Publications by authors named "N Q-X Wee"

281 Publications

CT and MRI findings of acute calculous cholecystitis and its complications in Singapore: A pictorial review.

Med J Malaysia 2021 Sep;76(5):706-713

Tan Tock Seng Hospital, Department of Diagnostic Radiology, Singapore.

Introduction: Acute cholecystitis (AC) is a common problem encountered in surgical practice. This occurs due to obstruction of the cystic duct by calculi resulting in inflammation of the gallbladder. Increasingly, contrast enhanced computed tomography (CECT) and Magnetic Resonance Imaging (MRI) scans are being used for assessment. While the imaging features of AC are well recognized and extensively described in the literature, radiological features of the rarer complications related to AC such as pseudoaneurysm formation and gallbladder volvulus are less well known. We aim to describe these rarer findings in our pictorial review, to better educate the clinician and radiologist, such that timely diagnoses can be reached, and relevant management can be affected.

Methods: A collection of cases showing the common acute gallbladder pathologies and complications such as acute cholecystitis, gangrenous cholecystitis, emphysematous cholecystitis, haemorrhagic cholecystitis, Mirizzi's syndrome, gallbladder perforation and abscess formation, were collected between July 2016 and March 2018 at two different medical institutions in Singapore. In addition, rarer cases of gallbladder volvulus and vascular complications such as cystic artery pseudoaneurysms and vessel erosions, were also followed up.

Results: The CT and MRI imaging features of these conditions were discussed, with key diagnostic imaging features emphasized.

Conclusion: Acute gallbladder pathologies are commonly encountered in day-to-day radiology practice. Knowledge of the rarer gallbladder pathologies and their key imaging features will help the radiologist, in particular, the on call radiologist in training, improve diagnostic accuracy and allow for timely management.
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September 2021

Social dysfunction is transdiagnostically associated with default mode network dysconnectivity in schizophrenia and Alzheimer's disease.

World J Biol Psychiatry 2021 Sep 17:1-14. Epub 2021 Sep 17.

Department of Psychiatry, Amsterdam Neuroscience and Amsterdam Public Health Research Institute, Amsterdam UMC, VU Medical Centre and GGZ inGeest, Amsterdam, The Netherlands.

Objectives: Social dysfunction is one of the most common signs of major neuropsychiatric disorders. The Default Mode Network (DMN) is crucially implicated in both psychopathology and social dysfunction, although the transdiagnostic properties of social dysfunction remains unknown. As part of the pan-European PRISM (Psychiatric Ratings using Intermediate Stratified Markers) project, we explored cross-disorder impact of social dysfunction on DMN connectivity.

Methods: We studied DMN intrinsic functional connectivity in relation to social dysfunction by applying Independent Component Analysis and Dual Regression on resting-state fMRI data, among schizophrenia (SZ; =48), Alzheimer disease (AD; =47) patients and healthy controls (HC; =55). Social dysfunction was operationalised via the Social Functioning Scale (SFS) and De Jong-Gierveld Loneliness Scale (LON).

Results: Both SFS and LON were independently associated with diminished DMN connectional integrity within rostromedial prefrontal DMN subterritories ( range=0.02-0.04). The combined effect of these indicators (Mean.SFS + LON) on diminished DMN connectivity was even more pronounced (both spatially and statistically), independent of diagnostic status, and not confounded by key clinical or sociodemographic effects, comprising large sections of rostromedial and dorsomedial prefrontal cortex (=0.01).

Conclusions: These findings pinpoint DMN connectional alterations as putative transdiagnostic endophenotypes for social dysfunction and could aid personalised care initiatives grounded in social behaviour.
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http://dx.doi.org/10.1080/15622975.2021.1966714DOI Listing
September 2021

Seeded Ising Model and Distributed Biometric Template Storage and Matching.

Entropy (Basel) 2021 Jul 1;23(7). Epub 2021 Jul 1.

Department of Mathematics, The Catholic University of Korea, Bucheon 14662, Korea.

It is known that a variant of Ising model, called , can be used to recover the information content of a biometric template from a fraction of information therein. The method consists in reconstructing the whole template, which is called the in this paper, using only a small portion of the given template, a . This reconstruction method may pose a security threat to the integrity of a biometric identity management system. In this paper, based on the Seeded Ising Model, we present a systematic analysis of the possible security breach and its probability of accepting the intruder templates as genuine. Detailed statistical experiments on the intruder match rate are also conducted under various scenarios. In particular, we study (1) how best a template is divided into several small pieces called partial templates, each of which is to be stored in a separate silo; (2) how to do the matching by comparing partial templates in the locked-up silos, and letting only the results of these intra-silo comparisons be sent to the central tallying server for final scoring without requiring the whole templates in one location at any time.
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http://dx.doi.org/10.3390/e23070849DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8303195PMC
July 2021

Contributing factors to advanced brain aging in depression and anxiety disorders.

Transl Psychiatry 2021 07 21;11(1):402. Epub 2021 Jul 21.

Department of Psychiatry, Amsterdam University Medical Centers, Vrije Universiteit and GGZ inGeest, Amsterdam Neuroscience, Amsterdam, The Netherlands.

Depression and anxiety are common and often comorbid mental health disorders that represent risk factors for aging-related conditions. Brain aging has shown to be more advanced in patients with major depressive disorder (MDD). Here, we extend prior work by investigating multivariate brain aging in patients with MDD, anxiety disorders, or both, and examine which factors contribute to older-appearing brains. Adults aged 18-57 years from the Netherlands Study of Depression and Anxiety underwent structural MRI. A pretrained brain-age prediction model based on >2000 samples from the ENIGMA consortium was applied to obtain brain-predicted age differences (brain PAD, predicted brain age minus chronological age) in 65 controls and 220 patients with current MDD and/or anxiety. Brain-PAD estimates were associated with clinical, somatic, lifestyle, and biological factors. After correcting for antidepressant use, brain PAD was significantly higher in MDD (+2.78 years, Cohen's d = 0.25, 95% CI -0.10-0.60) and anxiety patients (+2.91 years, Cohen's d = 0.27, 95% CI -0.08-0.61), compared with controls. There were no significant associations with lifestyle or biological stress systems. A multivariable model indicated unique contributions of higher severity of somatic depression symptoms (b = 4.21 years per unit increase on average sum score) and antidepressant use (-2.53 years) to brain PAD. Advanced brain aging in patients with MDD and anxiety was most strongly associated with somatic depressive symptomatology. We also present clinically relevant evidence for a potential neuroprotective antidepressant effect on the brain-PAD metric that requires follow-up in future research.
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http://dx.doi.org/10.1038/s41398-021-01524-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8295382PMC
July 2021

Dynamic time warp analysis of individual symptom trajectories in depressed patients treated with electroconvulsive therapy.

J Affect Disord 2021 10 2;293:435-443. Epub 2021 Jul 2.

Department of Psychiatry, Leiden University Medical Center (LUMC), the Netherlands. Electronic address:

Background: Although electroconvulsive therapy (ECT) effectively improves severity scores of depression, its effects on its individual symptoms has scarcely been studied. We aimed to study which depressive symptom trajectories dynamically cluster together in individuals as well as groups of patients during ECT using Dynamic Time Warp (DTW) analysis.

Methods: We analysed the standardized weekly scores on the 25-item abbreviated version of the Comprehensive Psychopathological Rating Scale (CPRS) in depressed patients before and during their first six weeks of ECT treatment. DTW analysis was used to analyse the (dis)similarity of time series of items scores at the patient level (300 'DTW distances' per patient) as well as on the group level. Hierarchical cluster, network, and Distatis analyses yielded symptom dimensions.

Results: We included 133 patients, 64.7% female, with an average age of 60.4 years (SD 15.1). Individual DTW distance matrices and networks revealed marked differences in hierarchical and network clusters among patients. Based on cluster analyses of the aggregated matrices, four symptom clusters emerged. In patients who reached remission, the average DTW distance between their symptoms was significantly smaller than non-remitters, reflecting denser symptom networks in remitters than non-remitters (p=0.04).

Limitations: The assessments were done only weekly during the first six weeks of ECT treatment. The use of individual items of the abbreviated CPRS may have led to measurement error as well as floor and ceiling effects.

Conclusion: DTW offers an efficient new approach to analyse symptom trajectories within individuals as well as groups of patients, aiding personalized medicine of psychopathology.
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http://dx.doi.org/10.1016/j.jad.2021.06.068DOI Listing
October 2021
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