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Biomedical subjects

M Skalej

Publications and source records attributed to M Skalej.

At least 55 records · Page 3Linked to original sources
PubMed1996

Friedreich's ataxia with retained tendon reflexes: molecular genetics, clinical neurophysiology, and magnetic resonance imaging.

Lower limb areflexia is generally regarded as an essential criterion for the diagnosis of Friedreich's ataxia (FRDA). We describe a family with a recessive form of early-onset ataxia in which one member had a phenotype typical of FRDA whereas another, with retained tendon reflexes in the lower limbs, did not have electrophysiologic evidence of the usual severe afferent axonal neuropathy of FRDA. In contrast, somatosensory evoked potentials, eye-movement recordings, and MRI of the head and cervical cord provided results highly suggestive of FRDA in both patients. We performed genetic linkage analysis in this family, using markers tightly linked to the FRDA locus on chromosome 9. Inheritance of identical paternal and maternal genotypes by the affected members, but not by their unaffected siblings, provided supporting evidence that this disorder may result from mutation within the FRDA gene or is tightly linked to the investigated loci on chromosome 9.

Adult↗
PubMed1996

A model for storage and retrieval of theoretical medical knowledge.

A database model for structure and access of theoretical medical knowledge is presented. The basic principle is the organization of knowledge in three dimensions: Each topic--first dimension--is explained with media--second dimension--in different versions of varying details--third dimension--suitable for different users. Every topic is one database entry. Topics are interconnected with heading and sub-topics (tree structure) and to logically related topics (cross references). Access follows the 3D-concept with initial access by topic, by media, or user specific, and with intra-unit access to related topics, media, and user specific versions. The model is discussed and possible implementations are described.

Computer-Assisted Instruction↗
PubMed1996

Cerebral activity during visual stimulation: a positron emission tomography and functional magnetic resonance imaging study.

Stimulation of cerebral areas induces a regional increase in blood flow and metabolism. Positron emission tomography (PET) is an established procedure to localize cerebral regions of enhanced activity. Exposure to a radioactive indicator and limited spatial and temporal resolution are disadvantages of this method as compared with other imaging techniques, but anatomical orientation can be improved by matching PET images with high-resolution magnetic resonance imaging (MRI) scans. Recently, functional MRI (fMRI) has arisen as an alternative method. This procedure presumably detects changes in the paramagnetic properties of hemoglobin, depending on its oxygenation state, as well as an increased regional blood flow in activated cerebral areas. These structures can be visualized using sensitive scanning techniques and appear with bright signal intensities. Visual stimulation was performed with the help of a high-resolution color VDU for PET registration and of an LCD video projector for fMRI (1.5 T). Hemifield stimulation as well as subtraction between images of flickering and stable random dot stimuli showed a preferential activation of the primary visual cortex. In addition, the first MRI results obtained during stimulation with moving gratings are demonstrated; hereby, preferentially extrastriate regions presumably responsible for motion detection were activated.

Adult↗
PubMed1995

Scotoma perception in white-noise-field campimetry and postchiasmal visual pathway lesions.

The authors examined 59 patients (32 women and 27 men) suffering from homonymous hemianopia by white-noise-field campimetry (Tübingen Electronic Campimeter) and by conventional perimetry (Tübingen Automatic Perimeter or Tübingen Manual Perimeter) and by computerized tomography (CT) or magnetic resonance imaging (MR). In all, 56 patients showed neuroradiologically detectable cerebral lesions, which were superimposed in a reconstructed "reference brain". Of these 56 patients, 18 were not capable of perceiving any white-noise-field scotoma, although their conventional perimetric findings showed defects. Lesions of these patients were concentrated along the optic radiation and spared the primary visual cortex. The lesions of the remaining 38 patients with scotoma detectable in both methods were accumulated in area V1, the primary visual cortex. The lesions of 6 patients, who had had persistent scotoma perception for more than 2 years, were situated at the occipital pole. The lesions of 8 patients with vanishing scotoma were concentrated in more rostral areas.

Adolescent↗
PubMed1993

[Magnetic resonance imaging in perianal Crohn's disease].

Magnetic resonance imaging (MRI) was undertaken in a prospective study of 34 consecutive patients (21 women, 13 men; median age 31 [18-53] years) suspected of having active perianal Crohn's disease. The results of the investigation were compared with those obtained by independent observers on proctological and intraoperative examination (n = 31). A total of 58 fistulas and 21 abscesses were noted intraoperatively, 47 fistulas and all 21 abscesses by MRI, and 40 fistulas and 13 abscesses proctologically. The proctological examination proved to be more sensitive in demonstrating short subcutaneous or anovaginal fistulas (three of four subcutaneous and two of five anovaginal fistulas were not shown by MRI). Intersphincteric, ischiorectal and supralevator involvement was shown better by MRI. These results indicate that in perianal Crohn's disease MRI is a useful addition to proctological examination.

Abscess↗
PubMed1993

Leukemic red bone marrow changes assessed by magnetic resonance imaging and localized 1H spectroscopy.

Red bone marrow of healthy persons has considerable contents of water and lipids. The cellularity and the corresponding fat-water ratio within the marrow show clear changes in hematological diseases. Magnetic resonance (MR) methods use the signals of the protons of water and lipids. This paper gives a comparison between different standard MR techniques and recently developed fat- and water-selective imaging methods, addressing their sensitivity to bone marrow changes in leukemia. Additionally, 1H results of spectroscopic methods are presented. The results and conclusions are based on the examination of 26 healthy volunteers and 106 patients with general or focal bone marrow alterations. Standard T1-weighted images did not distinguish bone marrow of young healthy volunteers with relatively high cellularity from acute leukemia. Using fat- and water-selective methods, patients with untreated leukemia showed only water proton signals and no lipid signals from red bone marrow of vertebral bodies and the pelvis. This phenomenon was never observed in healthy volunteers. Following chemotherapy, lipid and water contents normalize in successfully treated patients. Nonresponders did not show significant changes of the fat-water ratio after up to 3 weeks of therapy. Phase contrast imaging provides information about the difference between fat and water fractions within the bone marrow, but quantitative determination of the absolute fat and water fractions requires acquisition of several images and suffers from the susceptibility effects in trabecular bone marrow. The fat-water ratio and additional qualities of water and lipid protons (relaxation times) can be evaluated by volume-selective MR spectroscopy. Typical results of spectra from small-volume elements in hypercellular vertebral bone marrow of leukemic patients before cytotoxic treatment and of normocellular or hypocellular marrow after therapy are demonstrated.

Adolescent↗
PubMed1992

Volume-selective proton MRS in vertebral bodies.

Volume-selective 1H magnetic resonance spectra of small volume elements of (13 mm)3 positioned in lumbar vertebral bodies have been investigated in 15 healthy persons of different ages and sexes and in 11 patients with leukemia using double spin-echo sequences. Signal intensities and positions of the spectral lines have been evaluated. Interindividual spectra of VOI located in the center of vertebral bodies, intraindividual spectra of central VOI in different vertebral bodies, and spectra of different localizations within the same vertebral body have been compared as well as spectra before and partly after cytostatic treatment in leukemia patients. Unexpected phenomena of the signal shapes have been found. The water signal distributions in healthy persons compared to patients after bone marrow transplantation show significant differences. The success of the cytostatic treatment in cases of leukemia is accompanied by an increase in the intensity of the lipid signals and a decrease in the water signals.

Adipose Tissue↗
PubMed1992

Localized in vivo 1H spectroscopy of human skeletal muscle: normal and pathologic findings.

To obtain high signal to noise ratio in small volume elements (8 cm3), in vivo 1H NMR spectroscopy of normal and diseased human skeletal muscle was performed using a double spin-echo localization method on a 1.5-T whole body system. High resolved spectra of normal calf muscle show the well known resonances of lipids (methyl, methylene, olefinic, and other fatty acid resonances), creatine/phosphocreatine, choline/carnitine, taurine, and histidine with good intraindividual reproducibility. Pronounced intraindividual differences in the lipid range were found between different upper thigh muscle groups. On pathologic conditions like myopathy, myositis or irradiation damage the spectral lipid content was increased. Three months after local irradiation of the medial vastus muscle (50 Gy), the localized 1H NMR spectrum showed a complete loss of the choline and creatine signals. In a case of M. Behçet with muscular involvement the relative reduction of the choline signal may provide an insight in the pathobiochemistry. The results of our investigations in nine healthy volunteers and three patients are presented in detail including relaxation times of the metabolites.

Adolescent↗
PubMed1992

Computed tomography (CT) and magnetic resonance imaging (MRI) in T-stage evaluation of oral and oropharyngeal carcinomas.

174 CT and 32 MRI investigations were carried out on patients with carcinomas of the mouth and oropharynx. The methods were compared and their value in predicting the pre-therapeutic T-staging studied. The combination of CT and clinical examination was able to improve the T-staging considerably compared with clinical examination alone. MRI was superior to CT in delineating the tumour margins in 78% of patients. T1-weighted and gradient echo sequences after intravenous gadolinium injection were particularly useful. Nevertheless, T-staging based on clinical and CT-findings was changed in only 5% of patients by MRI. MRI is especially useful in T1 tumours and in cancer of the base of the tongue. MRI should also be used instead of CT were dental fillings obscure the region of interest. If there are good MRI facilities and an experienced team available MRI can be used before CT.

Diagnostic Errors↗
PubMed1991

Localized Larmor frequency-guided fat and water proton MRI of the spine: a method to emphasize pathological findings.

A measurement protocol providing a correct adjustment of the irradiation frequencies for well separated fat and water images of the lumbar spine is presented. To determine accurately the Larmor frequencies of water and fat protons within the vertebral bodies, a volume selective spectrum of a volume element (13 mm)3 located in a lumbar vertebral body was acquired with the 90 degrees-180 degrees-180 degrees double spin-echo method. These Larmor frequencies are used to adjust the frequency-selective pulse of the SENEX chemical-shift imaging sequence. This procedure provides well separated fat and water images for a large field of view even in the inhomogeneous region of the vertebral column. Their clinical importance is demonstrated by localized Larmor frequency-guided (LLFG) SENEX 1H images of the lumbar spine in healthy persons of different age and in a patient with acute myeloid leukemia.

Acute Disease↗
PubMed1991

[The value of NMR tomography in the planning of HDR-afterloading brachytherapy in cervical carcinomas. The experiences with 41 patients].

In 41 patients with inoperable cervical carcinomas, afterloading brachytherapy was used in combination with radiotherapy after planning with MRI (1.5 T spin echo multislice technique). In 27 women, phantoms neutral to MRI were introduced into the uterus to create a topographic situation comparable to that during brachytherapy; at the same time, the position of the applicators was marked. Under the circumstances, MRI demonstrated the position of the uterus and the tumour, the vagina, the bladder, the rectosigmoid and the applicator phantoms in every case. In 88% it was possible to demonstrate the margin of the tumour and normal myometrium. In 18% of the patients, the technique lead to a significant and, in a further 30%, to a marginal improvement in brachytherapy technique.

Brachytherapy↗
PubMed1990

[Meckel's diverticulum and lower gastrointestinal bleeding. Problems of preoperative diagnosis].

A hitherto perfectly healthy 28-year-old man suddenly passed stools containing bright red blood, and haemoglobin concentration fell at first to 10.1 g/dl. No bleeding source was found on gastroscopy and coloscopy. Nor was the source found by enteroclysis during a bleeding-free interval. Emergency laparotomy was performed after a recurrence of massive bleeding and revealed, 60 cm oral of the ileocaecal (Bauhin's) valve, a Meckel's diverticulum with ulcerated heterotopic gastric mucosa, 5 x 3 x 2 cm in size, and this was resected. 17 red blood cell concentrates had to be infused pre- and postoperatively, but there were no further complications.

Adult↗
PubMed1990

[Rapid and high-resolution 3D-imaging in MR tomographic diagnosis of diseases of the knee joint].

A new technique was developed for MR imaging of diseases of the knee joint to shorten the time required for examination. The acquisition of an isotropic 3D-dataset using a FLASH- or a FISP-sequence is the base for secondary reconstructions of planar high-resolution images (spatial resolution less than or equal to 1 mm) in free orientations. Acquisition time of the 3D-dataset is 16 minutes, additional one up to five minutes are needed for image calculation. The method can image structures of the knee joint such as the cartilage, the menisci or the ligament. The advantage of the decreased examination time of about 30 minutes has been proved, but further comparative clinical studies are needed to establish the diagnostic equivalence of this method and conventional techniques.

Adult↗
PubMed1989

[Magnetic resonance tomography of the oral cavity, the oropharynx and the mouth floor: comparison with computed tomography].

42 CT and MR examinations of orofacial tumours have been analysed and their value has been compared. In 78% of cases MR was superior to CT in delineating the tumour borders. T1-weighted and gradient echo sequences after intravenous gadolinium injection were particularly useful. Nevertheless, T-staging based on clinical and CT findings was altered in only two cases (5%) by MR. MR should, at present, be used in those cases where small tumours can not be demonstrated by CT, or where metal artifacts obscure the region of interest.

Adult↗
PubMed1989

[CT functional images of the larynx and hypopharynx].

Ten healthy volunteers and sixty-four patients with various abnormalities of the hypopharynx and larynx were examined by CT in different functional stages in order to study the normal anatomy and the diagnostic value of CT. CT images during quiet respiration are best for showing small glottic carcinomas. To demonstrate, or exclude, fixation of the vocal cords, it is important to obtain images during "E" phonation. Images during "E" phonation, or during Valsalva's manoeuvre, are essential for demonstrating small carcinomas of the hypopharynx and should be obtained in these cases. These images are also helpful in studying functional abnormalities from paralyses of the recurrent laryngeal nerve, trauma of the larynx and laryngoceles. Images during "E" phonation should therefore be obtained in addition to those during quiet respiration as part of the standard examination of the hypopharynx and larynx.

Cranial Nerve Diseases↗
PubMed1989

[The clinical value of computed tomography in the pretherapeutic T-staging of orofacial tumors].

The clinical role of contrast-enhanced CT for pre-operative T-staging of oro-facial tumours was evaluated in 174 patients. During stages T1 and T2, clinical examination is 90% accurate and has a significantly higher sensitivity than CT, with an accuracy of only 53%. The clinical diagnosis of T1 and T2 is, however, made with undue frequency; CT makes it possible to obtain correct staging. Combination of CT and clinical examination can improve correct staging from 46% to 81%. During stages T3 and T4. CT has sensitivity of 91% and is markedly superior to clinical examination, with a sensitivity of 34%. Combined clinical and CT examination improves the predictive value from 52% to 92%. Combination of clinical and CT staging, when the higher stage is accepted as being correct, has a sensitivity and reliability of over 90%. It can be used as a firm basis for treatment planning, judging the prognosis and the effects of treatment.

Adolescent↗
PubMed1988

[NMR tomography of bone-cartilage transplants in the knee joint: transplant morphology and an attempt at the quantitative assessment of cartilage changes].

MRT control examinations were carried out on 15 patients with allogenic bone-cartilage transplants in the knee. Spin-echo and gradient-echo sequences were obtained by using a flat surface coil. The results were compared with arthroscopic and operative findings. In 8 symptom-free patients, there was inclusion of the bone implant with narrow, but smooth, cartilage. 7 patients with recurrence of symptoms showed various complications such as oedema of the marrow, exudative synovitis, cartilage oedema, degenerative cartilagenous changes with regeneration of fibro-cartilage and localized cartilage defects. Spin-echo sequences were useful for showing bone, whereas gradient-echo sequences proved better for showing changes in the cartilage. MRT can be recommended as the method of choice for the non-invasive control of bone-cartilage transplants.

Adolescent↗