Biomedical subjects

Zsolt Lengyel

Publications and source records attributed to Zsolt Lengyel.

At least 19 recordsLinked to original sources

PubMed2006

Brain blood flow changes measured by positron emission tomography during an auditory cognitive task in healthy volunteers and in schizophrenic patients.

OBJECTIVE: Cognitive deficit is an essential feature of schizophrenia. One of the generally used simple cognitive tasks to characterize specific cognitive dysfunctions is the auditory "oddball" paradigm. During this task, two different tones are presented with different repetition frequencies and the subject is asked to pay attention and to respond to the less frequent tone. The aim of the present study was to apply positron emission tomography (PET) to measure the regional brain blood flow changes induced by an auditory oddball task in healthy volunteers and in stable schizophrenic patients in order to detect activation differences between the two groups. METHOD: Eight healthy volunteers and 11 schizophrenic patients were studied. The subjects carried out a specific auditory oddball task, while cerebral activation measured via the regional distribution of [15O]-butanol activity changes in the PET camera was recorded. RESULTS AND DISCUSSION: Task-related activation differed significantly across the patients and controls. The healthy volunteers displayed significant activation in the anterior cingulate area (Brodman Area - BA32), while in the schizophrenic patients the area was wider, including the mediofrontal regions (BA32 and BA10). The distance between the locations of maximal activation of the two populations were 33 mm and the cluster size was about twice as large in the patient group. CONCLUSIONS: The present results demonstrate that the perfusion changes induced in the schizophrenic patients by this cognitive task extends over a larger part of the mediofrontal cortex than in the healthy volunteers. The different pattern of activation observed during the auditory oddball task in the schizophrenic patients suggests that a larger cortical area - and consequently a larger variety of neuronal networks--is involved in the cognitive processes in these patients. The dispersion of stimulus processing during a cognitive task requiring sustained attention and stimulus discrimination may play an important role in the pathomechanism of the disorder.

Acoustic Stimulation↗

PubMed2006

Pattern of increased cerebral FDG uptake in Down syndrome patients.

Resting cerebral glucose metabolism was assessed by 18[F]-fluorodeoxyglucose in 11 Down syndrome patients. Standardized uptake values were determined on a pixel-by-pixel basis from the measured tissue-activity data. The results revealed a mean overall 18[F]-fluorodeoxyglucose uptake in the Down syndrome patients close to that observed in the control group, consisting of children and young adults. However, the standard deviation of the standardized uptake values was much higher in the Down syndrome group in almost all voxels relating to the gray matter. The statistical parametric mapping method was applied to compare the cerebral 18[F]-fluorodeoxyglucose accumulation patterns of the Down syndrome and control groups. Six regions (clusters) were found for which the glucose uptake was higher in the Down syndrome patients than in the control group. The anatomic localization of these clusters was based on magnetic resonance investigations and a brain-atlas technique. The localization of the identified clusters with an increased glucose metabolism in the Down syndrome patients suggests that these subjects have an enhanced resting neuronal activity in cortical areas involved in reasoning, cognition, and speech as compared with normal subjects.

Adolescent↗

PubMed2005

Detection of prostate cancer with 11C-methionine positron emission tomography.

PURPOSE: We studied the detection of primary prostate cancer with positron emission tomography (PET) using C-labeled methionine (MET) in patients with increased prostate specific antigen (PSA) levels and repeatedly negative biopsies. MATERIALS AND METHODS: A total of 20 consecutive patients with increased serum PSA and negative repeat biopsies were included in the study. Patient age ranged from 52 to 75 years (average 65). PSA levels ranged from 3.49 to 28.6 ng/ml (average 9.36). Dynamic PET images were obtained from the prostate region using C-labeled MET. Suspicious accumulations of the tracer were anatomically localized using magnetic resonance images and were used as guidance during the next biopsy. RESULTS: PET was positive in 15 (75%) patients, in 7 of whom (46.7%) the next repeat biopsy verified carcinoma. The overall detection rate was 35% (7 of 20) and 46.7% (7 of 15) in the whole group and in the positive PET group, respectively. All 5 of 5 patients with negative MET PET had negative biopsies. CONCLUSIONS: MET PET of the prostate with short dynamic scanning and multicore biopsy is a useful method to ensure a high detection rate of prostate cancer in patients with increased PSA and repeat negative biopsies.

Aged↗

PubMed2005

Does increased 18FDG uptake reflect malignant transformation of a low-grade glioma? A diagnostic dilemma.

Benign gliomas of the brain show decreased uptake of 18F fluorodeoxyglucose (FDG) on positron emission tomography (PET). Malignant transformation is usually manifested by an increase of 18FDG uptake. A 45-year-old female has been followed up since 1987 by means of 18FDG-PET for a right hemispheric World Health Organization Grade II oligoastrocytoma. In 1996, increased epileptic activity was accompanied by increased 18FDG uptake within the temporal part of the tumor. After surgery, the epileptic seizures diminished. Histological examination of the resected tumor showed no change in the pathology when compared with the first biopsy. Localized temporal increase of 18FDG uptake was not associated with malignant progression. The decrease of seizure frequency might shed light on a putative connection of hyperglycolysis and epileptic discharges.

Adult↗

PubMed2004

[Treatment of primary mediastinal large B-cell lymphomas].

INTRODUCTION: Primary mediastinal large B-cell non-Hodgkin's lymphoma is a relatively rare disease with specific clinical symptoms. This tumour originates from a subset of B-cells of the thymus and at the time of the diagnosis the disease is predominantly localised in the mediastinum. The tumor grows rapidly and frequently involves other thoracic structures. The majority of the patients are young females. There are no histologic features that reliably distinguish these tumors from other diffuse large B-cell lymphomas. This is the only lymphoma subtype which can only be defined by the combination of clinical and pathologic features. Analysis with DNA microarrays verified that primary mediastinal and diffuse large B-cell lymphomas are different diseases. AIMS: Comparing the effectiveness of two types of anthracycline-based standard chemotherapy regimens and the evaluation of the prognostic markers which are applied in large B-cell lymphomas. METHODS: 27 patients with primary mediastinal lymphoma were treated by the authors with anthracycline-based polychemotherapy with complementary radiotherapy from January 1995 to December 2002. RESULTS: Complete remission was obtained in 15 patients (56%) and no relapse was observed in this group. 9 additional patients (33%) achieved partial remission, while in 3 cases (11%) the treatment was ineffective. The patients who failed to achieve complete remission were subsequently treated with more intensive chemotherapy. Afterwards, those patients who were chemosensitive, underwent high-dose chemotherapy with autologous peripheral blood stem-cell transplantation. The chemoresistant patients received palliative chemotherapy. The 5-year overall survival rate of the 27 patients was 62.11%. CONCLUSION: The authors found that the procarbazine, prednisolone, adriamycin, cyclophosphamide, etoposide, cytosine-arabinoside, bleomycin, vincristine, methotrexate treatment was more effective than the cyclophosphamide, adriamycin, vincristine, prednisolone combination. The expected 5-year overall survival rates were 83.57% vs. 33.33%, respectively. This difference was significant (p = 0.017). No prognostic value of age adjusted international prognostic index, LDH- and b2-microglobulin levels were found. The results with the new standard of combined immuno-chemotherapy (rituximab--cyclophosphamide, adriamycin, vincristine, prednisolone) seem to be hopeful and more effective than earlier treatments.

Adult↗

PubMed2004

PET identifies transitional metabolic change in the spinal cord following a subthreshold dose of irradiation.

Positron emission tomographic (PET) investigations were performed to obtain in vivo information on symptomless radiation-induced pathological changes in the human spinal cord. PET investigations were carried out prior to radiotherapy and during the regular follow-up in an early hypopharyngeal cancer patient (the spinal cord was irradiated with a biologically effective dose of 80 Gy2), with [18F]fluorodeoxyglucose (FDG), [11C]methionine and [15O]butanol as tracers; radiosensitivity and electroneuronographic (ENG) studies were also performed. A very low background FDG accumulation (mean standardized uptake values, i.e. SUV: 0.84) was observed in the spinal cord before the initiation of radiotherapy. An increased FDG uptake was measured 2 months after the completion of radiotherapy (mean SUV: 1.69), followed by a fall-off, as measured 7 months later (mean SUV: 1.21). By 44 months after completion of irradiation, the FDG accumulation in the irradiated segments of the spinal cord had decreased to a level very close to the initial value (mean SUV: 1.11). The simultaneous [15O]butanol uptake results demonstrated a set of perfusion changes similar to those observed in connection with the FDG accumulation. The patient exhibited an extremely low [11C]methionine uptake within the irradiated and the nonirradiated spinal cord during the clinical course. She has not had any neurological symptoms, and the results of central ENG measurements before radiotherapy and 2 months following its completion proved normal. Radiobiological investigations did not reveal unequivocal signs of an increased radiosensitivity. A transitory increased spinal cord FDG uptake following radiotherapy may be related to the posttherapeutic mild inflammatory and regenerative processes. The normal [11C]methionine accumulation observed is strong evidence against intensive cell proliferation. The high degree of normalization of the temporarily increased FDG uptake of the irradiated spinal cord segments by 44 months is in good agreement with the results of monkey studies, which demonstrated a nearly complete recovery from radiation-induced spinal cord injury.

Butanols↗

PubMed2004

Subcortical [18F]fluorodeoxyglucose uptake in lesional epilepsy in patients with intracranial tumour.

BACKGROUND: We hypothesized that in patients with intracerebral tumours a subcortical metabolical shift may be present when the underlying pathology can, itself, be the epileptogenic focus. We also assumed that by studying the alterations in glucose metabolism beyond the tumour's borders we could identify a modulator area. METHODS: Sixty-seven patients with supratentorial brain tumour associated epilepsy were investigated interictally, in normoglycaemic conditions, by using [18F]fluorodeoxyglucose positron emission tomography (FDG PET). The studies were analysed semiquantitatively by calculating standardized uptake values and asymmetry indices. Normal subjects and patients with non-epileptic brain lesions were used as controls. RESULTS: Compared to normal controls frontal and temporal tumours showed significant changes in thalamic FDG uptake, which reflected hypometabolism of the affected side. It was noted in occipito-medial cortex in temporal tumours and in lentiform nucleus in frontal tumours as well. Comparison to lesional brains only proved that there was significant hypometabolism in lentiform nucleus in temporal tumours. CONCLUSIONS: The quantified values obviously reflect biological changes. The observed subcortical hypometabolism is most likely secondary to underlying pathology. Although seizures in tumorous patients do not originate from subcortical structures their influence on cortical sites of seizure initiation could be explained by defective subcortical regulation of cortical excitability.

Adolescent↗

PubMed2004

Mediastinal bulky tumour in Hodgkin's disease and prognostic value of positron emission tomography in the evaluation of post-treatment residual masses.

Among the 193 patients (82 female, 111 male) treated primarily for Hodgkin's disease at our clinic between 1990 and 2001 and followed up until 2003, 42 (22%) had mediastinal bulky tumours (MBTs) by the Cotswolds criteria. The rate of MBT diagnosis was significantly greater in the early stage of the disease, these patients were younger and--in contrast to the other group--they all received combined therapy. No significant differences were found in the overall and relapse-free survival rate in the two groups, but relapse and death rates were lower in the patients with bulky tumours. Of the total number of patients, 27 underwent a total of 31 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) examinations, mainly for the evaluation of post-treatment residual mass viability. In the 12 positive cases, the majority of patients received further therapy. During the mean follow-up time of 58 months (range 5-98 months) after obtaining negative results, progression of the disease was found in 2 cases 14 and 23 months later, respectively. Based on our results, we conclude that FDG-PET examinations show a good correlation with clinical follow-up results.

Child↗

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

Increased metabolic activity in the spinal cord of patients with long-standing Lhermitte's sign.

PURPOSE: To investigate the pathophysiology of the radiation-induced, chronic Lhermitte's sign (LS) on the basis of long-standing case histories with partial functional recovery. PATIENTS AND METHODS: As radiotherapy in two nasopharyngeal cancer patients, a biologically effective dose (BED) of 103.8 Gy(2) (case 1) and 94.8 Gy(2) (case 2) was delivered to the cervical spinal cord. Neurologic signs relating to the irradiated spinal cord segments developed after 2 months (case 1) and 5 years (case 2), with radiation-induced damage equivalent to grade 3 (case 1) and grade 2 (case 2) toxicity (Common Toxicity Criteria, Version 2.0). The clinical status improved to grade 2 (case 1) and grade 1 (case 2). Positron emission tomography (PET) and fibroblast clonogen assay were applied 25 and 7 years postirradiation, respectively, to characterize this rare clinical picture. RESULTS: PET demonstrated increased [(18)F]fluorodeoxyglucose (FDG) accumulation and [(15)O]butanol perfusion, but negligible [(11)C]methionine uptake in the irradiated spinal cord segments in both patients. In clonogenic assays, fibroblasts from case 1 displayed much higher radiation sensitivity than in healthy controls, while in case 2 the fibroblasts sensitivity was normal. CONCLUSIONS: These data suggests a close direct relationship between regional perfusion and metabolism of the spinal cord, similarly as in the brain. The postirradiation recovery may be related to energy-demanding conduction, explaining the increased metabolism and perfusion. The increased radiosensitivity and higher spinal cord BED may have contributed to the more severe sequelae in case 1.

Adult↗

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↗