Brain iron accumulation in Wilson disease: a post mortem 7 Tesla MRI - histopathological study.

AIMS: In Wilson disease (WD), T2/T2*-weighted (T2*w) MRI frequently shows hypointensity in the basal ganglia that is suggestive of paramagnetic deposits. It is currently unknown whether this hypointensity is related to copper or iron deposition. We examined the neuropathological correlates of this MRI pattern, particularly in relation to iron and copper concentrations. METHODS: Brain slices from nine WD and six control cases were investigated using a 7T-MRI system. High-resolution T2*w images were acquired and R2* parametric maps were reconstructed using a multigradient recalled echo sequence. R2* was measured in the globus pallidus (GP) and the putamen. Corresponding histopathological sections containing the lentiform nucleus were examined using Turnbull iron staining, and double staining combining Turnbull with immunohistochemistry for macrophages or astrocytes. Quantitative densitometry of the iron staining as well as copper and iron concentrations were measured in the GP and putamen and correlated with R2* values. RESULTS: T2*w hypointensity in the GP and/or putamen was apparent in WD cases and R2* values correlated with quantitative densitometry of iron staining. In WD, iron and copper concentrations were increased in the putamen compared to controls. R2* was correlated with the iron concentration in the GP and putamen, whereas no correlation was observed for the copper concentration. Patients with more pronounced pathological severity in the putamen displayed increased iron concentration, which correlated with an elevated number of iron-containing macrophages. CONCLUSIONS: T2/T2*w hypointensity observed in vivo in the basal ganglia of WD patients is related to iron rather than copper deposits.

[Ultrahigh field MRI in context of neurological diseases]. / Ultrahochfeld-MRT im Kontext neurologischer Erkrankungen.

Ultrahigh field magnetic resonance imaging (UHF-MRI) has recently gained substantial scientific interest. At field strengths of 7 Tesla (T) and higher UHF-MRI provides unprecedented spatial resolution due to an increased signal-to-noise ratio (SNR). The UHF-MRI method has been successfully applied in various neurological disorders. In neuroinflammatory diseases UHF-MRI has already provided a detailed insight into individual pathological disease processes and elucidated differential diagnoses of several disease entities, e.g. multiple sclerosis (MS), neuromyelitis optica (NMO) and Susac's syndrome. The excellent depiction of normal blood vessels, vessel abnormalities and infarct morphology by UHF-MRI can be utilized in vascular diseases. Detailed imaging of the hippocampus in Alzheimer's disease and the substantia nigra in Parkinson's disease as well as sensitivity to iron depositions could be valuable in neurodegenerative diseases. Current UHF-MRI studies still suffer from small sample sizes, selection bias or propensity to image artefacts. In addition, the increasing clinical relevance of 3T-MRI has not been sufficiently appreciated in previous studies. Although UHF-MRI is only available at a small number of medical research centers it could provide a high-end diagnostic tool for healthcare optimization in the foreseeable future. The potential of UHF-MRI still has to be carefully validated by profound prospective research to define its place in future medicine.

Acute interventional recanalisation of vertebrobasilar stenoses by angioplasty: complications and 12 months follow up.

INTRODUCTION: In acute symptomatic vertebrobasilar artery stenosis, the use of mechanical recanalisation remains controversial. The complication rate of acute interventional recanalisation (aIR) has to be considered, as evidence from randomised trials is lacking. In a single centre retrospective case series, we here describe complications and outcome after aIR. METHODS: We retrospectively assessed aIR in a tertiary care centre and included the following parameters: indication for aIR, national institute of health stroke scale (NIHSS) score on admission, recanalisation by thrombolysis in myocardial infarction score (TIMI) grades, post-interventional complications, mortality, NIHSS and modified Rankin scale at follow-up and rate of restenosis. RESULTS: We identified 14 aIR (14 percutaneous transluminal angioplasty with or without stent implantation in 12 patients; 6/12 with thrombolysis; n = 6 vertebral artery, n = 8 basilar artery; 4 women, mean age 67 years). Mortality was 25 % (3/12) after 7 days and 42 % (5/12) after 12 months. In 12/14, interventions are complete (TIMI 3, 86 %), in 2/14, a partial recanalisation (TIMI 2, 14 %) was achieved. In one case, a peri-interventional fatal intracerebral haemorrhage occurred (1/12, 8 %). At late follow-up (mean 342 days), one re-occlusion (1/7, 14 %) and one recurrent stroke (1/12, 8 %) were observed. CONCLUSIONS: In our single centre series of vertebrobasilar aIR recanalisation rate was high. However, procedural safety and clinical outcome varied considerably. The results of aIR need to be assessed in multicentric registers to define the procedural risk and outcome in the clinical setting.

Pregnancy outcome following use of levodopa, pramipexole, ropinirole, and rotigotine for restless legs syndrome during pregnancy: a case series.

BACKGROUND: Restless legs syndrome (RLS) is related to parity, and its symptoms may worsen during pregnancy. Treatment with levodopa or dopamine agonists is the first-line therapy for RLS; however, there are limited data on treatment in pregnancy. We therefore assessed the safety of levodopa, pramipexole, rotigotine, and ropinirole in pregnancy. METHODS: Prospective documentation of pregnancies exposed to levodopa, pramipexole, rotigotine, and ropinirole between 1998 and 2011 was evaluated as to their outcome (teratogenicity or fetotoxicity) by the Berlin Institute for Clinical Teratology and Drug Risk Assessment in Pregnancy. RESULTS: We were able to complete 59 pregnancy outcomes exposed to RLS pharmacotherapy. For specific treatments, the numbers of exposed pregnancies/live born children/spontaneous abortions/induced abortions/malformations were as follows: levodopa only: 38/29 (one pair of twins)/3/7/3; pramipexole only: 12/9/3/0/0; rotigotine only: 2/2/0/0/0; ropinirole only: 3/2/0/1/0; levodopa combined with pramipexole: 3/3/0/0/0; levodopa combined with ropinirole: 1/1/0/0/0. No major birth defects were found with any RLS treatment, and three infants exposed to levodopa had minor anomalies. CONCLUSIONS: In our small prospective case series, there was no increased risk above baseline for major malformations or other adverse outcomes for levodopa and pramipexole. If necessary, levodopa treatment may be considered as an alternative to cabergoline, for which safety has been well documented in pregnancy.

Systemic thrombolysis with rt-PA in patients under 40 years of age: a subgroup analysis of the Cologne Stroke Experience.

BACKGROUND: While the application of intravenous systemic thrombolysis (IVT) with rt-PA (recombinant tissue plasminogen activator) in older patients is currently moving into the focus of epidemiological studies, only few data are available regarding the application in young patients ≤40 years. Single-center data of a thrombolysis register were analyzed with respect to safety and efficacy of the treatment of young patients. METHODS: In a retrospective subgroup analysis of 450 patients treated by IVT within a 3-hour time window, patients ≤40 years were identified (n = 20). Clinical data [age, pretherapeutic stroke severity (National Institute of Health Stroke Scale, NIHSS), OTT (onset to-treatment time), rt-PA-dose, DNT (door[-]to[-]needle time), rate of symptomatic intracranial hemorrhages] and medical history were determined. The clinical outcome was assessed by the mRS (modified Rankin Scale). The results were compared to those of patients >40 years (n = 430). RESULTS: Twenty patients ≤40 years (mean age 32 years) out of 450 patients (4%) were treated by IVT. The percentage of predisposing diseases and vascular risk factors was significantly lower when compared to patients >40 years (p < 0.05). In contrast, the percentage of smokers was significantly higher (55 vs. 24%; p < 0.05). In comparison to patients >40 years, OTT, DNT and NIHSS at admission were not significantly different. After 3 months, 11 of 20 young patients (55%) showed a favorable outcome (mRS 0-1) and 80% were functionally independent (mRS 0-2). In the group of patients >40 years (n = 430), the respective percentages were significantly lower [p < 0.05; 34% (mRS 0-1) and 52% (mRS 0-2), respectively]. Symptomatic intracranial hemorrhages were not observed (in patients >40 years: 4%, p < 0.05). CONCLUSIONS: In comparison to the cohort of patients >40 years, IVT in young patients is safe and leads to a significantly better outcome after 3 months. Our data therefore encourage the use of IVT in young patients.

[Therapy of acute ischemic stroke]. / Akutversorgung des ischämischen Schlaganfalls.

New diagnostic and therapeutic developments have led to an innovative approach to stroke therapy. The slogan "time is brain" emphasizes that stroke is a medical emergency comparable to myocardial infarction. The stroke unit conception is an evidence based therapy for all stroke patients and improves outcome significantly. The monitoring of vital signs and the management of stroke specific complications are highly effective. Early secondary prophylaxis reduces the risk of recurrence. The effect of CT based thrombolysis within the time window of 4,5 h has been substantiated by current data. Stroke MRI holds the promise for an improved therapy by patient stratification and by opening the time window. Interventional recanalisation, vascular interventions and hemicraniectomy complement the therapeutic options in the acute phase of stroke.

Comparison of PET and DW/PW-MRI in acute ischemic stroke.

The penumbra--tissue perfused below the flow threshold for functional disturbance but above that for maintenance of morphological integrity--is the target for therapy in acute ischemic stroke. Irreversible tissue damage and penumbra can be reliably identified by multitracer positron emission tomography (PET) which has severe limitations due to complexity, invasiveness and radiation exposure. Therefore other modalities served as surrogate markers, with diffusion/perfusion-weighted magnetic resonance imaging (DW/PW-MRI) and perfusion computed tomography (PCT) being applied widely in clinical routine. In order to evaluate the limitations of DW/PW-MRI a comparative study was performed in acute stroke patients in whom cerebral perfusion was assessed by perfusion-weighted magnetic resonance imaging (PW-MRI) and H2(15)O-PET, tissue damage was estimated by diffusion-weighted magnetic resonance imaging (DW-MRI) and 11C-flumazenil (FMZ) PET and DW/PW-MRI mismatch was related to the tissue with increased oxygen extraction fraction (OEF) as an indicator of penumbra. The lesions in DW-MRI and in FMZ-PET were reliable predictors of final infarct on late MRI, but DW-MRI showed a high false positive rate. PW-MRI was limited in estimating flow and yielded values comparable to H2(15)O-PET only in the range between 20 and 30 ml/100 g/min. The DW/PW-MRI mismatch overestimated the penumbra as determined by increased OEF. These limitations of DW/PW-MRI have to be considered if used for selection of patients for treatment and might have an impact on the outcome of clinical trials based on this surrogate marker.

[Stroke prevention outside the pharmacy : risk factors and lifestyle]. / Schlaganfallprävention jenseits der Apotheke : Risikofaktoren und Lifestyle.

Advice on modifiable risk and lifestyle factors for stroke prevention should be an established component of medical consultation. It is most important to explain that alterations to the lifestyle can be highly efficient with respect to the individual risk profile. The following review describes the importance of lifestyle factors such as nutrition, smoking, alcohol consumption, psychiatric condition, sport, dental hygiene and sleep disturbances for the risk of stroke using current data. It provides evidence that lifestyle modifications are highly effective with respect to stroke prevention. Corresponding recommendations and preventive strategies are presented.

Immediate CEA for symptomatic carotid disease preferably performed under local anaesthesia is safe.

BACKGROUND: Previous general reservations against carotid endarterectomy (CEA) early after stroke, which were primarily based on concerns of postoperative intracerebral hemorrhage, are resolved. Moreover, a delay of surgery is proofed to be associated with a risk of recurrent cerebral ischemia. However, the complication rate of CEA seems to increase with less time interval to the onset of symptoms. The main purpose of this study was to assess the safety of very early CEA. PATIENTS AND METHODS: Patients having a symptomatic high-grade (> 70%) internal carotid artery (ICA) stenosis were referred by neurologists for CEA within different timeframes, so that they were later differentiated depending on whether surgery was performed within 2 days (immediate CEA = iCEA) or 2 weeks (urgent CEA = uCEA) after neurological deficits have occurred primarily. The perioperative complication rate in these groups was than evaluated and compared. RESULTS: From January 2000 until August 2006 130 consecutive patients (median age 68 years, range: 42-90; 66% male, 34%female)presenting with an ipsilateral TIA (n = 80), stroke (n = 50) underwent iCEA (n = 40) or uCEA (n = 90). Demographic and clinical characteristics were equally distributed between treatment groups. Mostly (121/130), CEA was performed under local anaesthesia with selective shunt use which became necessary in 26%. Besides postoperative hemorrhage (n = 4), cardiac complications (n = 2) and temporary cranial nerve lesions (n = 2), new perioperative neurological deficits occurred in total in 8 patients of which 6 were temporary. The other 2 patients developed strokes of which one patient died. Therefore, the combined stroke- and mortality rate was 1.5% (2/130) for the whole study population. With regard to the timing of surgery, a single incident was observed after iCEA (1/40) which also was the only intracerebral hemorrhage. CONCLUSIONS: It seems that patients with a symptomatic high-grade ICA stenosis can undergo CEA particularly under local anaesthesia as soon as possible without anticipating an increased complication rate.

Role of in vivo imaging of the central nervous system for developing novel drugs.

Over the past decade imaging technologies employed in clinical neurosciences have significantly advanced. Imaging is not only used for the diagnostic work-up of neurological disorders but also crucial to follow up on therapeutic efforts. Using disease-specific imaging parameters, as read-outs for the efficiency of individual therapies, has facilitated the development of various novel treatments for neurological disease. Here, we review various imaging technologies, such as cranial computed tomography (CT), magnetic resonance imaging (MRI) and spectroscopy (MRS), positron emission tomography (PET) and single-photon emission computed tomography (SPECT), with respect to their current applications in non-invasive disease phenotyping and the measurement of therapeutic outcomes in neurology. In particular, applications in neuro-oncology, Parkinson's disease, Alzheimer's disease, and cerebral ischemia are discussed. Non-invasive imaging provides further insights into the molecular pathophysiology of human diseases and facilitates the design and implementation of improved therapies.

Biochemical and bioimaging markers for risk assessment and diagnosis in major cardiovascular diseases: a road to integration of complementary diagnostic tools.

This report from the first International Course on Integrated Biomarkers, Biochemical and Bioimaging Endpoints in Cardiovascular Diagnosis, Prevention, Therapy and Drug Development provides the basis for optimizing diagnostic, prognostic and therapeutic information in four areas of cardiovascular medicine: primary prevention of cardiovascular diseases, acute coronary syndromes, heart failure and stroke. Risk stratification and treatment strategies can be refined and enhanced through integration of bioimaging and biochemical markers to characterize sub-clinical and clinical atherosclerosis. For the integrative approach to be useful, each of the biomarkers must be validated and cost-effective. Clinical decision is the primary level of integration and is based on clinical evaluation and the use of a combination of bioimaging and biochemical markers. The decision to initiate preventive or therapeutic intervention must take into account the factors affecting the levels of expression of the biomarker and the potential input the biomarker has on metabolic processes or modulation of other biomarkers. The optimal approach to intervention must take into consideration the risk-benefit and cost-effectiveness ratios.

Primary stroke unit treatment followed by very early carotid endarterectomy for carotid artery stenosis after acute stroke.

BACKGROUND: Although it is recognized that carotid endarterectomy (CEA) is the treatment of choice in symptomatic internal carotid artery (ICA) stenosis, in the past, very early CEA has been shown to carry substantial risks. We assessed an interdisciplinary concept of very early CEA in patients with high-grade (>70%) symptomatic ICA stenosis at a single center. PATIENTS AND METHODS: The course of treatment and outcomes of patients who underwent CEA as early as possible after being referred to the stroke unit for symptoms of transient ischemic attack and stroke were prospectively evaluated, including the following parameters: age, severity of ischemia-related symptoms according to the modified Rankin scale, duration of symptoms until admission, multimodal imaging findings (color-coded duplex, cranial computed tomography, magnetic resonance imaging, positron emission tomography), duration until CEA, perioperative course and complications, as well as duration of in-hospital care. RESULTS: Fifty consecutive patients (median age 68 years, range 44-90) with clinical and imaging signs of transient ischemic attack (n = 19) or stroke (n = 31) were included from January 2000 until December 2004. All except 1 patient showed a preoperative Rankin < 4. There was a median time period of 6 h between the onset of symptoms and admission (range 1 h to 15 days) and a median duration of 4 days after admission until operation (range 1-21 days). Seven patients underwent CEA of the contralateral, severely stenosed ICA after symptomatic ipsilateral ICA occlusion. Four out of 5 patients who primarily underwent systemic thrombolysis recovered almost completely. Three patients (6%) experienced a clinical deterioration before surgery. In the majority of patients (43/50), CEA was performed under local anesthesia with selective shunt use which became necessary in 26%. Three patients (6%) had postoperative worsening due to new infarcts. In 2 cases, an intracerebral hemorrhage occurred, of which 1 remained asymptomatic. In 1 case, surgical revision was necessary because of an ICA thrombosis without permanent neurological decline. Patients were discharged after a median time of 14.5 days (range 4-44). CONCLUSIONS: After careful selection and preparation in a stroke unit, patients with acute stroke due to carotid stenosis can undergo very early CEA under local anesthesia with a perioperative risk comparable with the risk of later endarterectomy, therefore preventing very early stroke recurrences.

Which time-to-peak threshold best identifies penumbral flow? A comparison of perfusion-weighted magnetic resonance imaging and positron emission tomography in acute ischemic stroke.

BACKGROUND AND PURPOSE: In acute ischemic stroke, the hypoperfused but viable tissue is the main therapeutic target. In clinical routine, time-to-peak (TTP) maps are frequently used to estimate the hemodynamic compromise and to calculate the mismatch volume. We evaluated the accuracy of TTP maps to identify penumbral flow by comparison with positron emission tomography (PET). METHODS: Magnetic resonance imaging (MRI) and PET were performed in 11 patients with acute ischemic stroke (median 8 hours after stroke onset, 60 minutes between MRI and PET imaging). The volumes defined by increasing TTP thresholds (relative TTP delay of >2, >4, >6, >8, and >10 seconds) were compared with the volume of hypoperfusion (<20 mL/100 g per min) assessed by 15O-water PET. In a volumetric analysis, each threshold's sensitivity, specificity, and predictive values were calculated. RESULTS: The median hypoperfusion volume was 34.5 cm3. Low TTP thresholds included large parts of the hypoperfused but also large parts of normoperfused tissue (median sensitivity/specificity: 93%/60% for TTP >2) and vice versa (50%/91% for TTP >10). TTP >4 seconds best identifies hypoperfusion (84%/77%). The positive predictive values increased with the size of hypoperfusion. CONCLUSIONS: This first comparison of quantitative PET-CBF with TTP maps in acute ischemic human stroke indicates that the TTP threshold is crucial to reliably identify the tissue at risk; TTP >4 seconds best identifies penumbral flow; and TTP maps overestimate the extent of true hemodynamic compromise depending on the size of ischemia. Only if methodological restrictions are kept in mind, relative TTP maps are suitable to estimate the mismatch volume.

PET-based molecular imaging in neuroscience.

Positron emission tomography (PET) allows non-invasive assessment of physiological, metabolic and molecular processes in humans and animals in vivo. Advances in detector technology have led to a considerable improvement in the spatial resolution of PET (1-2 mm), enabling for the first time investigations in small experimental animals such as mice. With the developments in radiochemistry and tracer technology, a variety of endogenously expressed and exogenously introduced genes can be analysed by PET. This opens up the exciting and rapidly evolving field of molecular imaging, aiming at the non-invasive localisation of a biological process of interest in normal and diseased cells in animal models and humans in vivo. The main and most intriguing advantage of molecular imaging is the kinetic analysis of a given molecular event in the same experimental subject over time. This will allow non-invasive characterisation and "phenotyping" of animal models of human disease at various disease stages, under certain pathophysiological stimuli and after therapeutic intervention. The potential broad applications of imaging molecular events in vivo lie in the study of cell biology, biochemistry, gene/protein function and regulation, signal transduction, transcriptional regulation and characterisation of transgenic animals. Most importantly, molecular imaging will have great implications for the identification of potential molecular therapeutic targets, in the development of new treatment strategies, and in their successful implementation into clinical application. Here, the potential impact of molecular imaging by PET in applications in neuroscience research with a special focus on neurodegeneration and neuro-oncology is reviewed.

Identification of malignant brain edema after hemispheric stroke by PET-imaging and microdialysis.

Cerebral blood flow (CBF) and extent of irreversible tissue damage as well as the time course of extracellular concentration of amino acids, substrates of energy metabolism, and purine metabolites, intracranial pressure and tissue oxygen tension were assessed in 34 patients with large strokes covering more than 50% of the MCA territory. The results were compared to findings in the experimental model of transient (for 3 hours) MCA occlusion in cats. In the experimental model as well as in the clinical setting development of malignant brain infarcts (due to formation of space occupying brain edema) was predicted by the size of critically hypoperfused tissue and the volume of irreversibly damaged tissue. The course of malignant infarcts was characterized by progressive increase in concentrations of excitatory amino acids, lactate, pyruvate, glycerol, hypoxanthine and in intracranial pressure, while cerebral perfusion pressure and tissue oxygen tension decreased. These results clearly differentiate a malignant from a benign course of large hemispheric infarction. The methods can be used to identify patients at risk for formation of space occupying edema and to select patients who could benefit from invasive therapeutic strategies.

The correlation between cerebral glucose metabolism and benzodiazepine receptor density in the acute vegetative state.

This paper compares the results of parallel positron emission tomography (PET) studies of regional cerebral glucose metabolism with the radiotracer 18F-fluorodeoxyglucose (FDG) and benzodiazepine receptor (BZR) density by PET using the BZR ligand 11C-flumazenil (FMZ), a tracer of neuronal integrity, in nine patients with acute vegetative state (AVS, duration <1 month). Overall glucose utilization was significantly reduced in AVS in comparison with age-matched controls (global metabolic rate for glucose 26 micromol/100 g/min in AVS vs. 31 micromol/100 g/min in controls). FMZ-PET demonstrated a considerable reduction of BZR binding sites in all cortical regions that grossly corresponded to the extent of reduction of cerebral glucose metabolism assessed with FDG-PET, whilst the cerebellum was spared from neuronal loss. In controls, cortical relative flumazenil binding was not lower than five times the average white matter activity, whilst in AVS, nearly all values were below this threshold. There was no relevant overlap of the data of relative flumazenil binding between both groups. The comparison of FDG- and FMZ-PET findings in AVS demonstrates that alterations of cerebral glucose consumption do not represent mere functional inactivation, but irreversible structural brain damage.

Differentiating multiple system atrophy from Parkinson's disease: contribution of striatal and midbrain MRI volumetry and multi-tracer PET imaging.

OBJECTIVES: The differential diagnosis between typical idiopathic Parkinson's disease (PD) and the striatonigral variant of multiple system atrophy (MSA-P) is often difficult because of the presence of signs and symptoms common to both forms of parkinsonism, particularly at symptom onset. This study investigated striatal and midbrain findings in MSA-P and PD patients in comparison with normal controls with the use of positron emission tomography (PET) and three dimensional magnetic resonance imaging (3D MRI) based volumetry to increase the differential diagnostic accuracy between both disease entities. METHODS: Nine patients with MSA-P, 24 patients with PD, and seven healthy controls were studied by MRI and PET with 6-[(18)F]-fluoro-L-dopa (FDOPA), [(18)F]fluoro-deoxyglucose (FDG), and 11-C-Raclopride (RACLO). Striatal and extrastriatal volumes of interest (VOI) were calculated on the basis of the individual MRI data. The PET data were transferred to the VOI datasets and subsequently analysed. RESULTS: MSA-P differed significantly from PD patients in terms of decreased putaminal volume, glucose metabolism, and postsynaptic D2 receptor density. The striatal FDOPA uptake was equally impaired in both conditions. Neither MRI volumetry nor PET imaging of the midbrain region further contributed to the differential diagnosis between PD and MSA-P. CONCLUSIONS: The extent and spatial distribution of functional and morphological changes in the striatum permit the differentiation of MSA-P from PD. Both, multi-tracer PET and 3D MRI based volumetry, may be considered equivalent in the assessment of different striatal abnormality in both disease entities. In contrast, MRI and PET imaging of the midbrain does not provide a further gain in diagnostic accuracy.

Feasibility of source images of computed tomographic angiography to detect the extent of ischemia in hyperacute stroke.

BACKGROUND AND PURPOSE: Computed tomographic angiography (CTA) is suggested to be a promising tool for patient selection for thrombolytic therapy of acute stroke. It does not only provide information on intracranial vasculature, but also on the capacity of the collateral circulation and the pattern of poorly perfused brain tissue. The objective of our study was to evaluate whether the presence and size of critically hypoperfused tissue assessed with flow positron emission tomography (PET) as a gold standard can reliably be identified on CTA source images. METHODS: Fifteen potential candidates for early thrombolysis underwent CTA 65-170 min (mean 107 min) after the onset of acute anterior circulation stroke. Regional cerebral perfusion was measured between 27 and 86 min (mean 59 min) later with [(15)O]-H(2)O and PET, and the volume of critically hypoperfused cortical tissue was assessed. CTA source images were evaluated by a neuroradiologist and an experienced stroke neurologist. The patients were classified into three groups according to the presumed size of the perfusion deficit on CTA (large, small, no perfusion deficit). RESULTS: PET revealed the presence of critical cortical hypoperfusion in 10 patients, 5 had no critical cortical hypoperfusion. The neuroradiologist correctly identified the presence of a perfusion deficit in all patients, the neurologist had two false negative and one false positive ratings. Concerning the size of the perfusion deficit, there was considerable inaccuracy in both raters. CONCLUSIONS: The usefulness of CTA source images in yielding information about the perfusion state of stroke patients in clinical routine should not be overestimated.

Impaired benzodiazepine receptor binding in peri-lesional cortex of patients with symptomatic epilepsies studied by [(11)C]-flumazenil PET.

Individual benzodiazepine receptor (BZR) binding of peri-lesional cortex was investigated in symptomatic epilepsies. Eleven patients aged 19-44 years were studied whose diagnosis was established by medical history, clinical, electroencephalographic, and magnetic resonance imaging (MRI) findings. Three-dimensional [11C]-flumazenil (FMZ) positron emission tomography and MRI scans were obtained and coregistered. Lesions (five low-grade brain tumours, one AV malformation, one cavernoma, one cystic lesion of unknown aetiology, one traumatic brain injury, one post-operative and one post-haemorrhagic defect) were outlined on individual MRI scans. Adjacent to those lesions, and in homologous contralateral structures, FMZ binding was analysed in four pairs of cortical 9 x 9-mm regions of interest (ROIs) placed on transaxial and coronal slices, respectively, as well as in the lesion volume and its mirror region. Percentage asymmetry ratios were calculated and those at or outside the 90-110% range were operationally defined significant. Peri-lesional FMZ binding asymmetries ranged from 70 to 125%, lesional asymmetries from 38 to 82%. Only one patient showed no significant change, whilst nine exhibited significant reductions of FMZ binding in at least one ROI (3 x 1, 4 x 2, 1 x 3, 1 x 4), and significant increases were observed in two ROIs of another patient. Therefore, peri-lesional disturbances of BZR binding are common but variable in location. Because a close correlation between regional decreases in FMZ binding and spiking activity was recently demonstrated in neocortical epilepsies, abnormal peri-lesional FMZ binding may bear some relation to the mechanisms of epileptogenesis in symptomatic epilepsies.

Molecular and functional imaging technology for the development of efficient treatment strategies for gliomas.

Gliomas are the most common types of brain tumors, which invariably lead to death over months or years. Before new and potentially more effective treatment strategies, such as gene therapy, can be effectively introduced into clinical application the following goals must be reached: (1) the determination of localization, extent and metabolic activity of the glioma; (2) the assessment of functional changes within the surrounding brain tissue; (3) the identification of genetic changes on the molecular level leading to disease; and in addition (4) a detailed non-invasive analysis of both endogenous and exogenous gene expression in animal models and in the clinical setting. Non-invasive imaging of endogenous gene expression by means of positron emission tomography (PET) may reveal insight into the molecular basis of pathogenesis and metabolic activity of the glioma and the extent of treatment response. When exogenous genes are introduced to serve for a therapeutic function, PET imaging techniques may reveal the assessment of the location, magnitude and duration of therapeutic gene expression and its relation to the therapeutic effect. Here, we review the main principles of PET imaging and its key roles in neurooncology research.