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Biomedical subjects

L M Vencken

Publications and source records attributed to L M Vencken.

At least 19 recordsLinked to original sources
PubMed1993

Computed tomography in differential diagnosis of temporomandibular joint disorders.

Computed tomography (CT) has great potential for imaging intra- and extracapsular hard-tissue abnormality of the temporomandibular joint (TMJ). CT is not the best method of imaging disk position and form. For differential diagnosis of TMJ disorders, CT is especially successful in bony lesions. The study includes 16 examples of TMJ hard-tissue abnormality. In the differential diagnosis of all cases, CT played a decisive role.

Adolescent↗
PubMed1992

In vivo phosphorus magnetic resonance spectroscopy in multiple sclerosis.

Localized phosphorus magnetic resonance spectroscopy at 1.5 T was performed in 39 patients with multiple sclerosis and in 15 healthy controls. The multiple sclerosis spectra showed increased creatine phosphate levels. This increase was correlated with the severity of the handicap and was greater in patients with a progressive course of the disease than in patients with relapsing-remitting disease. No clear abnormalities were observed in the spectra of patients with multiple sclerosis regarding the phosphomonoesters, phosphodiesters, inorganic phosphate, and beta-adenosine triphosphate or with respect to pH values. There was an increased creatine phosphate level in the spectra in relation to a low metabolic state of the brain.

Adenosine Triphosphate↗
PubMed1991

Vanishing calcification of the brain in an infant after open heart surgery.

Neurological complications after cardiac operations with the aid of cardiopulmonary bypass and hypothermia are well known. A 6 months-old child is described with severe neurological complications after cardiac surgery for Fallot's tetralogy. On the CT scan cortical calcification was seen to vanish. Such calcification has not been reported in similar patients. Possible causes are discussed but the precise pathophysiology of this phenomenon remains unclear.

Brain Diseases↗
PubMed1990

Temporomandibular joint direct sagittal computed tomography: evaluation of image-processing modalities.

Computed tomography (CT) is a useful method for examination of the temporomandibular joint because it allows visualization of the articular disk. In computed tomography many factors play an important role in image reconstruction and image processing. The use of image-processing modalities (such as window variation and level detection) has far-reaching consequences on the display and interpretation of the direct sagittal CT image of the temporomandibular joint (TMJ). In this study, the most important image reconstruction and processing factors were studied for use in the diagnosis of internal derangements and other disorders of the TMJ. Optimal values for the setting of the CT system for the different techniques are discussed.

Humans↗
PubMed1990

Temporomandibular joint computed tomography: development of a direct sagittal technique.

Radiology plays an important role in the diagnosis of temporomandibular disorders. Different techniques are used with computed tomography offering simultaneous imaging of bone and soft tissues. It is therefore suited for visualization of the articular disk and may be used in patients with suspected internal derangements and other disorders of the temporomandibular joint. Previous research suggests advantages to direct sagittal scanning, which requires special positioning of the patient and a sophisticated scanning technique. This study describes the development of a new technique of direct sagittal computed tomographic imaging of the temporomandibular joint using a specially designed patient table and internal light visor positioning. No structures other than the patient's head are involved in the imaging process, and misleading artifacts from the arm or the shoulder are eliminated. The use of the scanogram allows precise correction of the condylar axis and selection of exact slice level.

Adolescent↗
PubMed1987

Interpretation of magnetic resonance images making use of in vitro examinations of spinal tissue.

T1 and T2 relaxation times were determined in vitro at 21 MHz (0.5 T) for a variety of spinal and paraspinal tissues. Intensity formulas for spin echo and inversion recovery sequences were derived and used to calculate the intensities of these tissues as they would appear in magnetic resonance images. The intensity was calculated as a function of various repetition, echo, and inversion times. It is shown that the combination of acquiring in vitro relaxation time values and calculating intensity as a function of pulse timings is useful to predict the parameter setting for optimal contrast between certain tissues without applying series of magnetic resonance images.

Electron Spin Resonance Spectroscopy↗
PubMed1986

Progressive neurological deficit in children with spina bifida aperta.

The results of re-operation of 15 patients with spina bifida aperta are reported. The operation was necessary because of neurological deterioration with increasing motor and bladder dysfunction. In all patients a tethered cord syndrome was present (CT-myelography). The myelum was adherent to the scar of the myelomeningocele repair. At operation the myelum is released from the adherent scar and in this way untethered. The early complications were mild except for one patient with decompensation of hydrocephalus. The aim of the operation was to stop further progression. The results of the operation were satisfactory with stabilisation of motor function in four patients and improvement of motor dysfunction in ten patients. Backache or fixation, bladder dysfunction and abnormal foot shape improved in some of the patients. In our experience the operative untethering procedure was useful. Intensive neurological control of operated spina bifida aperta patients is mandatory especially in those patients who can walk.

Adolescent↗
PubMed1986

Interpretation of spinal MR images in relation to tissue parameters.

When relaxation parameters of tissues are known, selection of adequate instrumental parameters in magnetic resonance imaging is possible. The signal strength of various tissues is defined by proton density, T1 and T2. The calculation of this signal strength is given. The advantages of multiple echoes and the reason why they are used, are mentioned.

Brain Diseases↗
PubMed1985

Unexpected cure in metastatic rhabdomyosarcoma.

A 3 year old boy presented with a presumably incurable form of rhabdomyosarcoma. Conventional treatment for advanced stage rhabdomyosarcoma (chemotherapy plus radiotherapy) was not used and intensive chemotherapy alone was given, resulting in an apparent cure. Our treatment rationale is discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1984

Penetration of VP 16-213 into cerebrospinal fluid after high-dose intravenous administration.

VP 16-213 in standard doses is active against a number of solid tumors. Its penetration into the cerebrospinal fluid (CSF) is very limited at these dose levels. In 10 patients treated with high-dose VP 16-213 (0.9-2.5 g/m2), CSF levels of up to 0.54 microgram/mL were detected. In two patients with central nervous system (CNS) metastases of small cell lung cancer (SCLC) a response was seen after 1.0 and 1.5 g/m2 intravenously. High-dose VP 16-213 can possibly play a role in the treatment of CNS metastases of SCLC. Its application in late intensification regimens as a form of prophylaxis of CNS metastases should be investigated.

Adult↗
PubMed1984

Relationship between contrast medium dose and adverse effects in lumbar myelography.

In a prospective double-blind randomized study involving 40 patients undergoing lumbar myelography, an attempt was made to correlate adverse effects of the examination with contrast medium dosage. Metrizamide for myelography is dispensed in two dosage aliquots, 3.75 and 6.75 g. In one group of 20 patients (10 males and 10 females) the higher dose was utilized routinely, in a second similar group the lower dose. 24 h after myelography complaints of headache were noted in 9 out of 40 patients; nausea, sometimes with vomiting, in 3 out of 40, and giddiness or light-headedness in 6 out of 40. No other side effects were registered. Complaints after myelography occurred significantly more often in females than in males, but there was no correlation between the incidence of complaints and the dose of metrizamide administered.

Clinical Trials as Topic↗
PubMed1984

Complete delineation of an obstructing spinal mass in myelography through the lumbar route.

With a technique described earlier, but modified by special positioning of the patients and use of water-soluble contrast medium, we managed to pass an apparently total spinal block in 11 out of 14 patients. Apart from a shortlasting pain during the procedure, the patients suffered no harm. The duration of the examination could be shorter and less patient cooperation was necessary.

Adult↗
PubMed1983

Interpretation of nuclear magnetic resonance tomograms of the brain.

Nuclear magnetic resonance tomography is an imaging method based on the magnetic resonance behavior of protons, as they occur predominantly in tissue water or in fatty acids. This behavior, as characterized by the relaxation times T1 and T2, is determined by the chemical and physical environment of the protons. The relaxation properties of the tissue can be accentuated by selection of the appropriate pulse sequence. Interpretation of the images requires an understanding of the principles of the technique with which the relaxation times are expressed in the images, and acquaintance with the composition of the tissue in terms of relaxation properties (as in computerized tomography, tissue composition is expressed as attenuation coefficients).

Adult↗