people
Dr Angela Darekar
Imaging (human)

Lead for MRI Physics
Theme Group:
About:
Current theme Projects:
Permeability of the blood-brain barrier in Alzheimer’s disease (PEBBAL) measured using dynamic contrast-enhanced MRI: a pilot study
Inflammation is the body’s normal response to injury and infection. It can be healthy or harmful depending on the situation. We know that when people with dementia get infections their memory symptoms can get worse. …
Recent publications:
Automatic veins analysis of susceptibility weighted image in hypoxic-ischaemic encephalopathy
Automatic veins analysis of susceptibility weighted image in hypoxic-ischaemic encephalopathy
The purpose of this study is to evaluate venous vascular structure and distribution as prognostic indicators of developmental outcomes for infants with neonatal hypoxic-ischaemic encephalopathy (HIE) by detecting and analysing ridges representing vessels on susceptibility-weighted magnetic resonance images (SWIs).
Iron Deposition in the Brain After Aneurysmal Subarachnoid Hemorrhage
Iron Deposition in the Brain After Aneurysmal Subarachnoid Hemorrhage
After aneurysmal subarachnoid hemorrhage (SAH), thrombus forms over the cerebral cortex and releases hemoglobin. When extracellular, hemoglobin is toxic to neurones. High local hemoglobin concentration overwhelms the clearance capacity of macrophages expressing the hemoglobin-haptoglobin scavenger receptor CD163. We hypothesized that iron is deposited in the cortex after SAH and would associate with outcome.
Neuroanatomical markers of familial risk in adolescents with conduct disorder and their unaffected relatives
Neuroanatomical markers of familial risk in adolescents with conduct disorder and their unaffected relatives
Previous studies have reported brain structure abnormalities in conduct disorder (CD), but it is unclear whether these neuroanatomical alterations mediate the effects of familial (genetic and environmental) risk for CD. We investigated brain structure in adolescents with CD and their unaffected relatives (URs) to identify neuroanatomical markers of familial risk for CD.
A case-control study of the locus coeruleus degeneration in Alzheimer's disease
A case-control study of the locus coeruleus degeneration in Alzheimer's disease
The locus coeruleus (LC) is the major source of noradrenaline, which plays a key role in cognition. We aimed to detect the extent of the LC signal attenuation in Alzheimer's disease (AD) patients using a neuromelanin (NM)-sensitive MRI and how it may correlate with inflammatory and autonomic measures. An individually matched case-control study design was employed. 24 patients with AD and 24 age and gender matched controls with no cognitive impairment were recruited. The primary outcome measure was the LC signal intensity indicated by the LC contrast ratio (CR) and measured by the NM-sensitive MRI. Secondary outcome measures included neuropsychometric tests of cognitive state, peripheral inflammatory and autonomic measures. Conditional logistic regression analysis revealed a significant 22% LC-CR reduction in the AD group compared with the control group. However, there was no statistical significance from inflammatory or autonomic measures. This is the largest individually-matched case-control study to visualise the LC degeneration in AD patients. The study revealed significant LC degeneration which holds promise to stratify patients who may benefit from treatment targeting noradrenergic dysfunction.
The Locus Coeruleus in Aging and Alzheimer's Disease: A Postmortem and Brain Imaging Review
The Locus Coeruleus in Aging and Alzheimer's Disease: A Postmortem and Brain Imaging Review
The locus coeruleus (LC), a tiny nucleus in the brainstem and the principal site of noradrenaline synthesis, has a major role in regulating autonomic function, arousal, attention, and neuroinflammation. LC dysfunction has been linked to a range of disorders; however particular interest is given to the role it plays in Alzheimer's disease (AD). The LC undergoes significant neuronal loss in AD, thought to occur early in the disease process. While neuronal loss in the LC has also been suggested to occur in aging, this relationship is less clear as the findings have been contradictory. LC density has been suggested to be indicative of cognitive reserve and the evidence for these claims will be discussed. Recent imaging techniques allowing visualization of the LC in vivo using neuromelanin-sensitive MRI are developing our understanding of the role of LC in aging and AD. Tau pathology within the LC is evident at an early age in most individuals; however, the relationship between tau accumulation and neuronal loss and why some individuals then develop AD is not understood. Neuromelanin pigment accumulates within LC cells with age and is proposed to be toxic and inflammatory when released into the extracellular environment. This review will explore our current knowledge of the LC changes in both aging and AD from postmortem, imaging, and experimental studies. We will discuss the reasons behind the susceptibility of the LC to neuronal loss, with a focus on the role of extracellular neuromelanin and neuroinflammation caused by the dysfunction of the LC-noradrenaline pathway.
Contact:
Department of Medical Physics
University Hospital Southampton NHS Foundation Trust