PubMed Health⌕ Search

Biomedical subjects

K Wester

Publications and source records attributed to K Wester.

At least 55 records · Page 3Linked to original sources
PubMed1998

Automatic quantification of immunohistochemically stained cell nuclei using unsupervised image analysis.

A method for quantification of images of immunohistochemically stained cell nuclei by computing area proportions is presented. The image is transformed by a principal component transform. The resulting first component image is used to segment the objects from the background using dynamic thresholding of the P2/A-histogram, where P2/A is a global roundness measure. Then the image is transformed into principal component hue, defined as the angle around the first principal component. This image is used to segment positive and negative objects. The method is fully automatic and the principal component approach makes it robust with respect to illumination and focus settings. An independent test set consisting of images grabbed with different focus and illumination for each field of view was used to test the method, and the proposed method showed less variation than the intraoperator variation using supervised Maximum Likelihood classification.

Algorithms↗
PubMed1998

Dichotic memory: paradoxical effect of removing a left frontal gyrus: a case study.

A 27-year-old right-handed woman was operated with resection of an epileptogenic lesion, a nonmalignant tumor, in the left frontal lobe. The surrounding cortical and subcortical tissue in the tumor-containing gyrus was also resected. Care was taken during the operation not to interfere with motor or language related cortical areas. Pre- and postoperatively, she was tested with a dichotic memory test. In the preoperative test, she showed a marked Left Ear Advantage. In the corresponding tests on the second and fourth postoperative days and at follow-up, her performance had changed to a Right Ear Advantage. A possible explanation of this result is that neighboring cortical areas involved in hemispheric specialization for lateralized, verbal cognitive functions are suppressed by a focal epiletogeneic activity caused by the tumor. The subsequent removal of this influence allowed these cortical areas to function normally.

Adult↗
PubMed1997

[Cerebral metastases treated with stereotaxic gamma radiation. 6-year experience with the "gamma knife" at the Haukeland hospital].

During the last 6 years we have treated 32 patients with 45 metastases to the brain in the Gamma Knife unit. 21 of these were treated exclusively with the Gamma Knife. The remaining 11 patients received radiosurgery for recurrent disease after surgery and whole-brain irradiation (six patients), new metastases after whole-brain irradiation alone (three patients) or for local regrowth after surgery (two patients). The range of tumour volume was 0.1-43.3 cm3 (median 2.4 cm3). Marginal tumour dose was 5-30 Gy (median and mean: 25 Gy) to the 30-70% isodose-volume line according to tumour volume and localization. 19 patients died during the period of follow-up. Only three patients died from their intracranial metastases. Thus, local growth control was achieved in 29 patients. 16 patients died from extracranial manifestations. The average survival time for the patients who died during the observation period was 11 (1-37 months), and the survival time for patients still alive was 10-75 (median 14, average 29) months. Mean observation period for all patients was 17 (1-75) months. Brain metastases are physically and biologically ideal lesions to treat with radiosurgery. Stereotactic radiosurgery applied to radiographically small and distinct metastases is safe, non-invasive and highly effective. The treatment requires only a short stay in hospital, and is much less inconvenient to the patient than open surgery or whole-brain irradiation. Radiosurgery can be used on lesions inaccessible to open neurosurgery or resistant to classical fractionated radiotherapy. Gamma Knife treatment has become our first choice for patients with less than four intracranial metastases with diameters less than 3-3.5 cm.

Adult↗
PubMed1997

[Intracranial venous thrombosis].

Cerebral venous thrombosis has traditionally been considered to be a severe and rare condition. Our knowledge of this condition has increased, however, along with the development of better radiological methods for visualization of the brain and its vasculature. Cerebral angiography, computed tomography (CT) and, in particular, magnetic resonance imaging (MRI) have made it easier to diagnose this condition earlier. It has thus been discovered that cerebral venous thrombosis occurs more frequently than previously supposed and shows a wide variation of the clinical spectrum. We describe a series of eight patients with cerebral venous thrombosis who were admitted to the Neurosurgical Department, Haukeland Hospital, over a period of three years. The presentation shows the great variation in the clinical and radiological picture of this disease and the consequent diagnostic and therapeutic challenges. We conclude that this diagnosis should be considered in patients with cerebral symptoms of uncertain cause, and that MRI is an important tool in diagnosis.

Adolescent↗
PubMed1997

Effect of androgen deprivation on epithelial and mesenchymal tissue components in localized prostate cancer.

OBJECTIVE: To measure the area distribution of epithelial and mesenchymal components in the prostate of patients with localized prostate cancer after temporary androgen deprivation. PATIENTS AND METHODS: Surgical specimens from 38 patients treated with the gonadotrophin-releasing hormone agonist triptorelin for 3 months before radical prostatectomy were examined (group I). Specimens from a second group of 54 patients who underwent the same surgical procedure with no prior therapy were used as controls (group 2). The specimens were serially step-sectioned and whole-mount tissue sections prepared. The epithelial, smooth muscle and connective tissue components were stained separately with immunohistochemical and histochemical techniques, respectively. Using colour-based image analyses, the tissue components were classified into three categories, displayed in different colours. The percentage of tumour areas occupied by cancer epithelial cells, connective tissue and smooth muscle was determined. RESULTS: In specimens from group 1, the cancer epithelium was sparse and scattered throughout the tumour area. A mean (SD) of 21 (11)% of the area was occupied by cancer cells, compared with 40 (11)% in the corresponding material from group 2 (P < 0.001). The connective tissue/smooth muscle ratio in stroma (about 1:1) was similar in both groups. CONCLUSIONS: Neoadjuvant hormone treatment of patients with localized prostate cancer was associated with a marked reduction in tumour density and thus in the total amount of cancer epithelium.

Androgen Antagonists↗
PubMed1997

Neuroblastoma and venous sinus thrombosis in an adult patient.

A 35-year-old woman developed symptoms consistent with intracranial venous sinus occlusions that were demonstrated by MR angiography. After a few weeks of anticoagulant therapy, she became paraplegic due to haemorrhages in the caudal spinal canal. A decompressive laminectomy did not improve her neurological deficits. Up to this point, we assumed her condition to be caused solely by the intracranial venous thrombosis and complications of the treatment. A tumour diagnosis had so far not been considered. A few months later she became tetraplegic. MRI revealed fresh bleeding in the upper spinal cord and a dissemination of tumour along the entire craniospinal axis. Biopsy specimens obtained from the spinal canal contained tumour cells with the characteristics of neuroblastoma.

Adult↗
PubMed1997

Syringomyelia treated with a nonvalved syringoperitoneal shunt: a follow-up study.

OBJECTIVE: Eighteen patients with syringomyelia received nonvalved syringoperitoneal shunts during the years 1987 through 1996. In 15 cases, the fistulae were multicompartmental, either separated by segments of normal cord or septated. METHOD: Even in the multicystic cases, only one syringeal catheter was introduced, usually into the caudalmost cavity. Access to the fistula was obtained via a midline myelotomy, which was performed in an area at which the spinal cord overlying the fistula was at its thinnest. RESULTS: The progressive clinical course of syringomyelia was arrested in all patients. Surgery resulted in improvement for 11 patients. Five patients remained unchanged without further progression. Two patients became worse as the result of new deficits caused by surgery. In four patients, the myelotomy lead to new but discrete sensory loss of minor importance. Postoperative magnetic resonance images showed a rapid and persistent collapse of all fistulae in all patients. CONCLUSIONS: We conclude that syringoperitoneal shunting is favorable in patients with large fistulae. In patients with Chiari malformations, the procedure may be a second alternative to foramen magnum decompression.

Adolescent↗
PubMed1997

Image analysis based grading of bladder carcinoma. Comparison of object, texture and graph based methods and their reproducibility.

The possibility that computerized image analysis could increase the reproducibility of grading of bladder carcinoma as compared to conventional subjective grading made by pathologists was investigated. Object, texture and graph based analysis were carried out from Feulgen stained histological tissue sections. The object based features were extracted from gray scale images, binary images obtained by thresholding the nuclei and several other images derived through image processing operations. The textural features were based on the spatial gray-tone co-occurrence probability matrices and the graph based features were extracted from the minimum spanning trees connecting all nuclei. The large numbers of extracted features were evaluated in relation to subjective grading and to factors related to prognosis using multivariate statistical methods and multilayer backpropagation neural networks. All the methods were originally developed and tested on material from one patient and then tested for reproducibility on entirely different patient material. The results indicate reasonably good reproducibility for the best sets of features. In addition, image analysis based grading showed almost identical correlation to mitotic density and expression of p53 protein as subjective grading. It should thus be possible to use this kind of image analysis as a prognostic tool for bladder carcinoma.

Humans↗
PubMed1997

Thalamotomy and thalamic stimulation: effects on cognition.

Before, during and after ventrolateral thalamotomy, patients were subjected to neuropsychological tests with emphasis on verbal perception and memory. In the first study, the patients were tested with a dichotic listening task before surgery, during thalamic stimulation, and after the lesion. Left thalamic stimulation increased the number of correct responses from the right ear, whereas a left thalamotomy abolished the expected right ear superiority. Stimulation and lesions of the right thalamus did not have similar effects. In a second study, Parkinsonian patients were tested with an extended neuropsychological test battery before and after thalamotomy. The operation did not reduce the cognitive capacity in this group of patients. In the last study, the effects of thalamic stimulation on verbal memory was tested. High-intensity stimulation of the left thalamus resulted in fewer words being recalled as compared with right thalamic and low-intensity stimulation.

Auditory Perception↗
PubMed1997

Lateralized thalamic stimulation: effects on verbal memory.

This study was concerned with the effects of left- or right-thalamic stimulation on a simple verbal memory task, involving immediate free recall of lists of common words presented dichotically. The subjects were patients with Parkinson's disease undergoing stereotaxic thalamotomy. As a clinical routine, the patients also underwent a brief period of thalamic electrical stimulations before the lesion was made. The memory tests were performed during the stimulation phase of the operation and were accomplished inside the operating room. The main finding was a general deterioration of performance during thalamic stimulation compared with preoperative and postoperative testing. However, this general effect was modulated by stimulation intensity and side of stimulation. High-intensity stimulation of the left thalamus resulted in significantly fewer words being recalled compared with right thalamus stimulation and low-intensity stimulation. Finally, words presented in the first list were recalled better than words from the second and third lists, particularly during stimulation and at follow-up. The findings are discussed in relation to the thalamic activating-gating model originally proposed by Ojemann.

Adult↗
PubMed1996

Arachnoid cysts in adults: experience with internal shunts to the subdural compartment.

Twelve patients (10 males, 2 females) with symptomatic arachnoid cysts of the middle cranial fossa (9 patients) or overlying the frontal cortex (3 patients) were included. Under local anesthesia, an internal shunt was implanted from the cyst to the subdural compartment. Postoperative computed tomography scans showed volume reduction in eight patients. Permanent clinical improvement was also seen in eight patients. In the remaining four, the improvement was only temporary or partial, necessitating additional surgery in three patients. Complications (two subdural hematomas, one subdural infusion), were observed in three patients, all with large cysts. The complications were treated without sequelae. Internal shunts may be tried in adults as the first treatment for this condition.

Adult↗
PubMed1996

Cognitive function in patients with Parkinson's disease undergoing stereotaxic thalamotomy.

OBJECTIVE: To determine whether thalamotomy leads to cognitive disturbances in patients with Parkinson's disease. METHODS: A total of 53 patients with Parkinson's disease undergoing stereotaxic ventrolateral thalamotomy for tremor and rigidity were tested for cognitive functions before and after surgery. The cognitive functions investigated involved visuospatial perception and memory. verbal memory, attention shift, and executive functions including set maintenance and shift. A neuropsychological test battery was used that contained the Wisconsin card sorting test, Street completion test, Stroop test, a dichotic memory listening test, and a facial recognition test. RESULTS: Clinically, a good or moderately good effect on parkinsonian symptoms was obtained in 50 patients. The neuropsychological investigations showed that the patients were impaired compared with healthy age matched control subjects on most tests, showing slight improvement postoperatively on verbal memory and visuospatial perception. No major differences were found between tests before and after operation, and there were no significant differences between patients undergoing surgery in the right or in the left thalamus. CONCLUSION: The study indicates that ventrolateral thalamotomy does not reduce the cognitive capacity in this group of patients.

Adult↗
PubMed1996

DNA ploidy patterns in androgen-deprived localized prostate cancer.

Prostatectomy was performed in 48 patients with localized prostate cancer. Before surgery, they had been treated with the GnRH agonist triptorelin for 3 months. Specimens from the largest tumor focus (n = 6.3 + 3.6, mean + SD) were analyzed with regard to the DNA ploidy pattern. The results were compared with those obtained in a previous investigation of 54 patients who were subjected to surgery without hormone pretreatment. In both series, about 50% of the tumors showed a diploid DNA ploidy pattern, the rest being nondiploid. Ploidy heterogeneity, i.e., a mixture of diploid and nondiploid ploidy patterns in the single largest tumor focus, was found in 36% of the cases compared to 48% in the previous report (NS). In 13% of the tumors, all samples revealed a nondiploid DNA ploidy pattern as compared to 6% in the previous report (NS). In both series, needle biopsy examination (1/patient) prior to prostatectomy was associated with a significant and similar underestimate of the chromosomal aberration. In conclusion, despite the marked histopathological changes previously reported, there is no evidence that neoadjuvant triptorelin treatment during 3 months has any effect on the DNA ploidy pattern.

Androgen Antagonists↗
PubMed1995

[Surgical treatment of acute head injuries, especially epidural hematomas. Current and future practice in Norway].

A survey among the 13 general county hospitals and the five regional neurosurgical units in Norway showed that 263 patients were operated on for acute head injuries in 1993. More than 80% of these operations took place in a neurosurgical unit, and most county hospitals had only 1-2 such surgical procedures each year. Most county hospitals also limited their surgical activities to extradural conditions. Data from 68 patients operated on for epidural haematomas in our neurosurgical department were therefore analysed. The outcome of these operations was good in 83.8%, and only 5.9% showed a poor result. One patient died. It is concluded that these good results probably reflect the standard of handling, diagnostic work and transport of the patient prior to surgery, rather than the surgery itself. It seems unreasonable to continue the infrequent practice of treating these conditions surgically in local hospitals.

Adult↗
PubMed1995

Arachnoid cysts of the left temporal fossa: impaired preoperative cognition and postoperative improvement.

Thirteen adult patients were operated on for symptomatic arachnoid cysts in the left temporal fossa; seven with an internal shunt procedure during local anaesthesia, and five with a craniotomy with fenestration of the cyst to the basal cisterns. In one patient, an initial internal shunt was transformed to a cystoperitoneal shunt. After surgery, all patients experienced relief of symptoms. Reduction of cyst volume occurred in 11 patients. The patients were tested for brain asymmetries related to language and verbal memory before and after operation, with a dichotic listening technique with simultaneous presentation of different auditory stimuli to the two ears. In the preoperative memory test, the patients showed impaired total recall compared with healthy control subjects, and recall from the right ear was significantly impaired. The patients also performed poorly in a forced attention task consisting of dichotic presentations of consonant-vowel syllables. In addition to clinical improvement, the surgical procedures led to improvements in both dichotic perception and memory. Overall memory performance was enhanced, mainly because of improved recall from the right ear. This normalisation of memory function was found as early as four hours after the operation. The results indicate that arachnoid cysts in the left temporal fossa may impair cognitive function, that neuropsychological tests are necessary to disclose these impairments, and that cognitive improvement occurs after surgery.

Arachnoid Cysts↗
PubMed1995

Expanding cava septi pellucidi and cava vergae in children: report of three cases.

Three children with hydrocephalus and expanding cysts of the cavum septi pellucidi and cavum vergae are reported. In all the patients, the hydrocephalus was present before the persistent cava started to expand. The cava increased gradually, until they became cystic, but their growth did not affect the size of the ventricles. Two of the patients were treated with internal cystoventricular shunts, causing a prompt collapse of the cysts but no change in the concomitant hydrocephalus. In the third patient, the persistent cava started to expand only when a previously implanted ventriculoperitoneal shunt failed temporarily. The cyst disappeared when the shunt resumed its function. The possible mechanisms underlying the expansive growth of persistent cava are discussed. We propose the theory that the growth of the cava in our patients may be the result, rather than the cause, of the hydrocephalus.

Aging↗
PubMed1995

Grading of transitional cell bladder carcinoma by image analysis of histological sections.

Image analysis of histological sections was used to achieve a more objective malignancy grading of transitional cell carcinoma of the bladder. Images from Feulgen-stained sections from a clinical material of 197 tumours were analyzed. Features at various levels of analysis, e.g. mainly related to individual objects, neighbouring objects and the entire image, were analyzed. The features used were based on relational rather than individual nuclear features. With this technique, typical tissue architecture and degree of order/disorder can be described. These characteristics were compared by means of multivariate statistical methods with the subjective grading of the pathologists at our institution. This comparison provided the best subset of features and the agreement between the subjective and computer-based classification was 73%. The size, orientation and variation of the grey scale of the nuclei were particularly powerful. On a continuous scale, from grade 1 to 2A and 2B to 3, the four grades formed two distinct classes, low and high grade. In this distribution, the intermediate grade 2A was identified as a displaced grade 1 and the other intermediate grade 2B as a displaced grade 3.

Carcinoma, Transitional Cell↗