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Biomedical subjects

R M Seibel

Publications and source records attributed to R M Seibel.

8 recordsLinked to original sources
PubMed1995

Image-guided access techniques.

For increasing safety in access and guidance of endoscopes and instruments, fast real-time radiologic imaging should be integrated. Open designed Magnetic Resonance Imaging (MRI), Computer Tomography (CT), and Electron Beam Tomography (EBT) scanners permit adequate transparency of the operative field. CT and EBT as hybrid scanners can be combined with fluoroscopy. MRI avoids X-ray exposure and entails the possibility of 3D localisation, while open access and keyhole imaging allows nearly real-time guidance of instruments. EBT has the largest gantry (90 cm) for using long instruments, and the image acquisition requires only 50 msec (34 images/sec at 8 levels). However, computed reconstruction of the data takes about 3 times longer than conventional CT. Until EBT can be accelerated, CT will be the golden standard of guidance-techniques in high risk areas, because the tips of the instruments can be precisely visualised within +/- 0.5 mm (MRI: 3.5 mm). MRI-guidance can be used for low risk access techniques. This safe interactive transparent guidance technique has the potential to reduce complications, and it adds significant advantages to micro-invasive operative procedures such as percutaneous diskectomies, pain and cancer therapy with ethanol, or gene-technology implants in the new field of "surgical tomography".

Diagnostic Imaging↗
PubMed1994

[Pelvimetry using various magnetic resonance tomography techniques vs. digital image enhancement radiography: accuracy, time requirement and energy exposure].

In 50 patients with suspected or proven cephalo-pelvine disproportion pelvimetry was performed with MR-tomography using a gradient-echo-sequence (FLASH 2D) before or after labour. Results were compared with measurements using digital radiography. In principle, both methods are exchangeable. The sagittal pelvic in- and outlet bispinous diameters are well reproducible. On the other hand, the transverse pelvic inlet and the distance between the ischiatic tubera are not so reliably reproduced. The accuracy of measurement does not depend on individual pelvic distances. Critical statistical analysis demonstrates, that in the worst case differences between the two methods might become unacceptable. Our results indicate two major reasons: 1. there are interobserver problems which cannot be neglected, and 2. the anatomical definition of referential landmarks for the measurements is unsafe. In 10 volunteers, a comparison was made between a T1-weighted spin-echo sequence (SE), a fast gradient echo sequence (FLASH-2D) and an ultrafast gradient echo technique (Turbo-FLASH). For the examination techniques presented here, the high-frequency exposure load or specific absorption rate (SAR loc and SAR total) is below the values permitted by the German Federal Health Bureau (Bundesgesundheitsamt). Whereas the exposure load in case of spin-echo takes (SE) is 22fold higher than with the gradient echo technique (GHE), the load values of ultra-fast GE (usGE) are only about 16% of the 2D-FLASH sequence or about 0.007% of SE. The difference in image quality does not affect the accuracy of measurement.

Adolescent↗
PubMed1993

[Microinvasive CT-controlled tumor therapy of soft tissue and skeletal metastases].

Micro-invasive CT-guided intratumoral therapy (MIC-ITT) when used in combination with sympathectomy can be an excellent palliative treatment with little impairment of the patient. Rapid as well as complete reduction of pain without systemic side effects can be achieved under local anesthesia in patients in advanced tumor stages by the direct instillation of 50 to 96% alcohol and/or a locally efficacious low toxic cytostatic (Mitoxantron) under CT guidance. CT enables not only exact puncture without injuring endangered structures but also a controlled application of medication. The interventions can be performed with special probes with a diameter of 18 to 25 G. The study population consisted of 145 patients who received a total of 434 treatments. Repeated micro invasive intratumoral treatment was performed on 110 patients with bone and soft tissue metastases (Group I, 335 single treatments) and on 35 patients with vertebral metastases (Group II, 109 single treatments). In all patients conventional therapeutic strategies had been exhausted or were no longer applicable on the basis of a reduced Karnofsky Index. Treatment was performed in combination with sympathetic neurolysis at the upper tumor pole in all cases. The maximum follow-up time was 30 months. Pain reduction was estimated on a visual analogic scale. In Group I up to time of death a pain reduction of 75% or better was achieved in 88 patients (80%). A reduction in tumor size concomitant with a stabilization of the tumor region could be shown in 25% in this group, no change in 62% and progression in 13%. In Group II a pain reduction greater than 75% was achieved in 84% as well as a reduction in tumor size (< 50%) in 18% of the patients. Necrotic zones could be shown in 27% and calcification of tumor area in 35%. No change in tumor size was found in 66% of the patients, progression in 16%. All treatments were free of complications. On the whole the results of this therapeutic approach are encouraging. In particular one aspect should be mentioned: with respect to palliative treatment the reduction of tumor size is not crucial. The decisive factor is the improvement in quality of life of the patient using an intervention which impairs the patient only minimally. Furthermore this micro invasive approach should always involve the combination of local tumor treatment with treatment or lysis of the autonomic sympathetic nervous system in tumor vicinity.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Percutaneous nucleotomy with CT and fluoroscopic guidance.

Automated percutaneous diskectomy was performed with use of computed tomographic (CT) and fluoroscopic monitoring. Degenerative disease of the intervertebral disk was treated with local administration of anesthesia and use of a nucleotome. One hundred ten patients with neurologic symptoms and morphologic changes of one segment were selected for treatment. Previous conservative therapy had been unsuccessful. Patients with completely prolapsed and sequestered fragments of herniated disks ("uncontained disk"), narrow intervertebral spaces, posterior osteophytes, diseased facet joints, and spinal stenoses were not considered candidates for percutaneous nucleotomy (PNT). After PNT, 82% of the patients had complete remission of their neurologic symptoms; Lasègue sign was negative or improved in 92%. In 18% (20 patients), the symptoms did not improve sufficiently; 11% (12 of 110) of these patients underwent surgical nucleotomy. There were no serious complications, in particular, no injuries to vital structures (nerves, thecal sac, arteries, veins), except for one case of spondylodiskitis. Guiding PNT with CT and fluoroscopy provides a safe procedure with good clinical results. The addition of CT has shortened the operation but increased over-all procedure time. In the future, a shift to outpatient treatment may offset the additional time and cost of including CT guidance.

Adult↗
PubMed1989

[New possibilities and aspects of low-field magnetic resonance tomography].

Worldwide, MRI is going up to higher field-strength. For imaging, magnets with field-strength between 0.2 and about 2.5 Tesla are installed. Below 0.2 Tesla, Low-Field-systems have been used in research-projects to optimize image quality. New developments of 0.064 Tesla Permanent-Magnet-MRI are hopeful for clinical work. Future possibilities of Low-Field-MRI are shown. The advantages of this system are good image quality by low initial start-up and operating costs as well as ease of sitting and lack of need for cryogens. The open design has excellent patient acceptance and allows to examine patients with claustrophobia feelings. It allows easier monitoring during the examination-especially children and patients with cancer or polytraumatic diseases. The introduction of more affordable MRI-systems of low-field-strength may decrease the cost of MRI to the point where it is competitive with computer tomography.

Costs and Cost Analysis↗
PubMed1986

[Immunoglobulins for the prevention of radiation pneumonitis following large-volume irradiation in bronchial carcinoma].

In a randomized study 20 patients with non small cell lung cancer were treated for cure at a linear accelerator. Before, during and after treatment levels of immunoglobulins were measured. At the end of radiation therapy levels of IgA, IgG and IgM decreased. After therapy they increased slowly. 3 months after irradiation the average immunoglobulin levels showed a reduction of 16%. After substitution of immunoglobulins no decrease of the levels was seen. After substitution of immunoglobulins the Karnofsky index was significantly higher. Substituted patients showed a lower rate of radiation pneumonitis.

Carcinoma, Bronchogenic↗
PubMedDate not supplied

Technique for CT guided microendoscopic dissection of the spine.

The indications for percutaneous nucleotomy techniques are limited to disk herniation without dislocated free fragments. In cases with free fragments we have developed a new technique for percutaneous sequestrectomy. Under CT and fluoroscopic guidance spinal endoscopy was performed. In the past, percutaneous diskectomies were X-ray-guided with or without endoscopy. In this paper we describe the combination of CT-scanning, fluoroscopy and microendoscopy for guidance of nucleotomes, lasers, microendoscopes and micro-instruments. The technique was performed on 20 patients (17 outpatients) with chronic back pain. To date no major complications occurred. The method offers an effective outpatient treatment of small free fragments and scar tissue in the spinal canal and the foramen.

Adult↗