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L Eriksson

Publications and source records attributed to L Eriksson.

322 records · Page 18Linked to original sources
PubMedDate not supplied

PET study of methionine accumulation in glioma and normal brain tissue: competition with branched chain amino acids.

Five patients with glioma were examined with positron emission tomography using ([11C]methyl)-L-methionine. The study was repeated while the patient was being infused with branched chain amino acids (BCAA), 250 mumol/min. The accumulation rates of methionine in tumor tissue and in normal brain tissue were compared without and with the infusion of amino acids. Both tumor tissue and normal brain tissue showed a reduction in the methionine accumulation by 35% while the patient received the infusion. In one patient with a severe blood-tissue barrier disruption the tumor accumulation rate was unaffected. It is concluded that in gliomas without severe blood-tissue barrier disruption, the accumulation of methionine is governed by processes exhibiting similar properties regarding competition with BCAA as in normal brain tissue.

Amino Acids, Branched-Chain↗
PubMedDate not supplied

Performance evaluation of the positron scanner ECAT EXACT.

The Cologne Special is a prototype of the ECAT EXACT (model 921), a new generation of Siemens-CTI PET scanners. It consists of three rings of 48 BGO block detectors each, covering an axial field of view of 16.2 cm with a patient port of 56.2 cm diameter. This results in a total of 24 rings with 384 crystals each, giving 47 contiguous image planes in two-dimensional (2D) mode. Total system sensitivity is 216 kcps/microCi/ml for a 20 cm cylinder phantom in 2D. This increases to 1.5 Mcps/microCi/ml in 3D. Data are acquired in the stationary mode only (no wobble motion), resulting in a transaxial spatial resolution of better than 6 mm full width at half-maximum (FWHM) at the center, which degrades to 7.5 mm tangentially and 9.6 mm radially at a radius of 20 cm. Average axial resolution changes from 5.0 mm FWHM at the center to 8.1 mm at R = 20 cm. Count rate performance was investigated at different low energy discriminator settings and found to be linear up to 2.5 microCi/ml with a 20 cm phantom. The magnitude and distribution of scatter were evaluated for both septa-extended and septa-retracted conditions for a range of energy thresholds. Brain, heart, and whole-body studies with the new tomograph demonstrate the versatility of its applications without compromising on physical performance.

Equipment Design↗
PubMedDate not supplied

An atypical neuroleptic drug in the treatment of behavioural disturbances and psychotic symptoms in elderly people.

The present study is a retrospective study of remoxipride therapy. A total of 103 patients, 65 years or older, with a DSM-III-R diagnosis of dementia or delirium, were included. They had all been treated with remoxipride because of psychotic symptoms or behavioural disturbances. The dose range of remoxipride was 50-300 mg, the median dose being 75 mg. The clinical effect was rated as good in two thirds of the patients, and side-effects were noted in one fourth. When psychomotor hyperactivity was the dominating problem, a good effect was rated in 81% of the patients. Side-effects were few and mild, the most common being tiredness; only 5 patients showed extrapyramidal symptoms.

Aged↗
PubMedDate not supplied

Positron emission tomography of cavernous haemangiomas of the brain.

Four cases with lesions suspected to be low-grade intracerebral tumours but later proved to be cavernous haemangiomas are described. The patients were examined with contrast enhanced CT and with positron emission tomography (PET). The lesions were partly calcified with a mild or no mass effect and a slight contrast enhancement at CT. There were signs of disrupture of the blood-lesion barrier also on radionuclide studies. PET with 11C-methionine and 11C-glucose showed a normal or decreased accumulation of the tracers. This combination of findings has not been encountered in intracranial tumours. As a comparison, one case of glioblastoma is described. In this patient, the CT findings suggested a cavernous haemangioma. However, PET showed a markedly increased accumulation of 11C-methionine, which is compatible with brain tumour but not with haemangioma.

Adult↗
PubMedDate not supplied

Pseudomonas-induced lung damage in cystic fibrosis correlates to bactericidal-permeability increasing protein (BPI)-autoantibodies.

OBJECTIVE: Lung damage is the most common cause of death in cystic fibrosis (CF). It is induced by bacterial colonization and inflammatory activity perpetuates its course. Autoantibodies directed against BPI (bactericidal permeability increasing protein), called BPI-ANCA, have recently been associated with cystic fibrosis. Here we confirm this association and evaluate the relation between ANCA and total IgG level as they relate to bacterial colonization, pulmonary function, and musculoskeletal symptoms. METHODS: BPI-ANCA, MPO-ANCA, and PR3-ANCA were measured with ELISA in 46 adult patients with CF. Total IgG was determined by immunoturbidimetry. Results were correlated to bacterial colonization, lung function and musculoskeletal symptoms. RESULTS: BPI-ANCA was found in 33 patients. In the whole group, both BPI-ANCA and total IgG were inversely correlated to lung function, but in patients chronically colonized with Pseudomonas aeruginosa (P. aeruginosa), BPI-ANCA alone was correlated to lung damage (p = 0.01). Median lung function, measured as forced expiratory volume in 1 second, in P. aeruginosa colonized patients with high levels of BPI-ANCA was 43% of the predicted value. In BPI-ANCA negative, the corresponding figure was 83%. In patients not colonized with P. aeruginosa, this relation was less evident. No correlation between ANCA and musculoskeletal symptoms was seen. CONCLUSION: P. aeruginosa induced lung damage in CF patients is associated with the presence of BPI-ANCA. P. aeruginosa colonized patients without BPI-ANCA have almost normal lung function. We suggest that BPI-ANCA discriminate P. aeruginosa colonized CF patients with severe lung damage from those whose disease is less destructive. Vasculitis like symptoms in CF are not ANCA associated.

Adult↗
PubMedDate not supplied

A computerized brain atlas: construction, anatomical content, and some applications.

An adjustable computerized atlas of the human brain has been developed, which can be adapted to fit individual anatomy. It is primarily intended for positron emission tomography (PET) but may also be used for single photon emission CT, transmission CT, magnetic resonance imaging, and neuroimaging-based procedures, such as stereotactic surgery and radiotherapy. The atlas is based on anatomical information obtained from brains fixed in situ soon after death. All structures have been drawn in on digitized photos of slices from one cryosectioned brain. The definition and classification of the anatomical structures and divisions are in agreement with the standard textbooks of anatomy, and the nomenclature is that of the Nomina Anatomica of 1965. The boundaries of the cortical cytoarchitectonic areas (Brodmann areas) have been determined using information from several sources, since three-dimensional literature data on their distribution are incomplete, scarce, and partly contradictory. However, no analysis of the cytoarchitectonics of the atlas brain itself has been undertaken. At present the data base contains three-dimensional representations of the brain surface, the ventricular system, the cortical gyri and sulci, as well as the Brodmann cytoarchitectonic areas. The major basal ganglia, the brain stem nuclei, the lobuli of the vermis, and the cerebellar hemispheres are also included. The computerized atlas can be used to improve the quantification and evaluation of PET data in several ways. For instance, it can serve as a guide in selecting regions of interest. It may also facilitate comparisons of data from different individuals or groups of individuals, by applying the inverse atlas transformation to PET data volume, thus relating the PET information to the anatomy of the reference atlas rather than to the patient's anatomy. Reformatted PET data from individuals can thus be averaged, and averages from different categories or different functional states of patients can be compared.

Anatomy, Artistic↗
PubMedDate not supplied

Positron emission tomography compared with magnetic resonance imaging and computed tomography in supratentorial gliomas using multiple stereotactic biopsies as reference.

Ten patients with findings at computed tomography (CT) suggesting intracranial supratentorial glioma were investigated to compare the diagnostic efficacy of this technique with that of positron emission tomography (PET) using 11C-methionine and examinations with magnetic resonance (MR). The findings were related to histopathologic examination of serial stereotactic biopsies, which were guided by the appearance of the lesions on PET examination. To obtain corresponding slice orientation with the different examination techniques, an individually shaped helmet fixation was used. However, in 3 cases this fixation device could not be used for MR. Histopathologic diagnosis, obtained in all cases from multiple target stereotactic biopsies, included glioma in 9 patients and reactive gliosis in one case. A detailed comparison of the three imaging techniques and the findings at stereotactic biopsies was possible in 7 patients, while in 3 patients comparison with MR was less exact due to the patient's refusal to wear the helmet during this examination. MR was the most accurate method for outlining the total extent of a lesion, i.e. the tumor and the edema surrounding it. Four lesions had homogeneous signal characteristics and in 6 lesions two (or more) compartments could be distinguished with MR. In 5 cases the MR findings were in complete agreement with the histopathologic findings. However, a thorough correlation between signal characteristics and histology was not possible. Using PET the occurrence and the extent of tumor tissue was correctly predicted in 7 patients. The PET was normal in one case. Findings at CT were in agreement with the histopathologic diagnosis in 5 patients. MR was the most sensitive method for the detection of lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Comparison of the accumulation kinetics of L-(methyl-11C)-methionine and D-(methyl-11C)-methionine in brain tumors studied with positron emission tomography.

Five patients with glioma were examined with positron emission tomography after the administration of 11C-L-methionine and at a following day with 11C-D-methionine. The rates of accumulation of the tracers were determined in the tumor and in the normal brain tissue according to a graphical technique of Patlak et coll. The accumulation rates for L-methionine were on the average 2.4 times higher than those of D-methionine in the tumors. The corresponding ration for normal brain tissue was 2.3. It is concluded that in this group of tumors without obvious blood-tumor-barrier breakdown, a stereospecific process with similar properties as in the normal brain tissue, is responsible for the accumulation of the labelled methionine.

Astrocytoma↗
PubMedDate not supplied

Application of a kinetic model on the methionine accumulation in intracranial tumours studied with positron emission tomography.

Eleven patients were studied with positron emission tomography (PET) using 11C-methionine. They all had low-grade astrocytomas (Kernohan grade II). The PET studies were analyzed with a metabolic model to obtain values for the influx, the accumulation rate and the partition coefficient of methionine in normal and tumourous tissue. Seven of the tumours showed an increased accumulation of methionine as compared with normal tissue on the static PET scans and also had higher values as to the kinetic parameters. Four tumours had a methionine accumulation equal to or lower than that of normal tissue and the kinetic parameters were also lower. Application of the kinetic model did not aid significantly in the delineation of the tumours. There was a correlation between the three parameters indicating an adaptation of the transport of methionine to the regional metabolic demand. The accumulation rate for normal cortical tissue was 0.49 nmol/g/min, the influx 0.97 nmol/ml and the partition coefficient 0.45 ml/g. These values are considerably higher than those previously reported. The differences might be attributed to differences in the corrections introduced for i.a. the occurrence of labelled metabolites in serum. With the use of a kinetic model, more information about the tracer is utilized and gained compared with the previously used graphic approach.

Brain Neoplasms↗
PubMedDate not supplied

Low dose pelvimetry with biplane digital radiography.

The digital moving slit technique as used by most CT scanners for overview images, was used for antero-posterior and lateral views of the pelvis for pelvimetry. The method was evaluated in phantom experiments and clinical examinations were performed in 23 patients. The method was compared with conventional pelvimetry in 14 patients. Estimated ovarian dose was reduced by a factor of 14.2. The discrepancy in measurements of the pelvic diameters by computed tomography compared with conventional pelvimetry was considered to be without practical importance from an obstetric point of view. Digital pelvimetry is easier for the patient, faster and the need for repeated exposures is eliminated. Based on these facts it is suggested that digital pelvimetry should replace the conventional method whenever possible.

Female↗
PubMedDate not supplied

Positron emission tomography with 11C-methionine and computed tomography of intracranial tumours compared with histopathologic examination of multiple biopsies.

A selected group of 36 patients with suspected supratentorial gliomas were investigated with positron emission tomography (PET) using 11C-methionine and transmission computed tomography (CT) before and after intravenous injection of contrast medium. Every examination was performed with the head fixed in a plastic helmet and a baseplate to guarantee that the slice orientation was the same at examinations with the two modalities and over time. Guided by the examinations, multiple stereotactic biopsies were performed with the biopsy instrument mounted on the baseplate. Regional accumulation of methionine was compared with histology of the corresponding samples and with attenuation before and after injection of contrast medium as well as mass effect on CT. Typically, there was a low attenuating lesion with a slight mass effect on CT. There was an increased accumulation compared with normal brain tissue in 31 cases of tumours and ordinary or decreased accumulation in 3 cases of tumours. In 22 cases with increased accumulation of methionine the extension of the tumour judged by PET corresponded with that of histology. In 4 cases tumour cells were found outside the area with pathologic methionine uptake. In 5 patients there were areas with increased methionine accumulation where no tumour cells were found. In 22 cases PET using methionine was more accurate than CT in defining the tumour boundaries as determined from the histologic findings. Four groups of biopsy specimens with different amounts of methionine accumulation are described. The uptake in a single biopsy gives good but not exact information about the histology of the specimen.

Brain Neoplasms↗
PubMedDate not supplied

PET studies of glucose metabolism in patients with schizophrenia.

The hypothesis of abnormal patterns of metabolism in schizophrenia was examined in a series of six young patients with psychotic symptoms satisfying the research diagnostic criteria. After intravenous injection of 11C-glucose obtained through a photosynthetic process, the regional activity of 11C in brain was measured with a four-ring positron camera. Regions of interest were obtained from computed tomographic images. Each patient underwent a second positron emission tomographic examinations after 4-5 weeks of treatment with a neuroleptic drug. No evidence of a hypofrontal pattern was found, but after treatment there was a reduced frontal uptake on the left side compared with temporal regions. The left-right asymmetry in the lentiform nucleus was reduced after treatment.

Acute Disease↗
PubMedDate not supplied

Cerebrospinal fluid circulation: evaluation by single-photon and positron emission tomography.

Gamma camera cisternography after intrathecal administration of 111In-DTPA is a widely used and well established technique for studies of cerebrospinal fluid (CSF) circulation. The radiation dose from 111In, however, is a limiting factor that sometimes seriously affects the image quality and, hence, correct interpretation. This investigation was designed to assess the value of tomographic techniques for studies of CSF flow. Single-photon emission computed tomography (SPECT) was performed on 15 patients by means of the Karolinska Hospital rotating gamma camera system after injection of 111In-DTPA or 99mTc-DTPA. The combination of SPECT and 99mTc-DTPA proved to be a valuable technique. It permits a clear evaluation of the location of the isotope intracranially and its precise relation to the ventricles. Positron emission tomography (PET) applied after intrathecal administration of 68Ga-EDTA demonstrates that small amounts of radioactivity can be registered and that PET is a promising technique for the evaluation of CSF dynamics.

Cerebrospinal Fluid↗
PubMedDate not supplied

The ECAT EXACT HR: performance of a new high resolution positron scanner.

OBJECTIVE: The ECAT EXACT HR is a newly designed CTI-Siemens PET scanner with high spatial resolution. Its physical performance with respect to resolution, count rate efficiency, and scatter was investigated and evaluated with phantom studies. MATERIALS AND METHODS: The new tomograph consists of three rings of 112 BGO block detectors (50 mm x 23 mm x 30 mm deep) each, covering an axial field of view of 15 cm with a patient port of 56 cm diameter. Each block is sawed into an 8 x 7 matrix giving 24 detector rings with 784 crystals each. RESULTS: Total sensitivity for a 20 cm cylinder phantom is 177 kcps/microCi/ml in two-dimensional (2D) mode and increases to 1.46 Mcps/microCi/ml in 3D mode. Count rate performance was investigated for different low energy discriminator thresholds. Smaller detector blocks improve noise equivalent counts by approximately 50% compared with the EXACT system both in 2D and in 3D mode. Scatter fractions vary in 2D from 0.09 to 0.13 for energy thresholds from 450 to 250 keV for line sources in a 20 cm diameter phantom. In 3D mode an increase of scatter by a factor of 3 is observed. Transaxial spatial resolution varies from 3.6 mm full width at half-maximal (FWHM) at the center to 4.5 mm FWHM tangentially and 7.4 mm FWHM radially at R = 20 cm. Average axial resolution changes from 4.0 mm FWHM at center to 6.7 mm FWHM at R = 20 cm. CONCLUSION: Due to its special properties, the EXACT HR can be equally applied to routine clinical brain and whole-body imaging and to noninvasive experimental studies of regional tracer concentrations in medium-sized animals.

Animals↗