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(1) Background: Intracranial pressure (ICP) monitoring plays a key role in the treatment of patients in intensive care units, as well as during long-term surgeries and interventions. The gold standard is invasive measurement and monitoring via ventricular drainage or a parenchymal probe. In recent decades, numerous methods for non-invasive measurement have been evaluated but none have become established in routine clinical practice. The aim of this study was to reflect on the current state of research and shed light on relevant techniques for future clinical application. (2) Methods: We performed a PubMed search for “non-invasive AND ICP AND (measurement OR monitoring)” and identified 306 results. On the basis of these search results, we conducted an in-depth source analysis to identify additional methods. Studies were analyzed for design, patient type (e.g., infants, adults, and shunt patients), statistical evaluation (correlation, accuracy, and reliability), number of included measurements, and statistical assessment of accuracy and reliability. (3) Results: MRI-ICP and two-depth Doppler showed the most potential (and were the most complex methods). Tympanic membrane temperature, diffuse correlation spectroscopy, natural resonance frequency, and retinal vein approaches were also promising. (4) Conclusions: To date, no convincing evidence supports the use of a particular method for non-invasive intracranial pressure measurement. However, many new approaches are under development.

Coil embolization has become a well-established option for the treatment of intracranial aneurysms. Yet, wide-neck bifurcation aneurysms (WNBAs) remain a challenge. The pCONUS is the first generation of a stent-like implant for the bridging of WNBAs to enable coiling. The pToWin study was a prospective, single-arm, multicenter study conducted to analyze the safety and efficacy of the pCONUS in the treatment of WNBAs. The primary effectiveness endpoint was the rate of adequate occlusion of the aneurysm at 3–6 and 7–12 months. The primary safety endpoint was the occurrence of major ipsilateral stroke or neurological death during the follow-up. A total of 115 patients were included. Aneurysm locations were the middle cerebral artery in 52 (45.2%), the anterior communicating artery in 35 (30.4%), the basilar artery in 23 (20%), the internal carotid artery terminus in three (2.6%), and the pericallosal artery in two (1.7%) patients. Treatment was successfully performed in all but one patient. The morbi-mortality rate was 1.9% and 2.3% at 3–6 and 7–12 months, respectively. Of the aneurysms, 75.0% and 65.6% showed adequate occlusion at 3–6 and 7–12 months, respectively. pCONUS offers a safe and reasonably effective treatment of WNBAs, demonstrated by acceptable adequate aneurysm occlusion and low rates of adverse neurologic events.

This study provides first data about the spatial variability of fMRI sensorimotor localizations when investigating the same subjects at different fMRI sites. Results are comparable to a previous patient study. We found a median between-site variability of about 6 mm independent of task (motor or sensory) and experimental standardization (high or low). An intraclass correlation coefficient analysis using data quality measures indicated a major influence of the fMRI site on variability. In accordance with this, within-site localization variability was considerably lower (about 3 mm). We conclude that the fMRI site is a considerable confound for localization of brain activity. However, when performed by experienced clinical fMRI experts, brain pathology does not seem to have a relevant impact on the reliability of fMRI localizations. Hum Brain Mapp 37:2151-2160, 2016. © 2016 Wiley Periodicals, Inc.

The term "paraspinal arteriovenous shunts" (PAVSs) summarizes an inhomogeneous variety of rare vascular disorders. PAVSs have been observed as congenital or acquired lesions. The clinical course of PAVSs may be asymptomatic or present with life-threatening symptoms. Based on a collection of individual cases from three institutions and a literature evaluation, we propose the following classification: PAVSs that are part of a genetic syndrome are separated from "isolated" PAVSs. Isolated PAVSs are subdivided into "acquired", "traumatic" and "congenital" without an identifiable genetic hereditary disorder. The subgroups are differentiated by the route of venous drainage, being exclusively extraspinal or involving intraspinal veins. PAVSs associated to a genetic syndrome may either have a metameric link or occur together with a systemic genetic disorder. Again extra-vs intraspinal venous drainage is differentiated. The indication for treatment is based on individual circumstances (e.g. myelon compression, vascular bruit, high volume output cardiac failure). Most PAVSs can be treated by endovascular means using detachable coils, liquid embolic agents or stents and derivates.

Highlights • We assessed midbrain–hindbrain in a large series of cortical malformation patients. • Midbrain–hindbrain malformations are commonly linked to cortical malformations. • Midbrain–hindbrain malformations are associated with severe clinical phenotype., Summary Midbrain–hindbrain malformations (MHM) may coexist with malformations of cortical development (MCD). This study represents a first attempt to investigate the spectrum of MHM in a large series of patients with MCD and epilepsy. We aimed to explore specific associations between MCD and MHM and to compare two groups of patients: MCD with MHM (wMHM) and MCD without MHM (w/oMHM) with regard to clinical and imaging features. Two hundred and twenty patients (116 women/104 men, median age 28 years, interquartile range 20–44 years at the time of assessment) with MCD and epilepsy were identified at the Departments of Neurology and Pediatrics, Innsbruck Medical University, Austria. All underwent high-resolution MRIs (1.5-T) between 01.01.2002 and 31.12.2011. Midbrain–hindbrain structures were visually assessed by three independent raters. MHM were seen in 17% (38/220) of patients. The rate of patients wMHM and w/oMHM differed significantly (p = 0.004) in three categories of MCD (category I – to abnormal neuronal proliferation; category II – to abnormal neuronal migration; and category III – due to abnormal neuronal late migration/organization): MCD due to abnormal neuronal migration (31%) and organization (23%) were more commonly associated with MHM compared to those with MCD due to abnormal neuronal proliferation (9%). Extensive bilateral MCD were seen more often in patients wMHM compared to those w/oMHM (63% vs. 36%; p = 0.004). In wMHM group compared to w/oMHM group there were higher rates of callosal dysgenesis (26% vs. 4%; p

To investigate intersite variability of clinical functional magnetic resonance (MR) imaging, including influence of task standardization on variability and use of various parameters to inform the clinician whether the reliability of a given functional localization is high or low.Local ethics committees approved the study; all participants gave written informed consent. Eight women and seven men (mean age, 40 years) were prospectively investigated at three experienced functional MR sites with 1.5- (two sites) or 3-T (one site) MR. Nonstandardized motor and highly standardized somatosensory versions of a frequently requested clinical task (localization of the primary sensorimotor cortex) were used. Perirolandic functional MR variability was assessed (peak activation variability, center of mass [COM] variability, intraclass correlation values, overlap ratio [OR], activation size ratio). Data quality measures for functional MR images included percentage signal change (PSC), contrast-to-noise ratio (CNR), and head motion parameters. Data were analyzed with analysis of variance and a correlation analysis.Localization of perirolandic functional MR activity differed by 8 mm (peak activity) and 6 mm (COM activity) among sites. Peak activation varied up to 16.5 mm (COM range, 0.4-16.5 mm) and 45.5 mm (peak activity range, 1.8-45.5 mm). Signal strength (PSC, CNR) was significantly lower for the somatosensory task (mean PSC, 1.0% ± 0.5 [standard deviation]; mean CNR, 1.2 ± 0.4) than for the motor task (mean PSC, 2.4% ± 0.8; mean CNR, 2.9 ± 0.9) (P.001, both). Intersite variability was larger with low signal strength (negative correlations between signal strength and peak activation variability) even if the task was highly standardized (mean OR, 22.0% ± 18.9 [somatosensory task] and 50.1% ± 18.8 [motor task]).Clinical practice and clinical functional MR biomarker studies should consider that the center of task-specific brain activation may vary up to 16.5 mm, with the investigating site, and should maximize functional MR signal strength and evaluate reliability of local results with PSC and CNR.

The purpose of this study was to determine potential effects of isometric non-machine-based training on the cross-sectional area (CSA) of the paravertebral muscles in volunteers who were participants in a prevention program. An increase in the CSA of back muscles after various machine-based exercises have been reported but non-machine-based training programs have not been adressed before. In the study 14 volunteers, who were participants of a company internal prevention program, underwent a magnetic resonance (MR) examination before and after a 3 months training program to improve back muscle strength. The MRI protocol consisted of T1-weighted and T2-weighted images aligned to the intervertebral disc spaces. The CSAs of the erector spinae and quadratus lumborum muscles were assessed twice by 2 operators at the levels L3/4, L4/5 and L5/S1. Out of 14 subjects 11 completed the training. The recorded CSA values exhibited an intrarater and intrarater correlation coefficient ranging from 0.949 to 0.989. There was an increase in CSA in all subjects after the training period (mean increase 8%). A 3-month isometric training program is sufficient to effect measurable increases in back muscles volume. The study demonstrated the usefulness of MRI to quantify such changes as a measure of training efficacy and compliance into the training program. These results represent a rationale for further studies to determine the effect of different training methods on the CSA of back muscles and to correlate structural changes with clinical symptoms in chronic low back pain syndrome.

Objectives: 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. Methods: 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%). Results: 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%]). Conclusions: About a third of patients with malformations of cortical development had hippocampal abnormalities. Patients with hypoplastic hippocampus had the most severe clinical phenotype.

Caffeine has been consumed since ancient times due to its beneficial effects on attention, psychomotor function, and memory. Caffeine exerts its action mainly through an antagonism of cerebral adenosine receptors, although there are important secondary effects on other neurotransmitter systems. Recently, functional MRI (fMRI) entered the field of neuropharmacology to explore the intracerebral sites and mechanisms of action of pharmacological agents. However, as caffeine possesses vasoconstrictive properties it may interfere with the mechanisms underlying the functional contrast in fMRI. Yet, only a limited number of studies dealt with the effect of caffeine on measures in fMRI. Even fewer neuroimaging studies examined the effects that caffeine exerts on cognition: Portas and colleagues used fMRI in an attentional task under different levels of arousal (sleep deprivation or caffeine administration), concluding that the thalamus is involved in mediating the interaction of attention and arousal. Bendlin and colleagues found caffeine to stabilize the extent of neuronal activation in repetitive word stem completion, counteracting the general task practice effect. Recently, Koppelstaetter and colleagues assessed the effect of caffeine on verbal working memory demonstrating a modulatory effect of caffeine on brain regions (medial frontopolar and anterior cingulate cortex) that have been associated with attentional and executive functions. This review surveys and discusses neuroimaging findings on 1) how caffeine affects the contrast underlying fMRI techniques, particularly the blood oxygen level dependent contrast (BOLD fMRI), and 2) how caffeine operates on neuronal activity underlying cognition, to understand the effect of caffeine on behavior and its neurobiological underpinnings.

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.

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.

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, p0.001) 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.

Transmeatal cochlear laser (TCL) treatment has recently been proposed as a therapeutic procedure for cochlear dysfunction such as chronic cochlear tinnitus or sensorineural hearing loss. The aim of this study was to investigate whether TLC has any influence on the central nervous system using functional MRI with healthy young adults. The laser stimulation device was placed on the tympanic membrane of both ears. A laser stimulation run and a placebo run were performed in random order. The participants were unable to differentiate between verum and placebo stimulation. In the comparison of verum to placebo runs, we observed significant activations within the left superior frontal gyrus, the right middle and medial frontal gyrus, the right superior parietal lobule, the left superior occipital gyrus, the precuneus and cuneus bilaterally, the right anterior and the left and right middle and posterior cingulate gyrus and the left thalamus. This network of brain areas corresponds well to results from previous PET studies of patients with tinnitus. Though TCL seems to have a clinically measurable effect on the central nervous system the neurophysiological mechanism leading to the observed activated neuronal network remains unknown.

This study provides first data about the spatial variability of fMRI sensorimotor localizations when investigating the same subjects at different fMRI sites. Results are comparable to a previous patient study. We found a median between‐site variability of about 6 mm independent of task (motor or sensory) and experimental standardization (high or low). An intraclass correlation coefficient analysis using data quality measures indicated a major influence of the fMRI site on variability. In accordance with this, within‐site localization variability was considerably lower (about 3 mm). We conclude that the fMRI site is a considerable confound for localization of brain activity. However, when performed by experienced clinical fMRI experts, brain pathology does not seem to have a relevant impact on the reliability of fMRI localizations. Hum Brain Mapp 37:2151–2160, 2016. © 2016 Wiley Periodicals, Inc.

The purpose of this study was to investigate the sensorimotor cortex response to plantar vibrotactile stimulation using a newly developed MRI compatible vibration device. Ten healthy subjects (20-45 years) were investigated. Vibrotactile stimulation of the sole of the foot with a frequency of 50 Hz and a displacement of 1 mm was performed during fMRI (echo-planar imaging sequence at 1.5 T) using an MRI compatible moving magnet actuator that is able to produce vibration frequencies between 0 and 100 Hz and displacement amplitudes between 0 and 4 mm. The fMRI measurement during vibrotactile stimulation of the right foot revealed brain activation contralaterally within the primary sensorimotor cortex, bilaterally within the secondary somatosensory cortex, bilaterally within the superior temporal, inferior parietal, and posterior insular region, bilaterally within the anterior and posterior cingular gyrus, bilaterally within the thalamus and caudate nucleus, contralaterally within the lentiform nucleus, and bilaterally within the anterior and posterior cerebellar lobe. The advantages of the new MRI compatible vibration device include effective transmission of the stimulus and controlled vibration amplitudes, frequencies, and intensities. The results indicate that plantar vibration can be a suitable paradigm to observe activation within the sensorimotor network in fMRI. Furthermore, the method may be used to determine the optimal responsiveness of the individual sensorimotor network.

Purpose To study cerebral responses evoked from mechanoreceptors in the human foot sole using a computer-controlled vibrotactile stimulation system. Materials and Methods The stimulation system consisted of two stationary moving magnet actuators with indentors to gently contact and vibrate the foot sole during functional MRI (fMRI) experiments. To allow independent settings of contact force (0–20 N) and intensity of vibration (frequency range = 20–100 Hz) the actuators were controlled by a digital servo loop. For fMRI experiments with complex stimulus protocols, both vibrating probes were further operated under supervisory control. Results The MR compatibility of this electromagnetic system was tested in a 1.5T scanner with an actively shielded magnet (Siemens Magnetom Sonata). Blood oxygenation level-dependent (BOLD) responses were detected in the contralateral left pre- and postcentral gyrus, bilaterally within the secondary somatosensory cortex, bilaterally within the supplementary motor cortex, and bilaterally within the anterior cingular gyrus. Conclusion This stimulation device provides a new tool for identifying cerebral structures that convey sensory information from the foot region, which is of promising diagnostic value, particularly for assessing sensorimotor deficits resulting from brain lesions. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc.

CT perfusion imaging constitutes an important contribution to the early diagnosis of acute stroke. Cerebral blood flow (CBF), cerebral blood volume (CBV) and time-to-peak (TTP) maps are used to estimate the severity of cerebral damage after acute ischemia. We introduce functional cluster analysis as a new tool to evaluate CT perfusion in order to identify normal brain, ischemic tissue and large vessels. CBF, CBV and TTP maps represent the basis for cluster analysis applying a partitioning (k-means) and density-based (density-based spatial clustering of applications with noise, DBSCAN) paradigm. In patients with transient ischemic attack and stroke, cluster analysis identified brain areas with distinct hemodynamic properties (gray and white matter) and segmented territorial ischemia. CBF, CBV and TTP values of each detected cluster were displayed. Our preliminary results indicate that functional cluster analysis of CT perfusion maps may become a helpful tool for the interpretation of perfusion maps and provide a rapid means for the segmentation of ischemic tissue.

Zusammenfassung Grundlegende wissenschaftliche Untersuchungen in der Akupunktur sind bisher durch das Fehlen einer rigiden Kontrollbedingung schwierig. Als Kontrolle wurden Nichtakupunkturpunkte und Placebonadeln verwendet. Bei ersteren ist nicht gesichert, dass von ihnen nicht doch physiologische Wechselwirkungen ausgehen und im Ergebnis aufscheinen. Placebonadeln hingegen konnen von Verumakupunktur durch das Fehlen eines DeQi-Gefuhls unterschieden und erkannt werden. Eine Losung kann die Laserakupunktur sein. Hierbei wurden mittels funktioneller Magnetresonanztomographie (f-MRT) vergleichbare und reproduzierbare Ergebnisse wie bei Nadelakupunktur nachgewiesen. Gleichzeitig erlaubt der Laser ein Placebodesign, das vom Patienten/Probanden nicht vom Verum zu unterscheiden ist und keine physiologische Wirkung entfaltet. Durch Verwendung neuartiger Mehr-Kanal-Akupunkturlasergerate mit Computersteuerung konnte auch ein doppelt verblindetes Studiendesign ermoglicht werden.

Language deficits in 10 patients with medically intractable left-sided temporal lobe epilepsy prior to and following selective amygdalohippocampectomy are described. Preoperatively, a pattern of minor linguistic deficits was observed in three patients; isolated minor naming deficits were detectable in one additional patient. Three months after surgery, six patients' linguistic functions were unchanged, whereas in four patients, a significant decline in linguistic functions could be observed. All four patients revealed a very similar language syndrome characterized by reduced language comprehension and fluency, well-articulated speech, frequent word-finding difficulties, circumlocutions, and semantic paraphasias in the absence of any phonological disorder. These deficits remained stable during the 12-month follow-up period. However, magnetic resonance imaging did not show any neocortical lesions outside the resection area. Possible explanations for these findings include neuronal cell loss and deafferentiation in cortical areas, disruption of the basal temporal language area pathways, reorganization of the language network in chronic temporal lobe epilepsy, and neocortical lesions due to the surgical intervention. Furthermore, correlations between linguistic and demographic data for our patients suggest that patients older at epilepsy onset are at greater risk for developing postoperative language deficits.

OBJECTIVE We sought to evaluate the early angiographic and clinical outcomes of the first session of endovascular coil occlusion of a large number of patients with intracranial aneurysms treated by five neurointerventionalists during a decade at a single center. METHODS We performed retrospective analyses of pre- and postprocedural angiographic studies and early clinical outcomes. Enrolled patients underwent endovascular treatment of intracranial aneurysms with detachable coils. RESULTS A total of 1811 aneurysms in 1579 patients were treated with coil occlusion. Of these, 90 to 100% occlusion of 86.5% of the aneurysms was achieved. In 82.3% of the procedures, no complications occurred. The clinical outcome profile at primary discharge according to the Glasgow Outcome Scale was as follows: Grade V, 74.6%; Grade IV, 6.7%; Grade III, 11.1%; Grade II, 3.1%; and Grade I, 4.5%. In patients with large aneurysms with wide necks, a lower occlusion rate and an increased complication rate were encountered. The use of three-dimensional and fibered coils resulted in higher occlusion rates. Balloon remodeling and stent deployment increased the complication rate. Previous aneurysm rupture, procedural complications, and vasospasm correlated with poor outcome. Of the patients in poor grade after aneurysm rupture, 42% recovered to Glasgow Outcome Scale Grade IV or V, as opposed to 90% of patients who were treated for unruptured aneurysms. The ischemic complication rate was 9%, and the hemorrhagic complication rate was 3%. The early procedural morbidity rate was 5.3%, and the procedural mortality rate was 1.5%. The management mortality rate was 4.4%. CONCLUSION These data confirm the safety and efficacy of endovascular coil occlusion for patients with intracranial aneurysms.

Hintergrund: Die funktionelle Kernspintomographie (f-MRT) ermoglicht es, funktionelle Aktivierungen des Gehirns nicht-invasiv bildgebend nachzuweisen und diese Funktionen bestimmten Hirnarealen zuzuordnen. Anhand zweier Laserakupunkturstudien an den Punkten Bl 67 und Gb 43 sollte mittels f-MRT die Akupunkturwirkung auf das menschliche Gehirn untersucht werden. Methode: An den Studien nahmen 10 bzw. 11 gesunde mannliche Probanden teil. Es wurden am linken Punkt Bl 67 und an beiden Punkten Gb 43 sowohl Laserakupunktur als auch Placeboakupunktur durchgefuhrt. Weiterhin wurde ein NichtAkupunkturpunkt untersucht. Alle Versuche wurden an einem 1,5 Tesla MR-Scanner durchgefuhrt. Die Auswertung erfolgte mit der Software SPM99. Ergebnisse: Die Laserakupunktur an den Punkten Bl 67 und Gb 43 bewirkte jeweils ipsilaterale Aktivierungen in den Brodmann-Arealen (BA) 18 und 19 (Bl 67), 40 und 22 (Gb 43 re.), Nucleus ruber und Substantia nigra (Gb 43 li.) sowie Aktivierungen des ipsilateralen Hirnstamms (Gb 43 re./li.). Die Placebountersuchung und die Untersuchung an einem Nicht-Akupunkturpunkt fuhrten zu keinen Aktivierungen. Schlussfolgerung: Wir konnten zeigen, dass die Laserakupunktur an den Punkten Bl 67 und Gb 43 zu spezifischen ipsilateralen Aktivierungen von kortikalen und subkor-tikalen Hirnarealen fuhrt. Der Vergleich mit einer vorhergehenden Nadelakupunkturstudie zeigt, dass Laserakupunktur einen ahnlichen Einfluss auf den zerebralen Kortex aufweist wie Nadelakupunktur. Dies ist ein weiterer Hinweis fur die Effektivitat und das therapeutische Potenzial der Laserakupunktur. Weiterhin zeigen die Ergebnisse, dass die f-MRT ein hilfreiches Mittel ist, um die therapeutischen Wirkungen der Akupunktur zu untersuchen und besser verstehen zu konnen.

To evaluate biochemical changes in contrast-enhancing multiple sclerosis (MS) lesions, we examined 14 patients with relapsing-remitting MS at acute clinical exacerbation with the help of contrast-enhanced magnetic resonance imaging (MRI) and 1H magnetic resonance spectroscopic imaging (1H MRSI). Using a 1.5-tesla MR system (Magnetom Vision, Siemens, Germany), we followed 29 contrast-enhancing and 24 nonenhancing MS lesions as well as normal-appearing white matter (NAWM) before and during high-dose methylprednisolone (HDMP) therapy. Metabolite ratios of N-acetylaspartate (NAA), choline (Cho), creatine (Cr), and lactate (Lac) were calculated. A transient decrease in contrast enhancement under HDMP therapy was observed. Both groups of MS lesions showed significantly decreased NAA to Cr ratios compared to NAWM with no changes in time. Baseline 1H MRSI revealed significantly increased Cho to Cr ratios in the contrast-enhancing MS lesions (1.13 +/- 0.25) compared to the nonenhancing MS lesions (0.85 +/- 0.26, P0.001) and NAWM (0.97 +/- 0.22, P = 0.015). Both the contrast-enhancing and the nonenhancing MS lesions exhibited a significant increase in Cho to Cr ratios from the second to the third 1H MRSI. We identified resonances of lactate in both groups of MS lesions and NAWM without any significant group differences or changes over time. 1H MRSI provides additional information that help to estimate macrophages' activity, cell membrane activation, and neuronal impairment within MS lesions. We believe that combined contrast-enhanced MRI and 1H MRSI may help to further investigate inflammatory processes within active MS lesions and should be employed more frequently to the research on therapy effects in MS.

Verbal memory deficits are among the most severe cognitive deficits observed in patients with schizophrenia. This study examined patterns of brain activity during episodic encoding and recognition of words in patients with schizophrenia.Functional magnetic resonance imaging (fMRI) was used to study regional brain activation in 10 healthy male comparison subjects and 10 male outpatients with schizophrenia during performance of a modified version of the words subtest of Warrington's Recognition Memory Test.Despite having intact performance in word recognition, the patients with schizophrenia had less activation of the right dorsolateral and anterior prefrontal cortex, right anterior cingulate, and left lateral temporal cortex during word encoding, compared with the healthy comparison subjects. During word recognition, the patients had impairments in activation of the bilateral dorsolateral prefrontal and lateral temporal cortices.Schizophrenia was associated with attenuated frontotemporal activation during episodic encoding and recognition of words. These results from an fMRI study replicate earlier findings derived from a positron emission tomography study.

Functional magnetic resonance imaging was used to compare cortical activation patterns in healthy volunteers with those in patients with schizophrenia during a modified verbal Stroop task. Healthy subjects (n=13) and patients with schizophrenia (n=13) on stable antipsychotic treatment, matched on demographic variables, were included. Patients were preselected on the basis of good performance on a selective attention test. Patients with schizophrenia showed a significantly increased pattern of activation in the left and right inferior frontal cortex and the anterior cingulate cortex. A significant negative correlation between activation of the left prefrontal cortex and accuracy in the modified Stroop test was observed for healthy controls but not schizophrenia patients. Although both groups recruited the prefrontal cortex during the modified Stroop task, for the schizophrenia patients this activation was bilateral, whereas for the controls this activation was primarily in the left hemisphere, suggesting that patients with schizophrenia recruited more prefrontal regions to perform the task with the same accuracy as healthy controls. Our findings of increased activity across multiple areas of the brain, including dorsolateral frontal cortex and anterior cingulate, in patients with schizophrenia who perform relatively well on a task of selective attention give further evidence that task performance may be a confounding factor in the interpretation of neuroimaging results.

The purpose of this study was to investigate the fMRI response of the sensorimotor cortex to a vibration paradigm produced by a novel vibrotactile stimulator. Fifteen contiguous slices covering the sensorimotor cortex parallel to the anterior (AC) and posterior commissure (PC) line were obtained with echoplanar magnetic resonance imaging at 1.5T. Cortical activity in ten healthy subjects (20-45 years) was investigated during vibration (50 Hz) of the palm of the right hand and compared to a finger-to-thumb tapping paradigm. For the vibration paradigm a mechanically driven vibration head was mounted on the palm of the right hand. The new vibration device produces vibration frequencies (1-130 Hz) and displacement amplitudes (0.5-4 mm) suitable to elicit the tonic vibratory reflex. The fMRI measurement during vibratory stimulation revealed activation in the pre- and postcentral gyrus in all subjects. These activations were comparable to the finger-to-thumb tapping paradigm. The advantages of the new MR compatible vibration device include effective transmission of the stimulus and controlled vibration frequencies and intensities. These preliminary fMRI results indicate that vibration can be an alternative paradigm for the evaluation of sensory and motor functions in patients unable to perform active motor paradigms.

Magnetic resonance became an important tool for the differential diagnosis of dementia. Magnetic resonance imaging is the preferred method to exclude treatable entities accompagnied by dementing symptoms. New techniques including diffusion and perfusion magnetic resonance imaging are helpful for the differentiation between vascular dementia and degenerative disorders. Magnetic Resonance spectroscopy evolves as a tool for the diagnosis of different forms of degenerative dementia. Multimodal magnetic resonance holds promise to diagnose Alzheimer's disease at early clinical stages and to monitor the progression of the disease.

The aim of the study was to implement a vibrotactile stimulator using functional magnetic resonance imaging (fMRI). A fMRI compatible vibration device consisting of a pneumatically driven dual membrane pump was developed. Brain activation during 50 Hz vibrotactile stimulation of the right hand-palm were compared to a right 2 Hz finger-to-thumb-tapping in ten healthy, right-handed male volunteers. The vibration paradigm showed a comparable activation pattern with respect to finger-to-thumb-tapping in the contralateral perirolandic region. The advantage of the new vibration device is the possibility to elicit the vibratory-tonic-reflex due to the higher amplitude in context with the high frequency than established devices. This reflex is considered to be responsible for the activation in the primary motor cortex and the current paradigm might prove useful in future neurosurgical planning in patients with perirolandic lesions.

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.

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.

Anesthesia for diagnostic procedures, e.g., MRI measurements, has increasingly used sevoflurane and nitrous oxide in recent years. Sevoflurane and nitrous oxide are known cerebrovasodilatators, however, which potentially interferes with MRI examination of cerebral hemodynamics. To compare the effects of relevant equianesthetic concentrations (0.4 MAC) of both drugs on regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) we used contrast-enhanced magnetic resonance imaging (MRI) perfusion measurement, which has the advantage of providing regional anatomic resolution. Sevoflurane increased rCBF more than did nitrous oxide in all regions except in parietal and frontal gray matter. Nitrous oxide, by contrast, increased rCBV in most of the gray matter regions more than did sevoflurane. In summary we show that, in contrast to nitrous oxide, sevoflurane supratentorially reversed the anterior-posterior gradient in rCBF and typically redistributed rCBF to infratentorial gray matter. In contrast, nitrous oxide increased rCBV more than did sevoflurane. Both inhalational anesthetics had a drug-specific influence on cerebral hemodynamics, which is of importance when interpreting MRI studies of cerebral hemodynamics in anesthetized patients.

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.

Purpose: The purpose of this work was to investigate systematic errors in dynamic contrast-enhanced MR perfusion studies due to peak saturation of the arterial input function (AIF) and to introduce a simple correction algorithm. Method: Computer simulations were performed to evaluate the influence of AIF peak saturation and to demonstrate the effectiveness of the presented correction algorithm. To compare the computer simulations with real MR data, MR perfusion measurements were performed on volunteers. Results: The computer simulations show that AIF peak saturation leads to a systematic overestimation of cerebral blood volume (CBV) and cerebral blood flow (CBF) values, which was confirmed by comparing the obtained MR data with PET results. With use of an improved calculation algorithm correcting for AIF peak saturation, a significant improvement of the obtained CBV and CBF values could be demonstrated. Conclusion: Our results suggest that AIF peak saturation leads to a significant systematic error in the determination of CBV and CBF values and has necessarily to be taken into account for dynamic contrast-enhanced MR perfusion studies.

The use of sevoflurane is favored for its rapid onset and offset of anesthesia as well as good intraoperative titratability of the anesthetic. With regard to neuroanesthesia, the reported effects of sevoflurane on cerebral hemodynamics and cerebrospinal fluid dynamics are inconsistent. We used phase-contrast magnetic resonance imaging measurement of systolic cerebrospinal fluid peak velocity (CSFVPeak) to evaluate the effect of sevoflurane on cerebral compliance in healthy individuals. During administration of 0.4 MAC sevoflurane, systolic CSFVPeak in the aqueduct of Sylvius remained unchanged, thereby indicating unaffected cerebral compliance: (CSFVPeak baseline: -3.1 +/- 1.0 cm/s vs. sevoflurane: -3.0 +/- 1.2 cm/s). We conclude that low-dose administration of sevoflurane does not influence cerebral compliance in healthy individuals, but the influence of coexisting intracranial pathology or comedications on cerebral compliance requires further clinical investigation.

Purpose: To report a case of cerebral ischemia confirmed by magnetic resonance imaging after successful cardiopulmonary resuscitation (CPR) complicated by acute respiratory injury. Materials and methods: After 4 min of cardiac arrest, followed by 3 min of basic life support CPR, a female pig weighing 38 kg received every 5 min vasopressin (0.4, 0.4 and 0.8 U/kg). After 22 min of cardiac arrest, including 18 min of CPR, one defibrillation attempt employing 100 J resulted in return of spontaneous circulation. Neurological evaluation was performed 24 and 96 h after successful CPR. Magnetic resonance imaging was carried out 4 days after CPR using a clinical 1.5 T scanner. The magnetic resonance imaging protocol consisted of fast spinecho T2-weighted, as well as spinecho T1-weighted imaging of the brain. Results: CPR with vasopressin resulted in excellent coronary perfusion pressure ranging between 35 and 60 mmHg throughout CPR. Eight minutes after initiation of chest compressions, bleeding out of the tracheal tube occurred. This was later confirmed as originating from bilateral bloody pulmonary infiltrations, resulting in acute respiratory injury in the post-resuscitation phase. Ninety-six hours after successful CPR, magnetic resonance imaging revealed bilateral diffuse cerebral vasogenic edema. Conclusion: Although excellent coronary perfusion pressure renders a return of spontaneous circulation more likely, complications such as acute respiratory injury in the post-resuscitation phase have to be managed carefully in order to ensure good neurological recovery from cardiac arrest.

The effects of embryonic neural transplantation in experimental models of neurodegenerative disorders are commonly assessed by behavioral tests and postmortem neurochemical or anatomical analysis. The purpose of the present study was to evaluate embryonic neuronal grafts in a novel rat model of multiple system atrophy (MSA) with the help of in vivo magnetic resonance imaging (MRI) and to correlate imaging with histological parameters. Striatonigral double lesions were created in male Wistar rats by unilateral intrastriatal injection of 3-nitropropionic acid (3-NP). Seven weeks following lesion surgery animals were divided into four transplantation groups receiving either pure mesencephalic, pure striatal, mesencephalic-striatal cografts, or sham grafts. In vivo structural imaging was performed 21 weeks after transplantation using a whole body 1.5 Tesla MR scanner. The imaging protocol comprised T2-weighted TSE and T1-weighted TIR sequences. Immunohistochemistry using DARPP-32 as striatal marker and tyrosinhydroxylase as marker for nigral neurons was performed for correlation analysis of imaging and histological parameters. The sensitivity of graft detection by in vivo MRI was 100%. The graft tissue was clearly demarcated from the remaining striatal tissue in both T2- and T1-weighted sequences. Morphometrically, cross-sectional areas of the grafts and spared intact striatum as defined by immunohistochemistry correlated significantly with measurements obtained by in vivo MRI. In conclusion, we were able to evaluate in vivo both lesion-induced damage and graft size in a 3-NP rat model of MSA using a conventional whole body 1.5 Tesla MRI scanner. Additionally, we obtained an excellent correlation between MRI and histological measurements.

Inhaled anesthetics exert metabolically mediated effects on cerebral blood vessels both directly and indirectly. We investigated the effects of a 0.4 minimum alveolar subanesthetic concentration of sevoflurane on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), regional cerebrovascular resistance (rCVR), and regional mean transit time (rMTT) in volunteers by means of contrast-enhanced magnetic resonance imaging perfusion measurement. Sevoflurane increased rCBF by 16% to 55% (control, 55. 03 +/- 0.33 to 148.83 +/- 1.9 mL. 100 g(-1). min(-1); sevoflurane, 71.75 +/- 0.36 to 193.26 +/- 2.14 mL. 100 g(-1). min(-1)) and rCBV by 7% to 39% (control, 4.66 +/- 0.03 to 10.04 +/- 0.12 mL/100 g; sevoflurane, 5.04 +/- 0.03 to 13.6 +/- 0.15 mL/100 g); however, sevoflurane decreased rMTT by 7% to 18% (control, 3.75 +/- 0.04 to 5. 39 +/- 0.04 s; sevoflurane, 3.4 +/- 0.03 to 4.44 +/- 0.03 s) and rCVR by 22% to 36% (control, 0.74 +/- 0.01 to 1.9 +/- 0.2 mm Hg/[mL. 100 g(-1). min(-1)]; sevoflurane, 0.54 +/- 0.01 to 1.41 +/- 0.01 mm Hg/[mL. 100 g(-1). min(-1)]). Interhemispheric differences in rCBF, rCBV, and rCVR were markedly reduced after the administration of sevoflurane. These findings are consistent with the known direct vasodilating effect of sevoflurane. The decrease in rMTT further shows that rCBF increases more than does rCBV. Furthermore, we can show that the observed increase in rCBF during inhalation of sevoflurane is not explained by vasodilation alone.

Remifentanil, a short-acting potent m-opioid agonist proposed for intraoperative analgesia but also for postoperative pain therapy, has not been investigated with regard to the effects of the drug on cerebral capacity in awake humans. We assessed cerebral capacity noninvasively by means of phase-contrast magnetic resonance imaging measurement of systolic cerebrospinal fluid peak velocity in the aqueduct of Sylvius before and during infusion of remifentanil (0.1 mg z kg 21 z min 21 IV) in normocapnic humans. Remifentanil had no significant effect on systolic cerebrospinal fluid peak velocity as compared with baseline (mean 6 sd): baseline, 24.3 6 1.3 cm/s versus remifentanil (0.1 mg z kg 21 z min 21 ): 24.7 6 1.0 cm/s. Small-dose remifentanil (0.1 mg z kg 21 z min 21 ) did not influence cerebral capacity in healthy, awake volunteers free of intracranial pathology. Implications: Knowledge about the influence of remifentanil on cerebral capacity is crucial before routine use of the drug in neuroanesthesia. Thus, we assessed the influence of remifentanil on cerebral capacity noninvasively by means of phase-contrast magnetic resonance imaging measurement of systolic cerebrospinal fluid peak velocity in the aqueduct of Sylvius in humans. (Anesth Analg 2000;90:609 ‐13)

Propionic acidemia is an inherited disorder caused by a defect of propionyl CoA carboxylase. Untreated, propionic acidemia leads to metabolic decompensation and toxic encephalopathy. We report on the magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) findings in five children who were properly treated by protein restriction and carnitine supplementation, during a phase of clinically and metabolically stable conditions. The examinations were performed on a whole-body 1.5 T scanner. During the observation period, from 1992 to 1996 we employed long echo time single-voxel spectroscopy and chemical shift imaging in addition to a conventional MRI protocol. The two children with the longest delay before onset of therapy showed cerebral atrophy. MRS yielded elevated lactate peaks in four of the children. These results indicate that MRS can detect metabolic alterations in the brains of children with propionic acidemia during metabolically stable conditions. The presence of lactate could be caused by hampered aerobic oxidation within the citrate cycle due to intracellular elevated propionic metabolites.

Contrast‐enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased mean airway pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive airway pressure (CPAP) (12 cm H2O) to study the effects of increased mean airway pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when mean airway pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast‐enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive airway pressure. Hum. Brain Mapping 11:214–222, 2000. © 2000 Wiley‐Liss, Inc.

We evaluated the usefulness and reliability of intraventricular virtual neuroendoscopy based on a comparative anatomical study. Virtual intraventricular endoscopic images were calculated from 3D magnetic resonance images in five anatomic specimens. Contiguous 1.2 mm slices of the specimen heads were acquired at a 1.5 T MR scanner using a 3D-gradient echo sequence. The images were then transferred to an independent 3D-workstation (Sun Spark 20). After scanning the specimen heads, real endoscopy within the cerebral ventricles of these brains was performed with a standard rod lens system. Comparison between real and virtual endoscopic views of the intraventricular topography was based on the same anatomical reference and landmarks. Acquisition of MR data and virtual image post-processing have been possible in all specimens. The virtual endoscopic images of the ventricles were comparable to the intraventricular views obtained by a standard rod lens system. Virtual intraventricular neuroendoscopy can be employed for planning and simulating neuroendoscopic procedures. It enables the neurosurgeon to simulate the endoscopic procedure within the cerebral ventricles on the basis of the patient's individual anatomy prior to surgery.

Background Cerebrospinal fluid (CSF) outflow to intra- and extracranial subarachnoid spaces caused by arterial inflow to the brain predominantly compensates systolic increases in cerebral blood volume. Phase-contrast magnetic resonance imaging is a new tool for noninvasive assessment of CSF displacement by measuring CSF peak velocity (CSFV(Peak)). The authors tested this new tool in an experimental human model of increased intracranial pressure and reduced cerebral capacity by means of continuous positive airway pressure (CPAP) breathing. Methods The authors investigated systolic CSFV(Peak) in the aqueduct of Sylvius in 11 awake, normocapnic (end-tidal carbon dioxide [ET(CO2)] = 40 mmHg) volunteers without CPAP and at two different CPAP levels (6 and 12 cm H2O) by means of electroencephalography-gated phase-contrast magnetic resonance imaging. Results Administration of 6 cm H2O CPAP did not change systolic CSFV(Peak) (-4.9+/-2.8 cm/s vs. control: -5.1+/-2.7 cm/s), whereas 12 cm H2O CPAP significantly reduced systolic CSFV(Peak) (-4.0+/-1.8 cm/s vs. control: -5.1+/-2.7 cm/s; P < 0.05). Conclusions These findings in awake volunteers show that monitoring CSFV(Peak) in the aqueduct of Sylvius is a sensitive method for detecting even minor impairment of cerebral capacity caused by experimentally induced increases in intracranial pressure.

Intravascular pressure measurements are considered useful for the monitoring and assessment of endovascular treatment effects in intracranial vascular malformations. Experimental data on the accuracy of these measurements are limited. A flow phantom with defined intraluminal pressures and pulsatility flow waveforms was used in this study. Microcatheters commercially available for neuroendovascular procedures (length 140-155 cm), with different outer (0.5-0.83 mm) and inner (0.3-0.53 mm) diameters, were introduced into the phantom in the direction of flow. In a static experiment, pressure values from 0 to 75 mmHg were applied, and in the dynamic part of the experiment mean pressure values from 25 to 65 mmHg, with a pulsatile amplitude from 70 to 170 mmHg were employed. In the static experiment, there was a linear relationship between the pressure values obtained through the microcatheters and the local transducer of the flow phantom. The pulsatile experiments showed increased damping of the pressure waveforms with decreasing inner diameter of the microcatheters. However, the mean pressure values remained accurate. This experimental study has shown that mean pressure values can be accurately measured through microcatheters from 0.3-0.5 mm inner diameter and more than 140 cm in length. In vivo pressure measurements during interventional procedures are therefore reproducible and can be used for monitoring of embolization effects in patients.

The purpose of this retrospective study was to demonstrate the MRI features of cerebral manifestations in patients with fat embolism syndromes in comparison with cerebral CT (CCT). Magnetic resonance imaging was performed according to standard protocols revealing multiple small non-confluent hyperintense intracerebral lesions larger than 2 mm on proton-density and T2-weighted images to various extents in three of four patients with clinically suspected cerebral fat embolism. Cerebral CT was negative in all patients. Our findings confirm that MRI can detect cerebral fat embolism with a higher sensitivity than CCT. Thus, MRI should be the first choice for imaging of cerebral fat embolism.

The decrease in intracellular creatine concentration observed in a number of muscle diseases may deplete energy homeostasis and may, therefore, be one of the factors determining and/or aggravating muscle weakness and degeneration. Two hypotheses are put forward in the present communication to explain: (i) the mechanisms leading to the disturbances in creatine metabolism found in various muscle diseases; and (ii) the potential of oral creatine supplementation in alleviating the clinical symptoms.