[Show abstract][Hide abstract] ABSTRACT: Assessment of hemodynamics in arteriovenous malformations (AVMs) is important for estimating the risk of bleeding as well as planning and monitoring therapy. In tissues with perfusion values significantly higher than cerebral cortex, continuous arterial spin labeling (CASL) permits both adequate representation and quantification of perfusion. Thirteen patients who had cerebral AVMs were examined with two magnetic resonance imaging (MRI) techniques: perfusion imaging using a CASL technique with two delay times, 800 and 1200 ms, and T(2)-weighted dynamic contrast-enhanced MRI (T(2)-DCE-MRI). The signal-to-noise ratio obtained in our study with the CASL technique at 3 T was sufficient to estimate perfusion in gray matter. Both nidal and venous perfusion turned out larger by factors of 1.71±2.01 and 2.48±1.51 in comparison to T(2)-DCE-MRI when using CASL at delay times of 800 and 1200 ms, respectively. Moreover, the venous and nidal perfusion values of the AVMs measured at T(2)-DCE-MRI did not correlate with those observed at CASL. Evaluation of average perfusion values yielded significantly different results when using a shorter versus a longer delay time. Average gray matter perfusion was 15.8% larger when measured at delay times of w=800 ms versus w=1200 ms, while nidal perfusion was 15.7% larger and venous perfusion was 34.6% larger, respectively. In conclusion, the extremely high perfusion within an AVM could be successfully quantified using CASL. A shorter postlabeling delay time of w=800 ms seems to be more appropriate than a longer time of w=1200 ms because of possible inflow of unlabeled spins at the latter.
Magnetic Resonance Imaging 09/2011; 29(9):1157-64. DOI:10.1016/j.mri.2011.07.026 · 2.09 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A significant percentage of children with hemangiomas may have PHACES syndrome which refers to the association of posterior fossa malformations, facial hemangiomas, arterial cerebrovascular abnormalities, cardiovascular anomalies, eye abnormalities and ventral defects like sternal clefting or supraumbilical raphe. A variety of factors have led to under diagnosis of PHACES syndrome in the past including lack of awareness and limited imaging modalities. Also, patients with PHACES syndrome with arterial cerebrovascular abnormalities can present with acute ischemic stroke. However, these patients usually present before one year of age. We describe a 29-year-old woman with no history of cerebrovascular disease who initially presented with symptoms of a stroke and was subsequently diagnosed to have PHACES syndrome exhibiting an array of multiple unusual imaging findings. We also discuss the current literature and recommendations about PHACES syndrome.
[Show abstract][Hide abstract] ABSTRACT: We describe a 65-year-old woman with an asymptomatic idiopathic lingual artery aneurysm which is suspected to be congenital. We review the literature on external carotid artery branch aneurysms, diagnostic evaluation and discuss treatment options for the various types and the specific chosen in the case presented.
[Show abstract][Hide abstract] ABSTRACT: Melatonin plays a key role in the proper functioning of the circadian timing system (CTS), and exogenous melatonin has been shown to be beneficial in cases of CTS and sleep disturbances. Nevertheless, the concept of "melatonin deficit" has yet to be defined. The aim of our study was, therefore, to determine the relationship between the degree of pineal calcification (DOC) and a range of sleep parameters measured objectively using polysomnography (PSG).
A total of 31 outpatients (17 women, 14 men, mean age 45.9 years; SD 14.4) with primary insomnia were included in our study. Following an adaptation night, a PSG recording night was performed in the sleep laboratory. Urine samples were collected at predefined intervals over a 32-h period that included both PSG nights. The measurement of 6-sulphatoxymelatonin (aMT6s) levels was determined using ELISA. DOC and volume of calcified pineal tissue (CPT) and uncalcified pineal tissue (UPT) were estimated by means of cranial computed tomography.
UPT was positively associated with 24-h aMT6s excretion (r=0.569; P=0.002), but CPT was not. After controlling for age, aMT6s parameters, CPT, and UPT did not correlate with any of the PSG parameters evaluated. In contrast, DOC was negatively associated with REM sleep percentage (r=-0.567, P=0.001), total sleep time (r=-0.463, P=0.010), and sleep efficiency (r=-0.422, P=0.020).
DOC appears to be a superior indicator of melatonin deficit compared to the absolute amount of melatonin in the circulation. High DOC values indicate changes predominantly in the PSG parameters governed by the circadian timing system. DOC may thus serve as a marker of CTS instability.
Sleep Medicine 09/2008; 10(4):439-45. DOI:10.1016/j.sleep.2008.05.003 · 3.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Despite some limitations, a perfusion/diffusion mismatch can provide a working estimate of the ischemic penumbra in hyperacute stroke and has successfully been used to triage patients.
To evaluate whether the addition of magnetic resonance imaging (MRI) to clinical and non-contrast computed tomography (CT) data alters diagnosis and choice of therapy.
We retrospectively analyzed clinical records, and CT and MRI data fully available in 97 of 117 patients. Upon clinical examination and CT, a diagnosis and treatment path was scored and compared to treatment path after addition of MRI data. The MRI protocol included T2-weighted images, diffusion-weighted images (DWI), and perfusion-weighted images (PWI), and MR angiography (MRA).
MRI data were acquired in less than 15 min. In 20 of 97 patients (21%), the diagnosis changed after MRI. In 25 of 97 patients (26%), the presumptive treatment plan was changed after MRI evaluation. Thirteen patients had their treatment changed from thrombolytic to nonthrombolytic therapy. Three patients were changed from nonthrombolytic to intraarterial (IA) thrombolysis. In one patient, treatment was changed from intravenous (IV) to IA thrombolysis, and in five patients it was changed from IA to IV thrombolysis. In two patients, systemic heparin was added to antiplatelet therapy.
The expansion of the acute stroke protocol to include MRI altered the therapy plan in 26% of our patients. The utility of MRI, shown here to improve patient stratification into best-treatment options, demonstrates the value of using MRI to optimize care in hyperacute stroke patients.
[Show abstract][Hide abstract] ABSTRACT: The characterization of brain arteriovenous malformation (AVM) angioarchitecture remains rewarding in planning and predicting therapy. The increased signal-to-noise ratio at higher field strength has been found advantageous in vascular brain pathologies.
To evaluate whether 3.0T time-of-flight (TOF) magnetic resonance angiography (MRA) is superior to 1.5T TOF-MRA for the characterization of cerebral AVMs.
Fifteen patients with AVM underwent TOF-MRA at 3.0T and 1.5T and catheter angiography (DSA), which was used as the gold standard. Blinded readers scored image quality on a four-point scale, nidus size, and number of feeding arteries and draining veins.
Image quality of TOF-MRA at 3.0T was superior to 1.5T but still inferior to DSA. Evaluation of nidus size was equally good at 3.0T and 1.5T for all AVMs. In small AVMs, however, there was a tendency of size overestimation at 3.0T. MRA at 3.0T had increased detection rates for feeding arteries (+21%) and superficial (+13%) and deep draining veins (+33%) over 1.5T MRA.
3.0T TOF-MRA offers superior characterization of AVM angioarchitecture compared with 1.5T TOF-MRA. The image quality of MRA at both 3.0 and 1.5T is still far from equal to DSA, which remains the gold standard for characterization of AVM.
[Show abstract][Hide abstract] ABSTRACT: The 170-ms electrophysiological processing stage (N170 in EEG, M170 in MEG) is considered an important computational step in face processing. Hence its neuronal sources have been modelled in several studies. The current study aimed to specify the relation of the dipolar sources underlying N170 and M170. Whole head EEG and MEG were measured simultaneously during the presentation of unfamiliar faces. An Independent Component Analysis (ICA) was applied to the data prior to localization. N170 and M170 were then modelled with a pair of dipoles in a four-shell ellipse (EEG)/homogeneous sphere (MEG) arranged symmetrically across midline. The dipole locations were projected onto the individual structural MR brain images. Dipoles were localized in fusiform gyri in ten out of eleven individuals for EEG and in seven out of eleven for MEG. N170 and M170 were co-localized in the fusiform gyrus in six individuals. The ICA shifted some of the single-subject dipoles up from cerebellum to fusiform gyrus mainly due to the removal of cardiac activity. The group mean dipole locations were also found in posterior fusiform gyri, and did not differ significantly between EEG and MEG. The result was replicated in a repeated measurement 3 months later.
[Show abstract][Hide abstract] ABSTRACT: To propose a semi-quantitative computed tomography (CT) protocol for determining uncalcified pineal tissue (UCPT), and to evaluate its reproducibility in modification of studies showing that the degree of calcification is a potential marker of deficient melatonin production and may prove an instability marker of circadian rhythm.
Twenty-two pineal gland autopsy specimens were scanned in a skull phantom with different slice thickness twice and the uncalcified tissue visually assessed using a four-point scale. The maximum gland density was measured and its inverse graded on a non-linear four-point scale. The sum of both scores was multiplied by the gland volume to yield the UCPT. The within-subject variance of UCPT was determined and compared between scans of different slice thickness.
The UCPT of the first measurement, in arbitrary units, was 39+/-52.5 for 1 mm slice thickness, 44+/-51.1 for 2 mm, 45+/-34.8 for 4 mm, and 84+/-58.0 for 8 mm. Significant differences of within-subject variance of UCPT were found between 1 and 4 mm, 1 and 8 mm, and 2 and 8 mm slice thicknesses (P<0.05).
A superior reproducibility of the semi-quantitative CT determination of UCPT was found using 1 and 2 mm slice thicknesses. These data support the use of thin slices of 1 and 2 mm. The benefit in reproducibility from thin slices has to be carefully weighted against their considerably higher radiation exposure.
[Show abstract][Hide abstract] ABSTRACT: Cerebral vasospasm secondary to subarachnoid hemorrhage leads to increased cerebrovascular resistance and may cause ischemia in the affected vascular territories. The currently available therapeutic options for treating vasospasm are limited. The effect of ethanol at a concentration of 0.75 g/kg body weight on blood flow velocity in the major cerebral arteries was studied. In 31 healthy persons, the major extra- and intracranial cerebral vessels were examined by Doppler ultrasonography before and following oral ingestion of 0.75 g/kg body weight of ethanol. An additional 20 healthy subjects served as a control group. Ethanol in the applied concentration significantly increased the systolic, diastolic, and mean blood flow velocities and significantly decreased the pulsatility indices in the middle cerebral artery (MCA). It may reduce vascular resistance and may increase cerebral blood flow in the area supplied by the MCA in healthy persons.
[Show abstract][Hide abstract] ABSTRACT: Recent technical developments led to a change in the significance of the different imaging modalities in the whole spectrum of neuroradiology and thus also in the field of imaging of the cervical spine. The main part in diagnostic imaging of the upper cervical spine is taken by high-resolution multislice CT and MRI. Conventional X-rays serve as an initial screening technique if required.
Der Orthopäde 04/2006; 35(3):237-43. · 0.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Zusammenfassung Die technischen Entwicklungen des letzten Jahrzehnts haben zu einer Veränderung der Wertigkeit bildgebender Verfahren in der gesamten Neuroradiologie und damit auch für die Darstellung des kraniozervikalen Übergangs geführt. Den Hauptbeitrag zur bildgebenden Diagnostik der oberen Halswirbelsäule (HWS) liefern heutzutage die hochauflösende Mehrzeilenspiralcomputertomografie (CT) und die Magnetresonanztomografie (MRT). Konventionelle Röntgenübersichten dienen bei Bedarf noch zu einer ersten Orientierung.
Der Orthopäde 03/2006; 35(3):237-243. DOI:10.1007/s00132-005-0922-6 · 0.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Intracerebral hemorrhages after embolization of arteriovenous malformations (AVMs) are the most dreaded complications of this well-established therapy. Apart from the known risk factors, our center noticed a high incidence of complications during postinterventional monitoring in medical intensive care units (ICUs) and stroke units.
We report 125 consecutive interventions performed on 66 patients by using flow-dependent microcatheters and n-butyl cyanoacrylate as the embolic agent. Postinterventional intensive care monitoring was performed in an interdisciplinary operative ICU, a stroke unit, or a medical ICU. Patients were compared with regard to bleeding complications, AVM morphology, embolization result, postinterventional monitoring, and demographic factors.
Intracerebral hemorrhages occurred in 7 patients. Significant differences in outcome were found between 66 patients monitored in the interdisciplinary operative ICU from medical ICU or stroke unit. This was also true when adjusted for age and extent of AVM reduction by using exact logistic regression. A partial AVM reduction of >60% was a considerable risk factor for hemorrhage (odds ratio [OR] = 18.8; 95% confidence interval [CI] [1.341, not available]. Age was also an essential risk factor. An age difference of 10 years leads to an OR of 2.545 (95% CI [1.56, 7.35]).
A considerable AVM reduction in one session appears to increase the risk of hemorrhage technically. This suggests a distribution of the interventions in many partial steps.
American Journal of Neuroradiology 02/2006; 27(2):313-6. · 3.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A 39-year-old man with acquired torticollis suffering from cervicobrachialgia and neurological deficits is presented. Due to a change in head position a transient reproducible tetraplegia and severe vegetative dysfunctions were caused. The origin of this uncommon serious combination of symptoms and signs was a chordoma of the upper cervical spine. After surgical decompression the patient was free of neurological deficit and pain. Review of the literature did not reveal any similar case.