D Decoo

Accurate differentiation of parkinsonism and essential tremor using visual assessment of [123I]-FP-CIT SPECT imaging: the [123I]-FP-CIT study group.

To evaluate whether visual assessment of [123I]‐FP‐CIT (DaTSCAN , Nycomed Amersham, plc) single photon emission computerized tomography (SPECT) images can differentiate between parkinsonism and essential tremor (ET).

Endarterectomy for moderate symptomatic carotid stenosis : interim results from the MRC European carotid surgery trial

BACKGROUND The objective of this study was to assess whether carotid endarterectomy is an appropriate treatment for patients with recent cerebrovascular events in the territory supplied by a moderately stenosed (30-69%) internal carotid artery. Results have previously been reported for severe (70-99%) and mild (0-29%) stenosis. METHODS A multicentre randomised controlled trial recruited 1599 patients with moderate stenosis treated in 97 hospitals from 15 countries. 60% of patients were allocated to receive and 40% to avoid carotid endarterectomy. The analysis was by intention to treat. FINDINGS Nine patients were omitted from the analysis because no follow-up data were received. Stroke-free life expectancy (curtailed at 8 years) was shorter in the surgery patients than in the non-surgery control groups (patients with 30-49% stenosis, life expectancy = 6.16 years [controls: 6.63 years]; patients with 50-69% stenosis, life expectancy = 5.93 [6.14] years). It remains possible that patients might derive some benefit from surgery in the very long term; however, our data show that no benefit would be gained over a period of < 4-5 years in patients with 50-69% stenosis and < 6-7 years in patients with 30-49% stenosis. INTERPRETATION Previous interim results from this study showed that surgery is beneficial in patients with severe stenosis but harmful in those with mild stenosis. With more randomised patients and longer follow-up, the study now shows that endarterectomy is not indicated for most, possibly all, patients with moderate symptomatic carotid stenosis.Background The objective of this study was to assess whether carotid endarterectomy is an appropriate treatment for patients with recent cerebrovascular events in the territory supplied by a moderately stenosed (30-69%) internal carotid artery. Results have previously been reported for severe (70-99%) and mild (0-29%) stenosis. Methods A multicentre randomised controlled trial recruited 1599 patients with moderate stenosis treated in 97 hospitals from 15 countries, 60% of patients were allocated to receive and 40% to avoid carotid endarterectomy. The analysis was by intention to treat. Findings Nine patients were omitted from the analysis because no follow-up data were received. Stroke-free life expectancy (curtailed at 8 years) was shorter in the surgery patients than in the non-surgery control groups (patients with 30-49% stenosis, life expectancy=6.16 years [controls: 6.63 years]; patients with 50-69% stenosis, life expectancy=5.93 [6.14] years). It remains possible that patients might derive some benefit from surgery in the very long term; however, our data show that no benefit would be gained over a period of <4-5 years in patients with 50-69% stenosis and <6-7 years in patients with 30-49% stenosis. Interpretation Previous interim results from this study showed that surgery is beneficial in patients with severe stenosis but harmful in those with mild stenosis. With more randomised patients and longer follow-up, the study now shows that endarterectomy is not indicated for most, possibly all, patients with moderate symptomatic carotid stenosis.

Assessment of neuroinflammation and microglial activation in Alzheimer's disease with radiolabelled PK11195 and single photon emission computed tomography - A Pilot Study

Objectives: Inflammation contributes to degeneration in Alzheimer’s disease (AD), not simply as a secondary phenomenon, but primarily as a significant source of pathology. [123I]iodo-PK11195 is a single photon emission computed tomography (SPECT) ligand for the peripheral benzodiazepine receptor, the latter being expressed on microglia (brain resident macrophages) and upregulated under inflammatory circumstances. The objectives were to assess AD inflammation by detecting [123I]iodo-PK11195 uptake changes and investigate how uptake values relate with perfusion SPECT and neuropsychological findings. Methods: Ten AD and 9 control subjects were included. [123I]iodo-PK11195 SPECT images were realigned into stereotactic space where binding indices, normalized on cerebellar uptake, were calculated. Results: The mean [123I]iodo-PK11195 uptake was increased in AD patients compared with controls in nearly all neocortical regions; however, statistical significance was only reached in the frontal and right mesotemporal regions. Significant correlations were found between regional increased [123I]iodo-PK11195 uptake and cognitive deficits. Conclusions: [123I]iodo-PK11195 is a cellular disease activity marker and allows in vivo assessment of microglial inflammation in AD.

Imaging of the 5-HT2A system: age-, gender-, and Alzheimer’s disease-related findings

Serotonin (5-HT) and more specifically the 5-HT(2A) receptor is involved in cognitive and non-cognitive behavior and plays an important role in Alzheimers disease (AD). The objective was to assess the 5-HT(2A) binding potential (BP) in healthy volunteers and AD with SPECT and 123I-5-I-R91150, a selective radio-iodinated 5-HT(2A) receptor antagonist. Twenty-six controls and nine AD patients were included. A semiquantitive analysis with normalization on cerebellar uptake provided estimates of BP for 26 cortical regions of interest. An age-related decline of neocortical BP was found (11.6% per decade). Compared to age-matched controls, a generally decreased neocortical BP in AD was found with a significant regional reduction in the orbitofrontal, prefrontal, lateral frontal, cingulate, sensorimotor, parietal inferior, and occipital region. These results are in line with previous postmortem, in vitro, and PET findings. The age-related decline highlights the necessity for matched advanced age study samples. The fact that the 5-HT(2A) receptor is differentially affected in AD patients has implications for both the etiological basis and therapeutic management of AD.

Positron emission tomography in vascular dementia.

BACKGROUND Vascular dementia (VaD) is an ill-defined entity. It is not known how acute brain failure related to stroke becomes chronic leading to dementia. PURPOSE The present study investigates whether positron emission tomography (PET) can detect different metabolic patterns in VaD. PATIENTS AND METHODS Four groups of stroke patients were selected. The PET findings of 14 stroke patients with multiple large infarcts and dementia (MID) and 14 without dementia (MS) were compared. Sixteen stroke patients with lacunes, leukoaraiosis and dementia (LD) were assessed against nine without dementia (LS). The PET examination utilised the 15-O-steady-state technique in order to determine regional cerebral blood flow (rCBF), regional oxygen extraction rate (rOER) and regional cerebral metabolic rate for oxygen (rCMRO2) in different pre-established cortical, subcortical and cerebellar regions. RESULTS Decreased coupled mean rCBF and rCMRO2 with comparable rOER values were observed in all cerebral regions except in the cerebellum of the MID compared to the MS group. In the LD group mean rCBF and rCMRO2 were decreased with increased rOER in all cerebral regions except in the cerebellum compared to the LS group. CONCLUSIONS The PET findings in demented patients with multiple large infarcts are in agreement with the concept of multi-infarct dementia. In demented patients with lacunes and leukoaraiosis, the PET pattern suggests a state of misery perfusion not only in the deep structures but also in the whole cerebral cortex. The present PET study argues that there are at least two possible mechanisms that can explain the occurrence of VaD in stroke patients.

Acetazolamide Vasoreactivity in Vascular Dementia: A Positron Emission Tomographic Study

The present study investigates the vasoreactivity of the brain in patients with large infarcts and dementia (multi-infarct dementia; MID) and in patients with microangiopathy, lacunes, white matter changes and dementia (lacunar dementia; LD) using positron emission tomography (PET) and 13NH3 as regional cerebral blood flow (rCBF) tracer. In the control group, an increase in rCBF ranging from 32 to 43% was found in all brain regions after intravenous acetazolamide administration. In both the MID group and the group with multiple infarcts without dementia, moderate loss of vasoreactivity was observed in the frontal, temporal and parietal cortex compared to the control values. Vasoreactivity was severely impaired in all cerebral regions of the LD group and restricted to the thalamus in the group with lacunes and white matter changes without dementia (lacunar stroke; LS). This suggests that global loss of vasoreactivity is not a determining factor in the occurrence of MID, but might be important in LD. The present study shows that loss of the vascular reserve leading to exhausted metabolic reserve of the whole brain is one of the possible mechanisms for the occurrence of vascular dementia.

Does the Severity of Leukoaraiosis Contribute to Senile Dementia

The present study evaluates the origin, severity and location of leukoaraiosis in senile dementia and in normal ageing. The regional white-matter lucency scores, determined on computed-tomographic scan of the brain, are compared to the regional blood flow, oxygen extraction rate and oxygen consumption, determined by the [15O] steady-state technique with positron emission tomography. Thirty patients, classified according to the presence or absence of leukoaraiosis and their mental status, are examined. The occurrence and severity of dementia appear to be mainly correlated to decreased blood flow and oxygen metabolism in the frontal, temporal and parietal cerebral cortex. Leukoaraiosis in demented and nondemented patients is associated with lowered blood flow in the frontal and parietal white matter. The regional lucency score is increased, and blood flow and oxygen consumption decreased in the frontal white matter of severely demented patients. Frontal leukoaraiosis contributes to dementia and is probably of ischemic origin, while parietal and occipital leukoaraiosis is due to wallerian degeneration.

A positron emission tomography study of patients with acute carbon monoxide poisoning treated by hyperbaric oxygen

Seven patients with an acute and severe carbon monoxide intoxication were treated with hyperbaric oxygen and underwent a positron emission tomographic examination 2–5 days after the acute event. Although the final clinical outcome was good in all patients, ischaemic changes were observed. Three patients with temporary sequelae after hyperbaric oxygen treatment showed the most severe changes, mainly in striatum and thalamus. Although positron emission tomographic examination cannot predict the final outcome, it can show the regions at risk for development of late complications following carbon monoxide poisoning.

Late-onset epileptic seizures in patients with leukoaraiosis: a positron emission tomographic study.

Leukoaraiosis, found on computed tomographic scans of the brain, is suspected to be of ischemic origin and is frequently associated with progressive decline of cognitive functions in elderly persons. Some of them also develop late-onset epilepsy. The present positron emission tomographic study investigates if these seizures in mentally nonaffected patients with leukoaraiosis are related to an underlying ischemic process. Patients with leukoaraiosis and late-onset seizures have a more important decline of regional blood flow and oxygen consumption in the cortical areas, compared to normal age-matched controls, to patients with cryptogenic symptomatic late-onset epilepsy and to patients with a similar degree of leukoaraiosis but without epilepsy. The present study suggests that both the late-onset seizures and the leukoaraiosis in patients with, at that time, no obvious mental deterioration are premonitory signs of an encephalopathy of unknown origin, possibly leading to cognitive decline.

Significance of white matter lucencies in posthypoxic-ischemic encephalopathy : comparison of clinical status and of computed and positron emission tomographic findings

The clinical status and the computed and positron tomographic findings were compared in 10 patients with sequelae of hypoxic-ischemic encephalopathy after cardiopulmonary arrest and successful resuscitation. Conscious patients with moderate neuropsychiatric deficits had no significant computed tomography (CT) scan changes and normal values of regional cerebral blood flow and oxygen consumption, while patients in vegetative state had definite cerebral atrophy on CT scan and a severe and widespread decrease of regional cerebral blood flow and oxygen consumption. This decrease was even more pronounced in vegetative patients with the worst neurological score and with CT scans demonstrating additional diffuse white matter lucencies and hypodensities in the basal ganglia. In this group of patients increased regional oxygen extraction rates mainly in the white matter indicated the occurrence of delayed ischemic changes. The positron emission tomography and CT findings correlated well with the degree of posthypoxic-ischemic damage and the clinical status of the studied subjects.