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[show abstract]
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ABSTRACT: Diese Übersicht behandelt die Möglichkeiten der Time of flight MRA (TOF-MRA) und der kontrastmittelunterstützten MRA (KM-MRA)
bei zerebral entzündlichen Erkrankungen.
Vaskuläre Komplikationen bei entzündlichen Erkrankungen des Gehirns und der Meningen sind häufig. Bei der infektiösen Meningitis
kann die MRA eine sekundäre Vaskulitis des Circulus arteriosus Willisii und seiner Äste, aber auch eine septische Hirnvenen-
und Sinusthrombose nachweisen. Die TOF-MRA und KM-MRA liefern dabei komplementäre Informationen. In der gleichen Untersuchung
kann eine entzündliche Infiltration der Meningen bildgebend diagnostiziert werden. Bei der hämatogen Herdenzephalitis im Rahmen
einer Sepsis oder Endokarditis ist die MRA zur Diagnose embolischer Gefäßverschlüsse noch vor der Entstehung eines zerebralen
Abszesses und zum Nachweis sog. mykotischer Aneurysmen zielführend.
Bei der Vaskulitis im Rahmen nichtinfektiöser (systemischer) entzündlicher Erkrankungen genügt die TOF-MRA zum Nachweis segmentaler
Stenosen. Lediglich bei subtilen peripheren Gefäßveränderungen kann die Ortsauflösung zu gering sein. In diesem Fall ist eine
weiterführende intraarterielle digitale Subtraktionsangiographie notwendig.
Da die Sensitivität und Spezifität der MRA für diese Indikationen noch nicht ausreichend belegt sind, kann nur der positive
MRA-Befund die intraarterielle digitale Subtraktionsangiographie ersetzen.
In this review, we discuss the diagnostic potential of time of flight (TOF) MRA and contrast enhanced (CE) MRA in inflammatory
disorders of the meninges and the brain.
Cerebrovascular complications are frequently observed during infectious meningoencepalitis. 3D TOF-MRA and CE-MRA are complementary
for the detection of basal intracranial artery stenosis and septic cerebral vein and sinus thrombosis due to secondary vasculitis.
MRA reveals stenosis and occlusion as indirect signs of vasculitis, whereas MRI shows the inflammation of the brain and meninges
and occasionally the vessel wall, together with the ischemic or hemorrhagic complication. In case of septic emboli MRA can
detect peripheral occlusions and “mycotic” aneurysms.
For the diagnosis of noninfectious vasculitides of the intracranial vessels, high resolution 3D TOF-MRA is superior to CE-MRA
for the detection of multiloculated segmental stenoses.
However, there are presently no prospective studies on the sensitivity and specificity of MRA for these indications. Therefore,
only positive MRA results can directly influence clinical management. In case of normal MRA, confirmation by catheder angiography
may still be required.
Der Radiologe 04/2012; 40(11):1077-1089. · 0.61 Impact Factor
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G Kuchukhidze,
F Koppelstaetter,
I Unterberger,
J Dobesberger,
G Walser,
L Zamarian,
E Haberlandt,
H Maier,
M Ortler,
T Gotwald,
E Gelpi,
T Czech,
M Feucht,
G Bauer,
M Delazer, S Felber,
E Trinka
[show abstract]
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ABSTRACT: Hippocampal abnormalities may coexist with malformations of cortical development (MCD). This cross-sectional MRI study aimed at categorizing hippocampal abnormalities in a large group of MCD and comparing MCD patients with (group W) and without (group W/O) hippocampal abnormalities.
Hippocampal anatomy, rotation, size, internal structure, and MRI signal alterations were assessed visually by 3 independent raters in patients with MCD and epilepsy. Four types of hippocampal abnormalities were examined in 220 patients (116 women, mean age 31 +/- 16.6, range 2-76 years): partially infolded/hypoplastic hippocampus (HH), hippocampal sclerosis (HS), malrotated hippocampus (MH), and enlarged hippocampus (EH). The commonest MCD in the cohort were focal cortical dysplasia (27%), polymicrogyria (PMG) (21%), developmental tumors (15%), and periventricular nodular heterotopia (PNH) (14%).
Hippocampal abnormalities were seen in 69/220 (31%) patients: HH in 34/69 (49%); HS in 18/69 (26%); MH in 15/69 (22%); and EH in 2/69 (3%). PNH (21/30 [70%]) and PMG (22/47 [47%]) were most commonly associated with hippocampal abnormalities. Compared to the W/O group, patients in the W group had a higher rate of learning disability (W 41/69 [59%] vs W/O 56/151 [37%]; p = 0.003) and delayed developmental milestones (W 36/69 [52%] vs W/O 53/151 [35%]; p = 0.025); groups did not differ otherwise with regard to clinical presentation. HH was associated with symptomatic generalized epilepsies (11/34 [32%]) and high rate of learning disability (27/34 [79%]), neurologic deficits (25/34 [73%]), and delayed developmental milestones (23/34 [68%]).
About a third of patients with malformations of cortical development had hippocampal abnormalities. Patients with hypoplastic hippocampus had the most severe clinical phenotype.
Neurology 05/2010; 74(20):1575-82. · 8.31 Impact Factor
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C M Siedentopf,
K Heubach,
A Ischebeck,
E Gallasch,
M Fend,
F M Mottaghy,
F Koppelstaetter,
I A Haala,
B J Krause, S Felber,
F Gerstenbrand,
S M Golaszewski
[show abstract]
[hide abstract]
ABSTRACT: The aim of the present was study to evaluate cortical and subcortical neural responses on vibrotactile stimulation of the food and to assess somatosensory evoked BOLD responses in dependence of vibration amplitude and stimulus waveform. Sixteen healthy male subjects received vibrotactile stimulation at the sole of the right foot. The vibration stimulus was delivered through a moving magnet actuator system (MMAS). In an event-related design, a series of vibration stimuli with a duration of 1 s and a variable interstimulus interval was presented. Four stimulation conditions were realized using a 2 (amplitudes 0.4 mm or 1.6 mm) x 2 (waveform sinusoidal or amplitude modulated) factorial design. Stimulating with 0.4 mm amplitude compared to 1.6 mm stimulus amplitude more strongly activated the pre- and postcentral gyrus bilaterally and the right inferior, medial and middle frontal gyrus. In the reverse comparison significant differences were observed within the left inferior parietal lobule, the left superior temporal gyrus, and the left temporal transverse gyrus. In the comparison of sinusoidal versus modulated waveform and vice versa no significant activation differences were obtained. The inter-subject variability was high but when all four stimulation conditions were jointly analyzed, a significant activation of S1 was obtained for every single subject. This study demonstrated that the BOLD response is modulated by the amplitude but not by the waveform of vibrotactile stimulation. Despite high inter-individual variability, the stimulation yielded reliable results for S1 on the single-subject level. Therefore, our results suggest that vibrotactile testing could evolve into a clinical tool in functional neuroimaging.
NeuroImage 07/2008; 41(2):504-10. · 5.89 Impact Factor
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ABSTRACT: Metachromatic leukodystrophy (MLD) is a progressive white matter disease caused by arylsulfatase A deficiency. Demyelination in the nervous system is detected by cerebral magnetic resonance imaging (MRI) and neurophysiological studies. We present three children with infantile MLD, who had difficulties in standing and walking with absent reflexes. Protein levels in cerebral spinal fluid (CSF) were elevated and nerve conduction studies revealed slowing down of motor nerve conduction velocity. Initial cerebral MRIs showed no white matter changes. Consecutively, all three children developed clinical symptoms of neurodegenerative disease. Follow-up MRI and arylsulfatase A testing led to diagnosis of MLD. We conclude, that in young children who present with an acute/subacute demyelinating polyneuropathy, MLD is a differential diagnosis.
European journal of paediatric neurology: EJPN: official journal of the European Paediatric Neurology Society 07/2008; 13(3):257-60. · 2.01 Impact Factor
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G Kuchukhidze,
I Unterberger,
J Dobesberger,
N Embacher,
G Walser,
E Haberlandt,
T Gotwald,
H Maier,
M Ortler, S Felber,
G Bauer,
E Trinka
[show abstract]
[hide abstract]
ABSTRACT: Ulegyria refers to cerebral cortex scarring, which results from a perinatal ischaemic brain injury. It presents with a characteristic gyral pattern: small circumvolutions with atrophy at sulci bottom and spared apex. Ulegyria is frequently associated with epilepsy, cerebral palsy and mental disability. We analysed electroclinical and MRI features in patients with ulegyria and epilepsy.
We reviewed 25 patients (14 males/11 females) with ulegyria and epilepsy from the database (about 5000 patients with epilepsy) of our unit. Patients were examined clinically, underwent high resolution MRI, EEG recordings, positron emission tomography, single photon emission computed tomography and neuropsychological testing. Two patients with refractory seizures underwent epilepsy surgery.
Mean age of patients was 34 years (5-66) at the reassessment time. The majority (16/25, 64%) had a history of perinatal asphyxia. 15 patients had delayed developmental milestones; 20 had learning disabilities and five patients were severely disabled. Mean age at seizure onset was 4.2 years (1-18). 17 patients (68%) had medically intractable epilepsy. 11 patients (44%) had occipital lobe seizures. The majority (n = 24, 96%) had parieto-occipital lesions on MRI. In 13 patients (52%), ulegyria was bilateral. 12 patients (48%) had hippocampal sclerosis. Two patients underwent epilepsy surgery with an excellent postoperative outcome (Engel class IA and IC).
Patients with ulegyria often have a history of perinatal asphyxia and present with pharmacoresistant seizures. Their presurgical assessment is complicated because of frequent dual pathology (hippocampal sclerosis) and bilateral lesions.
Journal of neurology, neurosurgery, and psychiatry 06/2008; 79(5):547-52. · 4.87 Impact Factor
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F Koppelstaetter,
T D Poeppel,
C M Siedentopf,
A Ischebeck,
M Verius,
I Haala,
F M Mottaghy,
P Rhomberg,
S Golaszewski,
T Gotwald,
I H Lorenz,
C Kolbitsch, S Felber,
B J Krause
[show abstract]
[hide abstract]
ABSTRACT: To assess the effect of caffeine on the functional MRI signal during a 2-back verbal working memory task, we examined blood oxygenation level-dependent regional brain activity in 15 healthy right-handed males. The subjects, all moderate caffeine consumers, underwent two scanning sessions on a 1.5-T MR-Scanner separated by a 24- to 48-h interval. Each participant received either placebo or 100 mg caffeine 20 min prior to the performance of the working memory task in blinded crossover fashion. The study was implemented as a blocked-design. Analysis was performed using SPM2. In both conditions, the characteristic working memory network of frontoparietal cortical activation including the precuneus and the anterior cingulate could be shown. In comparison to placebo, caffeine caused an increased response in the bilateral medial frontopolar cortex (BA 10), extending to the right anterior cingulate cortex (BA 32). These results suggest that caffeine modulates neuronal activity as evidenced by fMRI signal changes in a network of brain areas associated with executive and attentional functions during working memory processes.
NeuroImage 02/2008; 39(1):492-9. · 5.89 Impact Factor
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A Zangerle,
S Kiechl,
M Spiegel,
M Furtner,
M Knoflach,
P Werner,
A Mair,
G Wille,
C Schmidauer,
K Gautsch,
T Gotwald, S Felber,
W Poewe,
J Willeit
[show abstract]
[hide abstract]
ABSTRACT: To estimate rates, predictors, and prognostic importance of recanalization in an unselected series of patients with stroke treated with IV thrombolysis.
We performed a CT angiography or transcranial Doppler (TCD) follow-up examination 24 hours after IV thrombolysis in 64 patients with documented occlusion of the intracranial internal carotid or middle cerebral artery (MCA). Complete recanalization was defined by a rating of 3 on the Thrombolysis in Myocardial Infarction or 4/5 on the Thrombolysis in Brain Ischemia grading scales. Information about risk factors, clinical features, and outcome was prospectively collected by standardized procedures.
Complete recanalization was achieved in 36 of the 64 patients (56.3%). There was a nonsignificant trend of recanalization rates to decline with a more proximal site of occlusion: 68.4% (M2 segment of MCA), 53.1% (M1 segment), and 46.2% (carotid T) (p for trend = 0.28). Frequencies of vessel reopening were markedly reduced in subjects with diabetes (9.1% vs 66.0% in nondiabetics, p < 0.001) and less so in subjects with additional extracranial carotid occlusion (p = 0.03). Finally, complete recanalization predicted a favorable stroke outcome at day 90 independently of the information provided by age, NIH Stroke Scale, and onset-to-needle time.
We found a high rate of vessel recanalization after IV thrombolysis occlusion. However, recanalization was infrequent in patients with diabetes and extracranial carotid occlusion. Information on recanalization was a powerful, early predictor for clinical outcome.
Neurology 02/2007; 68(1):39-44. · 8.31 Impact Factor
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ABSTRACT: Fibrocartilaginous embolism (FCE) of the spinal cord is a rare cause of ischemic myelopathy. We describe a 13-year-old patient with probable post-traumatic FCE. History of disease, clinical presentation, diagnostic workup, and disease course are outlined. Diagnosing FCE in the living often seems to be merely conjectural. Therefore, vertebral edema adjacent to the level of the spinal lesion is a possibly valuable diagnostic hint of spinal ischemia. Furthermore, exclusion of systemic embolism and other etiologies of myelopathy is necessary to corroborate the diagnosis of FCE. The postulated pathomechanism, diagnostic procedures, therapy, and prognosis of FCE are discussed in this article.
Der Nervenarzt 11/2005; 76(10):1246-9. · 0.68 Impact Factor
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C Brenneis,
W N Löscher,
K E Egger,
T Benke,
M Schocke,
M F Gabl,
G Wechselberger, S Felber,
S Pechlaner,
R Margreiter,
H Piza-Katzer,
W Poewe
[show abstract]
[hide abstract]
ABSTRACT: We studied cortical activation patterns by functional MRI in a patient who received bilateral hand transplantation after amputation 6 years ago and in a patient who had received unilateral hand replantation within 2 hours after amputation. In the early postoperative period, the patient who had had the hand transplantation revealed strong activation of a higher motor area, only weak activation of the primary sensorimotor motor cortex and no activation of the primary somatosensory cortex. At 1-year follow-up, a small increase in primary sensorimotor motor cortex activation was observed. Activation of the primary somatosensory cortex was only seen at the 2 year follow-up. By contrast, after hand replantation, the activation pattern was similar to that of the uninjured hand within 6 weeks. This included activation of the primary sensorimotor motor cortex, higher motor areas and primary somatosensory cortex. Transplantation after long-standing amputation results in cortical reorganization occurring over a 2-year period. In contrast, hand replantation within a few hours preserves a normal activation pattern.
The Journal of Hand Surgery British & European Volume 11/2005; 30(5):530-3. · 0.04 Impact Factor
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ABSTRACT: The present fMRI study investigates, first, whether learning new arithmetic operations is reflected by changing cerebral activation patterns, and second, whether different learning methods lead to differential modifications of brain activation. In a controlled design, subjects were trained over a week on two new complex arithmetic operations, one operation trained by the application of back-up strategies, i.e., a sequence of arithmetic operations, the other by drill, i.e., by learning the association between the operands and the result. In the following fMRI session, new untrained items, items trained by strategy and items trained by drill, were assessed using an event-related design. Untrained items as compared to trained showed large bilateral parietal activations, with the focus of activation along the right intraparietal sulcus. Further foci of activation were found in both inferior frontal gyri. The reverse contrast, trained vs. untrained, showed a more focused activation pattern with activation in both angular gyri. As suggested by the specific activation patterns, newly acquired expertise was implemented in previously existing networks of arithmetic processing and memory. Comparisons between drill and strategy conditions suggest that successful retrieval was associated with different brain activation patterns reflecting the underlying learning methods. While the drill condition more strongly activated medial parietal regions extending to the left angular gyrus, the strategy condition was associated to the activation of the precuneus which may be accounted for by visual imagery in memory retrieval.
NeuroImage 05/2005; 25(3):838-49. · 5.89 Impact Factor
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ABSTRACT: Sex differences in executive speech tasks, favoring women, have been noted in behavioral studies and functional imaging studies. In the present study ten female and ten male volunteers underwent functional magnetic resonance imaging in a conventional block design. All subjects were selected on the basis of high performance on the verbal fluency task. Regions of activation were detected after performance of a covert lexical verbal fluency task inside the scanner. Men and women who did not differ significantly in verbal fluency task performance showed a very similar pattern of brain activation. Our data argue against genuine between-sex differences in cerebral activation patterns during lexical verbal fluency activities when confounding factors like performance differences are excluded.
Neuroscience Letters 01/2004; 352(3):191-4. · 2.11 Impact Factor
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ABSTRACT: Sex differences in mental rotation tasks, favoring men, have been noted in behavioral studies and functional imaging studies. In the present study ten female and ten male volunteers underwent functional magnetic resonance imaging in a conventional block design. Regions of activation were detected after performance of a mental rotation task inside the scanner. In contrast to previous studies, confounding factors such as performance differences between genders or high error rates were excluded. Men showed significantly stronger parietal activation, while women showed significantly greater right frontal activation. Our results point to gender specific differences in the neuropsychological processes involved in mental rotation tasks.
Neuroscience Letters 08/2003; 344(3):169-72. · 2.11 Impact Factor
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Neuroscience Letters. 01/2003; 344:169-172.
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ABSTRACT: In oder to reduce surgical trauma to the lumbar spine during a multilevel laminectomy procedure we performed a multilevel, bilateral and interlaminar approach, with microsurgical and endoscopic techniques for removal of a large ependymoma of the lumbar spine in a 33-year-old female patient. Complete tumor removal has been achieved, while at the same time, the major elements that form the posterior spinal column could be preserved. The follow-up time is 4 years.
min - Minimally Invasive Neurosurgery 04/2002; 45(1):41-4. · 0.70 Impact Factor
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ABSTRACT: To evaluate the usefulness of virtual endoscopy (VE) in planning neuroendoscopic intraventricular surgeries, the technique was applied in 20 of 22 consecutive procedures. Thirteen endoscopic third ventriculostomies (ETV) in 12 patients, 3 endoscopic colloid cyst removals, 1 third ventricular arachnoidal cyst fenestration, 1 endoscopic ventricul-cysto-cisternostomy (suprasellar arachnoidal cyst), 1 endoscopic tumor biopsy, one third ventricular gross total tumor removal and 2 septostomies at the foramen of Monro due the septal occlusion were performed. Contrast medium-enhanced MR images (3DMPRAGE, Siemens, Germany) were semi-automatically segmented with a surface-rendering technique ("Navigator" software, General Electric Medical, Buc, France) to produce the virtual endoluminal views. Surgery was performed with cerebral ventriculoscopes by Wolf (Richard Wolf, Knittlingen, Germany). VE was feasible in all patients and the virtual endoscopic images were comparable with the real intraventricular views obtained by standard rod lens systems. After contrast medium administration intra- and paraventricular vessels such as the thalamocaudate vein, the septal veins, the basilar artery and its branches (distal BA complex) and the choroid plexus were identified on the virtual endoscopic images. In 8 patients, the additional anatomic information provided by VE profoundly influenced surgical planning. VE provides the neurosurgeon with additional morphological information supporting the planning process of neuroendoscopic intraventricular surgeries, contributing to the safety of the procedures.
min - Minimally Invasive Neurosurgery 04/2002; 45(1):24-31. · 0.70 Impact Factor
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ABSTRACT: Nitrous oxide and isoflurane have cerebral vasodilatory effects. The use of isoflurane in neuroanaesthesia is widely accepted, whereas the use of nitrous oxide in neuroanaesthesia is still the subject of debate. In the present study, contrast-enhanced magnetic resonance (MR) perfusion measurement was used to compare the effects of 0.4 MAC nitrous oxide (n=9) and 0.4 MAC isoflurane (n=9) on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV) and regional mean transit time (rMTT) in spontaneously breathing human volunteers. Nitrous oxide increased rCBF and rCBV in supratentorial regions more than did isoflurane. Isoflurane, by contrast, increased rCBF and rCBV in basal ganglia more than did nitrous oxide. An increased rMTT was caused by a relatively greater increase in rCBV than in rCBF supratentorially by isoflurane and infratentorially by nitrous oxide. In conclusion, nitrous oxide increases rCBF and rCBV predominantly in supratentorial grey matter, whereas isoflurane increases rCBF and rCBV predominantly in infratentorial grey matter.
BJA British Journal of Anaesthesia 12/2001; 87(5):691-8. · 4.24 Impact Factor
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ABSTRACT: Both sevoflurane and isoflurane are used in moderate concentrations in neuroanesthesia practice. The limiting factors for using higher concentrations of inhalational anesthetics in patients undergoing neurosurgery are the agents' effects on cerebral blood flow (CBF) and cerebral blood volume (CBV). In particular, an increase in CBV, which is a key determinant of intracranial pressure, may add to the neurosurgical patient's perioperative risk. To compare the effects of a subanesthetic concentration (0.4 minimum alveolar concentration) of sevoflurane or isoflurane on regional CBF (rCBF), regional CBV (rCBV) and regional mean transit time (rMTT), contrast-enhanced magnetic resonance imaging perfusion measurements were made in spontaneously breathing human volunteers. Absolute changes in rCBF, regional CBV, and rMTT during administration of either drug in regions of interest outlined bilaterally in white and grey matter were nonparametrically (Mann-Whitney test) analyzed. Sevoflurane increased rCBF in practically all regions (absolute change, 4.44 +/- 2.87 to 61.54 +/- 2.39 mL/100g per minute) more than isoflurane did (absolute change, 12.91 +/- 2.52 to 52.67 +/- 3.32 mL/100g per minute), which decreased frontal, parietal, and white matter rCBF (absolute change, -1.12 +/- 0.59 to -14.69 +/- 3.03 mL/100g per minute). Regional CBV was higher in most regions during isoflurane administration (absolute change, 0.75 +/- 0.03 to 4.92 +/- 0.16 mL/100g) than during sevoflurane administration (absolute change, 0.05 +/- 0.14 to 3.57 +/- 0.14 mL/100g). Regional mean transit time was decreased by sevoflurane (absolute change, -0.18 +/- 0.05 to -0.60 +/- 0.04 s) but increased by isoflurane (absolute change, 0.19 +/- 0.03 to 0.69 +/- 0.04 s). In summary, regional CBV was significantly lower during sevoflurane than during isoflurane administration, although sevoflurane increased rCBF more than isoflurane, which even decreased rCBF in some regions. For sevoflurane and, even more pronouncedly, for isoflurane, the observed changes in cerebral hemodynamics cannot be explained by vasodilatation alone.
Journal of Neurosurgical Anesthesiology 11/2001; 13(4):288-95. · 2.23 Impact Factor
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ABSTRACT: The objective of this study was to investigate cerebellar metabolism in patients with autosomal dominant cerebellar ataxia type 1 (ADCA-I) carrying two distinct mutations of spinocerebellar ataxia (SCA). Non-invasive image-guided proton magnetic resonance spectroscopy imaging (1H-MRSI) was performed in 4 patients with SCA2, and 3 patients carrying the SCA6 mutation. For MRSI, we employed a spin-echo sequence (TR = 1500 msec, TE = 135 msec, slice thickness = 15 mm, FOV = 240 mm) and a stimulated-echo sequence (TR = 1500 msec, TE = 20 msec, slice thickness = 15 mm, FOV = 240 mm). Measures included the peak integral ratios of neuronal and glial markers [N-acetylaspartate (NA) to creatine (Cr), choline-containing compounds (CHO) to Cr, and lactate (LAC) to Cr]. We found NA:Cr ratios were significantly lower in patients with SCA2 (40.4% lower) compared to patients carrying the SCA6 mutation. CHO:Cr ratios differed between the two mutations using short echo time (30.8% lower in SCA2), but not when applying long echo time 1H-MRSI. Measurements using long echo time revealed LAC peaks in all SCA2 patients. 1H-MRSI revealed metabolic differences between SCA2 and SCA6 patients. NA:Cr ratios were significantly lower in patients with the SCA2 mutation compared to the SCA6 mutation, and LAC signals were obtained in the cerebella of SCA2 patients. In addition, CHO:Cr ratios showed different behavior using short and long TE, indicating differences in relaxation times of choline compounds in SCA2.
Journal of Magnetic Resonance Imaging 05/2001; 13(4):553-9. · 2.70 Impact Factor
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[show abstract]
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ABSTRACT: Changes in both blood flow and blood oxygenation determine the functional MRI (fMRI) signal. In the present study factors responsible for blood oxygenation (e.g., FiO(2)) were held constant so that changes in pixel count would above all reflect changes in regional cerebral blood flow (rCBF). Continuous positive airway pressure (CPAP) breathing at 12 cm H(2)O, which was previously shown to influence rCBF, was applied in human volunteers (n = 19) to investigate the sensitivity of fMRI for changes in rCBF caused by increased mean airway pressure. Increasing the mean airway pressure decreased the pixel count in the primary visual cortex (median (range)): baseline: 219 (58-425) pixels vs. CPAP (12 cm H(2)O): 92 (0-262) pixels). These findings indicate that fMRI is sensitive to detect a reduced rCBF-response in the primary visual cortex. The underlying mechanism is likely to be a reduced basal rCBF due to constriction and/or compression of postcapillary venoles during CPAP breathing. These findings are important for interpreting fMRI results in awake and in artificially respirated patients, in whom positive airway pressure is used to improve pulmonary function during the diagnostic procedure.
Magnetic Resonance Imaging 02/2001; 19(1):7-11. · 1.99 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: In this review, we discuss the diagnostic potential of time of flight (TOF) MRA and contrast enhanced (CE) MRA in inflammatory disorders of the meninges and the brain. Cerebrovascular complications are frequently observed during infectious meningoencepalitis. 3D TOF-MRA and CE-MRA are complementary for the detection of basal intracranial artery stenosis and septic cerebral vein and sinus thrombosis due to secondary vasculitis. MRA reveals stenosis and occlusion as indirect signs of vasculitis, whereas MRI shows the inflammation of the brain and meninges and occasionally the vessel wall, together with the ischemic or hemorrhagic complication. In case of septic emboli MRA can detect peripheral occlusions and "mycotic" aneurysms. For the diagnosis of noninfectious vasculitides of the intracranial vessels, high resolution 3D TOF-MRA is superior to CE-MRA for the detection of multiloculated segmental stenoses. However, there are presently no prospective studies on the sensitivity and specificity of MRA for these indications. Therefore, only positive MRA results can directly influence clinical management. In case of normal MRA, confirmation by catheder angiography may still be required.
Der Radiologe 12/2000; 40(11):1077-89. · 0.61 Impact Factor
