Category: Statistics

Phys Med Biol. 2021 Apr 29. doi: 10.1088/1361-6560/abfce2. Online ahead of print.

ABSTRACT

Organ delineation is crucial to diagnosis and therapy, while is also labor-intensive and observer-dependent. Dual energy CT (DECT) provides additional image contrast than conventional single energy CT (SECT), which may facilitate automatic organ segmentation. This work aims to develop an automatic multi-organ segmentation approach using deep learning for head-and-neck region on DECT. We proposed a Mask scoring R-CNN where comprehensive features are firstly learnt from two independent pyramid networks and are then combined via deep attention strategy to highlight the informative ones extracted from DECT. To perform multi-organ segmentation and avoid misclassification, a mask scoring subnetwork was integrated into the Mask R-CNN framework to build the correlation between the class of potential detected organ’s region-of-interest (ROI) and the shape of that organ’s segmentation within that ROI. We evaluated our model on DECT images from 127 head-and-neck cancer patients (66 training, 61 testing) with manual contours of 19 organs as ground truth. For large- and mid-sized organs such as brain and parotid, the proposed method successfully achieved average Dice similarity coefficient (DSC) larger than 0.8. For small-sized organs with very low contrast such as chiasm, cochlea, lens and optic nerves, the DSCs ranged between around 0.5 and 0.8. With the propose method, using DECT images outperforms using SECT in almost all 19 organs with statistical significance in DSC (p<0.05). Meanwhile, by using the DECT, the proposed method is also significantly superior to a recently developed FCN-based method in most of organs in terms of DSC and the 95th percentile Hausdorff distance. Quantitative results demonstrated the feasibility of the proposed method, the superiority of using DECT to SECT, and the advantage of the proposed R-CNN over FCN on the head-and-neck patient study. The proposed method has the potential to facilitate the current head-and-neck cancer radiation therapy workflow in treatment planning.

PMID:33915524 | DOI:10.1088/1361-6560/abfce2

Public Health. 2021 Mar 26;194:149-155. doi: 10.1016/j.puhe.2021.03.011. Online ahead of print.

ABSTRACT

Definition of the incubation period for COVID-19 is critical for implementing quarantine and thus infection control. Whereas the classical definition relies on the time from exposure to time of first symptoms, a more practical working definition is the time from exposure to time of first live virus excretion. For COVID-19, average incubation period times commonly span 5-7 days which are generally longer than for most typical other respiratory viruses. There is considerable variability reported however for the late right-hand statistical distribution. A small but yet epidemiologically important subset of patients may have the late end of the incubation period extend beyond the 14 days that is frequently assumed. Conservative assumptions of the right tail end distribution favor safety, but pragmatic working modifications may be required to accommodate high rates of infection and/or healthcare worker exposures. Despite the advent of effective vaccines, further attention and study in these regards are warranted. It is predictable that vaccine application will be associated with continued confusion over protection and its longevity. Measures for the application of infectivity will continue to be extremely relevant.

PMID:33915459 | DOI:10.1016/j.puhe.2021.03.011

Surg Oncol. 2021 Apr 21;38:101566. doi: 10.1016/j.suronc.2021.101566. Online ahead of print.

ABSTRACT

OBJECTIVE: To evaluate the inter- and intra-rater variability of lymphovascular space invasion (LVSI) in early stage cervical cancer.

METHODS: We identified invasive cervical cancer tissue samples from radical hysterectomies in our institutional pathology database. The cases were stained with Hematoxylin & Eosin (H&E) and immunostains (CD-31 and D2-40). They were evaluated for the presence of LVSI by 6 pathologists on 3 separate occasions: with H&E staining only, then with H&E and immunostained specimens, and finally using a shared written criterion for diagnosis of LVSI. With 80 cases, a two-sided 95% confidence interval for the Kappa of 0.7 with a precision of 0.1 on each side was estimated.

RESULTS: Stage distribution was: IA 10%, IB 85%, and IIA 5%. The majority of cases were squamous cell carcinoma (55%), followed by adenocarcinoma (39%) and adenosquamous or other histology (6%). The mean inter-rater Kappa was 0.41 (95% CI: 0.37-0.45) for H&E. Usage of immunohistochemistry made a statistically significant improvement in the mean Kappa, but it still remained low: 0.52 (p = 0.02). Adding evaluation criteria for LVSI did not significantly increase the mean Kappa: 0.49 (p = 0.16). The mean intra-rater variability of H&E staining alone compared with H&E staining plus immunostaining was 0.53 (range: 0.43-0.64). The mean Kappa comparing H&E staining and H&E staining with criteria was 0.50 (range: 0.40-0.59).

CONCLUSIONS: We noted high inter- and intra-rater variability in the diagnosis of LVSI underscoring the challenges of LVSI diagnosis. Considering the significance assigned to LVSI and its implication for treatment, comprehensive guidelines with regards to determination of LVSI status are of paramount importance.

PMID:33915484 | DOI:10.1016/j.suronc.2021.101566

Eur J Obstet Gynecol Reprod Biol. 2021 Apr 15;261:103-109. doi: 10.1016/j.ejogrb.2021.04.014. Online ahead of print.

ABSTRACT

OBJECTIVE: The association between vitamin D deficiency and devastating preeclampsia is still debated. In this present study, our aim is to evaluate whether a statistically significant association exists between vitamin D deficiency and preeclampsia in Indian gravidas. As to the best of our knowledge, no study of this context with such a large sample size is done in the Indian population till now.

METHOD: A case-control study was performed in the year 2015-2019 where we enrolled 1000 pregnant women with preeclampsia admitted either in labor or for induction of labor in the study group and 1000 pregnant women without preeclampsia either in labor or admitted for induction of labor at term gestation in the control group. Serum 25-hydroxyvitamin D [25 (OH)] D levels of both the groups were measured through the radioimmunoassay method and analyzed. In both the groups, samples were collected equally across all the seasons of the year to avoid confounding by seasonal variation of vitamin D. Primary outcome measures the association of vitamin D deficiency and preeclampsia. While secondary outcome measures the correlation between levels of vitamin D deficiency with the severity of preeclampsia.

RESULT: A significantly low mean vitamin D level was seen in preeclamptic women (11.0 ± 7.1 ng /ml) compared to normotensive (31.4 ± 1.7 ng/ml) with p < .001. We observed approximately 11 fold increased odds of having preeclampsia in vitamin D deficient women (OR: 11.308; 95 % CI 7.5982-14.0097). Moreover, we observed that as vitamin D level decreases, the severity of preeclampsia increases (p < .001).

CONCLUSION: Compared with normotensive women, preeclamptic women had a significantly low level of vitamin D, suggesting a significant association between vitamin D deficiency and preeclampsia.

PMID:33915489 | DOI:10.1016/j.ejogrb.2021.04.014

Sleep Med. 2020 Aug 28;82:134-143. doi: 10.1016/j.sleep.2020.08.026. Online ahead of print.

ABSTRACT

OBJECTIVES: To investigate alterations in neurocognitive, attention, paediatric sleep questionnaire (PSQ) scores and whole brain white matter (WM) integrity between children with mild and severe obstructive sleep apnoea (OSA) according to sex and whether these changes are associated with OSA severity.

METHODS: Fifty-seven children (36 males and 21 females) diagnosed with OSA were recruited for this study. Children of both sexes were divided into mild (male-MG, female-MG) and severe (male-SG, female-SG) groups according to OSA severity. Polysomnography (PSG), neurocognitive, attention and PSQ tests were compared between groups by one-way samples analysis of variance (ANOVA) F test. Diffusion tensor imaging (DTI) was scanned using a 3T GE MRI scanner and analysed by Tract-based Spatial Statistics (TBSS). Spearman correlation was calculated between DTI Eigenvalues and clinical characteristics.

RESULTS: Compared to mild OSA patients, severe OSA patients presented greater severity of obstructive apnoea hypopnea index (OAHI), neurocognition, PSQ and attention tests in both male and female patients. Brain WM integrity in the male-SG, compared to the male-MG, demonstrated significantly reduced fractional anisotropy (FA) values in the right middle frontal gyrus and the right frontal sub-gyral regions and increased axial diffusivity (AD) values in the right inferior frontal gyrus, left parietal angular gyrus and sub-gyral regions, while no differences were found between the female-MG and female-SG. Alterations in male-SG brain regions were observably correlated with severity in male OSA patients.

CONCLUSIONS: The integrity of WM, which regulates autonomic, cognitive, and attention functions, is impaired in male, but not female, children with severe OSA.

PMID:33915429 | DOI:10.1016/j.sleep.2020.08.026

Neural Netw. 2021 Feb 28;140:336-343. doi: 10.1016/j.neunet.2021.01.017. Online ahead of print.

ABSTRACT

A differential-algebraic neural network (DANN) with delay (DDANN) is proposed. Firstly, the global existence and uniqueness theorems are established for a DDANN, respectively. Next, a new differential-algebraic inequality is established. Then, a theorem on global exponential stability of DDANN is shown by using this inequality. As an application of DDANN, a very concise criterion on global exponential stability for a neutral-type neural network is given by using DDANNs. Finally, two examples are given to illustrate the theoretical results.

PMID:33915455 | DOI:10.1016/j.neunet.2021.01.017

Oral Dis. 2021 Apr 29. doi: 10.1111/odi.13892. Online ahead of print.

ABSTRACT

OBJECTIVE: To evaluate the accuracy of MeMoSA^® , a mobile phone application to review images of oral lesions in identifying oral cancers and oral potentially malignant disorders requiring referral.

SUBJECTS AND METHODS: A prospective study of 355 participants, including 280 with oral lesions/variants was conducted. Adults aged ≥18 treated at tertiary referral centres were included. Images of the oral cavity were taken using MeMoSA^® . The identification of the presence of lesion/variant and referral decision made using MeMoSA^® were compared to clinical oral examination, using Kappa statistics for intra-rater agreement. Sensitivity, specificity, concordance and F1 score were computed. Images were reviewed by an off-site specialist and inter-rater agreement was evaluated. Images from sequential clinical visits were compared to evaluate observable changes in the lesions.

RESULTS: Kappa values comparing MeMoSA^® with clinical oral examination in detecting a lesion and referral decision was 0.604 and 0.892 respectively. Sensitivity and specificity for referral decision was 94.0% and 95.5%. Concordance and F1 score were 94.9% and 93.3% respectively. Inter-rater agreement for a referral decision was 0.825. Progression or regression of lesions were systematically documented using MeMoSA^® .

CONCLUSION: Referral decisions made through MeMoSA^® is highly comparable to clinical examination demonstrating it is a reliable telemedicine tool to facilitate the identification of high-risk lesions for early management.

PMID:33914993 | DOI:10.1111/odi.13892

Acta Physiol (Oxf). 2021 Apr 29:e13670. doi: 10.1111/apha.13670. Online ahead of print.

ABSTRACT

Physiological outputs are characterised by constant fluctuations, even under resting conditions.¹ Quantifying this variability represents an important methodological challenge. Variability in physiological outputs has traditionally been quantified according to its magnitude, using measures such as the standard deviation (SD).² Such magnitude-based measures have provided substantial insight into the analysis of physiological outputs, with changes in the magnitude of variability associated with adverse events in a number of systems.² However, physiological outputs are characterised by irregular self-similar fluctuations (“complexity”) over multiple orders of temporal magnitude (i.e. seconds, minutes, hours), a property magnitude-based measures cannot quantify.¹ Complexity measures derive from non-linear dynamics, and include metrics related to information theory (e.g. entropy statistics), which measure the apparent regularity or randomness of an output, and metrics drawn from fractal geometry, which identify long-range correlations present in an output.³ It has been suggested that neither magnitude- nor complexity-based metrics should be used as the sole indicator of system characteristics; rather, they should be used in conjunction, in order to provide a more complete understanding of variability.^2,4.

PMID:33915024 | DOI:10.1111/apha.13670

Dent Med Probl. 2021 Apr 29. doi: 10.17219/dmp/127963. Online ahead of print.

ABSTRACT

BACKGROUND: Telescopic implant-retained overdentures are considered one of the most common treatment modalities for edentulous patients.

OBJECTIVES: The aim of the study was to evaluate the retention of a BioHPP (biocompatible highperformance polymer) telescopic overdenture supported by customized abutments made from 2 different materials after the simulation of 1 year in function.

MATERIAL AND METHODS: Twelve models of a completely edentulous mandible were three-dimensionally (3D)-printed. Two implants and 2 groups of customized abutments – group Bio: BioHPP (n = 6) and group Ti: titanium (n = 6) – were used to support BioHPP telescopic overdentures. A vertically dislodging force was applied to each denture until its separation before and after 240,000 cycles of chewing simulation and 1,440 iterations of cyclic dislodgement for the simulation of 1 year in function in order to measure maximum tensile loads needed to dislodge the overdenture. Student’s t test and the paired t test were used for the statistical analysis (α = 0.05).

RESULTS: The initial and final retentive forces of the Ti group were significantly higher than in the case of the Bio group. A significant decrease in the retentive forces within the 2 groups after chewing simulation was observed and it was higher in group Ti; however, there was no statistically significant difference between the 2 groups.

CONCLUSIONS: The retentive force values for implant-retained telescopic overdentures significantly decreased after the simulation of 1 year of overdenture use. Both BioHPP and titanium are considered suitable abutment materials to retain telescopic overdentures.

PMID:33915039 | DOI:10.17219/dmp/127963

J Eur Acad Dermatol Venereol. 2021 Apr 29. doi: 10.1111/jdv.17318. Online ahead of print.

ABSTRACT

While there is clear evidence of an association between psoriasis and type 2 diabetes mellitus¹ , limited information is available on the prevalence of psoriasis in children and adolescents with type 1 diabetes mellitus (T1D).².

PMID:33914987 | DOI:10.1111/jdv.17318