Biomedical subjects

Zsolt Lengyel

Publications and source records attributed to Zsolt Lengyel.

16 recordsLinked to original sources

PubMed2003

A review on radiogenic Lhermitte's sign.

Radiation myelopathy is a rare, but extremely serious side-effect of radiotherapy. Recovery from radiation-induced motor sequelae is rare, whereas, the regeneration of sensory losses is relatively frequent. Among the sensory radiogenic injuries of the spinal cord, Lhermitte's sign (LS) is most frequent. This review describes the clinical picture and diagnostic imaging signs of radiogenic LS. There have been only a few studies on large patient groups with radiogenic LS, demonstrating a rate of occurrence of 3.6-13%, relating mainly to mantle irradiation or the radiotherapy of head and neck tumors. These cases typically manifest themselves 3 months following radiotherapy and gradually disappear within 6 months. Only 3 LS cases have been described in the English literature with extraordinarily severe symptoms lasting for more than 1 year. MRI, a sensitive tool in the detection of demyelination, failed to reveal any pathological sign accompanying radiogenic LS. However, positron emission tomography demonstrated increased [18F]fluorodeoxyglucose accumulation and [15O]butanol perfusion, but a negligible [11C]methionine uptake in the irradiated spinal cord segments in patients with long-standing LS. These imaging data are suggestive of a close direct relationship between the regional perfusion and metabolism of the spinal cord, very much like the situation in the brain. We postulate that an altered, energy-demanding conduction along the demyelinated axons of patients with chronic radiogenic LS may explain the increased metabolism and perfusion.

Butanols↗

PubMed2003

[Principles of radiotherapy of non-small cell lung cancer].

The long-term survival probability for Hungarian lung cancer patients is 10% worse than the best results published in the most highly developed countries (the mean 5-year survival probability in Hungary is 5%, in contrast with the 15% survival probability in the USA). On the basis of the international recommendations and personal experience, an attempt was made to formulate the guidelines for radiotherapy as one of the fundamental non-small cell lung cancer (NSCLC) treatment modalities for national use. An expert panel was set up comprising physicians from 6 radiotherapeutic centers (the National Institute of Oncology / Semmelweis University, Budapest; the Beth Israel Medical Center, New York; the University of Kaposvár; the University of Essen; the University of Debrecen; and the County Hospital of Gyula). Experts in two important medical fields closely related to radiotherapy (surgery and diagnostic imaging) were also engaged in the elaboration of the manuscript. Discussion of the most important principles of the radiotherapy and an overview of the prognostic factors was followed by a critical analysis of the protocols applied in the radiotherapy of Hungarian NSCLC patients during recent decades. The new guidelines suggested for the radiotherapy of NSCLC are presented separately for the postoperative period, marginally resectable tumors, and the aggressive or non-aggressive radiotherapy of inoperable tumors. Detailed accounts are given of the techniques of external irradiation and brachytherapy, and of the acute and late radiation-induced damage of normal tissues. The authors believe that this document may be instrumental in improving the survival index of Hungarian NSCLC patients in the near future.

Brachytherapy↗

PubMed2003

Cortical projection of peripheral vestibular signaling.

The cerebral projection of vestibular signaling was studied by using PET with a special differential experimental protocol. Caloric vestibular stimulation (CVS)-induced regional cerebral blood flow (rCBF) changes were investigated in two populations. Butanol perfusion scans were carried out on six healthy volunteers and on six patients following the removal of tumors from the right cerebello pontine angle. The complete loss of the vestibular function postoperatively allowed a comparison of the rCBF changes in the populations with or without this input and offered a promising functional approach whereby to delineate the cortical region most responsive to pure vestibular input. The activations by left-sided and right-sided CVS were determined for both the healthy volunteers and the patient population. Statistical analysis of the data obtained following left-sided CVS did not reveal any cerebral region for which there was a significant difference in CVS-induced response by these two populations. In the case of right-sided CVS, however, the statistical comparison of the CVS-related responses demonstrated a single contralateral area characterized by a significantly different degree of response. This cortical area corresponds to part of the cortical region described recently which can be activated by both CVS and neck vibration. It appears to be anatomically identical to the aggregate of the somatosensory area SII and the retroinsular cortex described in primates, a region identified by other investigators as an analog of the parietoinsular vestibular cortex.

Brain Mapping↗

PubMed2002

[Cost-effective PET investigations in oncology].

The authors have reviewed the financial considerations of oncological FDG PET examinations by the guidelines of the Health Care Financing Administration (USA). By critical assessment of large number of clinical investigations,the cost-effectiveness of FDG PET scans has been confirmed in the following cases: differential diagnosis of solitary pulmonary nodule, diagnosis,staging and restaging of non-small cell lung cancer, colorectal cancer, malignant lymphomas, melanoma malignum, esophageal neoplasms and cancers of the head and neck. The role of this method in breast cancer is currently under intensive investigation. Due to the correct staging, PET examinations in these indications enable the clinicians to choose the optimal treatment ensuring the maximum probability of recovery and being cost-effective as unnecessary medical interventions become avoidable.

Breast Neoplasms↗

PubMed2002

[Standard PET examination protocols].

The authors briefly review the most important components, concepts and procedures of the PET method. They present the basic examination protocols and the special features of each type of investigation. A short summary of issues relating to the daily routine, the image processing and visualization as well as the data archiving is also included.

Brain↗

PubMed2002

[Cost-effective PET scans in oncology].

The authors have reviewed the financial considerations of oncological FDG PET examinations by the guidelines of the Health Care Financing Administration (USA). By critical assessment of large number of clinical investigations, the cost-effectiveness of FDG PET scans has been confirmed in the following cases: differential diagnosis of solitary pulmonary nodule, diagnosis, staging and restaging of non-small cell lung cancer, colorectal cancer, malignant lymphomas, melanoma malignum, esophageal neoplasms and cancers of the head and neck. The role of this method in breast cancer is currently under intensive investigation. Due to the correct staging, PET examinations in these indications enable the clinicians to choose the optimal treatment ensuring the maximum probability of recovery and being cost-effective as unnecessary medical interventions become avoidable.

Breast Neoplasms↗

PubMed2002

[Diagnostic possibilities of positron emission tomography in oncologic pulmonology].

The authors present the possibilities of applying positron emission tomography (PET) in oncopulmonology. In addition to reviewing the literature, they share their own experience obtained during the diagnostic work-up and follow-up of twenty-three patients. The basic indications and the relevant properties of the most frequently used radiopharmaceuticals are discussed. Finally, the authors raise the question of cost-effectiveness of PET-investigations vs. conventional techniques, and suggest possible algorithms to include this non-invasive imaging method in the diagnostic work-up of patients with malignant or benign pulmonary diseases.

Adult↗

PubMed2002

[The role of PET scan in the investigation of the lymphatic spreading of Hodgkin's disease].

The authors investigated the role of PET, as a non-invasive diagnostic method, in the analysis of lymphatic spreading of Hodgkin's disease (HD). Whole-body FDG scans were carried out in 71 patients along with [11C]-methionine examinations, if necessitated by inconclusive FDG results. Based on these findings involvement-frequencies were calculated for each lymphatic region. The three most frequently involved lymphatic regions were the mediastinum (83.1%), the left cervical and left supraclavicular regions (78.9%) and the right cervical and right supraclavicular regions (76.1%). These data support the hypothesis that HD originates from the cervical or supraclavicular regions and reaches the distant sites by basically retrograde spreading in a non-random manner. The appropriate values of site involvement-rate were compared with those obtained by other authors based on pathologic staging and a good correlation was found. The high level of correspondence between these involvement-frequencies supported the general validity (i.e. valid for both treated and untreated cases) of the principles governing lymphatic spreading of HD.

Adult↗

PubMed2002

[PET scan in patients with epipharyngeal tumors].

Whole-body FDG PET examinations in 10 cases of epipharyngeal tumour (8 males, 2 females, mean age: 48 years) have been performed since January 1999. The PET examinations were aimed at the accurate staging, follow-up of the patients after the treatment, identification of recurrencies and localization of the unknown primary tumor. Functional imaging resulted in "upstaging" in 3 patients as compared to staging by the conventional diagnostic tools. Four additional patients with hyperplastic epipharyngeal tissue were investigated for occult primary cancer after negative results of multiple excisions, resulting in one case of primary epipharyngeal cancer. Correct staging, early detection of recurrencies, localization of occult primary tumor and the better post-therapeutic assessment of epipharyngeal masses all facilitate a more reasonable therapeutic approach, which may improve survival results.

Adult↗

PubMed2002

[Cerebral glucose metabolism in Down syndrome using positron emission tomography].

Resting cerebral glucose metabolism was assessed by PET using FDG in eleven Down syndrome (DS) patients. Standardized uptake values (SUV) were determined on a pixel by pixel basis from the measured tissue FDG-activity data. The results showed that the mean value of the global FDG-uptake in the DS patients was not significantly different from the one obtained in the control group consisting of children and young adults. The standard deviation of SUV, however, was much higher in the DS group in almost all regions. The statistical parametric mapping (SPM) method was applied to compare the relative cerebral FDG accumulation pattern of the populations. Six regions (clusters) were found in which the glucose-uptake was higher in the DS patients than in the control group. The anatomical localization of these clusters was based on MRI investigations and brain-atlas technique.

Adolescent↗

PubMed2002

[Use of positron emission tomography in psychiatry].

For the past years, substantial amount of experimental data has been published on the use of positron emission tomography in different psychiatric disorders. The different PET methods, which evaluate the whole-brain or regional metabolism, tissue perfusion or receptor density may help to identify the disorder specific changes in brain function and also better understand the underlying pathophysiology. In the clinical practice, PET plays an important role in the diagnosis and differential diagnosis of dementias and, presumably, in the near future the PET technique will be also extensively used in the clinical examination of other psychiatric disorders.

Alcoholism↗

PubMed2002

[In vivo investigation of the A2A adenosine receptor distribution using the [11C]-CSC radioligand].

A 11C labeled selective adenosine A2A antagonist, (E)-8-(3-chlorostyryl)-1,3-dimethyl-7-[11C]-methylxanthine [(11C)-CSC] was prepared reacting (E)-8-(3-chlorostyryl)-1,3,-dimethylxanthine and [11C]-methyl iodide. A primary evaluation of [11C]-CSC as a potential tracer for mapping adenosine A2A receptors by positron emission tomography (PET) was also presented. Autoradiographic studies were carried out on Swiss mice. A high level accumulation of radioactivity was observed in the striatum and medulla oblongata in accordance with previous findings on the specific spatial distribution of A2A adenosine receptors. Dynamic PET studies on rabbits showed a fast brain uptake of CSC, reaching a maximum in less than 2 minutes. Competition experiments with the unlabeled ligand proved [11C]-CSC to bind specifically to the appropriate receptor.

Animals↗

PubMed2002

[The [18F]-FNECA serves as a suitable radioligand for PET investigation of purinergic receptor expression].

The well known and widely used P1 adenosine agonist, 5'-N-ethyl-carboxamidoadenosine (NECA), was labelled with 18F isotope for the in vivo PET investigation of A1, A2 and A3 adenosine receptor expression. The precursor 2-[18F]fluoroethylamine was reacted with 2',3'-O-isopropylideneadenosine-5'-uronic acid. Specific activity of the [18F]-FNECA was (2.3 +/- 1.1) TBq/mmol (60 Ci/mmol). Dynamic PET measurements were carried out in rabbits to study the in vivo kinetics of the receptor saturation with the labelled ligand. The time dependent accumulation was followed up in the heart, lungs, liver, brain and testis. The radiotracer uptake was rapid and reached its maximum in less than two minutes in the heart and testes after v. injection of the radiopharmaceutical, while it took about 6 minutes in the brain, lungs and liver. High [18F]-FNECA accumulation was detected in the intestines, too. The specific binding of the [18F]-FNECA was tested in competition experiments in brain and heart sections using autoradiographic technique. The outlined synthesis provided sufficient amounts of [18F]-FNECA to map adenosine receptor expression under physiological conditions.

Adenosine-5'-(N-ethylcarboxamide)↗

PubMed2002

[Auditory event related potential and PET scan: a possibility for the comprehensive evaluation of cognition].

The authors studied the parallel use of event related potential (ERP) and brain activation PET in nine healthy volunteers. The presence of P300 wave in the EEG recording was accompanied by a parallel increase in the blood perfusion of the anterior cingulate gyrus. Furthermore, the functional connectivity between cortical and subcortical structures was also present during the task. This method combines the fine temporal-resolution of ERP and spatial-resolution of PET, which allows for the complex examination of fast cognitive processes. This approach may be useful in the investigation of psychiatric disorders.

Brain↗

PubMed2002

[Movement-activated [15O]-butanol PET scan in patients with Parkinson disease].

The regional cerebral perfusion has been studied by [15O]-butanol PET in bradykinetic patients with Parkinson's disease. In comparison with the rest condition significantly higher perfusion was detected in the primary sensorimotor cortex, parietal cortex, premotor cortex and supplementary motor area. A decrease of activity was observed in the lateral motor cortex, medial frontal cortex, dorsolateral prefrontal cortex and bilaterally in the head of the caudate nuclei. The method is capable of demonstrating the reorganisation of extrapyramidal movement regulation and the impact of medical and surgical treatment modalities. Based on the results conclusions can be drawn for the modes of action of the different treatment modalities.

Butanols↗

PubMed2002

[Effect of pathologic and induced peripheral vestibular balance disturbance on the central nervous system].

The authors investigated the central projection of excitement in acute stage vestibular neuronitis using positron emission tomography. The changes in the pattern of regional cerebral blood flow caused by the disease were compared with the effect of cold caloric stimulation known to provoke similar signs. It was concluded that the involved brain regions overlapped each other only partially. The mismatch could be explained by the compensatory processes developing during the disease. These processes do not normally develop during the caloric vestibular stimulation because of its short duration.

Adult↗