Biomedical subjects

Gábor Bajzik

Publications and source records attributed to Gábor Bajzik.

9 recordsLinked to original sources

PubMed2005

[Volumetric changes following 125I interstitial brachytherapy of gliomas].

BACKGROUND: Image fusion permits quantitative analysis of the consequences of 125 Iodine interstitial irradiation of brain tumors. The volume of tumor necrosis, reactive zone and edema can be compared to the dosimetric data. PATIENTS AND METHOD: Nineteen patients with low grade glioma were analyzed on the average 14.5 months following 125 Iodine interstitial irradiation. Dose planning and image fusion were performed with the Target 1.19 (BrainLab) software. The CT/MR images showing the so called "triple ring" (necrosis, reactive ring and edema) developing after the interstitial irradiation of brain tumors were fused with the planning images and the isodose curves. The volume of the three regions was measured. Values at the intersections of isodose curves and necrosis borders were averaged and used for calculation of tumor necrosis. The volume of normal brain tissue irradiated by given dose values, as well as homogeneity and conformality indices were also determined. RESULTS: The relative volumes of the different parts of the "triple-ring" compared to the reference dose volume were the following: necrosis 54.9%, reactive zone 59.7%, and edema 445.3%. Tumor necrosis developed at 71.9 Gy dose. At the irradiation of an average size glioma with a volume of 12.7 cm3, 5 to 7 cm3 normal brain tissue around the tumor received 60-70 Gy dose. The average homogeneity and conformality indices were 0.24 and 0.57, respectively. CONCLUSION: The analysis of changes in the volume of edema, reactive ring and necrosis caused by interstitial irradiation, and their correlation with the dosimetric data using the image fusion method provide useful information for patient follow-up, clinical management and further therapeutic decisions.

Adult↗

PubMed2004

[Virtual bronchoscopy for follow-up investigation of main airway stenoses].

The aim of the study was to compare the utility and effectivity of conventional and virtual bronchoscopy in the follow up of patients with main airway stenosis. 23 patients with trachea or main bronchi stenosis were enrolled in the study. The causes of the stenosis were malignant or benign tumor, struma and stent. The stenoses were evaluated before and after the different interventions (i.e. mechanical dilatation, laser photocoagulation, stent implantation, radiotherapy, chemotherapy or surgical resection.) The mean time between the first and second endoscopic and virtual bronchoscopic examinations was 140 days. The authors found good correlation between bronchofiberoscopy and virtual bronchoscopy findings. The data of virtual bronchoscopy were more exact. Based on this study the virtual bronchocopy can replace the traditional invasive method to follow-up patients with main airway stenosis.

Adult↗

PubMed2004

Partial breast irradiation with interstitial 60CO brachytherapy results in frequent grade 3 or 4 toxicity. Evidence based on a 12-year follow-up of 70 patients.

PURPOSE: To investigate the radiation-induced toxicity and cosmesis of brachytherapy (BT) alone in early stage breast cancer. METHODS AND MATERIALS: A total of 70 women diagnosed with Stage I or II breast carcinoma participated in a BT study at the Municipal Oncoradiological Center, Uzsoki Hospital, Budapest, Hungary, between November 1987 and June 1992. They had undergone breast-conserving surgery with an unknown surgical margin. The postoperative tumor bed irradiation was performed with interstitial (60)Co sources with an active length of 4 cm, with 10-mm center-to-center spacing arranged in a single plane. The median number of inserted sources was 5 (range, 2-8), with a linear activity of 133-137 MBq/cm at the beginning of the study. The 50 Gy delivered dose at 5 mm from the surface of the (60)Co sources was administered during 10-22 h to the virtual postoperative lumpectomy cavity (i.e., plane). For radiobiologic considerations, the clinical target volume (CTV) was calculated retrospectively with a 10-mm safety margin, resulting in a 72-cm(3) median CTV (range, 36-108 cm(3)) irradiated with a reference dose of 28 Gy. In the assessment of the skin and subcutaneous toxicity, the RTOG late radiation morbidity scoring system was applied. The radiosensitivity of the cultured fibroblasts was determined by clonogenic assay to check whether individual radiosensitivity played a role in the development and course of radiation-induced side-effects. RESULTS: The median follow-up was 12 years (range, 10-15 years). The population of the final study (34 cases) comprised all survivors with tumor-free breasts (27 cases) and patients with breasts erroneously ablated/excised for misinterpreted radiation-induced sequelae (7 patients). A total of 97% of the cohort (33/34) had grade > or =2, and 59% (20/34) had grade > or =3 radiation-induced toxicity. By the end of the follow-up, 85% of the patients experienced Grade > or =2 telangiectasis and 41% had Grade 3 telangiectasis. Eighty-eight percent had fibrosis of some form, and 35% had grade > or =3 fibrosis. Forty-one percent of the cohort displayed fat necrosis, which was always accompanied by Grade > or =3 fibrosis or telangiectasis. The cosmetic results were poor in 50% (17/34) of the patients. The radiosensitivity of the fibroblasts was increased in only 2/24 patients (8% of the investigated cases, in agreement with data published for the general population). Comparisons of our fibrosis prevalence data with those of others allowed an estimate of 0.47 h(-1) for the rate of recovery of DNA damage in the fibroblasts. CONCLUSIONS: Interstitial (60)Co BT of the breast tumor bed alone with a limited CTV (median, 72 cm(3)) and a total dose of 28 Gy is associated with a high rate (59%) of grade > or =3 radiation-induced toxicity and a high rate (50%) of poor cosmetic outcome at the end of a median follow-up of 12 years. A relatively high BT dose rate (1.3-2.8 Gy/h) applied during a short overall treatment time (10-22 h) and a possible geographic miss (close to skin implantation) might have contributed to the development of these sequelae.

Adult↗

PubMed2004

[Brachytherapy of brainstem tumors].

INTRODUCTIONS: The optimal therapy of brain stem tumours of different histopathology determines the expected length of survival. Authors report 125Iodine interstitial irradiation of brain stem tumours with stereotactic brachytherapy. CASE REPORTS: Two patients having brain stem tumours were suffering from glioma or from metastases of a carcinoma. In Case 1 the tumour volume was 1.98 cm3 at the time of planning interstitial irradiation. The control MRI examination performed at 42 months post-op showed a postirradiation cyst size of 5.73 cm3 indicating 65.5% shrinkage. In Case 2 the shrinkage was more apparent as the tumour volume measured on the control MRI at 8 months post-op was only 0.16 cm3 indicating 97.4% shrinkage of the 6.05 cm3 target volume at the time of brachytherapy with the metastasis practically disappearing. Quick access to histopathological results of the stereotactic intraoperative biopsy made it possible to carry out the 125Iodine stereotactic brachytherapy immediately after the biopsy, resulting in less inconvenience for patients of a second possible intervention. The control MRI scans show significant shrinkage of tumours in both patients. CONCLUSION: The procedure can be performed as a biopsy. The CT and image fusion guided 125Iodine stereotactic brachytherapy can be well planned dosimetrically and is surgically precise.

Brachytherapy↗

PubMed2004

Iodine-125 brachytherapy of brain stem tumors.

PURPOSE: To report on iodine-125 ((125)I) interstitial irradiation in the treatment of brain stem tumors. PATIENTS AND METHODS: Two patients with brain stem tumors were treated with CT- and image fusion-guided (125)I stereotactic brachytherapy. RESULTS: By March 2003, the patients had been followed up for 47 and 13 months, respectively. In case 1, the tumor volume was 1.98 cm(3) on the control CT, indicating a 65.5% shrinkage as compared to a target volume of 5.73 cm3 at the time of brachytherapy. In case 2, shrinkage was more distinct. After irradiation, the cyst volume was 0.16 cm(3) on the control MRI, indicating a 97.4% shrinkage as compared to a target volume of 6.05 cm(3) at the time of brachytherapy, i. e., the metastasis had virtually disappeared. CONCLUSION: CT- and image fusion-guided (125)I stereotactic brachytherapy can be performed during the biopsy session. The procedure can be well planned dosimetrically and is surgically precise.

Brachytherapy↗

PubMed2003

[Three-dimensional contrast-enhanced MR angiography].

INTRODUCTION: Three-dimensional contrast enhanced magnetic resonance angiography (3D CE MRA) is an increasingly important tool in modern noninvasive vascular imaging. MR angiography has rapidly advanced in the past few years making vascular imaging throughout the body safer and more accurate. AIM: The authors analyse the diagnostic and clinical value of the method based on their own experience and guidelines given by the literature. This article describes the basic technical principles of 3D CE MRA, and gives a short overview of the usefulness of this technique investigating vascular diseases. METHOD: Between August 17, 1999 and September 28, 2001 the authors performed eighty nine contrast-enhanced MR angiography with a 1.5 T scanner. Contrast material was administered intravenuosly with a power injector. The most frequent examinations included imaging of the aorta, supraaortic and renal arteries. RESULT: 82 technically successful angiography was performed. The images could not be evaluated due to poor quality in 5 cases and failure in 2 cases. MR angiographic images provided adequate spatial resolution within single breathhold. CONCLUSION: The time-of-flight and phase contrast MR angiographic techniques have been replaced in most vascular territories by the contrast-enhanced method. With future technical developments greater spatial and temporal resolution will become possible, thus increasing the usefulness of 3D CE MR angiography. In the near future this method of imaging will become the method of choice in the investigation of the arterial system, and in some special cases of the venous system.

Contrast Media↗

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↗

PubMed2002

[FDG PET scan of metastases in recurrent medullary carcinoma of the thyroid gland].

Searching for metastases of medullary thyroid cancer (MTC), FDG PET was applied. PET results were compared with those of conventional diagnostic imaging procedures. After primary treatment, 52 MTC patients with elevated serum tumor marker levels and/or general symptoms (diarrhoea/flush) underwent radiological (CT/MRI), 131-iodine labeled metaiodo-benzylguanidine (MIBG) whole-body scintigraphy and FDG PET investigations. At least one pathological lesion was detected in 49 patients by PET, 35 by CT, 32 by MRI and 3 by MIBG. FDG PET was far superior to the other methods in identifying metastases in the supradiaphragmatic lymphatic regions. In the follow-up of MTC patients, FDG PET was more sensitive in localizing tumorous LN involvement, especially in the cervical, supraclavicular and mediastinal lymphatic regions, compared to other imaging modalities.

Adult↗

PubMed2002

18F-FDG PET detection of lymph node metastases in medullary thyroid carcinoma.

UNLABELLED: Postsurgically elevated or increasing serum calcitonin levels strongly suggest the presence of residual or recurrent medullary thyroid carcinoma (MTC). Several imaging modalities (sonography, MRI, CT, scintigraphy with different types of radiolabeled ligands, etc.) are routinely used in an attempt to localize tumorous tissue, but such efforts often fail. In the search for a more reliable method, 18F-FDG PET was applied to detect tumor tissue of residual or recurrent MTC. METHODS: Forty patients with a postoperatively elevated plasma calcitonin level were included. These patients underwent routine diagnostic imaging procedures (CT, MRI, and 131I-metaiodobenzylguanidine [MIBG] whole-body planar scintigraphy or SPECT) and 18F-FDG PET examinations. Two independent experts visually analyzed the images provided by each method to detect pathologic lesions. Lymph nodes of > or = 1 cm in short diameter that were detected by radiologic methods were considered to be pathologic. 18F-FDG accumulation with a sharp contour reported by both independent observers was similarly regarded as pathologic. RESULTS: PET detected 270 foci with a high tracer accumulation, whereas only 116 lesions were detected by MRI and 141 by CT. The numbers of such foci determined by PET, MRI, and CT were 98, 34, and 34, respectively, in the neck; 25, 5, and 6, respectively, in the supraclavicular regions; and 117, 35, and 39, respectively, in the mediastinum. 131I-MIBG scintigraphy findings were positive for only 3 patients. CONCLUSION: For MTC patients with a postoperatively elevated plasma tumor marker level, PET was more sensitive and superior in localizing tumorous lymph node involvement than were the other imaging modalities, especially in the cervical, supraclavicular, and mediastinal lymphatic regions.

Biomarkers, Tumor↗