Henry Mak

The University of Hong Kong | HKU · Department of Diagnostic Radiology

Rationale How striatal dopamine synthesis capacity (DSC) contributes to the pathogenesis of negative symptoms in first-episode schizophrenia (SZ) and delusional disorder (DD) has seldom been explored. As negative symptoms during active psychotic episodes can be complicated by secondary influences, such as positive symptoms, longitudinal investigati...

To evaluate the incremental diagnostic value of 18F-Flutemetamol PET following MRI measurements on an unselected prospective cohort collected from a memory clinic. A total of 84 participants was included in this study. A stepwise study design was performed including initial analysis (based on clinical assessments), interim analysis (revision of ini...

Olfactory dysfunction (OD) is a common symptom in coronavirus disease 2019 (COVID-19) patients. Moreover, many neurological manifestations have been reported in these patients, suggesting central nervous system involvement. The default mode network (DMN) is closely associated with olfactory processing. In this study, we investigated the internetwor...

Parkinson’s psychosis (PDP) describes a spectrum of symptoms that may arise in Parkinson’s disease (PD) including visual hallucinations (VH). Imaging studies investigating the neural correlates of PDP have been inconsistent in their findings, due to differences in study design and limitations of scale. Here we use empirical Bayes harmonisation to p...

Magnetic resonance imaging is a key diagnostic tool in modern healthcare, yet it can be cost-prohibitive given the high installation, maintenance and operation costs of the machinery. There are approximately seven scanners per million inhabitants and over 90% are concentrated in high-income countries. We describe an ultra-low-field brain MRI scanne...

Background Grey matter abnormalities and neurological soft signs (NSS) have been found in schizophrenia patients and their unaffected relatives. Evidence suggested that NSS are associated with grey matter morphometrical alterations in multiple regions in schizophrenia. However, the association between NSS and structural abnormalities at network lev...

Resting-state functional magnetic resonance imaging (rs-fMRI) has been actively used in the last decade to investigate brain functional connectivity alterations in Type 2 Diabetes Mellitus (T2DM) to understand the neuropathophysiology of T2DM in cognitive degeneration. Given the emergence of new analysis techniques, this scoping review aims to map...

Positron emission topography (PET) and magnetic resonance imaging (MRI) are two common in‐vivo techniques for supporting clinical diagnosis of dementia. The correlated neuropathological changes including amyloid‐beta (Aβ) deposition, and cortical atrophy may have the potential to predict conversion from cognitively normal elderly adults (HC), to mi...

Mild behavioral impairment (MBI) is a neurobehavioral syndrome characterized by later life emergent neuropsychiatric symptoms (NPS). There has not been any systematic review or meta‐analysis on the prevalence of MBI. Main aim of the study is to calculate the pooled prevalence of MBI. A search of the literature on MBI in mild cognitive impairment (M...

In previous decades, structural MRI has been widely adopted in the diagnosis of AD, MCI and other forms of dementia[1]. Through quantitative measurement of volume of regions‐of‐interest (ROI), it is suggested that hippocampal volume reduction and the rate of reduction can be use in dementia diagnosis and predict the disease progression[2]. However,...

Previous studies demonstrated that when compare to healthy control (HC), patients with AD and amnesic mild cognitive impairment suffered degeneration in corpus callosum (CC) [2], [3]. The volume of CC and its sub‐regions associate with cognitive impairment in AD and MCI[3]. 52 participants (25 healthy controls HC, 16 AD, 11 amyloid MCI), were recru...

Previous studies have demonstrated that functional connectivity and relative cerebral blood flow were altered in patients suffered from Alzheimer’s disease (AD) and Mild cognitive impairment (MCI). However, the application on vascular dementia (VD) and non‐amyloid mild cognitive impairment (VMCI) are still unclear. 65 participants (18 healthy contr...

Previous studies have demonstrated that the accumulation of amyloid-β (Aβ) pathologies has distinctive stage-specific effects on the structural and functional brain networks along the Alzheimer’s disease (AD) continuum. A more comprehensive account of both types of brain network may provide a better characterization of the stage-specific effects of...

Background Mild behavioural impairment (MBI) is a neurobehavioural syndrome characterised by later life emergence of persistent neuropsychiatric symptoms. Our previous meta-analysis showed that MBI is prevalent among cognitively normal (CN), subjective cognitive impairment (SCI) and mild cognitive impairment (MCI) subjects. This study is to calcula...

Previous studies have demonstrated that functional connectivity (FC) of different brain regions in resting state function MRI were abnormal in patients suffering from mild cognitive impairment (MCI) and Alzheimer’s disease (AD) when comparing to healthy controls (HC) using seed based, independent component analysis (ICA) or small world network tech...

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, in which the immune system attacks the myelin and axons, consequently leading to demyelination and axonal injury. Magnetic resonance imaging (MRI) plays a pivotal role in the diagnosis of MS, and currently various types of MRI techniques have been used to detect the pat...

Background Recent trials have shown that low‐density lipoprotein cholesterol (LDL‐C) <1.80 mmol/L (<70 mg/dL) is associated with a reduced risk of major adverse cardiovascular events in White patients with ischemic stroke with atherosclerosis. However, it remains uncertain whether the findings can be generalized to Asian patients, or that similar L...

The glutamatergic cycle is essential in modulating memory processing by the hippocampal circuitry. Our combined ¹H-MRS and task-based fMRI study (using face-name paired-associates encoding and retrieval task) of a cognitively-normal cohort of 67 healthy adults (18 ApoE4 carriers and 49 non-ApoE4 carriers) found altered patterns of relationships bet...

Non-conductive olfactory dysfunction (OD) is an important extra-pulmonary manifestation of coronavirus disease 2019 (COVID-19). Olfactory bulb (OB) volume loss and olfactory network functional connectivity (FC) defects were identified in two patients suffering from prolonged COVID-19-related OD. One patient received olfactory treatment (OT) by the...

Background Apolipoprotein E ɛ4 allele (ApoE4) is the most common gene polymorphism related to Alzheimer's disease (AD). Impaired synaptic dysfunction occurs in ApoE4 carriers before any clinical symptoms. It remains unknown whether ApoE4 status affects the hippocampal neuromodulation, which further influences brain network topology. Purpose To stu...

Background Balancing the risks of recurrent ischaemic stroke and intracranial haemorrhage is important for patients treated with antithrombotic therapy after ischaemic stroke or transient ischaemic attack. However, existing predictive models offer insufficient performance, particularly for assessing the risk of intracranial haemorrhage. We aimed to...

Background Non-conductive olfactory dysfunction (OD) is an important extra-pulmonary manifestation of coronavirus disease 2019 (COVID-19). Prolonged COVID-19-related OD is a serious neurosensory disability. Treatment for the restoration of smell is urgently needed. Case presentation Two patients presenting with prolonged COVID-19-related OD underwe...

Studies have shown that the brain’s rich-club organization may underpin brain function and be associated with various brain disorders. In this study, we aimed to investigate the relation between poststroke brain functions and functional recovery versus the rich-club organization of the structural brain network of patients after first-time acute isc...

Parkinson’s psychosis (PDP) describes a spectrum of symptoms that may arise in Parkinson’s disease (PD) including visual hallucinations (VH). Imaging studies investigating the neural correlates of PDP have been inconsistent in their findings, due to differences in study design and limitations of scale. Here we use empirical Bayes harmonisation to p...

Parkinson's psychosis (PDP) describes a spectrum of symptoms that may arise in Parkinson's disease (PD) including visual hallucinations (VH). Imaging studies investigating the neural correlates of PDP have been inconsistent in their findings, due to differences in study design and limitations of scale. Here we use empirical Bayes harmonisation to p...

Cerebellar dysfunction is associated with neurological soft signs (NSS), which is a promising endophenotype for schizophrenia spectrum disorders. However, the relationship between cerebellar-cerebral resting-state functional connectivity (rsFC) and NSS is largely unexplored. Moreover, both NSS and cerebellar-cerebral rsFC have been found to be corr...

Background: With the more widespread use of 18F-radioligand-based amyloid-β (Aβ) PET-CT imaging, we evaluated Aβ binding and the utility of neocortical 18F-Flutemetamol standardized uptake value ratio (SUVR) as a biomarker. Objective: 18F-Flutemetamol SUVR was used to differentiate 1) mild cognitive impairment (MCI) from Alzheimer's disease (AD)...

Mild cognitive impairment (MCI) is a transition stage between cognitively unimpaired and Alzheimer’s Disease (AD). Accumulation of amyloid‐β (Aβ) is considered as upstream event in the development of AD, while grey matter (GM) atrophy occurs in the late stage (Jack et al., 2010). In the cognitive continuum from MCI to AD, the correlation between tw...

Fibrillary beta amyloid deposits and cerebral hypoperfusion are upstream and downstream pathological features in demented individuals respectively. Asymptomatic amyloid plaque deposition begins and becomes saturated way before cerebral structural and metabolic changes in the course of Alzheimer’s disease dementia, and their relationships been vigor...

Previous studies have demonstrated that accumulations of amyloid fibrils (AF) altered the cognitive performance in patients suffered from Alzheimer’s disease (AD) and Mild cognitive impairment (MCI). 85 participants (25 healthy controls HC, 16 AD, 21 MCI, 10 Mixed dementia (MD), 13 vascular dementia (VD) )were recruited to undergo Resting state fun...

Introduction Dementia is a group of disabling disorders that can be devastating for persons living with it and for their families. Data-informed decision-making strategies to identify individuals at high risk of dementia are essential to facilitate large-scale prevention and early intervention. This population-based case–control study aims to devel...

To clarify the involvement of the cerebellum in impaired sensory integration in patients with schizophrenia, 52 first-episode patients with schizophrenia and 52 age- and sex-matched healthy controls underwent a verified sensory integration imaging task to examine the whole-brain dysfunction underlying impaired sensory integration. The familiality o...

There have been few studies performed to examine the pathophysiological differences between different types of psychosis, such as between delusional disorder (DD) and schizophrenia (SZ). Notably, despite the different clinical characteristics of DD and schizophrenia (SZ), antipsychotics are deemed equally effective pharmaceutical treatments for bot...

Studies have shown that rich-club may underlie brain function and be associated with many brain disorders. In this study, we aimed to investigate the relation between poststroke brain functions and functional recovery versus the rich-club organization of the structural brain network of patients after first-time acute ischemic stroke. A cohort of 16...

Background Neurological softs signs (NSS) are defined as subtle neurological abnormalities with manifestations of motor coordination, sensory integration and disinhibition. Evidence has suggested NSS as one of the most promising endophenotypes for schizophrenia spectrum disorders. Moreover, accumulating evidence also suggest that NSS may be associa...

Background There is growing evidence suggesting that the abnormal pituitary volume (PV) may be an essential deficit in schizophrenia spectrum disorders, and PV may change depending on the stage of the illness. However, previous studies assessing PV in schizophrenia spectrum disorders, especially in ultra-high risk individuals, were confounding. The...

Sinking skin flap syndrome (SSFS) is a complication among long-term survivors of stroke or traumatic brain injury treated by decompressive craniectomy. The syndrome encompasses a wide spectrum of neurological symptoms including cognitive decline, seizures, speech and sensorimotor deficits. Early cranioplasty appears to improve cerebral perfusion, b...

The link between non-demented type 2 diabetes mellitus (T2DM) and different types of cognitive impairment is controversial. By controlling for co-morbidities such as cerebral macrovascular and microvascular changes, cerebral atrophy, amyloid burden, hypertension or hyperlipidemia, the current study investigated the cerebral blood flow of T2DM indiv...

Background/objectives: Silent cerebrovascular lesions (SCLs) and their underlying pathology are now recognized as important causes of cognitive impairment in the elderly. However, the distinct profile of cognitive deficits associated with each type of SCLs remains unclear. Methods: Of 497 otherwise healthy hypertensive elderly Chinese, 398 parti...

Background: Cerebral microbleeds are a neuroimaging biomarker of stroke risk. A crucial clinical question is whether cerebral microbleeds indicate patients with recent ischaemic stroke or transient ischaemic attack in whom the rate of future intracranial haemorrhage is likely to exceed that of recurrent ischaemic stroke when treated with antithrom...

Background Recent studies in Caucasians with transient ischaemic attack or ischaemic stroke have demonstrated significant age-specific associations between cerebral small vessel disease (SVD) burden on magnetic resonance imaging and renal impairment. We aimed to validate these findings in a large cohort of Chinese with ischaemic stroke. Methods In...

This special report introduces native flow quantitative imaging for evaluating stroke risk. Moreover, the advantage of combining three imaging techniques [magnetic resonance angiography (MRA), phase-contrast (PC) flow imaging, and arterial spin-labeling imaging] is shown to be beneficial for responding to ischemia and preserving viable neurons. The...

Late stage Parkinson's disease (PD) patients were commonly observed with other non-motor comorbidities such as dementia and psychosis. While abnormal iron level in the substantia nigra was clinically accepted as a biomarker of PD, it was also suggested that the increased iron deposition could impair other brain regions and induce non-motor symptoms...

This study aims to develop a super slice interpolation (SSI) method that generates thin-slice images from multichannel multislice images by exploiting the intra-slice coil sensitivity variations. SSI first calculates the thin-slice sensitivity maps by through-plane interpolation of the sensitivity maps computed from the acquired multislice images....

Background: Schizophrenia has been characterized as a neurodevelopmental disorder of brain disconnectivity. However, whether disrupted integrity of white matter tracts in schizophrenia can potentially serve as individual discriminative biomarkers remains unclear. Methods: A random forest algorithm was applied to tractography-based diffusion prop...

Different cerebral small vessel disease (SVD) lesion types have been shown to disrupt structural brain network individually. Considering that they often coexist, we investigated the relation between their collective effect using the recently proposed total SVD score and structural brain network on MRI in 95 patients with first transient ischemic at...

Background and purpose: In patients with transient ischemic attack/ischemic stroke, microbleed burden predicts intracerebral hemorrhage (ICH), and ischemic stroke, but implications for antiplatelet treatment are uncertain. Previous cohort studies have had insufficient follow-up to assess the time course of risks, have not stratified risks by antit...

We report a case of unique location of an aneurysm at the atlanto-axial extradural segment of a unilateral aberrant vertebral artery. The MRI vessel wall imaging findings and possible mechanism of aneurysm formation were discussed. A 5 mm extracranial vertebral artery aneurysm located at the interlaminar space between C1 and C2 was diagnosed in a w...

Background This study was performed to determine the clinical correlates and long‐term prognostic implications of microbleed burden and location in Chinese patients with ischemic stroke. Methods and ResultsWe recruited 1003 predominantly Chinese patients with ischemic stroke who received magnetic resonance imaging at the University of Hong Kong. We...

Background: Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are central nervous system (CNS) inflammatory demyelinating disorders. It is clinically important to distinguish MS from NMOSD, as treatment and prognosis differ. Brainstem involvement is common in both disorders. Purpose: To investigate whether the patterns...

Background: Gamma-aminobutyric acid (GABA) dysfunction and its consequent imbalance are implicated in the pathophysiology of schizophrenia. Reduced GABA production would lead to a disinhibition of glutamatergic neurons and subsequently cause a disruption of the modulation between GABAergic interneurons and glutamatergic neurons. In this study, lev...

Objective: In patients with TIA and ischemic stroke, we validated the total small vessel disease (SVD) score by determining its prognostic value for recurrent stroke. Methods: Two independent prospective studies were conducted, one comprising predominantly Caucasian patients with TIA/ischemic stroke (Oxford Vascular Study [OXVASC]) and one predo...

Background and purpose: Perivascular spaces (PVSs) are considered markers of small vessel disease. However, their long-term prognostic implications in transient ischemic attack/ischemic stroke patients are unknown. Ethnic differences in PVS prevalence are also unknown. Methods: Two independent prospective studies were conducted, 1 comprising pre...

Background: Abnormalities of striatal structure and function have been considered a core feature of psychosis, especially schizophrenia. Empirical findings from resting-state functional connectivity of subdivisions of the striatum have shown that the ventral and dorsal section of the striatum are connected with the cerebral cortex with different pa...

Purpose: Correlation of arterial stenosis with cortical and subcortical cerebral blood flow (CBF) in the middle cerebral artery (MCA) territory. Methods: 126 patients with acute cerebrovascular symptoms from March to June 2015 underwent MRI and MR Angiography (MRA) in a University hospital using a 3.0 Tesla scanner. Sequences included T1W, T2W, FLA...

Rheumatoid arthritis (RA) is associated with increased vascular calcification, although the rate of progress of calcification is uncertain. The aim of the study was to evaluate the progression of and the predictors for calcification in different vascular beds over 10 years. The 10-year actual coronary calcium score (CS) and 10-year predicted corona...

Background and purpose: Patients with neuropsychiatric systemic lupus erythematosus have worse outcomes compared with those with systemic lupus erythematosus. A better understanding of the mechanisms of neuropsychiatric systemic lupus erythematosus could potentially improve diagnosis and management. The goal of this study was to investigate the di...