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Biomedical subjects

C Vollmar

Publications and source records attributed to C Vollmar.

7 recordsLinked to original sources

[Combined Scanners (PET/CT, SPECT/CT) Versus Multimodality Imaging with Separated Systems].

With increasing use of combined PET/CT scanners in the last few years, multimodality imaging (Nuclear Medicine/Radiology) found its way into clinical routine diagnostics. In this overview, necessary components for multimodality imaging, strategies for image analysis and image presentation, and diagnostic goals of combined imaging are demonstrated and discussed. A special focus is on the question, whether combined scanners can be replaced by a software approach with separated modalities. Advantages and limitations of multimodality imaging with combined or separated scanners are shown.

Computers↗

No evidence of cerebral oedema in severe acute mountain sickness.

In a randomized, double-blind cross-over study 10 subjects were exposed to a simulated altitude of 4500 m for 10 h after administration of placebo, acetozolamide (250 mg bid) or theophylline (250 mg bid). T2-weighted magnetic resonances images (MRI) and diffusion weighted MRI were obtained directly after exposure to altitude under hypoxic conditions. Although eight of 10 subjects had moderate to severe acute mountain sickness (AMS), we found no evidence of cerebral oedema, irrespective of the medication taken. Almost all subjects showed a decrease in inner cerebrospinal fluid (iCSF) volumes (placebo - 10.3%, P= 0.02; acetazolamide - 13.2%, P= 0.008, theophylline -12.2%, n.s.). There was no correlation between AMS symptoms and fluid shift. However, we found a significantly positive correlation of large (>10 ml) iCSF volume and more severe AMS after administration of placebo (r = 0.76, P= 0.01). Moderate to severe AMS after high altitude exposure for 10 h is associated with a decreased iCSF-volume independent of AMS severity or medication without signs of cerebral oedema.

Acetazolamide↗

Direct costs of microsurgical management of radiosurgically amenable intracranial pathology in Germany: an analysis of meningiomas, acoustic neuromas, metastases and arteriovenous malformations of less than 3 cm in diameter.

BACKGROUND: The purpose of the analysis was to appreciate and compare the effective direct costs of microsurgical treatment of intracranial pathology potentially amenable to radiosurgery as they arose in 1998-99. METHOD: Treatment costs of 127 microsurgically treated patients harbouring an arteriovenous malformation (AVM), acoustic nEuroma, meningioma or brain metastasis potentially amenable to radiosurgery were reviewed. Costs for the surgical procedure, ICU care, medical and nursing care on the ward, interclinical bills (ICB) for services provided by other departments and the overhead for basic hotel service were added. For comparison Gamma Knife costs were calculated by dividing the global operating cost of the Gamma Knife centre by the number of patients treated in 1999. FINDINGS: Average hospitalisation time for the entire microsurgical patients was 15,4+/-8,6 days. The patients spent an average of 1,2+/-2,8 days on ICU. Average operating time for all patients, including preparation, was 393+/-118 minutes. Average costs for the microsurgical therapy were Euro10.814+/-6.108. These consisted of Euro1417+/-426 for the surgical procedure, Euro1.188+/-2.658 for ICU care, Euro2.333+/-1.582 for medical and nursing care on the ward, Euro1.671+/-1.433 for interclinical bills and Euro 4.204+/-2.338 for basic hotel service (overhead, Euro273/day). 70% of the microsurgically treated patients needed ancillary inpatient rehabilitation or radiotherapy resulting in an average additional cost for all patients of Euro2.744. Furthermore 20% of the microsurgically treated patients required an unplanned readmission after discharge, resulting in an average additional costs for all patients of Euro1.684. Average overall costs per patient including ancillary therapy and unplanned readmissions amounted to Euro15.242. For comparison, Gamma Knife treatment costs per patient amounted to Euro7.920 in 1999. INTERPRETATION: The current analysis showed that for established radiosurgical indications the primary costs of microsurgery exceeded the costs of radiosurgery. Differences with regard to additional expenses as a consequence of disability were not addressed in this study. Microsurgical management as well as Gamma Knife radiosurgery have potential for economic improvement.

Brain Neoplasms↗

Usefulness of 3-D reconstructed images of the human cerebral cortex for localization of subdural electrodes in epilepsy surgery.

Three-dimensional (3-D) images of 14 patients, in whom subdural electrodes were implanted for epilepsy surgery evaluation, were produced by fusing computerized tomography (CT) scans and magnetic resonance images (MRI) to determine the exact location of the electrodes. In 25% (198 of 806) of the subdural electrodes an exact location for resection strategy was not evident from the X-rays. The location of these electrodes ('doubtful location', DL) was compared to the 3-D images. Intraoperative inspection served as the gold standard. Concordance score was defined as good for 75-100% concordance, moderate for 50-75%, and poor for less than 50% concordance of the DL electrodes to the intraoperatively determined location. A comparative analysis of the 3-D images and X-ray films showed a highly significant difference (P < 0.0002) in favor of 3-D images. The concordance score for the DL electrodes in the 3-D images was good in 93% of the patients and moderate in 7%. In contrast, the concordance score was good in only 7% of the patients for the two-dimensional (2-D) skull films, moderate in 57%, and poor in 36%. Interobserver reliability was better for 3-D images (93%) than for the 2-D X-rays (43%). These findings suggest that 3-D images aid preoperative planning for resective epilepsy surgery.

Adolescent↗

Quantitative comparison of automatic and interactive methods for MRI-SPECT image registration of the brain based on 3-dimensional calculation of error.

UNLABELLED: A wide range of techniques for registration of medical images has been devised in recent years. The aim of this study is to quantify the overall spatial registration error of 3 different methods for image registration: interactive matching, surface matching, and uniformity index matching as described by Woods. METHODS: MRI and ethylcysteinate dimer-SPECT images of the brain were registered for 15 patients. The matching error was assessed by determining intra- and interobserver variability of registrations. Quantification of the registration error was based on the mean spatial distance of 5000 voxels between 2 image positions. The mean position after repeated registrations in each patient was used as the gold standard. To evaluate the coherence of the 3 different registration methods, intermethod variability was determined. RESULTS: Interactive matching showed an intraobserver/interobserver variability of 1.5+/-0.3 mm/1.6+/-0.3 mm (mean +/- SD). The time demand for this method was 11+/-5 min. Surface matching revealed a variability of 2.6+/-1.1 mm/3.8+/-1.0 mm and a time demand of 26+/-12 min. Reproducibility of Woods' algorithm was 2.2+/-0.8 mm with a time demand of 9+/-3 min. In 4 of the 15 cases, Woods' method failed. The mean deviation between all 3 methods was 2.3+/-0.8 mm. CONCLUSION: With a suitable user interface, interactive matching had the lowest registration error. The influence of subjectivity was shown to be negligible. Therefore, interactive matching is our preferred technique for image fusion of the brain.

Adult↗

Normative volumetric data of the developing hippocampus in children based on magnetic resonance imaging.

PURPOSE: To acquire normative data of the hippocampus and its postnatal growth in 50 children (age, 1 month to 15 years) without epilepsy. METHODS: Morphometry of the hippocampus was carried out by using a spoiled FLASH 3D sequence (sagittal orientation), whereas the volume of the brain was assessed with a T2-weighted spin-echo sequence (transverse orientation). The volume of the hippocampus and the brain was determined by following Cavalieri's principle. Growth curves of the brain and hippocampus were fitted to a nonlinear Boltzmann sigmoidal equation. RESULTS: Intra-/interobserver coefficient of variation was 2.0/4.9% for hippocampal volume measurements and 2.0/2.1% for brain volumetry. A significant difference in volume was noted between the right and left hippocampus (p < 0.001), with the right side being larger on average by 0.10 cc. Correlation coefficients of growth curves ranged between 0.71 and 0.94. Growth curves demonstrated a faster development of the hippocampus in girls. A steeper slope of hippocampal growth as compared with brain growth was found in girls, whereas in boys, the slope of brain growth was steeper. CONCLUSIONS: Our findings will be of help in evaluating vulnerable phases of the hippocampal formation with accelerated growth, thereby leading to a better understanding of the development of hippocampal sclerosis in early childhood.

Adolescent↗