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Biomedical subjects

B Wallner

Publications and source records attributed to B Wallner.

At least 37 records · Page 2Linked to original sources
PubMed1997

Induction of EAE in mice with recombinant human MOG, and treatment of EAE with a MOG peptide.

Myelin oligodendrocyte glycoprotein (MOG) is a transmembrane glycoprotein expressed on the surface of central nervous system (CNS) myelin membranes, which has been shown to induce experimental autoimmune encephalomyelitis (EAE) in rodents. Here we describe the induction of EAE in SJL and (PLJ X SJL)F1 mice with truncated human recombinant MOG (thr-MOG, amino acids 1-120) which has been expressed in insect cells in soluble form. We show that in SJL mice, immunization with thr-MOG produces an immune response to the 1-30 and the 81-110 regions of the MOG molecule. We also demonstrate effective treatment of thr-MOG-induced EAE in SJL mice with intravenous injections of a single peptide, MOG 91-110. These results support the possibility of treating MS using an antigen dependent approach.

Amino Acid Sequence↗
PubMed1993

[MR-myelography of the lumbar spine using a PSIF sequence: first experiences].

A rapid gradient-echo acquisition (PSIF) was used to delineate the lumber spine. Because this sequence is heavily T2 weighted the cerebrospinal fluid shows a bright signal, the myelon has a poor signal. 5 healthy volunteers and 5 patients with suspected lumbar disc herniation were examined by this technique. All MR myelograms were compared with spin-echo sequences (sagittal and transversal slices). All lumbar disc herniations which were recognized by MRI were also delineated by MR myelography.

Adult↗
PubMed1992

[MR angiography of occlusive changes in the superior thoracic inlet veins].

We used MR angiography to assess the thoracic inlet veins in 5 normal volunteers and 14 patients with thrombosis of these veins. The results were compared with conventional venography and contrast-enhanced computed tomography (CT). The normal anatomy was readily depicted by MR angiography in all normal volunteers. Pathology was assessed correctly by MR angiography in all patients. Thrombosis of the internal jugular vein was seen on MR angiography in all cases whereas conventional venography failed to demonstrate this region adequately in 3 cases. The best overview of the thoracic inlet veins was achieved in the coronal plane; however, for detailed demonstration of pathology, imaging in additional planes was necessary. We conclude that MR angiography is a promising method for non-invasive assessment of thoracic veins.

Evaluation Studies as Topic↗
PubMed1992

[The imaging of regional brain perfusion with dynamic magnetic resonance tomography].

Bolus injections of gadolinium-DTPA result in high contrast concentration in the distal vessels within the brain and cause a local disturbance of the magnetic field with a shortening of T2 relaxation time. Pulse frequencies were designed to demonstrate inhomogeneities in the magnetic field. The resultant reduction in T2-weighted gradient echo signals was used in order to examine changes in regional perfusion caused by pathological conditions. Cerebral tumours showed variable perfusion patterns but were always better perfused than surrounding brain tissue; oedema surrounding the tumour resulted in reduced perfusion. Ischaemic infarcts showed significant underperfusion compared with control areas. In both groups the areas involved were larger on the perfusion scans than on T2-weighted images.

Brain↗
PubMed1992

[Magnetic resonance tomography of the liver with TurboFLASH and segmented acquisition. Fast imaging with flexible image contrast].

The value of a fast imaging sequence in diagnosing focal liver lesions was assessed in 43 patients. The sequence (TurboFLASH with segmented acquisition) allows the acquisition of T1- and T2-weighted images within a breath-hold interval. Lesion-liver contrast was compared with T2-weighted spin-echo, T1-weighted gradient-echo, and single shot TurboFLASH sequences. All lesions that were seen with the latter sequences were also visible on the segmented TurboFLASH images. Contrast on the segmented TurboFLASH images was similar to that of T2-weighted spin-echo sequences and superior to T1-weighted gradient-echo sequences. Signal of fat could be nulled at an inversion time of 10 ms, signal from liver tissue could be nulled at an inversion time of 300 ms. By minimising the liver signal, the lesions could be "highlighted". This was not possible with the other imaging sequences. The segmented TurboFLASH technique allows breath-hold imaging of the liver with arbitrary image contrast. The lesion-liver contrast is comparable to time-consuming T2-weighted spin-echo sequences.

Biopsy, Needle↗
PubMed1992

[Clinical potentialities and limitations of two- and three-dimensional time-of-flight MR angiography in the diagnosis of carotid stenosis].

For diagnosing a carotid artery stenosis, 26 patients underwent MR angiography. A spin echo (SE) sequence with presaturation on which the flowing blood appears with low signal intensity was applied, as well as a two- and three-dimensional gradient echo (GRE) sequence with flow compensation, showing blood flow with high signal intensity. Subsequently, projection angiograms were made from the MR images with a maximum intensity projection algorithm. Degree, length and localisation of a carotid artery stenosis were reviewed. To find out the clinical usability, the results of the MR angiograms were compared subsequently with the findings of intravenous digital subtraction angiography (i.v. DSA). In comparison with DSA a correlation in the degree of stenosis was noticed in 42 out of 48 SE-, in 39 out of 52 2-D GRE and in 41 out of 48 3-D GRE sequence angiograms. The length of 34 moderate and severe stenoses, demonstrated by DSA, was overestimated 5 times with the SE-sequence, 9 times with the 3-D and 23 times with the 2-D GRE sequence. MR angiography with a 3-D GRE sequence is suitable for screening for carotid artery stenosis. In cases of severe stenosis an SE sequence should be performed for more precise delineation of the stenotic lesion.

Aged↗
PubMed1992

[Potentialities and limitations of MR angiography in the imaging of intracranial aneurysms].

The potential value of MR angiography in imaging of intracranial aneurysms was analyzed in seven patients. Six cases were confirmed by angiography or computed tomography. In one patient MR angiography was not useful in distinguishing bleeding from an aneurysm. Five aneurysms were imaged by 3D angiography, one was diagnosed by 2D angiography. The extent of thrombosis was evaluated by selective presaturation. MR angiography was a useful non-invasive method in imaging of intracranial aneurysms. However, for complete work-up angiography is mandatory.

Humans↗
PubMed1992

[Computed tomographic aspects of intestinal intussusception].

This article describes typical CT findings of intestinal intussusception of different genesis and localisation. It is shown that a characteristic image resembling a target is obtained both in case of an invaginated Meckel's diverticulum, an idiopathic ileocolic intussusception in an infant, and in colorectal invagination in condition after resection of a polyp of the sigmoid. Compared with the conventional imaging methods such as sonography, colon contrast enema or contrast imaging of the small intestine, CT enables not only unequivocal diagnosis of intestinal invagination but frequently also the identification or exclusion of underlying causes that trigger the phenomenon.

Colonic Diseases↗
PubMed1991

[Biliary obstruction: MR-cholangiography with a rapid gradient-echo sequence (2D CE-Fast)].

Magnetic resonance (MR) was used to delineate the biliary tree in patients with obstructive jaundice originating from various types of malignant or benign processes at different locations. With the aid of a rapid sequential gradient-echo acquisition (CE-Fast) and 3D post-processing, heavily T2-weighted images could be obtained to identify the site of obstruction in ten out of eleven patients. Slices were acquired during breath-holding periods of about 12 sec with a total examination time of 10-15 min. The three-dimensional display reliably demonstrated the dilated bile ducts in pre-stenotic areas whereas in the majority of cases post-stenotic ductal segments could not be visualised.

Cholangiography↗
PubMed1991

[Imaging of cerebral flow dynamics using MR angiography and selective pre-saturation: initial experiences].

MR angiography with selective pre-saturation was applied in 5 normal volunteers, 22 patients with cerebrovascular disease, 3 patients with arteriovenous malformations (AVM) and one patient with thrombosis of the superior sagittal sinus. The results were compared with Doppler ultrasound and conventional angiography. MR angiography reliably demonstrated the direction of blood flow and the presence or absence of collateral flow in the circle of Willis. Collateral flow via leptomeningeal vessels and the ophthalmic artery could not be demonstrated. In the patient with superior sagittal sinus thrombosis, the absence of flow was well seen. MR angiography was able to demonstrate the major supplying arteries in the patients with AVMs. MR angiography is a valid noninvasive means to demonstrate direction of flow and blood supply of the major intracranial arteries.

Cerebral Angiography↗
PubMed1991

Cerebral venography with MR.

The authors describe a two-dimensional time-of-flight magnetic resonance (MR) angiography technique to create projection venograms of the head. The technique was applied to 27 healthy volunteers and 39 patients. The superior sagittal and straight sinuses, the internal cerebral veins, and the Galen vein were visualized in all the volunteers. Other veins were seen in a high percentage of subjects. Systematic comparison of digital subtraction angiography (DSA) after intraarterial contrast medium injection and MR venography in patients showed good correlation between the two techniques. MR venography proved helpful in identifying thrombosis or patency of cerebral veins and sinuses and showed collateral venous drainage and venous drainage from arteriovenous malformations. There was good correlation between conventional contrast angiography and MR venography. In conclusion, MR venography is considered reliable for showing the cerebral venous system and provides information additional to that of conventional spin-echo imaging.

Adolescent↗