Biomedical subjects

Katalin Borbély

Publications and source records attributed to Katalin Borbély.

9 recordsLinked to original sources

PubMed2006

Optimization of semi-quantification in metabolic PET studies with 18F-fluorodeoxyglucose and 11C-methionine in the determination of malignancy of gliomas.

The treatment of the glioma patient depends on the nature of the lesion and on the aggressiveness of the tumor. The management of gliomas continues to be a challenging task, because morphological neuroimaging techniques do not always differentiate them from nontumoral lesions or high grade tumors from low grade lesions. Positron Emission Tomography (PET) offers the possibility of the in vivo quantitative characterization of brain tumors. Despite decades of useful application of PET in the clinical monitoring of gliomas, no consensus has been reached on the most effective image analysis approach for providing the best diagnostic performance under heavy-duty clinical diagnostic circumstances. The main objective of the present study was to find and validate optimal semi-quantitative search strategies for metabolic PET studies on gliomas, with special regard to the optimization of those metabolic tracer uptake ratios most sensitive in predicting histologic grade and prognosis. 11C-Methionine (11C-Met, n = 50) and/or 18F-Fluorodeoxyglucose (18F-FDG, n = 33) PET measurements were performed in 59 patients with primary and recurrent brain gliomas (22 high grade and 37 low grade tumors) in order to correlate the biological behavior and 11C-Met/18F-FDG uptake of tumors. Data were analyzed by region-of-interests (ROI) methods using standard uptake value calculation. Different ROI defining strategies were then compared with each other for two of the most commonly used metabolic radiotracers, 18F-FDG and 11C-Met, in order to determine their usefulness in grading gliomas. The results were compared to histological data in all patients. Both ANOVA and receiver operating characteristic (ROC) analysis indicated that the performance of 18F-FDG was superior to that of 11C-Met for most of the ratios. 18F-FDG is therefore suggested as the tracer of choice for noninvasive semi-quantitative indicator of histologic grade of gliomas. 11C-Methionine has been suggested as a complimentary tracer, useful in delineating the extent of the tumor. The best diagnostic performance was obtained by calculating the ratio of the peak 18F-FDG uptake of the tumor to that of white matter (p < 0.001; ANOVA). This metabolic tracer uptake ratio is therefore suggested as an easily obtained semi-quantitative PET indicator of malignancy and histological grade in gliomas.

Adolescent↗

PubMed2005

Comparative overview of brain perfusion imaging techniques.

BACKGROUND AND PURPOSE: Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks. SUMMARY OF REVIEW: This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview established by consensus among specialists of the various techniques. CONCLUSIONS: For clinicians, this article should offer a clearer picture of the pros and cons of currently available brain perfusion imaging techniques and assist them in choosing the proper method for every specific clinical setting.

Aged↗

PubMed2004

[Functional imaging of cerebrospinal fluid pathology].

The most common problem addressed by dynamic radionuclide imaging of cerebrospinal fluid (CSF) abnormalities is differentiating patients with normal-pressure hydrocephalus (NPH) from those with other forms of degenerative brain disorder who would clearly not benefit from surgical treatment by ventricular shunting. Radionuclide cisternography (RC) SPECT and regional cerebral blood flow (rCBF) SPECT are critically important for the diagnosis and therapy management of patients with chronic hydrocephalus. However, radionuclide imaging is helpful not only in identifying patients with NPH showing improvement after shunting. RC reveals tracer activity outside the intracranial cavity, indeed. The importance of establishing the diagnosis arises from the fact that untreated leaks can be followed by meningitis in up to one quarter of patients. CSF collections may communicate with the subarachnoid space. RC SPECT has proved useful in assessing the communication of the arachnoid cysts (CSF collection) with the ventricular or subarachnoid compartment. Improved anatomical detail revealed by SPECT imaging is helpful in solving problems of the CSF pathology. Sensitive and accurate assessments of normal and disordered CSF dynamics can be obtained with RC SPECT.

Cerebral Ventriculography↗

PubMed2004

[Functional imaging in brain tumors].

Over the last two decades, the routine imaging methods available for the diagnosis and monitoring of intracranial tumors are computer tomography and magnetic resonance imaging. Both procedures provide precise anatomical delineation of the lesions, determine changes in tumor volume in response to therapy. However, they are not effective in differentiating low-grade from high-grade lesions and residual or recurrent tumor from radiation/chemo necrosis. Radionuclide procedures (positron emission tomography and single photon emission computer tomography), especially positron emission tomography is an example of a technique with high sensitivity and accuracy that has the potential to yield the information necessary not only to provide a means for diagnosis of tumors based on altered tissue metabolism but also to serve as a tool for monitoring the effects of the therapy. Measurements of the rate of glucose metabolism by 18F-FDG uptake in brain lesions are the most frequent applications in order to discriminate low-grade from high-grade lesions and tumor recurrence from radiation necrosis. 11C-methionine positron emission tomography is used to delineate the boundaries of tumors, providing information of value in directing stereotactic biopsy, planning the approach and extent of brain surgery, and permitting differentiation of the metabolizing neoplasm from simple disruption of the blood-brain barrier. Another substrate, 11C-thymidine has been used to measure nucleotide metabolism and utilization in DNA synthesis. Activation studies are useful in patients suffering from lesions near to or in the eloquent areas. It is likely that multiple positron emission tomography radioligands and multimodality imaging are the standards for diagnosis and monitoring of the effects of therapeutic intervention.

Adenoma↗

PubMed2004

[Functional imaging in mental disorders].

Considerable progress has been achieved by functional brain imaging over the past 20 years in uncovering the biological basis of major psychiatric disorders and to more effectively target therapeutics. Radioligand techniques, especially the PET (positron emission tomography) method, are specific and sensitive tools for quantitative in vivo imaging of molecular pathways and molecular interactions within brain tissues. Since 1980s, advances in neuroimaging and neurophysiological techniques have provided tremendous merits for investigations into different psychiatric disorders. PET and SPECT (single photon emission computer tomography) neuroreceptor imaging, especially in schizophrenia has been an extremely fruitful area of research. Evidences from these studies suggest that schizophrenia affects various cortical and subcortical regions involved in cognitive, emotional, and motivational aspects of human behavior. PET and SPECT provide useful data in studying the fundamental neurobiology of mood disorders. Both techniques are playing a central role in studying patients with new methods and ligands for specific receptor subtypes, and are likely to increase the application of PET/SPECT in the development of new pharmacotherapies. Nuclear medicine plays an important role in studying patients with other psychiatric disorders such as obsessive-compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), anxiety, etc. Some forms of OCD seem to share a common genetic etiology with Tourette-syndrome (TS) and to be a facultative part of the TS phenotypic spectrum. In conclusion, PET and SPECT methods seem to be helpful in the diagnosis and management of patients with different psychiatric disorders and may provide a better understanding of clinical symptomatology or the relationship of these physiological parameters to the patient's prognosis. Additionally, radionuclide techniques may improve medical therapy by demonstrating individual biochemical abnormalities of altered brain functions.

Anorexia Nervosa↗

PubMed2003

Speech activation of language dominant hemisphere: a single-photon emission computed tomography study.

We tested the prediction that single photon emission computed tomography (SPECT) of the blood flow distribution in speech-activated brain identifies the language-dominant hemisphere. We based the prediction on the hypothesis that language activation leads to focally increased regional cerebral blood flow (rCBF), which is reflected in the uptake of a flow tracer recorded by SPECT. We compared the results of speech activation to the results of functional transcranial Doppler (fTCD) monitoring in the same subjects. Preoperatively, 17 patients (10 women and 7 men with a mean age of 36 +/- 15 years) with diagnoses of epilepsy (n = 14) or arteriovenous malformation (AVM) (n = 3) had two SPECT and two stereo-TCD monitoring studies in each case, one at rest, and one during 3 min of speech activation. Except for two left-handed patients with right-hemisphere dominance, the subjects had the highest changes of rCBF from baseline to activation in the left posterior inferior frontal cortex and in contralateral cerebellum. The results show that changes of the level of neuronal activity reflected by the measurement of rCBF variations might be detected by SPECT. Additionally, the evaluation of hemispheric language dominance based on SPECT showed a complete agreement with the evaluation based on fTCD results (yielding a kappa coefficient equal to 1), and therefore, speech-activation SPECT mapping might be helpful in the evaluation of hemispheric language dominance, especially when fMRI and PET are not available or they are contraindicated for some reason.

Adolescent↗

PubMed2002

[Role of SPECT scans in the diagnosis of cerebrovascular diseases].

With an incidence of 200-250 in 100,000 persons year, cerebrovascular disease (CVD) is the most common neurological disorder. In most countries, CVD is the third most frequent cause of death, exceeded only by heart disease and cancer. There are roughly 5.000 new cases per year in Hungary. Additionally, it should be emphasized that there are facts suggesting a more severe population of patients with CVD compared to the analogue group in more developed countries. There are several causes of stroke, but common to all is a critical reduction in cerebral blood flow, resulting in a focal neurological deficit. Functional imaging, particularly of cerebral perfusion, should therefore have a major role to play in the management of these patients. SPECT methods are of high importance in the diagnosis of CVD and in the patients follow-up.

Acute Disease↗

PubMed2002

[Pathophysiology of cerebrovascular disorders: PET imaging of the brain].

To understand the underlying mechanisms that occur during cerebral ischaemia and stroke one needs to assess the relationship between blood flow, oxygen and glucose metabolism, and other physiological processes as a function of the site of deficit, the time course of the tissue damage, and the etiology of the ischaemia. PET has already demonstrated its ability to provide in vivo biochemical and pathophysiological information. PET can provide the necessary understanding of the abnormal cellular biochemical processes that occur in response to perfusion insufficiencies in humans. The application of PET to cerebrovascular disease has provided information on temporal course of blood flow and volume, oxygen, and glucose utilization, as well as the respective extraction fractions for these substrates. Additionally, PET provides useful information on neurotransmission, by using receptor ligands one can measure the different receptor systems in the brain.

Brain↗

PubMed2002

[Clinical positron emission tomography: brain imaging].

PET produces images of physiological functions at molecular level which can be used to measure different vital processes, including blood flow and perfusion, glucose metabolism, oxygen utilization and receptor-ligand binding rates. Unlike anatomical imaging modalities, such as CT and MR, PET allows for the assessment of biochemical and physiological changes related to any function. Recently, the clinical indications for PET have increased dramatically. PET can reduce the overall cost of medical care, because it increases the certainty of diagnosis and clinical stage of disease, and therefore eliminates the expense of unnecessary testing or treatment.

Brain↗