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Biomedical subjects

J Koivukangas

Publications and source records attributed to J Koivukangas.

At least 19 recordsLinked to original sources
PubMed2003

Intraoperative imaging in a comprehensive neuronavigation environment for minimally invasive brain tumour surgery.

BACKGROUND: Development of an image-guided operation theatre offering multimodal information for mini-invasive neurosurgical brain tumour operations. METHODS: A multi-purpose resistive low-field MR scanner with on-off capability, was installed in a radio frequency-shielded operating room with in-room control panel and display. Intraoperative ultrasound imaging with Doppler mode as needed is used to provide check-up image data between intraoperative MR-imaging sessions. Cortical stimulation and registration are performed during awake craniotomies. The neuronavigation systems are customised arm-based and passive optical. The navigation systems show the positions of the ultrasound probe, cortical stimulation electrode, biopsy needles, endoscope and other instruments on the intraoperative MR-images. FINDINGS: Since 1999, 70 patients (mean age 47, range 3-88 years) have been operated with intraoperative MR-guidance (including 10 tumour biopsies, 56 resections). Twenty-one patients (mean age 46, range 16-67 years) underwent awake craniotomy and tumour resection secured with cortical stimulation and usually preoperative fMR-imaging. The present operating environment offered useful multimodal information for surgery of brain tumours in critical locations. Surgical mortality was 0%, morbidity included 3 (4.3%) infections and 2 (2.9%) permanent hemiparesis. Further removal of tumour was continued in 17 cases (57%) out of the 30 cases where intraoperative MR imaging was used for controlling completeness of the resection.

Adolescent↗
PubMed2003

The effect of brain tumour laterality on anxiety levels among neurosurgical patients.

OBJECTIVES: The aim of this study was to investigate the level of anxiety in patients with a primary brain tumour and to analyse the effect of tumour laterality and histology on the level of anxiety. Recurrent measurements were assessed preoperatively, three months, and one year after operation. METHODS: The study population consisted of 101 patients with a primary brain tumour from unselected and homogeneous population in northern Finland. The patients were studied preoperatively with CT or MRI to determine the location of the tumour. The histology of the tumour was defined according to WHO classification. The level of anxiety was obtained by Crown-Crisp Experiential Index (CCEI) scale. RESULTS: The patients with a tumour in the right hemisphere had statistically significantly higher mean anxiety scores compared to the patients with a tumour in the left hemisphere before surgery of the tumour. By three months and by one year after surgical resection of the tumour, the level of anxiety declined in patients with a tumour in the right hemisphere. A corresponding decline was not found in patients with a tumour in the left hemisphere. According to laterality by tumour histology, the level of anxiety decreased significantly in male and female patients with a glioma in the right hemisphere, but a corresponding decline was not significant in the female patients with a meningioma in the right hemisphere. Decreased level of anxiety was not found in patients with gliomas or meningiomas in the left hemisphere by follow up measurements. CONCLUSIONS: Primary brain tumour in right hemisphere is associated with anxiety symptoms. The laterality of anxiety seems to reflect the differentiation of the two hemispheres. The level of anxiety declined after operation of right tumour, approaching that of the general population. The effect of right hemisphere gliomas on anxiety symptoms deserves special attention in future research.

Adult↗
PubMed2002

Versatile intraoperative MRI in neurosurgery and radiology.

BACKGROUND: Several models for the application of intra-operative magnetic resonance imaging (IMRI) have recently been reported, most of them unique. Two fundamental issues need to be addressed: optimal use of the scanner to ensure a wide base for research, development and clinical application, and an organisational model that facilitates such use. METHOD: While in our setting the IMRI project was initiated by the neurosurgeons, the need for wider use of the facilities was recognised since the beginning of the planning phase in 1996. An organisational model was developed that allowed for development of neurosurgical applications, radiological imaging, and radiological interventions and for the research and development work of the vendor. A resistive 0.23 T MR scanner was installed in a dedicated operating room environment. Unique to this scanner is the ability to turn off the magnet, allowing for normal OR activities and devices, and to turn on the magnet as needed with a relatively short six-minute ramp up time. A staged surgical technique was perfected, allowing for transfer of data to the neuronavigator outside the scanner during surgery. In neurosurgery, IMRI was used as one part of a neuronavigational system that included ultrasound imaging, intra-operative cortical stimulation during awake procedures, electrocorticography and two neuronavigators. FINDINGS: 34 neurosurgical cases included 27 brain tumour resections, 5 brain tumour biopsies, 1 extirpation of an arterio-venous malformation, and 1 haematoma evacuation. The scanner could also be used for normal clinical imaging where obese patients, children, claustophobic patients and postoperative control examinations were the major groups. The radiologists performed 110 interventions, including bone and abdominal biopsies, nerve root infiltrations and local pain therapies, with the optical needle tracking system under continuous MRI guidance. The organisational model allowed frequent use of the facilities for both neurosurgery and radiology and continuous development of the facilities. Intra-operative ultrasound was used in 20 tumour resections and in two open brain biopsies. This resulted in reduction of the number of MR imaging sessions during surgery. Five of the 27 resections were performed as awake craniotomies with cortical stimulation. For two of the resections, electrocorticography and depth electrode registrations were used. Furthermore, various non-MRI-compatible instruments and devices were used. INTERPRETATION: Intra-operative MRI is an imaging tool that can be useful especially in the context of neuronavigation. A scanner that can be turned off during surgery is particularly appropriate for neurosurgery. The concept of joint use of such facilities with other clinicians is mutually worthwhile.

Adult↗
PubMed2002

Effect of brain tumour laterality on patients' perceived quality of life.

OBJECTIVES: There is little reliable quantitative information on preoperative quality of life of patients with brain tumours. The aim of this study was to clarify the effect of the volume, location, and histological grade of brain tumours on the preoperative quality of life of patients. METHODS: The study population consisted of 101 successive patients with brain tumour at Oulu Clinic for Neurosurgery studied with CT or MRI for preoperative determination of tumour location and size. The Nottingham health profile (NHP) and Sintonen's 15D scale were used at that time to measure quality of life. RESULTS: Tumour size did not correlate linearly with impairment of quality of life. Large tumours (>25 ml) were associated with poorer quality of life than small tumours (< or =25 ml). The patients with a tumour located on the right side or in the anterior region reported a poorer quality of life than those with a tumour on the left side or posteriorly. Quality of life assessments made by doctors using the Karnofsky performance scale showed no differences between the two hemispheres. Patients with the most malignant gliomas (grades III-IV) displayed the poorest quality of life. CONCLUSIONS: Large tumours apparently damage several parts of the brain and/or raise intracranial pressure to a level that exceeds the brain's compensatory capacity. Contrary to earlier understanding, tumours in the right hemisphere seemed to be related to poorer quality of life. This effect was especially clear in the patients' subjective evaluation of their quality of life. As the location of the brain tumour thus affects perceived quality of life, any measurements of the quality of life of patients with brain tumours should take into account the location and laterality of the tumour.

Activities of Daily Living↗
PubMed2001

Registration in interventional procedures with optical navigator.

Performing interventional procedures in the close proximity to an MR scanner widens the range of operations available for an optical tracking system. In order to gain the full benefits from both unrestricted use of surgical instruments outside the magnet and intraoperative imaging, a method for transferring the registration data of the optical navigator between two locations is required. An optical tracking system, which provides such a transfer method and tracks patient position during a surgical procedure, has been developed, tested, and demonstrated with two patient cases. J. Magn. Reson. Imaging 2001;13:93-98.

Adult↗
PubMed2001

Second primary glioblastoma.

Although characterized by a highly variable phenotype and multiple genetic alterations, glioblastomas are considered monoclonal in origin. We here report on a 64-yr-old patient who developed a second glioblastoma in the left frontal lobe 10 yr after surgical resection of a glioblastoma of right frontal lobe. The first tumor contained 2 p53 mutations, in codon 213 (CGA-->TGA, Arg-->stop) and codon 306 (CGA-->TGA, Arg-->stop), further, 1 missense PTEN mutation (codon 257, TTC-->TTA, Phe-->Leu) and a silent PTEN mutation (codon 154, TTC-->TTT, Phe-->Phe). The second glioblastoma also contained multiple, but different mutations: p53 mutations in codons 158 (CGC-->CAC, Arg-->His) and 273 (CGT-->TGT, Arg-->Cys), and a PTEN mutation in codon 233 (CGA-->TGA, Arg-->Stop). Both neoplasms had a homozygous p16 deletion. The discordant pattern of mutations indicates that the second glioblastoma was not a recurrence but an independent second glioblastoma. The presence in these neoplasms of multiple mutations in tumor suppressor genes suggests the involvement of a novel disease mechanism but there was no indication of a DNA mismatch repair deficiency or of an inherited tumor syndrome.

Chromosomes, Human, Pair 10↗
PubMed1999

Cost-effectiveness analysis of nimodipine treatment after aneurysmal subarachnoid hemorrhage and surgery.

OBJECTIVE: To assess the cost-effectiveness ratio of nimodipine administration after aneurysmal subarachnoid hemorrhage (SAH) and surgery. METHODS: One hundred twenty-seven patients of both sexes who had a ruptured aneurysm (verified using angiography), who presented with Hunt and Hess Grades I to III on admission, who underwent an operation within the first week after SAH, and who had participated in a randomized prospective clinical trial of nimodipine medication were enrolled in the study. The efficiency (cost-effectiveness) of nimodipine treatment was evaluated by incremental cost-effectiveness analysis. The cost-effectiveness ratio was evaluated for two groups: patients treated with nimodipine and patients given placebo. The cost was estimated as direct hospitalization costs, and the patient outcome was measured as life years gained. RESULTS: The incremental cost-effectiveness ratio for nimodipine treatment was $223 per life year gained on the basis of 1996 monetary values and contemporary management of SAH. Patients in the nimodipine group had an average of 3.46 years longer life expectancy (incremental effectiveness) than those in the placebo group. There was a significant difference in 3-month follow-up mortality and a slight difference in sickness pensions during the 10 years after SAH. Nimodipine treatment was associated with a significant decrease in mortality. There were no statistically significant differences between the treatment groups in the length of hospital stay. There were no statistically significant differences between the treatment groups in sickness pensions. CONCLUSION: Nimodipine is cost-effective. Therefore, its use in the management of patients with SAH seems economically justified because it increases patient life years at very low incremental cost.

Adolescent↗
PubMed1998

Spontaneous migration of foreign bodies in the central nervous system.

The authors present four cases where foreign bodies within the central nervous system had spontaneously migrated. Two of these were surgical clips and two were bullets. The clips seemed to pass intradurally into the lumbar region with minor or no symptoms. Possible explanations for the migration are the circulation of CSF and the gravity. A new observation was that an infection may develop at the site where the foreign body had been situated before migration. From the clinical point of view, the removal of foreign bodies from the intradural space is not indicated, if the patient has no connected symptoms.

Adolescent↗
PubMed1997

Computed tomography data based rapid prototyping model of the temporal bone before cochlear implant surgery.

Rapid prototyping (RP) technique allows automatic fabrication of 3D model parts. This method was applied to make a temporal bone model before cochlear implant surgery. A helical CT scan is used to acquire high resolution data from the middle and the inner ear of the patient. From the scanning data bone structures and soft tissues can be separated because their different grayscale pixel values. By using a guided image processing tool the desired parts of the anatomy can be extracted and 3D data created. The segmented data are processed to the form suitable for creating a high accuracy RP model. The RP model is made in the stereolithography (SLA) process by means of a computer guided HeCd laser beam inducing polymerisation of acrylic solution as it passes layer by layer over the surface of the polymer solution. In this prototype model the anatomy of the temporal bone can be clearly visualised, including, e.g., mastoid cells, tympanic cavity, bony canal of facial nerve, and round and oval windows. The inner ear spaces including vestibule, semicircular canals and cochlear turn are also shaped. The transparent acrylic material allows bonelike mechanical handling. The RP model can be dissected and used in individual surgical planning and simulation prior to cochlear implantation.

Cochlear Implants↗
PubMed1993

Neuronavigator-guided cerebral biopsy.

Neuronavigators are new dynamic interactive instruments that use on-line computers to orient imaging data to the surgical field and guide the neurosurgeon to his target. We have been working since 1987 on a neuronavigator that serves not only as a precise pointer, but also as a dynamic arm that can be used to hold instruments, such as biopsy guides. The neuronavigator arm consists of six joints with optical encoders and is attached to the Mayfield headholder. The arm is connected to a workstation running customized 3D image graphics software. Special instruments and surgical technique have been developed. Here, we report on early clinical experience with ten biopsy procedures: 4 low-grade and 3 high-grade astrocytomas, one craniopharyngioma and one chronic intracerebral haematoma and intracerebral cyst, both of the latter with surrounding tumour suspect tissue. In all glioma cases serial biopsies were taken from optimal sites under ultrasound imaging control. Eight cases showed representative tumour tissue, while in two cases neoplasia was ruled out. The neuronavigator proved to be versatile, allowing comprehensive imaging data to be adapted to the surgical field.

Astrocytoma↗
PubMed1993

Ultrasound-controlled neuronavigator-guided brain surgery.

The development of a unique neurosurgical navigator is described and a preliminary series of seven cases of intracerebral lesions approached with the assistance of this neuronavigation system under ultrasound control is presented. The clinical series included five low-grade astrocytomas, one chronic intracerebral hematoma, and one porencephalic cyst. Management procedures included biopsy in all cases, drainage of the hematoma, and endoscopy and fenestration for the cyst. The features of the neuronavigation system are interactive reconstructions of preoperative computerized tomography and magnetic resonance imaging data, corresponding intraoperative ultrasound images, versatility of the interchangeable end-effector instruments, graphic presentation of instruments on the reconstructed images, and voice control of the system. The principle of a common axis in the reconstructed images served to align the navigational pointer, biopsy guide, endoscope guide, ultrasound transducer, and surgical microscope to the brain anatomy. Intraoperative ultrasound imaging helped to verify the accuracy of the neuronavigator and check the results of the procedures. The arm of the neuronavigation system served as a holder for instruments, such as the biopsy guide, endoscope guide, and ultrasound transducer, in addition to functioning as a navigational pointer. Also, the surgical microscope was aligned with the neuronavigator for inspection and biopsy of the hematoma capsule to rule out tumor etiology. Voice control freed the neurosurgeon from manual exercises during start-up and calibration of the system.

Adult↗
PubMed1990

Ultrasonic reflection mode computed tomography through a skull bone.

An ultrasonic reflection-mode CT method was applied to transskull imaging of brain. The method involves only a single transducer and a single scan to acquire data from the object. In reconstruction an ordinary Fourier slice theorem is applied. The average velocity changes of ultrasound due to the skullbone can be compensated. In experiments the object immersed in water was scanned by a wide-angle transducer through the viewing angle of 360 degrees. When imaging through bone a simplified approach was employed in which a piece of skullbone (thickness 3-4 mm) was attached firmly to the transducer. For comparison, the same object was then imaged without the skullbone. A two-point resolution better than 3 mm was achieved for transskull imaging using 1 MHz ultrasound. The experiments with brain specimens show that transskull images compare well with the images of the same specimens obtained without the bone interference. The findings are clinically significant in terms of pediatric brain diagnosis and postoperative follow up. Based on the method, a clinical prototype imager is currently being developed especially for diagnosis of children's brain diseases.

Adult↗
PubMed1990

Evaluation of image quality of ultrasound scanners in medical diagnostics.

The evaluation of the properties of ultrasound diagnostic scanners has not yet been standardized. Because the image itself is the basis of diagnostic decisions, it should also be the basis of evaluation of the capabilities of scanners. This study is aimed to help the standardization work by suggesting a procedure for testing the image quality of the scanners. The image quality depends on the tissue resolution, which is difficult to determine without real tissue studies. Therefore, the presented testing procedure consists of two parts: first, lateral and longitudinal resolution, image uniformity, sensitivity, and cyst and tumor imaging are determined by phantom tests; second, imaging experiments of formalin-fixed tissue samples are used to give information on the imaging capability of selected tissue details and boundaries. The procedure has been carried out by an experimental comparative test of 30 scanner and transducer combinations. The role of real tissue tests is important. A reliable whole-body phantom, including liquids flowing in veins, would be a breakthrough in testing real-time image quality.

Brain↗
PubMed1990

Computer-guided laser for neurosurgery.

On the basis of over 40 neurosurgical laser operations, including CO2, Nd-YAG and simultaneous CO2/Nd-YAG laser procedures, a computer-guided system for spatial control of the laser beam has been developed. The pilot laser has several modes: it can direct the neurosurgeon along the central axis of the surgical microscope to stereotactically determined point-like targets or outline selected layers of underlying volume targets onto superficial surfaces such as scalp and cortex and onto the tissue at the appropriate depth. The active treatment laser can be guided by preoperative CT/MRI or intraoperative ultrasound image data for layer-by-layer resection of tumor. The laser system can be connected to the surgical field by rigid stereotactic means or by neuronavigator. In the present system, a special brain surgery adapter coordinates the imaging system and laser to the surgical field. Thus, the laser system can be used for image-guided surgical orientation, for demarcation of lesions and for actual layer-by-layer removal of tumor.

Brain Neoplasms↗
PubMed1989

Intraoperative ultrasound imaging in lumbar disc herniation surgery.

The diagnosis of lumbar disc herniation has improved with metrizamide rhizography and CT. Also, visualization of the operative site has been enhanced with use of the operating microscope. However, evaluation of the completeness of herniated disc removal can be difficult, especially in the case of medially located lesions. Also, intradural extension of the herniation can be impossible to rule out in some cases without intradural exploration. Intraoperative ultrasound imaging is safe, rapid and readily available in most hospitals. Its application to real-time imaging control of 10 selected cases of herniated lumbar disc showed that the herniated material could be visualized in relation to the interspace and dural sac in all cases. The effect of removal of the herniation on nerve root compression could also be evaluated. Especially in cases involving extension of the herniation to the medial region under the dura, or into the intradural space, the removal of herniated material could be adequately confirmed without the need for further manipulation with surgical instruments. With appropriate transducer design and frequency, the method can be applied to microsurgical technique to rule out sequestration outside of the surgical exposure.

Adult↗
PubMed1989

Transabdominal ultrasound measurement of the lumbar spinal canal. Its value for evaluation of lumbar spinal stenosis.

Lumbar spinal stenosis, most commonly caused by hypertrophic changes in the soft tissues of the spinal canal, is itself a clinical entity, but in the early phase it can also serve as a factor influencing general back disorder morbidity. It can be identified reliably by measuring the anteroposterior diameter of the dural sac on myelography films and/or the transverse area of the dural sac on computed tomography (CT) scans. In the present study, 76 patients with general back disorders were examined with ultrasound (US) transabdominally through the intervertebral disc. In those 50 patients (66%) in which all three of the lowest lumbar intervertebral spaces could be visualized, the measurements made by US differed by +/- 5 mm from those obtained by myelography and +/- 25 mm2 from those made by CT. In a subset of ten patients with spinal stenosis, US was able to demonstrate the small size of the dural sac, but the cause of the stenosis could not be reliably evaluated. In addition to diagnosing central spinal stenosis, ultrasonography is also well suited for screening purposes.

Abdomen↗