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W Reith

Publications and source records attributed to W Reith.

At least 73 records · Page 4Linked to original sources
PubMed2002

[Modern diagnosis in acute cerebral infarct. Diffusion weighted imaging and ADC (apparent diffusion coefficient) calculations].

Many different methods have been established for the diagnosis of cerebral stroke. During the acute phase, small infarctions are often not detectable by computer tomography (CT). Diffusion weighted imaging (DWI) is a new tool which enables the detection of cerebral infarction earlier than is possible by CT. By using DWI it is possible to quantify changes in diffusion by calculating the apparent diffusion coefficient (ADC). ADC maps calculated using DWI therefore enable the quantification of the apparent diffusion conditions and allow the determination of the onset of cerebral ischemia. DWI can be used in the evaluation of new therapeutic strategies by controlling and quantifying the effect of new therapeutic agents.

Acute Disease↗
PubMed2002

[Evaluation of MR angiography in the presentation of intracranial aneurysms].

In recent years the diagnostic potential of magnetic resonance angiographic acquisition techniques has been improved. Today aneurysms are investigated by MR angiography with a high diagnostic potential. In the pretreatment assessment important details can be depicted by MRA with high efficacy. This review article gives an evaluation on the most important techniques, CE-MRA and 3D-TOF-MRA.

Contrast Media↗
PubMed2002

[Screening for aneurysms in risk groups: meaningful?].

There is a controversy discussion on screening for aneurysms in risk groups. True guidelines do not exist so far. It seems that screening for familial aneurysms is not advisable today. But adult dominant polycystic kidney disease (ADPKD) patients with a familial history of SAH should be screened because of a high prevalence rate of 25% for intracranial aneurysms in this population. Screening should be performed every 2 to 3 years by MRI angiography in this special risk group.

Genetic Predisposition to Disease↗
PubMed2002

[Nonruptured intracranial aneurysms: therapeutic recommendations].

With the development of new diagnostic noninvasive tools an increase in the diagnosis of asymptomatic nonruptured intracranial aneurysms has been shown. Physician and patient now have to decide wether to treat or to follow-up these aneurysms. This paper tries to review and to discuss the literature and to give guidelines for therapeutic decisions. The decision to treat an unruptured intracranial aneurysm must always comprise the individual factors such as age, life prognosis, neurological status, and the advantages and disadvantages of the considered method.

Aneurysm, Ruptured↗
PubMed2002

[Clinic, diagnosis, and therapy of subarachnoidal hemorrhage].

In most cases a saccular aneurysm is the cause of acute subarachnoidal hemorrhage (SAH). The usual symptoms are severe headache and meningism. Due to the high mortality rate caused by rebleeding an early occlusion of the aneurysm should be strived for. For this early diagnosis an exact identification of the aneurysm and its configuration is essential.

Angiography, Digital Subtraction↗
PubMed2002

[Accuracy of fluoroscopic navigation of pedicle screws. CT-based evaluation of bone screw placement].

While the advantages of C-arm navigation in computer-assisted spine surgery are obvious, the accuracy of pedicle screw placement with virtual fluoroscopy still needs to be verified. The C-arm-based ION system (Medtronic Sofamor Danek) was used to navigate pedicle screw insertion in patients undergoing spinal surgery for various conditions. In a prospective study, a total of 160 screws were inserted in the first 30 consecutive patients since introduction of the system at our institution: 54 at the thoracic spine (highest level: TH4) and 106 at the lumbar spine. Computed tomography (CT) scans were performed postoperatively by two independent radiologists to control the accuracy of screw placement at the level of the pedicles after reconstruction of axial images according to Laine et al. The comparison of the calculated accuracy rate of pedicle screw placement using virtual fluoroscopy with reported results achieved with CT-based navigation shows similar results for virtual fluoroscopy and a remarkable increase of accuracy in comparison to reports on conventional pedicle screw placement.

Bone Screws↗
PubMed2002

[MR imaging of gastric wall layers in vitro: correlation to thehistologic wall structure].

PURPOSE: To correlate gastric wall layers visible of MRI with the anatomical structure of the gastric wall. METHODS: After macroscopic preparation 5 x 5 cm post-mortem tissue sections of the gastric antrum were evaluated using a 2.4 Tesla MR unit (Bruker, Ettlingen, Germany). MR imaging consisted of T2-weighted multi-spinecho sequences in longitudinal and axial directions. The specimens then were stained with hematoxylin-eosin for histological examination. After that histological correlation of the gastric wall layers visible on MRI was performed. RESULTS: In all specimens four gastric wall layers could be clearly identified on MRI. The direct comparison of those layers to the histological findings showed the following correlation: 1) intermediate signal = mucosa, 2) hypointense signal = lamina muscularis mucosae, 3) hyperintense signal = submucosa, 4) intermediate signal = muscularis propria. CONCLUSIONS: Gastric wall layers visible on MRI were successfully correlated to the anatomic layers of the gastric wall. This allows us for the first time to classify invasion of gastric carcinoma using high spatial-resolution MR imaging. However, the subserosa and serosa are excluded from this conclusion, because so far a reliable statement concerning the value of MRI to depict these very variable layers is not possible.

Cadaver↗
PubMed2002

What is effective in malignant middle cerebral artery infarction: reperfusion, craniectomy, or both? An experimental study in rats.

BACKGROUND AND PURPOSE: We sought to evaluate the effects of reperfusion and craniectomy treatment at different time points after middle cerebral artery (MCA) occlusion on infarct volume and neurological outcome in MCA infarction in rats. METHODS: We used an endovascular technique to obtain MCA occlusion in 182 rats. Thirteen groups with 14 animals each were investigated: control group 1 with no treatment; groups 2 to 7 with only reperfusion or craniectomy at 1, 4, or 12 hours, respectively; and groups 8 to 13 with reperfusion at 1 or 4 hours combined with craniectomy at 1, 4, or 12 hours, respectively. We used infarct volume and neurological performance as study end points in all animals at day 7. RESULTS: Neurological score and infarct volume in animals undergoing early reperfusion at 1 hour were significantly smaller (1.8/79+/-59 mm3) than those in control animals (3.8/225+/-26 mm3) (P<0.01). Reperfusion at 4 hours (2.8/182+/-62 mm3) and 12 hours (3.7/231+/-69 mm3) did not result in significant improvement. Animals undergoing craniectomy at 1, 4, and 12 hours demonstrated significantly better outcome and significantly reduced infarct volume (1.6/96+/-30 mm3, 1.9/109+/-39 mm3, and 2.6/150+/-34 mm3, respectively) (P<0.05). Compared with 1 treatment at a time, combined reperfusion and craniectomy did not result in a significant additional benefit. CONCLUSIONS: Early reperfusion and craniectomy at 1 hour are both effective in large MCA infarction. While reperfusion later than 1 hour was not beneficial, late craniectomy at 4 and 12 hours still resulted in significant improvement of neurological score and reduction of infarction size. Combined treatment at different time points yields no significant additional benefit compared with 1 treatment at a time.

Acute Disease↗
PubMed2002

Oligodendrogliomas.

PURPOSE: To study the pattern of contrast enhancement in MR and CT of oligodendrogliomas and to compare this with other imaging findings and with histopathological grading criteria. MATERIAL AND METHODS: 20 patients with oligodendrogliomas (12 low-grade WHO II and 8 anaplastic WHO III) were reviewed. 20 complete MR investigations, 20 non-enhanced CT studies and 16 CTs after contrast enhancement were estimated blindly without knowledge of the tumour histological grades. RESULTS: All anaplastic oligodendrogliomas showed tumour contrast enhancement on MR and CT images. Also in 6/12 low-grade oligodendrogliomas the contrast was enhanced on MR imaging. In 5 of these, tumour calcifications were detected by CT. The remaining 6/12 WHO grade II cases showed no significant MR contrast enhancement. Of the oligodendrogliomas grade II, CT showed contrast uptake in 3 cases and no enhancement in 6, while in 3 cases postcontrast CT was not available. A comparison of contrast enhancement with tumour grade resulted in a p-value of 0.042 for MR and of 0.011 for CT. A combined statistical test of tumour grade and calcifications detected by CT compared with MR contrast enhancement showed a significant correlation (p=0.014). CONCLUSION: These data demonstrated that a clear grading of oligodendrogliomas based on the image criterion MR contrast enhancement was not possible. We suppose that, besides tumour neovascularisation, additional factors such as calcifications may disturb the blood-brain barrier.

Brain Neoplasms↗
PubMed2001

Maturation of dendritic cells is accompanied by rapid transcriptional silencing of class II transactivator (CIITA) expression.

Cell surface expression of major histocompatibility complex class II (MHCII) molecules is increased during the maturation of dendritic cells (DCs). This enhances their ability to present antigen and activate naive CD4(+) T cells. In contrast to increased cell surface MHCII expression, de novo biosynthesis of MHCII mRNA is turned off during DC maturation. We show here that this is due to a remarkably rapid reduction in the synthesis of class II transactivator (CIITA) mRNA and protein. This reduction in CIITA expression occurs in human monocyte-derived DCs and mouse bone marrow-derived DCs, and is triggered by a variety of different maturation stimuli, including lipopolysaccharide, tumor necrosis factor alpha, CD40 ligand, interferon alpha, and infection with Salmonella typhimurium or Sendai virus. It is also observed in vivo in splenic DCs in acute myelin oligodendrocyte glycoprotein induced experimental autoimmune encephalitis. The arrest in CIITA expression is the result of a transcriptional inactivation of the MHC2TA gene. This is mediated by a global repression mechanism implicating histone deacetylation over a large domain spanning the entire MHC2TA regulatory region.

Animals↗
PubMed2001

Selective abrogation of major histocompatibility complex class II expression on extrahematopoietic cells in mice lacking promoter IV of the class II transactivator gene.

MHC class II (MHCII) molecules play a pivotal role in the induction and regulation of immune responses. The transcriptional coactivator class II transactivator (CIITA) controls MHCII expression. The CIITA gene is regulated by three independent promoters (pI, pIII, pIV). We have generated pIV knockout mice. These mice exhibit selective abrogation of interferon (IFN)-gamma-induced MHCII expression on a wide variety of non-bone marrow-derived cells, including endothelia, epithelia, astrocytes, and fibroblasts. Constitutive MHCII expression on cortical thymic epithelial cells, and thus positive selection of CD4(+) T cells, is also abolished. In contrast, constitutive and inducible MHCII expression is unaffected on professional antigen-presenting cells, including B cells, dendritic cells, and IFN-gamma-activated cells of the macrophage lineage. pIV(-/-) mice have thus allowed precise definition of CIITA pIV usage in vivo. Moreover, they represent a unique animal model for studying the significance and contribution of MHCII-mediated antigen presentation by nonprofessional antigen-presenting cells in health and disease.

Animals↗
PubMed2001

[Spinal arteriovenous malformations].

The vascular malformations of the spine and spinal cord are rare diseases. Possible symptoms may consist in a transient neurological deficit, a progressive sensorimotor transverse lesion or an acute para- or tetraplegia. Damage to the spinal cord occurs by bleeding, space-occupying effects and venous congestion, rarely by steal effects. Classification of the true inborn malformations differentiates between arteriovenous malformations (AVMs), cavernomas and capillary teleangiectasias. The more frequent spinal dural arteriovenous fistula (SDAVF) of the elderly patient is a probably acquired lesion which is presented in a separate paper. Capillary teleangiectasias are mostly incidental findings but may cause differential diagnostic problems. Cavernomas are important causes of hemorrhage and may initially be obscured within the bleeding. MRI is the most relevant imaging procedure in the early diagnostic workup. In case of an AVM selective spinal angiography is required to define the type of the lesion and to decide about the appropriate therapy which may be endovascular-interventional, neurosurgical, combined or attentive.

Adult↗
PubMed2001

[Spinal angiography: vascular anatomy, technique and indications].

The indication for spinal angiography has to be closely set as in case of inadequate handling this procedure bares the risk of paraplegia. In unclear spinal symptoms lasting over a longer period of time, spinal vascular malformation have to be considered. Spinal vascular malformations are often reversible, especially if diagnosed early. Diagnostic methods have to include spinal angiography if other non-invasive methods do not lead to results. The main point is to consider spinal vascular malformations in unclear cases.

Adolescent↗
PubMed2001

Does the "keyhole" technique improve spatial resolution in MRI perfusion measurements? A study in volunteers.

We examined the potential of the 'keyhole' technique to improve spatial resolution in perfusion-weighted MRI on whole-body imagers with standard gradient hardware. We examined 15 healthy volunteers. We acquired a high-resolution image with 256 phase-encoding steps before a bolus-tracking procedure. For the dynamic series we collected only 34 lines in the center of k-space. Data reconstruction was performed by both zero-filling and keyhole methods. The dynamic datasets, concentration-time curves calculated from user-defined regions and maps of the cerebrovascular parameters using both reconstruction methods were compared. Using keyhole series, anatomical structures could easily be defined which were not seen on the original dynamic series because of blurring due to ringing artefacts. Comparison of signal-time curves in large regions yielded no significant difference in signal loss during bolus passage. In the parameter maps truncation artefacts were significantly reduced using keyhole reconstruction. The keyhole method is appropriate for enhancing image quality in perfusion-weighted imaging on standard imagers without sacrificing time resolution or information about transitory susceptibility changes. However, it should be applied carefully, because the spatial resolution of the dynamic signal change and the cerebrovascular parameters is less than that afforded by the spatial resolution of the reconstructed images.

Brain↗