Biomedical subjects

Witold Cholewiński

Publications and source records attributed to Witold Cholewiński.

10 recordsLinked to original sources

PubMed2005

[Relationship between plasma brain natriuretic peptide level and left ventricular systolic function in coronary artery disease].

UNLABELLED: THE AIM of the study was to assess the brain natriuretic peptide (BNP) plasma concentrations in patients with CAD and to evaluate the relationships between BNP levels and such parameters of the left ventricular (LV) systolic function as ejection fraction (LVEF) and peak LV emptying rates (PER). MATERIAL AND METHODS: The study population comprised 69 patients with CAD, aged 30-79 years. All subjects underwent gated equilibrium radionuclide ventriculography at rest. From the data acquired, LVEF and PER were calculated. The plasma BNP concentrations were determined in blood samples taken from patients with CAD and in 18 healthy subjects and the obtained results were compared with those by radionuclide ventriculography. For this purpose patients with CAD were divided into two subgroups: dLVEF (LVEF<50%) and nLVEF (LVEF>50%). Subjects with normal LVEF (nLVEF) were divided into subgroups with PER greater than median value of this parameter and lower than or equal to the median. RESULTS: In patients with CAD both the BNP concentration and its frequency were significantly higher than in controls. In patients with CAD and dLVEF the BNP concentration was significantly higher than in nLVEF cases. Increased BNP concentration was distinctly more frequent in dLVEF group than in nLVEF, but the difference was not significant (p>0.05). In group with nLVEF, the BNP concentration was higher in patients with PER<2.33 (dPER) in comparison to those with PER>2.3 (p>0.05). Not very close, but statistically significant correlation was found between the BNP level on the one hand and the LVEF and PER on the other. CONCLUSIONS: Increased plasma BNP in patients with CAD seem to depend not only on the degree of the myocardial contraction, but also on the dynamics of the left ventricular emptying. The reason for the BNP elevation in cases with CAD and reduced LV ejection rate but normal EF needs to be investigated.

Adult↗

PubMed2005

[Algorithms of artificial neural networks--practical application in medical science].

Artificial Neural Networks (ANN) may be a tool alternative and complementary to typical statistical analysis. However, in spite of many computer applications of various ANN algorithms ready for use, artificial intelligence is relatively rarely applied to data processing. This paper presents practical aspects of scientific application of ANN in medicine using widely available algorithms. Several main steps of analysis with ANN were discussed starting from material selection and dividing it into groups, to the quality assessment of obtained results at the end. The most frequent, typical reasons for errors as well as the comparison of ANN method to the modeling by regression analysis were also described.

Algorithms↗

PubMed2005

[Lymphoscintigraphy in oncology--the role in the preoperative diagnosis].

Lymphoscintigraphy is the nuclear medicine procedure, which visualize the distribution of radiolabelled particles in the lymph vessels and lymph nodes. The sentinel node concept presumes that the first lymph node to receive drainage from a tumour will show the metastasis if there has been lymphatic tumour spread. Detection of metastatic involvement of lymph nodes is essential for management and prognostic evaluation in cancer patients. Sentinel lymph node biopsy, radioguided intraoperative lymph node detection widely increased the role of lymphatic mapping in oncology. This article provides a brief history of the sentinel lymph node concept, discusses radiopharmaceuticals, equipment and techniques in lymphatic mapping mainly in melanoma and breast cancer.

Breast Neoplasms↗

PubMed2004

Prediction of left ventricular ejection fraction in patients with coronary artery disease based on an analysis of perfusion patterns at rest. Assessment by an artificial neural network.

BACKGROUND: In CAD, left ventricular function depends on the condition of myocardial perfusion, hence it may be presumed that blood flow abnormalities may enable the LVEF to be predicted. The aim of the study was to apply an Artificial Neural Network (ANN) to investigate the relationships between myocardial perfusion and LVEF, measured simultaneously. MATERIAL AND METHODS: gSPECT examinations were performed in 95 patients with CAD, divided into training (n = 50) and testing (n = 45) groups. using the acquired data, in each subject the LVEF was calculated and a perfusion polar map was constructed and divided into 25 segments. Based on results obtained in the training group, a characteristic configuration of segments was defined, with features enabling differentiation between the individual subjects of that group. The set of those segments, as well as the corresponding LVEF values enabled the optimum network architecture to be constructed and trained. The trained ANN was verified by application to the testing group. RESULTS: Using the above-described procedure, 15 polar map segments were defined which enabled the patients of the training group to be differentiated sufficiently enough to make their further recognition possible. The optimal network structure consisting 25 neurons was obtained by comparing the activity in those segments in individual subjects with corresponding LVEF values. Based on the above model, the obtained network was able to reproduce learning data (r = 0.832; learning error = 4.84%) and to apply the gained knowledge to the testing cases (r = 0.786; testing error = 4.99%). CONCLUSIONS: The obtained network can generalise learned information. To predict LVEF, some polar map segments should be excluded from the analysis. Erroneous LVEF prediction may occur resulting mainly from conditions independent from perfusion abnormalities.

Artificial Intelligence↗

PubMed2004

Relationship between plasma BNP levels and left ventricular diastolic function as measured by radionuclide ventriculography in patients with coronary artery disease.

BACKGROUND: Radionuclide ventriculography enables such parameters of the left ventricular (LV) function as the ejection fraction (EF), ejection rate (ER) and filling rate (FR) to be measured correctly. The impairment of the LV function in coronary artery disease (CAD) results in an increase in plasma brain natriuretic peptide (BNP). The aim of this study was to check whether the reduction of the average filling rate (AFR) leads to an increase in plasma BNP levels in patients with CAD and nEF and whether that increase is comparable to that occurring in subjects with a reduced PER. MATERIAL AND METHODS: The study population comprised 69 patients with CAD and 18 healthy subjects--a control group (CG). In all cases radionuclide ventriculography was performed at rest and the plasma BNP level was estimated. RESULTS: The plasma BNP concentration was significantly higher in the group with CAD than in those with CG . In patients with CAD and a decreased LVEF (dEF), the BNP level was significantly higher than in those with normal LVEF (nEF). In the subgroup with nEF and an AFR < or = 1.04 EDV/s, the level of plasma BNP was significantly higher than in that with an AFR >1.04. In the total CAD group, a significant correlation was found between plasma BNP concentrations and the LVEF, PER and AFR. In patients with nEF, the level of plasma BNP correlated only with the AFR. CONCLUSIONS: It is concluded that the diastolic dysfunction of the left ventricle in patients with CAD leads to an elevation of plasma BNP concentrations despite the normal ejection fraction. A diastolic dysfunction of the left ventricle affects the BNP plasma concentration to a greater degree than a systolic dysfunction.

Adult↗

PubMed2003

Long lasting effect of physical stress on the LVEF.

BACKGROUND: Animal and clinical studies have shown that exercise can deteriorate myocardial contractile function. The aim of this study was to examine whether the decrease of LVEF measured with gated SPECT lasts as long as 3 hours after exercise. MATERIAL AND METHODS: 46 patients with CAD and a control group comprising 10 healthy subjects were studied. All patients underwent myocardial perfusion gated SPECT with (99m)Tc-tetrofosmin at rest and during stress. SPECT was started 1 hour p.i. at rest and twice - 1 hour and 3 hours after injection at stress. LVEF values were calculated by the method of Germano, using QGS software. RESULTS: LVEF values measured at all time points were significantly lower in CAD patients than in control group. In normals mean LVEF values 1h after rest injection were similar to those obtained 1 and 3 hours after stress injection (59.0 +/- 4.1 v. 60.0 +/- 5.9 v. 58.0 +/- 4.6 respectively; p > 0.05). One hour post exercise a decrease of LVEF was observed in 2 patients and 3 hours after injection also in 2 patients. CAD subjects showed slightly lower LVEF values determined 1h after stress than 1 hour after rest injection (50.8 +/- 13.6 v. 49.3 +/- 12.8; p < 0.05). More expressed reduction of LVEF was observed 3 hours after stress injection as compared to both rest and stress study (50.8 +/- 13.6 v. 46.0 +/- 12.2; p < 0.001 and 49.3 +/- 12.8 v. 6.0 +/- 12.2; p < 0.001 respectively). One hour post exercise, a decrease of LVEF values was observed in 18 patients and 3 hours after injection in 36 patients out of 46. CONCLUSIONS: In the majority of patients with CAD physical stress applied for the purposes of myocardial perfusion SPECT study results in an impairment of the LV function. The impairment of the LVEF caused by physical stress is observed 1 hour after exercise, but it increases markedly in frequency and grows stronger during the next 2 hours. Patients with CAD who underwent cardiac examination connected with physical stress should remain under observation for several hours after termination of exercise.

Adaptation, Physiological↗

PubMed2003

Application of artificial neural network algorithm to detection of parathyroid adenoma.

BACKGROUND: The most common radionuclide procedures for parathyroid imaging are (99m)Tc-MIBI/ (99m)Tc pertechnetate subtraction scintigraphy and (99m)Tc-MIBI double-phase imaging, with estimation of MIBI wash-out rate. Those two methods are by some authors regarded as complementary techniques, yielding the best evaluation of parathyroid gland if performed conjointly. By such an approach it seems reasonable to substitute the visual assessment of neck scintigrams and semiquantitative evaluation of MIBI wash-out rate with a single, common procedure. The aim of this study was application of the Artificial Neural Network (ANN) simulated by the computer program to detection and localisation of pathological parathyroid tissue in the planar neck scintigrams. MATERIAL AND METHODS: The applied algorithm was based on simultaneous data processing in sets of 3 single pixels, each of them belonging to one of the three consecutive neck scintigrams generated 20 min. after (99m)TcO(4 )- administration, 10 min. after (99m)Tc-MIBI injection and 120 min. after (99m)Tc-MIBI injection, respectively. Those scintigrams were aligned which each other according to the same vertical and horizontal co-ordinates. The training patterns were obtained from 25 patients by searching for maximum count numbers within small ROIs drawn in selected scintigraphic areas, arbitrarily classified and coded in a numerical scale. In 10 pts the results of ANN simulation were compared with those obtained by common conventional assessment of two radionuclide parathyroid examinations: subtraction method and (99m)Tc-MIBI double-phase imaging. RESULTS: The training patterns processed by the neural network showed a close relationship with the results of visual assessment of original neck scintigrams, with R square coefficient R(2) = 0.717, and standard error equal to 0.243. Similar comparison between original data and results of multidimensional regression analysis yielded weaker relationship, with R(2) = 0.543 and standard error 0.567. Parametric images obtained by the neural network presented regions with homogeneously distributed, relatively high activity, greater than or equal to 750 cts/pixel, visualized in areas of confirmed abnormal parathyroid location. In all 10 patients with suspected parathyroid adenoma results obtained by ANN simulation agreed with those by conventional methods. In five of these cases no parathyroid abnormalities were found. In the remaining 5 subjects results of both approaches were positive but the abnormalities were depicted more distinctly and visualised more clearly in parametric images received by ANN than in original scans. CONCLUSIONS: Application of trained ANN enables objective and quantitative detection and localisation of parathyroid adenoma and is a good alternative for conventional radionuclide imaging procedures used in diagnosing parathyroid abnormality. Including in neural network simulation not only scintigraphic data, but also clinical symptoms and/or some other indicators of parathyroid abnormality, parathormone level first of all, should be a next step in developing a procedure for assessing parathyroid abnormality, of high diagnostic accuracy.

Adenoma↗

PubMed2002

The influence of nitroglycerin on myocardial 99mTc-Tetrofosmin uptake defects in coronary artery disease.

Nitroglycerin (Ntg) is known to increase blood flow to the hypoperfused myocardial area and thus to reduce regional ischaemia of the heart muscle in coronary artery disease (CAD). The aim of this study was to assess the effect of a therapeutic dose of Ntg on 99mTc-Tetrofosmin uptake defects occurring in patients (pts) with CAD in myocardial SPECT at rest. The study population comprised 34 pts with CAD. All subjects underwent myocardial perfusion SPECT at rest, using 2-day, protocol. On the first day 99mTc-Tetrofosmin was injected in baseline conditions and on the second day, after sublingual administration of 0.5 mg Ntg. The baseline examination revealed altogether 78 Tetrofosmin uptake defects in all 34 pts. The SPECT after Ntg showed improved tracer uptake in 33/78 perfusion defects in 18/34 pts, no change in 29/78 defects in 7/34 cases and more reduced tracer uptake in 16/78 defects in 9/34 pts. No explicit, significant relationship was found between 99mTc-Tetrofosmin uptake changes after Ntg on the one hand and the number of involved vessels, degree of coronary artery stenosis, history of myocardial infarction and LV global and regional function on the other. It is concluded that sublinqual administration of Ntg may result in improvement as well as in deterioration of regional perfusion defects, assessed with 99mTc-Tetrofosmin in CAD. The relationships between Ntg-augmented changes in uptake defects of this tracer on the one hand and conditions of the LV function and severity of heart muscle perfusion abnormalities on the other are unclear and should be verified on a larger study population.

Adult↗

PubMed2002

Effect of biventricular pacing on heart function evaluated by gated blood pool study in patients with end-stage heart failure.

BACKGROUND: Biventricular cardiac pacing has been used as a complementary form of therapy in patients with severe heart failure. The aim of this study was to evaluate the effect of the synchronous stimulation of both ventricles on the heart function measured by gated blood pool study (GBP). MATERIAL AND METHODS: Ten patients (9 men and 1 woman aged 53-74 years) with end-stage heart failure (HF) were studied. In all patients long-term biventricular pacing (BV) was applied. The obtained results were compared with single-chamber stimulation in 5 patients and with sinus rhythm (SR) in 8 patients. All patients underwent repeated GBP with RBC labelled with 740 MBq of 99 mTc-pertechnetate. The LVEF was calculated according to the standard method based on the count rates. Phase analysis was performed with the standard method using first Fourier element. RESULTS: Clinically in almost all patients moderate to important symptomatic improvement has been observed. The analysis of LVEF values revealed that BV pacing resulted in significantly higher values only in comparison with SR (21.6% +/- 10.3 v. 20.1% +/- 10.1; p < 0.05). The phase shift between both ventricles by BV pacing was positive and similar to that obtained with SR and RV stimulation (14.0 degrees +/- 29.6 v. 13.4 degrees +/- 37.6 and 7.4 degrees +/- 26.5 v. 6.0 degrees +/- 17.1 respectively). However, in comparison with LV pacing, BV stimulation revealed a change of dominant conduction abnormalities with a delay of RV contraction in relation to LV (9.0 degrees +/- 17.5 v. -3.0 degrees +/- 11.4). CONCLUSIONS: Biventricular pacing results in slight improvement of LVEF in patients with heart failure and can be considered a promising approach in patients with end-stage heart failure. Synchronous stimulation of both ventricles not always results in decrease of interventricular shift, however that observation requires further studies on a larger population.

Journal Article↗

PubMedDate not supplied

[SPECT imaging of cerebral arteriovenous angiomas. A preliminary report].

BACKGROUND AND PURPOSE: The purpose of this study was to demonstrate scintigraphic evaluation of cerebral perfusion in patients with intracranial hemangiomas. MATERIAL AND METHOD: The examination was carried out in 12 patients aged from 12 to 67 years. In all the patients cerebral angiomas were previously diagnosed and all of them were qualified for intravascular embolization. Brain scintigraphy was performed after IV injection of 99mTcECD and included the dynamic phase with images obtained every 2 seconds for 1.5 minutes and SPECT imaging. The semiquantitative analysis of regional cerebral blood flow was based on the comparison between activity in two symmetrical regions of interest. Cerebral angiography combined with intravascular embolization followed the scintigraphic examination. RESULTS: Based on angiograms, the size of the nidus was estimated at 1.0 to 9.0 cm. In 8 patients the dynamic study showed an increased tracer accumulation in the region of angioma. On SPECT images the nidus was visualized as focally decreased perfusion in all cases. A decreased tracer accumulation in the area adjacent to the nidus was detected in 8 patients. The ratio of activity in the region of angioma to activity in normally perfused tissue calculated using the semiquantitative analysis was 52% to 89%. CONCLUSIONS: SPECT images and dynamic phase of cerebral perfusion scintigraphy allow perfusion changes caused by the presence of intracranial angiomas to be identified.

Adolescent↗