Limitations In Terms Of Reproducibility Research Articles

Imaging Evaluation of Intervertebral Disc Degeneration and Painful Discs-Advances and Challenges in Quantitative MRI.

In recent years, various quantitative and functional magnetic resonance imaging (MRI) sequences have been developed and used in clinical practice for the diagnosis of patients with low back pain (LBP). Until now, T2-weighted imaging (T2WI), a visual qualitative evaluation method, has been used to diagnose intervertebral disc (IVD) degeneration. However, this method has limitations in terms of reproducibility and inter-observer agreement. Moreover, T2WI observations do not directly relate with LBP. Therefore, new sequences such as T2 mapping, T1ρ mapping, and MR spectroscopy have been developed as alternative quantitative evaluation methods. These new quantitative MRIs can evaluate the anatomical and physiological changes of IVD degeneration in more detail than conventional T2WI. However, the values obtained from these quantitative MRIs still do not directly correlate with LBP, and there is a need for more widespread use of techniques that are more specific to clinical symptoms such as pain. In this paper, we review the state-of-the-art methodologies and future challenges of quantitative MRI as an imaging diagnostic tool for IVD degeneration and painful discs.

Optimization of extrusion process for 3D hard candy manufacture

In the domain of 3D food printing, previously developed 3D candy printers focused majorly on soft candy materials, such as chocolate, gum, and jelly. These techniques also presented limitations in terms of reproducibility and model diversity. Accordingly, this study aimed to address these problems via investigation of the behavior of sugar, a printing material, with respect to the extrusion process of 3D hard candy manufacture and analysis of the reproducibility. Moreover, the relationship among the nozzle movement speed, extrusion speed, and pattern spacing was analyzed to derive the optimal conditions for the extrusion process for reproducing a 3D virtual model. It was observed that the pattern spacing was optimized at 0.9 mm, considering a stable manufacturing process and manufacturing speed. The optimized parameter values of nozzle diameter, nozzle-substrate distance, pneumatic pressure, control temperature, printing speed, and standoff distance were computed through a correlation analysis conducted with pattern spacing. Under these conditions, moldings with a total height of 6 cm could be built. Moreover, a considerably high reproducibility of the 3D model was achieved on consideration of changes in the pattern thickness according to the nozzle movement speed and extrusion speed. Overall, this study contributes to literature and bridges a gap therein by presenting a process technology for guaranteeing the reproducibility of 3D models. It also demonstrates that the production of personalized custom shapes will be effective and feasible in the future.

Multijoint Musculoarticular Stiffness Derived From a Perturbation Is Highly Variable.

Schofield, M, Tinwala, F, Cronin, J, Hébert-Losier, K, and Uthoff, A. Multijoint musculoarticular stiffness derived from a perturbation is highly variable. J Strength Cond Res 35(9): 2498-2503, 2021-Testing musculoarticular stiffness may provide insights into multijoint elastic properties. Yet, most research has focused on quantifying stiffness, or elastic potential, at a single joint. The purpose of this study was to quantify the test-retest reliability of musculoarticular stiffness derived from the perturbation technique across the bench pull, bench press, and squat movements. Eight resistance-trained men performed bench pull, bench press, and squat repetition maximums, after which a perturbation protocol was tested over multiple days. During the 3 movements, a brief perturbation was applied to the bar. The resulting sinusoidal wave was measured by an underbench force plate and a linear position transducer attached to the bar. From the sinusoidal wave, stiffness was derived and found to be unreliable across movements and days (change in mean: -35.1 to 15.8%; coefficient of variation: 7.1-111%; intraclass correlation: -0.58 to -0.89). Squat data were removed from the analysis entirely because of the inability to consistently determine the perturbations on the force plate. Practitioners need to be aware that musculoarticular stiffness as measured using the perturbation technique on the movements performed in this study has considerable limitations in terms of reproducibility.

46 MRI and intracerebral iron quantification: Methodological development of R2∗ relaxometry and magnetic susceptibility imaging

Introduction The intracerebral iron quantification in MRI is of great clinical interest for aging and neurodegeneration studies. Currently, the most widely used techniques are R2∗ relaxometry and QSM. Despite their limitations in terms of reproducibility [1] , they are the most adapted to clinical constraints. The work mainly focused on the most robust technique, R2∗ relaxometry, and its optimization and evaluation for the specific iron quantification task. Methods The physiological aging model was used in two structures of interest (putamen and thalamus) as a modification source. A brain MRI (Intera Achieva 3 Tesla, Philips) was acquired for 39 young subjects (29 ± 6 years old) and 38 elderly subjects (68 ± 6 years old). For each subject, gradient echoes (3D FFE EPI) were acquired with 6 different echo times (TE): 6, 12, 20, 30, 45 et 60 ms. R2∗ maps using the 6 TEs (R2∗s) then the first 3 (R2∗p) and finally the last 3 (R2∗t) were made by mono-exponential non-linear voxel-to-voxel regression. Results For the thalamus, all subjects combined, R2∗p and R2∗t were significantly different from R2∗s. This invalidates the hypothesis of a strictly mono-exponential decay signal. Between young and elderly subjects, a significant difference was found for R2∗s (p = 0.025) and R2∗p (p = 0.001) but none for R2∗t (p = 0.38). The taking into account of the first TEs increases the interindividual heterogeneity while the R2∗t present a small variance between the subjects. The same results were found for the putamen. The use of late TEs increases the magnetic susceptibility artefacts in areas near interfaces (such as sinuses). This artifact common to all subjects standardizes the different groups. More pronounced differences between groups are observed using R2∗p. In this case, the use of short TEs did not allow the signal sensitization to a specific quantity but the eviction of standardization due to the artifact. In areas distant from the artifact, short TEs sensitize R2∗ to fast signal components such as myelin-bound water. Conclusions Although the mono-exponential decay model assumes that R2∗ is an absolute quantity, this is not really the case for a voxel. Therefore, it is not necessary to try to make R2∗ a reproducible quantity. The research for reproducibility can be done at the expense of sensitivity. On the contrary, a relaxometry adapted to the quantity measured or to the studied zone should be considered by playing among other things on the TEs selections.

Geographical variation in clinical signs and prevalence of Leishmania sp. infection among dogs in Fortaleza, Ceará State, Brazil

Background: Leishmaniosis are anthropozoonosis caused by protozoa of the genus Leishmania, representing a complex of diseases with significant diversity epidemiological and clinical spectrum and can affect 40% of the canine population. Infected dogs may be asymptomatic or may develop canine leishmaniasis (CL), a severe and progressive disease associated with the appearance of clinical signs. Serological tests are frequently used for screening of dogs, however, these techniques present limitations in terms of reproducibility and specificity. In this way, information on the geographical distribution and prevalence of CL is essential to the implementation of appropriate control measures. Therefore, the aim of this study was to determine geographical variations in clinical signs and prevalence of Leishmania sp. infections from dogs in Fortaleza, Ceara state, Brazil. Materials, Methods & Results: Bone marrow samples of 2829 domestic dogs were collected by puncture for parasitological diagnosis of canine leishmaniasis (CL), being considered positive by the presence of Leishmania sp. All dogs were examined and clinical signs were classified as score 0: no clinical signs, score 1: skin lesions, score 2: visceral signs and score 3: skin lesions + visceral signs. Kruskal-Wallis (P <0.05) was used to compare the scores and parasitological diagnosis among the seven regions of Fortaleza. So, it was observed that 72% of dogs were positive and the regions I and V had the highest prevalence (78.3% and 80% respectively), no significant differences among the seven regions. Asymptomatic dogs represented 55% of infected dogs, and the main clinical sign, among symptomatic dogs (45%), was skin lesion, visualized in 43% of dogs. Furthermore, 70% of all dogs had ectoparasites. Discussion: These results show that, despite of the campaign against the disease, there is no great progress in the control of visceral leishmaniasis in the urban areas like Fortaleza, which present an easy access in the fight against the disease. The diagnostic in dogs based in the Indirect Fluorescent Antibody Test (IFAT) associated to others factors, like irregular serological inquiry and no-treated performer personal, perhaps made possible the permanence of susceptibility animals in this area, beyond of the high number of asymptomatic and no-identified dogs. In this study, it was observed that 55% of dogs were asymptomatic, without showing evidence of risk of transmission to human population, escaping from controlling methods. From this we can imply that most of these dogs to LC are asymptomatic and the prevalence did not differ significantly in different regions of Fortaleza, requiring equal attention throughout the city. Moreover, our results demonstrate that Fortaleza city has favorable areas for the maintenance of the parasite cycle, with a high risk of transmission to human and canine population, and it requires special attention because of the large number of asymptomatic cases. Therefore, it is necessary to control the population of asymptomatic dogs with more efficient controlling methods, with the change of methodology of serological screening raising the number of detected dogs, reducing the diagnostic time and the use of diagnostic techniques with levels of specificity higher.