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C Nasel

Publications and source records attributed to C Nasel.

At least 19 recordsLinked to original sources
PubMed2005

Visualization of intracranial vessel anatomy using high resolution MRI and a simple image fusion technique.

A new technique for fusion and 3D viewing of high resolution magnetic resonance (MR) angiography and morphological MR sequences is reported. Scanning and image fusion was possible within 20 min on a standard 1.5 T MR-scanner. The procedure was successfully performed in 10 consecutive cases with excellent visualization of wall and luminal aspects of the intracranial segments of the internal carotid artery, the vertebrobasilar system and the anterior, middle and posterior cerebral artery.

Cerebrovascular Circulation↗
PubMed2004

Familial hemiplegic migraine: follow-up findings of diffusion-weighted magnetic resonance imaging (MRI), perfusion-MRI and [99mTc] HMPAO-SPECT in a patient with prolonged hemiplegic aura.

Familial hemiplegic migraine (FHM) is a rare inherited autosomal dominant disorder. Migraine aura may last up to several weeks and then resolve without sequel. We report a 21-year-old male with FHM since the age of 3 years. Diffusion-weighted magnetic resonance imaging (DWI), perfusion-MR imaging (P-MRI) and [99mTc] hexamethyl-propyleneamine-oxime-single photon emission tomography (HMPAO-SPECT) were performed on day 2, when he was somnolent with right-sided hemiplegia, on day 9 when a mild hemiparesis was still present and on day 24 after recovery. The right central region showed normal findings in DWI, whereas P-MRI and SPECT revealed hyperperfusion on day 2, less marked on day 9, and normal findings on day 24. In conclusion, this case report indicates for the first time, by means of SPECT, P-MRI and DWI studies, that even extremely long-lasting migraine aura is not associated with cerebral ischaemia. Therefore, it supports the revised International Headache Society criteria where the term 'persistent' aura is proposed.

Child, Preschool↗
PubMed2003

Preserved memory traces within diencephalic amnesia.

A male patient with bilateral thalamic lesions (medio-ventral nuclei) was investigated. Despite explicit memory impairments his lexical ability was normal. We recorded magnetic field changes (magnetoencephalography, MEG) during the performance of an animate/inanimate discrimination task in which some words where repeated after long delays. Normally, repeated items are classified significantly faster than their first presentations which is accomplished by an unconscious process called priming. The patient did not show any behavioural evidence of priming but the physiological data indicated preservation of this robust form of memory. Brain activation associated with repetitions was attenuated at early stages. The activity difference was posteriorly distributed which is consistent with previous reports about repetition priming. The present study indicated that the bilateral thalamic lesions of our patient disconnected the information processing stream between the primed information and the behavioural response.

Amnesia↗
PubMed2002

[Measuring perfusion and diffusion in neuroradiology].

Neuroradiology should be regarded as a discipline with a strong focus on integral diagnosis of morphology and function of the central nervous system. With perfusion magnetic resonance imaging (P-MRI) and diffusion-weighted magnetic resonance imaging (DWI) the functional micro-structural analysis of the central nervous system has been made possible. So, disease processes may be characterised on a molecular level and P-MRI as well as DWI are now integrated in clinical routine diagnosis to improve therapy planning.

Brain↗
PubMed2001

Tracheal intubation and cervical spine excursion: direct laryngoscopy vs. intubating laryngeal mask.

Until recently, the most appropriate technique of intubating a patient with a cervical spine injury has been the subject of debate. Tracheal intubation by means of the intubating laryngeal mask (Fastrach), a modified conventional laryngeal mask airway, seems to require less neck manipulation. The aim of this study was to compare the excursion of the upper cervical spine during tracheal intubation using direct laryngoscopy with that during intubation via the laryngeal mask (Fastrach), by examination of lateral cervical spine radiographs in healthy young patients. The intubating laryngeal mask (Fastrach) caused less extension (at C1-2 and C2-3) than intubation by direct laryngoscopy. Direct laryngoscopy is still the fastest method to secure an airway provided no intubating difficulties are present. However, in trauma patients requiring rapid sequence induction and in whom cervical spine movement is limited or undesirable, the intubating laryngeal mask (Fastrach) is a safe and fast method by which to secure the airway.

Adult↗
PubMed2001

[Cerebrovascular emergency in neuroradiology].

Common causes to consultate a neuroradiologist in case of emergencies are trauma, brain infarction, or intracranial bleeding. Patients with brain infarction need a rapid assessment of the potentially nonnecrotic area within the ischaemic lesion. If haemorrhage, mostly occurring in the form of subarachnoid bleeding, is suspected, the source of bleeding has to be detected. With cranial computed tomography (CT) a thorough evaluation and staging of ischaemic stroke is possible with respect to thrombolysis. To detect irreversible damage of brain tissue, a combined perfusion-diffusion MRI should be performed.

Brain Infarction↗
PubMed2000

Intra-arterial thrombolysis for the treatment of perioperative childhood cardioembolic stroke.

Local intra-arterial lysis using recombinant tissue plasminogen activator (rTPA) was performed in a 6 and 2/3-year-old patient with major cardioembolic ischemic stroke 48 hours after intracardiac surgery. Selective application of 2.5 mg rTPA (0.11 mg/kg body weight) resulted in recanalization of the occluded cerebral vasculature with good neurologic recovery.

Cardiac Surgical Procedures↗
PubMed2000

Does (99m)Tc-Sestamibi in high-grade malignant brain tumors reflect blood-brain barrier damage only?

(99m)Tc-Sestamibi (MIBI) has been successfully applied in recurrent glioblastoma. The aim of this study was to evaluate the incremental diagnostic information of MIBI as a tumor-avid radiopharmaceutical compared with (99m)Tc-pertechnetate ((99m)Tc) as sole indicator of the integrity of the blood-brain barrier. Twenty-five patients with confirmed recurrent brain tumors were included. MIBI SPET was performed 10 min after injection of 555 MBq MIBI intravenously with a triple-headed gamma camera equipped with LE-UHR-PAR collimators over 360 degrees (3 degrees /step) and stored in a 128(2) matrix. Identical acquisition parameters were used for (99m)Tc SPET, which was acquired 3 h after injection of 740 MBq (99m)Tc. Normalized tumor uptake (NU) was calculated from attenuation-corrected transaxial slices. In addition, tumor/plexus, tumor/nasopharynx, and tumor/parotid gland ratios were assessed in both studies. No statistically significant differences were detected for the mean NU of tumor tissue with MIBI (0.26 +/- 0.10) and (99m)Tc (0.39 +/- 0. 33) and for the tumor/nasopharynx and tumor/parotid gland ratios; only the tumor/plexus ratio was significantly higher for (99m)Tc than for MIBI (p < 0.05). In conclusion, our data indicate that MIBI scintigraphy in brain tumors at 10 min postinjection reveals no additional visual information over that provided by the conventional (99m)Tc-pertechnetate brain scan, and in addition, tracer retention reflects primarily blood-brain barrier damage.

Adult↗
PubMed2000

[The indications and embolism monitoring in lumen-opening therapies of the a. carotis].

Carotid endarterectomy (CEA) is proven to be beneficial in symptomatic patients with high-grade carotid stenosis (70% to 99%; residual lumen as a percentage of the normal distal internal carotid artery) on condition that the peri-operative risk for mortality and morbidity is less than 6%. A minority of the "leading experts" in North America (48%) and Western Europe (28%) recommends carotid endarterectomy in asymptomatic patients in general. Most experts suggest to perform surgery only in asymptomatic patients who are at risk for carotid occlusion in the near future or embolism. At its present state, angioplasty and stenting is an experimental although promising technique which will have to be compared to carotid endarterectomy. Criteria for duplex grading of internal carotid stenosis have been established and systematically validated to results of angiography. Pre-surgical use of angiography will more and more be restricted to selected patients in whom the results of duplex sonography remain inconclusive. The detection of microemboli with transcranial doppler sonography seems to be of particular importance before and during carotid angioplasty and stenting.

Angioplasty, Balloon↗
PubMed2000

Magnetic resonance imaging of the distribution of local anesthetic during the three-in-one block.

UNLABELLED: The three-in-one technique of simultaneously blocking the femoral, the lateral femoral cutaneous (LFC), and the obturator nerves by a single injection of a local anesthetic was first described in 1973, and it was suggested that the underlying mechanism was one of cephalad spread resulting in a blockade of the lumbar plexus. Today, the technique is widely used in surgery and pain management of the lower limb. Many investigators have, however, reported suboptimal analgesia levels, particularly in the obturator nerve. The purpose of this prospective study was to trace the distribution of a local anesthetic during a three-in-one block by means of magnetic resonance imaging (MRI). Seven patients scheduled for surgery of the lower limb were analyzed with the aid of a primary MRI and then received three-in-one blocks using 30 mL of bupivacaine 0.5% under the guidance of a nerve stimulator. A secondary MRI was performed to determine the distribution pattern of the local anesthetic. It emerged that the local anesthetic blocks the femoral nerve directly, the LFC nerve through lateral spread, and the anterior branch of the obturator nerve by slightly spreading in a medial direction. No involvement of the proximal and posterior portions of the obturator nerve was observed, nor was there any cephalad spread that could have resulted in a lumbar plexus blockade. We therefore conclude that the basis of the three-in-one block is confined to lateral, medial, and caudal spread of the local anesthetic, which effectively blocks the femoral and LFC nerves, as well as the distal anterior branch of the obturator nerve. IMPLICATIONS: We demonstrate by using magnetic resonance imaging that the mechanism of a three-in-one block is one of lateral, caudal, and slight medial spread of a local anesthetic with subsequent blockade of the femoral, the lateral femoral cutaneous, and the anterior branch of the obturator nerves. It does not involve cephalad spread of the local anesthetic with blockade of the lumbar plexus.

Aged↗
PubMed2000

A standardized method of generating time-to-peak perfusion maps in dynamic-susceptibility contrast-enhanced MR imaging.

BACKGROUND AND PURPOSE: Perfusion MR imaging, performed as dynamic-susceptibility contrast-enhanced MR imaging, is sensitive to hemodynamic risks for patients with cerebrovascular disease. We sought to define a quantitative parameter for perfusion MR imaging, which shows brain areas at hemodynamic risk and enables direct comparison of different perfusion MR imaging examinations. METHODS: A new standardization procedure for the time-to-peak (TTP) parameter, standardized time to peak (stdTTP), was introduced. The stdTTP automatically calculates a time offset correlated to the earliest enhancing voxels in a section and rescales all TTP values accordingly. Because of a close relation between this offset and stdTTP of early enhancing voxels in central vascular territories (CVTs), stdTTP provides an estimate of the bolus run time between CVTs and related border zones (BZs). The stdTTP in CVTs and BZs was measured in 11 patients without hemodynamic impairment by using high temporal resolution dynamic-susceptibility contrast-enhanced perfusion MR imaging. RESULTS: An excellent comparability of different dynamic susceptibility contrast-enhanced MR imaging studies was found. The stdTTP in CVTs was 0.4 +/- 0.5 s (minimum, 0 s; maximum, 1.3 s) for the anterior, 0.5 +/- 0.3 s (minimum, 0 s; maximum, 1.0 s) for the middle, and 1.4 +/- 0.5 s (minimum, 0.4 s; maximum, 2.4 s) for the posterior cerebral artery. In the anterior BZ, stdTTP was 2.3 +/- 0.4 s (minimum, 1.6 s; maximum, 3.2 s), and in the posterior BZ, stdTTP was 2.8 +/- 0.4 s (minimum, 2.0 s; maximum, 3.4 s). CONCLUSION: The results suggest a limit for stdTTP of approximately 3.5 s in the anterior and posterior BZs. The stdTTP could serve as a quantitative measure for the hemodynamic risk assessment of patients with cerebrovascular disease. Because stdTTP can be directly derived from the measured curves, the hemodynamic situation of a patient can be judged with a minimum of computational effort.

Adult↗
PubMed1999

[Magnetic resonance tomography in dental radiology (dental MRI)].

PURPOSE: To demonstrate the usefulness of Dental-MRT for imaging of anatomic and pathologic conditions of the mandible and maxilla. METHODS: Seven healthy volunteers, 5 patients with pulpitis, 9 patients with dentigerous cysts, 5 patients after tooth transplantation and 12 patients with atrophic mandibles were evaluated. Studies of the jaws using axial T1- and T2-weighted gradient echo and spin echo sequences in 2D and 3D technique have been to performed. The acquired images were reconstructed with a standard dental software package on a workstation as panoramic and cross sectional views of the mandible or maxilla. RESULTS: The entire maxilla and mandibula, teeth, dental pulp and the content of the mandibular canal were well depicted. Patients with inflammatory disease of the pulp chamber demonstrate bone marrow edema in the periapical region. Dentigerous cysts and their relation to the surrounding structures are clearly shown. After contrast media application marked enhancement of the dental pulp can be found. CONCLUSION: Dental-MRT provides a valuable tool for visualization and detection of dental diseases.

Diagnostic Imaging↗
PubMed1998

[Xenon-CT and perfusion MRI in the diagnosis of cerebral gliomas].

Within certain limits the vascularity of cerebral gliomas correlates with dysplasia. Xenon CT and perfusion MRI can be used to investigate tumor vascularity. Using an optimized wash in/out protocol with inhalation of 30% xenon gas, xenon CT was performed and regional cerebral blood flow (rCBF) and blood/tissue partition coefficient (lambda) calculated. Furthermore, perfusion MRI was performed using a dynamic T2*w EPI sequence with intravenous administration of Gd-DTPA. The relative regional cerebral blood volume, arrival time, time to peak and mean transit time were calculated. Both modalities were used in patients with supratentorial gliomas and compared with conventional contrast-enhanced MRI (ceMRI). Calculation of regional cerebral blood flow, as compared to ceMRI, did not contribute to the diagnostic approach of tumor dysplasia. Tumour vascularity was better estimated by measurement of lambda. Measurement of relative regional cerebral blood volume also correlated with tumor vascularity. Mainly the possibility of direct quantification of the Xe-CT data was advantagenous compared to perfusion MRI, and the XeCT data could be interpreted more clearly. Further upgrades of the technical equipment of MR as well as upgrades of available software will increase the applicability of perfusion MRI. However, both modalities offer a more precise investigation of tumor vascularization compared to ceMRI since potential dysplastic alteration may be detected earlier, which will be advantageous for planning bioptical approach of such tumours.

Astrocytoma↗
PubMed1998

Contrast-enhanced computed tomography of freely transplanted jejunal patches after surgery in the oral cavity and oropharynx.

Thirty-two patients with jejunal patches in the oral cavity and oropharynx were examined with contrast-enhanced computed tomography (CT). The morphology of the intestinal wall, the mesenteric fatty tissue, mesenteric lymph nodes and the region of the anastomosis were evaluated and correlated with clinical findings. The size and number of mesenterial lymph nodes, which were found in 16 cases, did not correlate with tumour recurrence. The benign alterations of the intestinal wall ranged from flat surfaces with no enhancement to significant enhancement with persisting folds. In cases with persisting intestinal folds, separation of tumour recurrence was achieved by identification of a typical double-layer configuration of the enhancing mucosa, and the restriction of alterations to the intestinal wall compartment. Tumour recurrences occurred at patch margins and were reliably distinguished from normal patches. For differentiation of findings, an exact localization of jejunum-patch compartments and margins with contrast-enhanced CT was, therefore, necessary.

Adult↗
PubMed1998

Localization of the mandibular neurovascular bundle using dental magnetic resonance imaging.

OBJECTIVE: To assess the reliability of a commercially available 3D-MPR MRI program for the jaws for imaging the mandibular neurovascular bundle. METHODS: A gradient echo sequence (TR: 49 ms/TE: 6.3 ms/flip angle: 25 degrees/excitations: 3) with a spectral fat suppression pre-impulse and a voxel size of 0.9 x 0.9 x 0.8 mm was designed. Cross-sectional and panoramic reconstruction of the whole mandible were performed from the axial scans using Easy Vision (Philips, Best, The Netherlands) software package. The ability of differentiate the mandibular neurovascular bundle was assessed in 11 patients. RESULTS: The mandibular neurovascular bundle was clearly visualized in all cases. CONCLUSION: Dental MRI is a possible alternative to plain films or CT for patients requiring surgery near the mandibular canal.

Anatomy, Cross-Sectional↗
PubMed1998

[Dental magnetic resonance tomography (dental MRI) as a method for imaging maxillo-mandibular tooth retention structures].

PURPOSE: To establish a new method for dental imaging using magnetic resonance tomography named Dental-MRT and to demonstrate its usefulness in diagnosing dentogen pathologies of the mandible and maxilla. METHODS: Seven healthy volunteers, three patients with pulpitis, two patients with dentigerous cysts, two patients after tooth transplantation, and three patients with atrophic mandibles have been evaluated. Optimized axial T1- and T2-weighted gradient echo and spin echo sequences in 2D and 3D technique have been established to perform studies of the jaws. The acquired images were reconstructed with a standard dental software package on a work-station as panorama and cross-sectional views of the mandible or maxilla. RESULTS: The entire maxillo-mandibular bone, teeth, dental pulp, and the content of the mandibular canal were well depicted. Patients with pulpitis demonstrate bone marrow edema in the periapical region. Dentigerous cysts and their relation to the surrounding structures are clearly shown. After contrast media administration marked enhancement of the dental pulp can be demonstrated. CONCLUSION: Dental-MRT promises to provide a new tool for visualization and detection of dental diseases.

Adolescent↗
PubMed1998

Frameless stereotactic-directed tissue sampling during surgery of suspected low-grade gliomas to avoid histological undergrading.

Detection of anaplastic tumor foci for precise grading of gliomas is crucial for prognostic assessment and appropriate postoperative treatment planning. To avoided undergrading in large suspected low-grade gliomas, we employed frameless sterotaxy during open surgery for tissue sampling of radiologically suspected anaplastic foci. In nine patients (mean age 44 years, range 10-67) with large supratentorial suspected low-grade gliomas (32.4 ccm mean vol, range 17.9-68.6 ccm) with small contrast enhancing areas (7.7% mean of total volume, range 0.7-15.3%), a neuronavigation system with a pointer device (Easy Guide System Philips) or a navigating microscope (MKM System Zeiss) was used to target small enhancing tumor parts for cytological investigation during open surgery. Consecutive cytological smears revealed anaplastic tumor foci in all patients, correlating with neuroradiologically demonstrated small contrast enhancing areas, although biopsies from all other tumor parts showed low-grade tumors. Final neuropathological diagnosis confirmed anaplasia within the neuroradiologically suspected low-grade gliomas in all patients (2 grade IV, 5 WHO grade III and 2 grade II-III tumors, WHO classification). In our experience frameless stereotactic-directed intraoperative tissue sampling during open surgery of large suspected low-grade gliomas helps to identify small anaplastic areas in mostly large low-grade tumors, and therefore, permits optimum planning of postoperative treatment.

Adolescent↗