Biomedical subjects

I Repa

Publications and source records attributed to I Repa.

At least 19 recordsLinked to original sources

PubMed2006

Development of a computed tomographic calibration method for the determination of lean meat content in pig carcasses.

Sixty left sides of pig carcasses were scanned by spiral computed tomography (CT) to measure lean meat weight and percentage. The carcasses were fully dissected and scanned to develop a calibration protocol. Different image analyses were performed on the basis of anatomically defined scans, direct volumetric estimation, body- and grey-scale ranges and using Partial Least Squares (PLS) regression of data provided by CT. The R2 values of the calibrations for lean meat weight were 0.874, 0.976, 0.983 and 0.992, respectively, depending on the method applied. The PLS proved to be the best approach with a calibration RSD of 232 g. When changing from lean meat weight to percentage, the statistical goodness drops-to a very small extent (R2 = 0.988, RSD = 0.56). According to the results, the CT method can be recommended as a reference for determining the lean meat content of pig carcasses.

Adipose Tissue↗

PubMed2006

Magnetic resonance imaging technique for the examination of canine mammary tumours.

The aim of this study was to adapt the human magnetic resonance imaging (MRI) sequences for use in the routine examination of canine mammary glands. MRI was performed on 10, middle- to old-aged dogs of different breeds. It was found that T1- and T2-weighted spin echo, short T1 inversion recovery sequences and a gradient echo (GE) dynamic T1-weighted measurement made in the coronal and transversal planes were the most informative MR diagnostic methods for imaging canine mammary tumours. The static MR technique is the most detailed imaging modality for differentiating the tissue types in the substance of the mammary gland. The MRI findings were in close relationship with the histological result (five malignant mixed tumours and five cases of invasive ductal carcinoma). Using the GE dynamic contrast-enhanced sequence the morphological patterns as well as the kinetic parameters proved to be malignant. By the dynamic measurement technique initial information was obtained on the contrast enhancing properties, which are valuable factors during in vivo staging and in the prognostic work.

Animals↗

PubMed2005

Angiography-proven liver metastases explain low efficacy of lymph node dissections in medullary thyroid cancer patients.

AIM: To report the role of liver angiography in the staging of medullary thyroid cancer (MTC) patients. MATERIAL AND METHODS: Sixty MTC patients with persistent or recurrent hypercalcitonemia (n=49), a characteristic general symptom (diarrhea, n=4) or a normal basal calcitonin level without general symptoms (n=7) were investigated by dynamic liver CT, MRI and angiography between 06/1998 and 06/2002. RESULTS: Dual-phase CT and MRI investigations identified hepatic metastases with relatively low frequency (8/58 on MRI, and 7/60 on CT). Angiography indicated liver involvement in 54/60 cases. The hepatic metastases were typically multiple, hypervascular, small foci (only 13 foci measured >/=10 mm). With one exception significant disease progression was not observed over 5 years of follow-up. CONCLUSIONS: Liver angiography is a powerful tool to reveal hepatic metastases in MTC patients. Frequent, inoperable liver metastases in hypercalcitoninemic MTC patients demonstrate that secondary lymph node dissection is an inefficient technique for restoration of a normal calcitonin level.

Angiography↗

PubMed2005

Aortic cannulation and cardiopulmonary bypass independently produce selective brain lesions in pig.

Whether cardiopulmonary bypass alone or together with the manipulation of the aorta produce neurological complication remains controversial. Using a domestic pig model of cardiopulmonary bypass, we investigated the immediate effects of aortic cannulation and cardiopulmonary bypass on neuronal injury in different brain regions. We compared the presence of neuronal injury in three experimental groups: non-operated controls (n = 3); operated controls with aortic cannulation without cardiopulmonary bypass (n = 5); operated animals undergoing cardiopulmonary bypass (n = 5). Pyknotic cells were counted in the prefrontal cortex, cerebellum and in the hippocampal formation. Calretinin immunohistochemistry was used to show possible ischemic damages in the hippocampus which is known to be one of the most sensitive brain regions to ischemia. Decreased calretinin immunoreaction and reduced number of calretinin-positive neurons were observed in the hippocampal dentate gyrus following aortic cannulation or cardiopulmonary bypass compared to the non-operated control group. Changes were more severe following cardiopulmonary bypass than after cannulation of the aorta alone. The frequency of pyknotic cell nuclei was not different in the control and experimental groups. Our experimental study suggests that both cannulation of the aorta alone and cardiopulmonary bypass affect a selected population of neurons.

Animals↗

PubMed2004

Comparison of the navicular region of newborn foals and adult horses by magnetic resonance imaging.

Magnetic resonance imaging (MRI) was tested for evaluation of the soft tissue structures of the equine digit in 16 limbs, derived from three adult warmblood horses and two newborn warmblood foals. The following measuring sequences were used in sagittal, transversal and coronal planes: spin echo, gradient echo, inversion recovery. The images were made with a 1.5 Tesla Siemens scanner in a CP-Helmholtz circular coil. To compare the visualization of the same tissue structures in adult and in newborn cases the limbs were imaged with the routinely used MRI sequences that are used for mature tissues. In newborn foals the bursa podotrochlearis could not be determined with the used sequences. For both the adult and newborn limbs the most visualization of the same tissue structures including the fluid spaces and growth plates were taken by the inversion recovery sequence. T2 sequence was very informative in adult cases but moderately in newborn foals.

Animals↗

PubMed2004

A novel technique with a flexible applicator for MRI-based brachytherapy of cervical cancer.

PURPOSE: To introduce a novel technique for magnetic resonance (MR)-based 3-dimensional planned high-dose rate intracervical brachytherapy (BT). MATERIALS AND METHODS: During 2002, 16 patients received external beam radiotherapy and BT as part of radiochemotherapy for cervical cancer. A special adjustable applicator device was designed and used for BT. The isodose distribution was calculated from MR images with the applicator in place. RESULTS: The planning target volume coverage was adequate and the radiation burden on the organs at risk was within acceptable limits. Complete regression was achieved in two patients (12.5%), and partial regression in ten (62.5%) patients. The overall response rate for the complex treatment was 93.75%. In three cases the disease was considered to be stable. CONCLUSION: The MR-compatible, flexible applicator allows safe and reproducible cervical radiotherapy with no added discomfort or hazard for the patient.

Adult↗

PubMed2003

Effects of transcutaneous electrical nerve stimulation on the fatty acid profile of rabbit longissimus dorsi muscle (preliminary report).

This study was designed to investigate whether transcutaneous electrical nerve stimulation (TENS) of the longissimus dorsi muscle (MLD) of rabbits induces specific proportional changes in the muscle fatty acid composition. Ten 4-week-old Pannon White rabbits were exposed to TENS treatment two times a day, with the following settings: 30 Hz, 20 micros impulse length, 10 mA, 2 x 20 min. After a treatment period of 50 days rabbits were slaughtered and the fatty acid composition of the MLD was determined by gas chromatography. The TENS treatment increased the proportions of linoleic (C18:2 n-6), linolenic (C18:3 n-3) and gondoic acids (C20:1 n-9), compared with the control group. The level of palmitic (C16:0), stearic (C18:0), oleic (C18:1 n-9) and eicosapentaenoic (C20:5 n-3) acids significantly decreased. The proportion of total unsaturated fatty acids significantly increased. On the basis of the results obtained, TENS may have similar effects on the muscle fatty acid profile like physical training. Based on the supposal that the composition of membrane structure was also affected, the electrical stimulation of muscles may have further consequences, e.g. on membrane properties.

Animals↗

PubMed2003

Turbinate atrophy evaluation in pigs by computed tomography.

Computed tomography (CT), a non-invasive visualisation technique was applied for imaging the bony structures of the nasal cavity of pigs, and compared to the traditional scoring system of turbinate atrophy in swine. Twenty-three 27-week-old pigs representing various stages of turbinate atrophy were used. Nasal structures were visually scored on CT scans and transversal cuts of the noses at the level of the first upper premolar teeth using the same scoring system in both cases. A tissue/air area ratio was also determined based on density differences. A highly significant correlation was found between visual scoring of CT images and transversal cuts of pig noses (r = 0.98, p < 0.0001) as well as between visual scoring of CT images and tissue/air area ratio determination (r = -0.82, p < 0.0001).

Animals↗

PubMed2002

Effects of prolonged exposure to low-dose fumonisin B1 in pigs.

From the point of view of human exposure, fumonisins (FB1, FB2, FB1, FB4), a relatively recently (1988) discovered and identified group of mycotoxins, represent one of the five most important mycotoxin groups causing human disease. In an earlier experiment studying the effects of relatively low doses (10, 20 and 40 p.p.m.) of FB1 in weaned piglets, it was established that the 4-week feeding of 10 p.p.m. (mg/kg feed) FB1 produced mild pulmonary oedema. This suggested the importance of studies with even lower doses of the toxin to determine the tolerable limits. The objective of this experiment was therefore to study the effects of prolonged (8-week) exposure to still lower concentrations (0, 1, 5 and 10 mg/kg feed) of FB1. The 8-week feeding of FB1 in low concentrations (1-10 p.p.m.) did not cause clinical signs and significant performance impairment in pigs, but rendered irreversible the chronic changes that had already developed in the animals in a dose-dependent manner. Dissection revealed pathological alterations of the lungs in one of the animals given 1 p.p.m. (n = 4), in two animals exposed to 5 p.p.m. (n = 5), and in three animals given 10 p.p.m. (n = 4). In all three treatment groups, proliferation of the connective tissue fibres, primarily of those around the lymphatic vessels, in the subpleural and interlobular connective tissue of the lungs, extending to the peribronchial and peribronchiolar areas, was seen. The results of this experiment call attention to the risk of prolonged low-dose toxin exposure, which has very important public health implications.

Animal Feed↗

PubMed2001

Angiography effectively supports the diagnosis of hepatic metastases in medullary thyroid carcinoma.

BACKGROUND: Medullary thyroid carcinoma (MTC) belongs in the group of neuroendocrine tumors with early lymphatic and hepatic dissemination. A high rate of undetectable metastases is hypothesized to be responsible for the frequent mismatch between the apparent relatively small tumor burden and the elevated plasma tumor marker level. METHODS: Thirty-six MTC patients with residual/recurrent biochemical signs (elevated basal calcitonin level) and/or characteristic general symptoms (diarrhea and/or flushing) were systematically examined by conventional radiology, whole-body 18F-deoxyglucose positron emission tomography (PET), dynamic liver computed tomography and magnetic resonance imaging, and hepatic angiography. RESULTS: Conventional diagnostic imaging revealed lymph node (LN) involvement in the cervical, mediastinal, supraclavicular, and axillary regions (16 cases), and multiple pulmonary (3 cases), bony (1 solitary and 1 multiple case), and breast (1 case) metastases. (18)F-deoxyglucose PET identified all these extralymphatic metastatic lesions (except 2 cases with multiple pulmonary metastases), and also supradiaphragmatic LN involvement in 34 (94%) patients. In 32 (89%) cases, multiple small (generally < or = 1 cm) hypervascular, hepatic metastases undetectable by other imaging methods were localized angiographically. Of the 23 original pathologic specimens investigated, 18 (78%) exhibited LN involvement. The smallest primary tumor in patients with hepatic metastases was 1 cm. CONCLUSIONS: Hepatic angiography is recommended for primary staging in MTC patients with a primary tumor measuring 1 cm or larger, and/or pathologically proven LN involvement, and also during restaging for suspected recurrences to avoid unnecessary extensive surgical LN dissection in the neck and mediastinum.

Adult↗

PubMed2001

[Virtual bronchoscopy: a new non-invasive diagnostic method in pulmonology].

Virtual reality (3 dimensional modelling of the human body) has developed as a convergence of advancing digital imaging modalities and computer graphics technologies. With this method endoscopic simulations of cavitary organs are feasible. Virtual bronchoscopy was initially described in 1993. The authors selected patient with previously detected stenosis of the trachea or the main bronchi with bronchofiberscope. They performed targeted, thin-slice helical computer tomography of the lesions. These data were transferred to a workstation and the virtual endoscopic models of the airways were generated using dedicated software. Based on cases the authors describe their preliminary experience with the method. The findings were compared with those of bronchofiberscopy. Analyzing these results and the literature the potential clinical applications of virtual bronchoscopy are discussed.

Adult↗

PubMed2001

Normal brain and brain tumor: multicomponent apparent diffusion coefficient line scan imaging.

Magnetic resonance line scan diffusion imaging of the brain, with diffusion weighting between 5 and 5,000 sec/mm(2), was performed in healthy subjects and patients with a 1.5-T machine. For each voxel, biexponential signal decay fits produced two apparent diffusion constants and respective signal amplitudes. Images based on these parameters show potential for use in the differentiation of gray and white matter, edema, and tumor.

Brain↗

PubMed2001

Brain water and proton magnetic resonance relaxation in preterm and term rabbit pups: their relation to tissue hyaluronan.

The present study was performed to investigate simultaneously total brain water, T1 and T2 relaxation times, and hyaluronan (HA) in fetal and neonatal rabbits. Attempts were also made to establish the relationship of HA to total brain water and to T2-derived motionally distinct water fractions, since HA is known to bind water and to limit tissue water mobility. Experiments were carried out in fetal Pannon white rabbit pups at gestational ages of 25, 27, 29, and 31 days and at a postnatal age of 4 days. The brain tissue water content (desiccation method), T1 and T2 relaxation times (H1-NMR method), and HA concentration (radioassay HA 50) were measured, and free and bound water fractions were calculated by using multicomponent fits of the T2 relaxation curves. Compared with values in newborn pups, water and HA contents were found to be highly elevated in the preterm brain and decreased markedly during early postnatal life. The trends and time courses of T1 and T2 relaxation times proved to be similar, but the postnatal decrease in T2 was preceded by a significant decline in late gestation. Maturity-related changes occurred in the T2 relaxation derived bound water fraction which amounted to 4-19% of brain water. The bound water fraction appeared to be independent of total brain water and HA concentration, and HA is, therefore, unlikely to be the only factor controlling brain water mobility. The clear dissociation of bound water fraction from total water suggests restructuring of brain water during the perinatal period.

Animals↗

PubMed2001

ECG-gated dynamic magnetic resonance imaging method for examination of the pig heart.

A dynamic magnetic resonance imaging (MRI) method was developed for in vivo examination of the pig heart. Measurements were carried out on 15 meat-type pigs of different liveweight using a 1.5 T equipment. Inhalation anaesthesia was applied, then data acquisition was synchronised by ECG gating. Depending on the heart rate and heart size, in each case 8 to 10 slices and in each slice 8 to 14 phases were acquired prospectively according to one heart cycle. During the post-processing of the images the left and the right ventricular volumes were determined. The values measured at 106 kg liveweight are 2.5 times higher than those obtained at 22 kg, while the ejection fractions are equal. The calculated cardiac output values were 3.5 l (22 kg, 132 beats/min.), and 6.0 l (106 kg, 91 beats/min.), respectively. After measuring the wall thickness, the contraction values were also determined for the septum (70%), and for the anterior (61%), posterior (41%) and lateral (54%) walls of the left ventricle. Three-dimensional animated models of the ventricles were constructed. Based on the investigations performed, the preconditioning, the anaesthetic procedure, the specific details of ECG measurement and the correct MR imaging technique were worked out.

Animals↗

PubMed2000

[MR-guided diagnostic and therapeutic interventions. Review and own preliminary experience].

Magnetic resonance (MR) guided diagnostic and therapeutic interventions are relatively new methods in the larger field of radiologic interventions. Good spatial resolution and soft tissue characterisation, multiplanar imaging capability, functional imaging and up-to-date computer systems enable MR imaging to guide a wide range of interventional procedures. Biopsies, punctures and drainages of fluid collections, tumor ablations and vascular interventions can be performed with the help of MRI. MR imaging provides an unique opportunity for planning, guiding and monitoring certain types of intraoperative procedures. The authors outline the basic features of MR intervention and report their own initial experience in interventional procedures in 8 cases for the first time in Hungary.

Abscess↗

PubMed2000

[Dynamic MR examination of the breast--histological correlations].

The authors outline dynamic MR mammography (dMRM) as a highly sensitive diagnostic method for the examination of the breast. In a retrospective study relating to 84 processed cases, in the knowledge of the cytological-histological findings the diagnostic accuracy of the examinations was determined. The role of the method in detecting benign and malignant changes of the breast has been estimated. Misdiagnosed cases have been analysed and recommendations for the application of the method are included. The MR proved to be positive in 32 cases and negative in 3 cases of the analysed 35 malignant tumors. Benign lesions were found at microscopy in 49 cases, of which MR correctly diagnosed 40. The sensitivity and the specificity of dynamic MR mammography were 91% and 82%.

Breast Diseases↗

PubMed2000

[Current diagnostic method, prognosis estimation and therapy of papillary thyroid cancer: recommendations of the medical universities and the National Oncologic Institute of Budapest].

Physical examination, cervical ultrasonography (US) and aspiration cytology are the mainstays of the preoperative diagnostics of papillary thyroid carcinoma. For the staging of suspected malignant cases, cervical and mediastinal CT (MRI for inconclusive results) is indicated before any surgery. The end-result of primary treatment is assessed by total-body iodine scintigraphy and the serum human thyroglobulin (hTG) level. For long-term follow-up, physical examination and the serum hTG level are the most reliable tools (6-monthly), supplemented by cervical US and chest X-ray (yearly), and total-body iodine scintigraphy (2-yearly). If these furnish positive results, further examinations may be indicated. In suspected relapses of hTG non-producing and iodine non-accumulating papillary carcinomas, 201thallium chloride or 99mTc-sesta-MIBI (methoxy-isobutyl-isonitrile) scintigraphy, and positron emission tomography with 18fluoro-deoxyglucose or 11C-methionine may be of help. For estimation of the prognosis (cause-specific survival) of the patients, the MACIS score system of the Mayo Clinic is widely accepted, the patients being divided into low-risk and intermediate/high-risk categories. The recommended standard surgical intervention is near-total thyroidectomy (2-4 g residual glandular tissue left at the upper pole of the less-involved lobe), with a central cervical lymph node dissection for diagnostic purposes. In cases of lymph node dissemination, dissection (radical, modified radical, selective or microdissection) of any of the involved compartments (central, right or left cervical, or upper mediastinal) is indicated for therapeutic reasons, the method of which is depending on the extent of the metastatic involvement. Following adequate surgical intervention, no adjuvant radioiodine therapy is indicated for low-risk cases with a tumour of less than 1 cm diameter. For other low-risk or intermediate/high-risk patients, radioiodine ablation (R0N0M0) or a therapeutic radioiodine dosage (R2N1M1) is indicated. In cases at high-risk of local/regional relapse and in radioiodine non-accumulating tumorous cases, external radiotherapy may be applied. Thyroid hormone medication in a TSH suppressive dose is indicated during the first 5 postsurgical years: the goal is to achieve a TSH level below 0.1 (determined by a 3rd generation assay). If no relapse occurs or the case is a low-risk one, following the 5 years, it is enough to maintain the TSH level in a subnormal range (0.1-0.3).

Carcinoma, Papillary↗

PubMed2000

Experiment to determine limits of tolerance for fumonisin B1 in weaned piglets.

In Hungary almost 70% of mould-affected maize inspected since 1993 was found to be contaminated with fumonisin B1 (FB1) (mean 2.6-8.65 mg/kg; maximum 9.8-75.1 mg/kg), the degree of this contamination was found to increase from year to year (Fazekas et al., 1997b). In this experiment, in order to define tolerance limit values, the effect of exposing weaned piglets to FB1 in low doses over a 4-week period was examined. The experiment was performed with 20 weaned barrows of Danish Landrace breed. After a 5-day adaptation period cultures of the fungus Fusarium moniliforme were mixed into the animals' feed in concentrations that resulted in a daily intake of fumonisin B1 of 0, 10, 20 and 40 mg/kg feed. Feeding with the toxin was observed to exert no significant effect on body weight gain or feed consumption in the animals, no clinical signs were observed and no mortality traceable to toxic effects occurred. In computer tomography examinations performed in the second and fourth weeks mild and more severe pulmonary oedema was diagnosed in the experimental animals. The processes developing in the pulmonary parenchyma were corroborated by the mathematical and statistical evaluation procedures applied. The haematological parameters examined revealed no change attributable to toxic effects, while with respect to the biochemical parameters, an increase in aspartate aminotransferase (AST) activity dependent on dosage, indicating a pathological change in the liver, was ascertained in all three experimental groups. The free sphinganine to sphingosine ratio (SA/SO), which is regarded as the most sensitive bioindicator of fumonisin toxicosis, showed an increase proportionate to toxin concentration for all three dosages. Dissection revealed mild cases of pulmonary oedema in three of the animals given doses of 10 p.p.m. (n = 4), two mild and two severe cases in those exposed to 20 p.p.m. (n = 5), and severe cases in all five animals given 40 p.p.m. The oedema of non-inflammatory origin was confirmed by histopathological examinations. The findings of this experiment which indicate that in this study FB1 administered in substantially lower concentrations than those reported in the literature resulted in severe pathological changes, point to the importance of studies involving even lower doses.

Animal Feed↗