjusted urinary biomarker concentrations and hair mercury concentrations among 380 couples enrolled in the Environment and Reproductive Health (EARTH) study at the Massachusetts General Hospital Fertility Center (2004–2017). We calculated intra-class correlation coefficients (ICCs) for couple's biomarkers to assess the temporal variability of these exposures within a couple using multiple paired-samples from couples. ResultsAll biomarkers were positively correlated within couples (range: 0.05 for tert-butylphenyl phenyl phosphate to 0.66 for triclosan). In general, the biomarkers with the highest within couple correlation were those of chemicals for which diet (e.g., di(2-ethylhexyl) phthalate), personal care products use (e.g., triclosan, benzophenone-3), and the indoor environment (e.g., 2,5-dichlorophenol) are considered primary exposure sources. Most other biomarkers were moderately correlated (0.3–<0.6). Similar patterns of temporal reliability were observed across biomarkers. ConclusionsUrinary concentrations of several biomarkers were mostly moderately correlated within couples, suggesting similar exposure sources. Future epidemiological studies should collect samples from both partners to be able to accurately determine the contribution of maternal and paternal exposures to offspring health.

A Marine Reservoir Effect ∆R Value for Kitandach, in Prince Rupert Harbour, British Columbia, Canada

AbstractPrince Rupert Harbour (PRH), on the north Pacific Coast of British Columbia, contains at least 157 shell middens, of which 66 are known villages, in an area of approximately 180 km2. These sites span the last 9500 yr and in some cases are immense, exceeding 20,000 m2 surface area and several meters in depth. Recent archaeological research in PRH has become increasingly reliant on radiocarbon dates from marine shell for developing chronologies. However, this is problematic as the local marine reservoir effect (MRE) remains poorly understood in the region. To account for the MRE and to better date the Harbour’s sites, we propose a ΔR of 273±38 for the PRH area, based on our work at the site of Kitandach (GbTo-34), a massive shell midden-village centrally located within the Harbour. We followed the multiple paired sample approach for samples from specific contexts and ensured contemporaneity within the groups of marine and terrestrial materials by statistically assessing for outliers using the χ2 test. Taking together, the results for this and previous studies, it appears the MRE was fairly constant over the past 5000 yr.

Intrahepatic natural killer cell NKp46 expression drives HCV-associated liver inflammation and viral resistance to treatment with interferon alpha

BackgroundThere is evidence that natural killer (NK) cells help control persistent viral infections including hepatitis C virus (HCV). HCV infection is treated with interferon (IFN) alpha, which stimulates the immune system, and is successful in 40–80% of patients. Detailed comparison of the phenotype and function of blood and intrahepatic NK cells in chronic HCV infection and in response to treatment with IFN alpha has not been elucidated. MethodsWe performed a comparison of NK cells derived from blood and intrahepatic compartments in multiple paired samples from 24 HCV infected patients pretreatment and 22 patients with non-viral chronic liver disease (CLD). NK phenotype (CD16, NKp30, NKp46, NKG2D, and NKG2A) and functional profile (CD107a, IFNγ, and granzyme B) were assessed with flow cytometry. In a separate cohort of 17 patients with HCV, who had completed treatment, rate of viral clearance was calculated and pretreatment peripheral blood NK phenotype and CD107a expression (degranulation) in response to increasing stimulation was measured. FindingsNK cells in the liver demonstrate a distinct phenotype compared with blood, manifested as downregulation of the NK cell activation receptors CD16, NKG2D, and NKp30. By contrast, NKp46 expression was not downregulated. Intrahepatic NK cells appeared to be more activated with increased spontaneous degranulation (reduced granzyme B, p<0·001 and increased CD107a, p=0·006) and production of IFNγ (p=0·05). NKp46 expression correlated with NK-cell activation, and correlated closely with the severity of liver inflammation (p=0·035). The rate of viral clearance during treatment with IFN alpha inversely correlated with NKp46 expression at baseline (p=0·01). However, the ability to increase cytotoxic NK function in response to increasing stimulation ex vivo correlated with viral clearance (p=0·029) and inversely with NKp46 (p=0·005). InterpretationThese findings indicate that NKp46 marks out pathologically activated NK cells in HCV, which are unlikely to be involved in viral control in IFN alpha-treated individuals. FundingWelsh Assembly.

Examining the Inherent Variability in ΔR: New Methods of Presenting ΔR Values and Implications for MRE Studies

Currently, there is significant ongoing research into the temporal and spatial variability of marine radiocarbon reservoir effects (MREs) through quantification of ΔR values. In turn, MRE studies often use large changes in ΔR values as proxies for changes in ocean circulation. ΔR values are published in a variety of formats with variations in how the errors on these values are calculated, making it difficult to identify trends or to compare values, unless the method of calculating the ΔR is explicitly described or all of the data are made available in the publication. This paper demonstrates the large range in ΔR values (+34 to −122) that can be obtained from a single, secure archaeological context when using the multiple paired sample approach, despite the fact that the terrestrial entities were of statistically indistinguishable 14C ages, as were the marine samples. This demonstrates the inherent variability in the ΔR calculations themselves and we propose that, together with calculation of mean ΔR, the distribution of ΔR values should be displayed, e.g. as histograms in order to illustrate the full data range. This spread is only apparent when employing a multiple paired sample approach as the uncertainty derived on a single pair of samples, taking account only of the errors on the individual 14C ages, will never truly represent the overall variability in ΔR that results from the intrinsic variability in the population of 14C ages in samples that might have been used. Consequently, ΔR values and the associated uncertainty calculated from single pairs should be treated with some caution. We propose that, where possible, when using paired archaeological samples, that a multiple paired approach should be employed as it will test the context security of the material used in the ΔR calculations. When summarizing the values by the weighted average, we also propose that the standard error for predicted values should be employed as this will fully encompass the uncertainty of a future ΔR calculation, using different samples for a similar time and location. Finally, we encourage future publishing of ΔR values using the histogram format, making all of the data available. This will help ensure that ΔR values are comparable across the literature and should provide a framework for standardization of publication methods.

Species specific marine radiocarbon reservoir effect: a comparison of ΔR values between Patella vulgata (limpet) shell carbonate and Gadus morhua (Atlantic cod) bone collagen

A number of recent studies of the UK coastal environment have assessed the 14C marine radiocarbon reservoir effect (MRE) via quantification of ΔR values for several periods throughout the Holocene using marine mollusc shells. However, none have employed fish bone as the marine sample, and the importance of being able to use this material as a reliable dating tool is evident when considering the boom in the British fish trade during the first millennium AD, the so-called ‘fish event horizon’, and the corresponding volume of fish remains that appear in the archaeological record from this time. This study compares ΔR values derived using the multiple paired sample approach employing burnt cereal grain ( Hordeum sp.) as the terrestrial sample and either fish bone [North Sea cod ( Gadus morhua)] or marine shell [limpet ( Patella vulgata)] as the marine sample. The results show a general trend of increasing ΔR for the fish bone compared to shell, however, the differences are not statistically significant when the standard error for predicted values is used as the measure of variability in the ΔR values.

North Atlantic marine 14C reservoir effects: Implications for late-Holocene chronological studies

We investigated surface ocean–atmosphere 14C offsets for the later Holocene at eight locations in the eastern North Atlantic. This resulted in 11 new Δ R assessments for the west coast of Ireland, the Outer Hebrides, the north coast of the Scottish mainland, the Orkney Isles and the Shetland Isles over the period 1300–500 BP. Assessments were made using a robust Multiple Paired Sample (MPS) approach, which is designed to maximize the accuracy of Δ R determinations. Assessments are placed in context with other available data to enable reconstruction of a realistic picture of surface ocean 14C activity over the Holocene period within the North Atlantic region.

Outcome prediction to cetuximab in advanced colorectal cancer: Analysis of EGFR and HER2 gene copy number by fluorescence in situ hybridization

10569 Background: Recent studies suggest that increased epidermal growth factor receptor (EGFR) gene copy number assessed by in situ hybridization predicts response to cetuximab in patients (pts) with advanced colorectal cancer (mCRC). Additionally, preclinical data indicate that HER2, a member of the EGFR family, can modulate the efficacy of anti-EGFR monoclonal antibodies. Methods: We assessed EGFR and HER2 gene copies by fluorescent in situ hybridization (FISH) on paraffin-embedded samples from 70 pts with mCRC treated with cetuximab alone or with irinotecan. FISH was assessed either on primary tumors (55 pts) or on metastases (15 pts) according to two parameters: the absolute copy number of genes and chromosome (chr) centromeres, and their frequencies in 100 tumor cells. A sensitivity analysis was performed and fitted to outcome data in an attempt to define relevant cutoffs. EGFR protein expression by immunohistochemistry was deemed positive with =10% tumor cells being stained. Multiple paired samples originating from different tumor sources were analyzed whenever available (27 pts). Results: The overall response rate was 25%. Prevalent FISH patterns were disomy (8%) and balanced polysomy (90%) for EGFR gene and chr 7. EGFR amplification was seen in two pts (2%), of which only one responded. HER2 amplification was seen in two of 54 pts (3%), both experiencing stable disease. Average EGFR copies and frequency of tumor cells with &gt;2 copies respectively ranged from 1.6 to 4.0 and from 10% to 90%, thus reflecting a substantial tumor heterogeneity. Despite assessing multiple centile cutoffs of gene copy numbers and their frequencies in tumor cells, we found no association between EGFR and HER2 copy numbers and objective response, time to progression, and overall survival. Analysis of paired samples did not improve the predictive value of EGFR copies by FISH. Excluding EGFR amplification, associated to a strong (3+) EGFR staining, we found no correlation between EGFR copy number and protein expression. Conclusions: Neither EGFR nor HER2 copies by FISH, nor EGFR expression, are predictors of outcome in mCRC pts treated with cetuximab. FISH might still play a role in screening EGFR and HER2 amplification, but cost-effectiveness is debatable. [Table: see text]

Reservoirs and Radiocarbon:14C Dating Problems in Mývatnssveit, Northern Iceland

This paper examines 2 potential sources of the radiocarbon offset between human and terrestrial mammal (horse) bones recovered from Norse (∼AD 870–1000) pagan graves in Mývatnssveit, north Iceland. These are the marine and freshwater14C reservoir effects that may be incorporated into human bones from dietary sources. The size of the marine14C reservoir effect (MRE) during the Norse period was investigated by measurement of multiple paired samples (terrestrial mammal and marine mollusk shell) at 2 archaeological sites in Mývatnssveit and 1 site on the north Icelandic coast. These produced 3 new δR values for the north coast of Iceland, indicating a δR of 106 ± 1014C yr at AD 868–985, and of 144 ± 2814C yr at AD 1280–1400. These values are statistically comparable and give an overall weighted mean δR of 111 ± 1014C yr.The freshwater reservoir effect was similarly quantified using freshwater fish bones from a site in Mývatnssveit. These show an offset of between 1285 and 183014C yr, where the fish are depleted in14C relative to the terrestrial mammals. This is attributed to the input of geothermally derived CO2into the groundwater and subsequently into Lake Mývatn. We conclude the following: i) some of the Norse inhabitants of Mývatnssveit incorporated non-terrestrial resources into their diet that may be identified from the stable isotope composition of their bone collagen; ii) the MRE off the north Icelandic coast during the Norse period fits a spatial gradient of wider North Atlantic MRE values with increasing values to the northwest; and iii) it is important to consider the effect that geothermal activity could have on the14C activity of samples influenced by groundwater at Icelandic archaeological sites.

Characterizing the Hematologic and Plasma Chemistry Profiles of Captive Chinese Water Dragons, Physignathus cocincinus

Twenty-six (one to six years of age) Chinese water dragons, Physignathus cocincinus, from two different captive populations, Massachusetts (MA) and Mississippi (MS), were selected for this study. The lizards were given a thorough examination, and a blood sample was collected for a complete blood count (CBC) and plasma biochemistry. Whole blood was stored in both lithium heparin and Ca- EDTA; Ca-EDTA was considered the superior anticoagulant based on multiple paired samples. The packed cell volume (PCV) for the water dragons was 32 - 40%. The lymphocyte was the most common cell found on the CBC. There were significant differences in the plasma uric acid (MS: 2.3; MA 6.0; p=0.001) and phosphorus (MS: 5.7, MA:7.1; p=0.04) concentrations between the two populations. Younger dragons ( 3 yr: 2.3, p=0.01) than dragons > 3 yr of age. There were no significant differences in the bio- chemistries based on the origin (wild-caught vs. captive bred) of the lizards or between genders. Overall, the dragons in this study were clinically healthy, and the reference range established from these two pop- ulations may be used as a basis for comparison in clinical cases.

The oxygen saturation of blood in the venae cavae, right-heart chambers, and pulmonary vessels of healthy subjects.

Abstract Twenty-six healthy ambulatory subjects with cardiovascular respiratory systems normal in all clinical and laboratory aspects were investigated by cardiac catheterization. Multiple determinations of blood oxygen saturations were made in rapid succession by cuvette oximeter at various sites in the right side of the heart. With the subject breathing air, the mean and range of the percentage oxygen saturation of radial arterial blood equalled 97.3 (95 to 99) per cent and of the venous blood withdrawn from the inferior vena cava, superior vena cava, right atrium, right ventricle, and pulmonary artery, 83.0 (76 to 88) per cent, 76.8 (66 to 84) per cent, 79.5 (72 to 86) per cent, 78.5 (64 to 84) per cent, and 78.4 (73 to 85) per cent, respectively, while that from the pulmonary artery wedge position equalled 98.2 (90 to 100) per cent. The factors responsible for the variation in the oxygen saturation of venous blood were analyzed and methods suggested for reducing this variation. The mean of the average differences in oxygen saturation between multiple paired samples of blood withdrawn in rapid succession from the right atrium and inferior vena cava, right atrium and superior vena cava, right atrium and lower part of the right ventricle, and upper part of the right ventricle and pulmonary artery equaled −2.2, + 3.2, + 0.1, and + 0.1 per cent, respectively. With this method there is a 95 per cent likelihood that an abnormal source of arterialized blood (left-to-right shunt) is present within the right atrium when saturation of blood from it uniformly exceeds that in the inferior vena cava by more than 4 per cent, that in the superior vena cava by more than 8 per cent, or an average of the inferior and superior caval samples by more than 3 per cent. In the absence of an atrial septal defect, arterialization in the right ventricle at the 95 per cent likelihood level can be considered to be demonstrated when its saturation exceeds that in the right atrium by more than 3 per cent and, in the absence of a ventricular septal defect, arterialization in the pulmonary artery is indicated when oxygen saturation of blood from it exceeds that from high in the right ventricle by more than 2 per cent. Comparison of the average oxygen saturation of blood withdrawn from all positions within the right ventricle with those obtained from the right atrium and pulmonary artery was suggestive of a slight but significant reduction in the oxygen saturation of the venous blood during its passage through the ventricle. Streamline flow of blood from the coronary sinus and thebesian veins draining into the right ventricle was considered a likely explanation of this finding, although transient increases in cardiac output engendered by anxiety consequent to ectopic beats during manipulation of the catheter may be involved. Variations in the oxygen saturation of multiple samples of mixed venous blood from the pulmonary artery from the same individual were consistent with the interpretation that the average maximal intra-individual variation in cardiac output, in these healthy subjects under conditions of supine rest, was ±17 per cent.