Miroslaw Swiercz - Academia.edu (original) (raw)
Papers by Miroslaw Swiercz
ICSC Symposium on Neural Computation, 1998
Neurologia i neurochirurgia polska
Intracranial pressure (ICP) is influenced by an array of predictable and unpredictable factors. S... more Intracranial pressure (ICP) is influenced by an array of predictable and unpredictable factors. Statistical modelling of this signal has only limited applicability because of the significant load of stochastic components. We tested the efficiency of an alternative approach, based on the methodology of artificial neural networks (ANNs) in the on-line prediction of future values of ICP and in the classification of signal properties. Satisfactory accuracy of forecasting was achieved with the ANNs for a 3-minute prediction horizon, while the prediction quality with autoregressive models of statistical origin was proved unsatisfactory. The results obtained with the ANNs were further improved when signal pre-processing with wavelet transform was employed. Nevertheless, even with the ANN methodology, no sudden breakdowns in the ICP signal (which in this respect might be compared to a "catastrophe") can be forecast with any practical applicability. We therefore applied two ANN alg...
Neurologia i neurochirurgia polska
Transcranial colour-coded Doppler sonography enables estimation of blood flow parameters in the b... more Transcranial colour-coded Doppler sonography enables estimation of blood flow parameters in the basal cerebral arteries. Reference values as well as age and gender dependence of these parameters are not sufficiently established in transcranial Doppler studies. There are no reports regarding blood flow in the respective arteries of the circle of Willis. Therefore we examined 185 healthy volunteers--82 men (mean age 47, range 20-78 years old) and 103 women (mean age 47, range 22-86 years old). The subjects were divided into three age groups: 20-40 years old (group I), 41-60 years old (group II) and more than 60 years old (group III). The examinations were performed via the temporal acoustic window with a 2.5 MHz probe. Angle-corrected peak systolic, mean and end-diastolic velocities as well as impedance indices were determined in the anterior, middle and posterior cerebral arteries. In the group I mean velocity values (mean +/- SD) for the anterior, middle and posterior arteries amoun...
Klinika oczna, 1997
The authors present the "pattern" visual evoked potentials (VEP) analysis with use of t... more The authors present the "pattern" visual evoked potentials (VEP) analysis with use of the artificial neural networks (ANN). The study involved 11 patients with compressive chiasmal optic neuropathy, 20 patients with optic neuritis, 12 patients with anterior ischaemic optic neuropathy, 20 patients with optic nerve atrophy from neuritis, 8 patients with demyelinative neuropathy, 5 patients with oedema optic nerve, 20 healthy persons. The tests of visual evoked potentials were performed with the use of computer system UTAS-E1000. Classification of potentials was made by correlation of outputs of ANN with results of confirmed neuro-ophthalmology conditions. ANN of different architecture were classified correctly in 80-100% of VEP record samples. The obtained correctness of classification confirms usefulness of VEP analysis as the objective diagnostic method in some neuro-ophthalmological diseases and indicates application of ANN in multifactor analysis.
Medical & Biological Engineering & Computing, 1998
The problem of reliable detection of life-threatening situations in the neurosurgical patient und... more The problem of reliable detection of life-threatening situations in the neurosurgical patient undergoing treatment in the ICU is still far from reaching a satisfactory solution, although several methods of clinical and instrumental evaluation have recently been developed for the early detection of oncoming signs of danger. Continuous monitoring of intracranial pressure (ICP) provides neurosurgeons with valuable information about the current condition of the patient. However, it is increasingly felt that traditional methods of extracting information from the ICP signal have reached their natural limits, mostly because of difficulties in fitting the appropriate mathematical model to this nonlinear and non-stationary process. Successful implementations of artificial neural networks in many medical tasks have encouraged the application of this method to ICP processing. Two problems are considered: the prediction of trends in ICP, and recognition of the configuration of unfavourable symptoms likely to signal danger for the neurosurgical patient. The construction of neural network predictors of ICP trends is based on wavelet pre-processing of the original signal. The approach to the second task involves preprocessing of the ICP with spectral and statistical methods and classification of the extracted features of the current signal on an arbitrarily selected scale of danger.
Ultrasound in Medicine & Biology, 2010
Neuroinformatics, 2008
To determine the performance of an artificial neural network in transcranial color-coded duplex s... more To determine the performance of an artificial neural network in transcranial color-coded duplex sonography (TCCS) diagnosis of middle cerebral artery (MCA) spasm. TCCS was prospectively acquired within 2 h prior to routine cerebral angiography in 100 consecutive patients (54M:46F, median age 50 years). Angiographic MCA vasospasm was classified as mild (<25% of vessel caliber reduction), moderate (25-50%), or severe (>50%). A Learning Vector Quantization neural network classified MCA spasm based on TCCS peak-systolic, mean, and end-diastolic velocity data. During a four-class discrimination task, accurate classification by the network ranged from 64.9% to 72.3%, depending on the number of neurons in the Kohonen layer. Accurate classification of vasospasm ranged from 79.6% to 87.6%, with an accuracy of 84.7% to 92.1% for the detection of moderate-tosevere vasospasm. An artificial neural network may increase the accuracy of TCCS in diagnosis of MCA spasm.
Medical science monitor : international medical journal of experimental and clinical research, 2007
Vascular reactions after cerebral angiography have not been hitherto extensively explored due to ... more Vascular reactions after cerebral angiography have not been hitherto extensively explored due to the lack of a simple, easily available, and safe method for the measurement of cerebral circulation. We attempted to study cerebral circulation with color Doppler transcranial sonography (TCCS) in consecutive patients before and immediately after digital subtraction angiography (DSA). TCCS examination of the major cerebral arteries was carried out in 52 patients (25 females and 27 males), mean age 50.3+/-11.5 years, before and 10-20 minutes after cerebral angiography. A Toshiba Aplio SSA 770A system with a 2.5-MHz sector transducer was used. In general terms, there was a tendency after DSA towards a slight decrease in peak systolic blood velocity and an increase in mean and end-diastolic velocity in all the major cerebral arteries which, in turn, led to a decrease in the impedance index (pulsatility index, PI). In 19 patients, the impedance index as measured in the middle cerebral artery decreased after DSA, in 29 it did not change, while in 4 patients PI increased. Discriminant analysis showed that the factors predisposing individuals to these adverse reactions were a low score on the Glasgow Coma Scale, etiological diagnosis of intracerebral bleeding, and a high value of the impedance index prior to the procedure. Contrast cerebral angiography may affect the tonus of cerebral vessels. In the majority of patients it caused vasodilatation to varying degrees and in a small sub-group vasoconstriction.
Journal of Neurosurgery, 2002
The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MC... more The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MCA) spasm has been asserted. None of the published studies, however, has adequately scrutinized the overall diagnostic accuracy of this procedure. There are only sporadic reports concerning the utility of transcranial color Doppler (TCCD) ultrasonography, although this method has been proved to be more precise. In this study the authors attempted to estimate the performance of TCCD ultrasonography in detecting MCA narrowing by using receiver operating characteristic (ROC) curve analysis, based on TCCD studies obtained in a relatively large, randomly selected population of patients. Transcranial color Doppler ultrasonography studies were obtained in 100 consecutive patients (54 men and 46 women ages 18-74 years, median age 50 years) routinely referred by neurosurgeons for intraarterial angiography. The M1 segment of the MCA was insonated using a 2.5-MHz probe via a temporal acoustic window, and angle-corrected flow velocities were obtained. Angiographically depicted vasospasm was graded as none, mild (&amp;amp;amp;amp;amp;amp;amp;lt; or = 25% vessel caliber reduction), and moderate to severe (&amp;amp;amp;amp;amp;amp;amp;gt; 25% vessel caliber reduction). The effectiveness of TCCD ultrasonography in diagnosing MCA spasm was evaluated by calculating the areas under the ROC curves (Az). Of the 200 MCAs examined, 173 were successfully visualized with the aid of TCCD ultrasonography. Mild vasospasm was angiographically diagnosed in 15 arteries and moderate-to-severe vasospasm in 28. The best-performing TCCD parameter for the detection of MCA narrowing was revealed to be peak systolic velocity. The Az value for moderate-to-severe vasospasm only was 0.93 and that for all vasospasms was 0.8. The best efficiency, that is, the optimal tradeoff between sensitivity and specificity in diagnosing vasospasms, was associated with a peak systolic velocity of 182 cm/second. The performance of TCCD ultrasonography in the diagnosis of advanced MCA narrowing is very good, and is acceptable for all vasospasms. The best-performing parameter was peak systolic velocity.
Neuroinformatics, 2008
To determine the performance of an artificial neural network in transcranial color-coded duplex s... more To determine the performance of an artificial neural network in transcranial color-coded duplex sonography (TCCS) diagnosis of middle cerebral artery (MCA) spasm. TCCS was prospectively acquired within 2 h prior to routine cerebral angiography in 100 consecutive patients (54M:46F, median age 50 years). Angiographic MCA vasospasm was classified as mild (<25% of vessel caliber reduction), moderate (25-50%), or severe (>50%). A Learning Vector Quantization neural network classified MCA spasm based on TCCS peak-systolic, mean, and end-diastolic velocity data. During a four-class discrimination task, accurate classification by the network ranged from 64.9% to 72.3%, depending on the number of neurons in the Kohonen layer. Accurate classification of vasospasm ranged from 79.6% to 87.6%, with an accuracy of 84.7% to 92.1% for the detection of moderate-tosevere vasospasm. An artificial neural network may increase the accuracy of TCCS in diagnosis of MCA spasm.
Ultrasound in Medicine & Biology, 2010
The goal of the study was to compare performances of transcranial color-coded duplex sonography (... more The goal of the study was to compare performances of transcranial color-coded duplex sonography (TCCS) and transcranial Doppler sonography (TCD) in the diagnosis of the middle cerebral artery (MCA) narrowing in the same population of patients using statistical and nonstatistical intelligent models for data analysis. We prospectively collected data from 179 consecutive routine digital subtraction angiography (DSA) procedures performed in 111 patients (mean age 54.17 ± 14.4 years; 59 women, 52 men) who underwent TCD and TCCS examinations simultaneously. Each patient was examined independently using both ultrasound techniques, 267 M1 segments of MCA were assessed and narrowings were classified as #50% and .50% lumen reduction. Diagnostic performance was estimated by two statistical and two artificial neural networks (ANN) classification methods. Separate models were constructed for the TCD and TCCS sonographic data, as well as for detection of ''any narrowing'' and ''severe narrowing'' of the MCA. Input for each classifier consisted of the peak-systolic, mean and end-diastolic velocities measured with each sonographic method; the output was MCA narrowing. Arterial narrowings less or equal 50% of lumen reduction were found in 55 and .50% narrowings in 26 out of 267 arteries, as indicated by DSA. In the category of ''any narrowing'' the rate of correct assignment by all models was 82% to 83% for TCCS and 79% to 81% for TCD. In the diagnosis of .50% narrowing the overall classification accuracy remained in the range of 89% to 90% for TCCS data and 90% to 91% for TCD data. For the diagnosis of any narrowing, the sensitivity of the TCCS was significantly higher than that of the TCD, while for diagnosis of .50% MCA narrowing, sensitivity of the TCCS was similar to sensitivity of the TCD. Our study showed that TCCS outperforms conventional TCD in detection of #50% MCA narrowing, whereas no significant difference in accuracy between both methods was found in the diagnosis of .50% MCA Diagnosis of the middle cerebral artery narrowing d M. SWIERCZ et al.
Acta Neurochirurgica, 2000
ABSTRACT Intracranial pressure (ICP) is commonly used by neurosurgeons as a source of valuable in... more ABSTRACT Intracranial pressure (ICP) is commonly used by neurosurgeons as a source of valuable information about the current condition of the neurosurgical patient. Nevertheless, despite years of effort, extracting clinically valuable information from the ICP signal is still problematical. Approaches, using current values of ICP, may fail to disclose imminent risk, because unpredictable factors can rapidly change the properties of the signal. An alternative approach is to determine some global characteristics of the signal within a longer time interval and such statistical analyses have been proposed by several authors. A further, rarely considered, problem is assessment of the results obtained from the point of view of their practical utility and/or such classification of the obtained properties of the signal that they correspond to certain clinical states of the patient. While this might be a typical task for discriminant analysis, we approached the analysis using an alternative methodology, that of computational intelligence, implemented in artificial neural networks (ANN). We tested two variants of the ANN algorithms for classification and discrimination of global properties of the ICP signal. In a "dynamic pattern classification" the network was presented with several sections of ICP records together with information from the expert-neurosurgeon, classifying 4 risk groups. In this mode no data pre-processing was carried out, in contrast to our second approach, in which the signal had been pre-processed using published statistical analyses and only these intermediate coefficients were fed into the ANN classifier. The results obtained with both classification methods at their current stage of training were similar and approximated to a 70% rate of judgements consistent with the expert scoring. Nevertheless, the method based on the assessment of global parameters from the ICP record looks more promising, because it leaves the possibility for modification of the set of parameters analysed. The new parameters may include information extracted not only from the ICP signal, but also from other diagnostic modalities, like colour coded Doppler ultrasonography. The ultimate goal of this work is to build up a pseudo-intelligent computer expert system, which would be able to reason from a reduced set of input information, available from a standard monitoring modality, because it had been taught salient links between these data and higher-order data, upon which expert scoring was based.
Journal of Neuroimaging, 2001
This study was undertaken to assess the effect of ultrasound on human brain temperature in vivo. ... more This study was undertaken to assess the effect of ultrasound on human brain temperature in vivo. The investigation consisted of direct recording of intracranial temperature during color transcranial Doppler (TCD) sonography in a neurosurgical patient. The temperature was recorded from 3 thermocouples. One was implanted together with an intracranial pressure sensor into a surgically reduced intraparenchymal hematoma, the second was placed within the subdural space close to the temporal acoustic window, and the third was located extracranially at the outer surface of the temporal bone. Tympanic temperatures were also measured to give an approximation of global brain temperature. A 2.5-MHz transducer was used, and the system settings were as follows: spatial peak temporal average intensity = 234 mW/cm2 in B-mode at a maximum power of 32.3 mW and 2132 mW/cm2 in Doppler mode at a maximum power of 149.3 mW. Neither increase in the intraparenchymal brain temperature nor increase in the temperature at the bone/soft tissue interface was observed during 30 minutes of insonation. The ipsilateral tympanic temperature increased by only 0.06 degree C, and this value may be regarded as a measure of the overall increase in brain temperature. Passive cooling effect produced by the transducer, which was at ambient temperature, was found to reach the brain surface and to surpass any possible heating caused by the ultrasound. The results indicate that no noticeable increases in human brain temperature occur in response to ultrasound emitted by a color TCD device at high transmitter power settings within the diagnostic range.
Journal of neurosurgery, 2002
The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MC... more The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MCA) spasm has been asserted. None of the published studies, however, has adequately scrutinized the overall diagnostic accuracy of this procedure. There are only sporadic reports concerning the utility of transcranial color Doppler (TCCD) ultrasonography, although this method has been proved to be more precise. In this study the authors attempted to estimate the performance of TCCD ultrasonography in detecting MCA narrowing by using receiver operating characteristic (ROC) curve analysis, based on TCCD studies obtained in a relatively large, randomly selected population of patients. Transcranial color Doppler ultrasonography studies were obtained in 100 consecutive patients (54 men and 46 women ages 18-74 years, median age 50 years) routinely referred by neurosurgeons for intraarterial angiography. The M1 segment of the MCA was insonated using a 2.5-MHz probe via a temporal acoustic window...
computer.org
... Poznan University of Technology, Poznan, Poland Bartlomiej Beliczynski, Warsaw University of ... more ... Poznan University of Technology, Poznan, Poland Bartlomiej Beliczynski, Warsaw University of Technology, Poland Chng Eng SIong, Nanyang Technological University, Singapore Christine Fernandez-Maloigne, Université de Poitiers, France Dietmar Heinke, University of ...
Journal of …, Jan 1, 2002
Journal of …, Jan 1, 2002
… medical journal of …, Jan 1, 2007
Vascular reactions after cerebral angiography have not been hitherto extensively explored due to ... more Vascular reactions after cerebral angiography have not been hitherto extensively explored due to the lack of a simple, easily available, and safe method for the measurement of cerebral circulation. We attempted to study cerebral circulation with color Doppler transcranial sonography (TCCS) in consecutive patients before and immediately after digital subtraction angiography (DSA). TCCS examination of the major cerebral arteries was carried out in 52 patients (25 females and 27 males), mean age 50.3+/-11.5 years, before and 10-20 minutes after cerebral angiography. A Toshiba Aplio SSA 770A system with a 2.5-MHz sector transducer was used. In general terms, there was a tendency after DSA towards a slight decrease in peak systolic blood velocity and an increase in mean and end-diastolic velocity in all the major cerebral arteries which, in turn, led to a decrease in the impedance index (pulsatility index, PI). In 19 patients, the impedance index as measured in the middle cerebral artery decreased after DSA, in 29 it did not change, while in 4 patients PI increased. Discriminant analysis showed that the factors predisposing individuals to these adverse reactions were a low score on the Glasgow Coma Scale, etiological diagnosis of intracerebral bleeding, and a high value of the impedance index prior to the procedure. Contrast cerebral angiography may affect the tonus of cerebral vessels. In the majority of patients it caused vasodilatation to varying degrees and in a small sub-group vasoconstriction.
Studies in Fuzzines and Soft Computing,(ed.) PS …, Jan 1, 1998
ICSC Symposium on Neural Computation, 1998
Neurologia i neurochirurgia polska
Intracranial pressure (ICP) is influenced by an array of predictable and unpredictable factors. S... more Intracranial pressure (ICP) is influenced by an array of predictable and unpredictable factors. Statistical modelling of this signal has only limited applicability because of the significant load of stochastic components. We tested the efficiency of an alternative approach, based on the methodology of artificial neural networks (ANNs) in the on-line prediction of future values of ICP and in the classification of signal properties. Satisfactory accuracy of forecasting was achieved with the ANNs for a 3-minute prediction horizon, while the prediction quality with autoregressive models of statistical origin was proved unsatisfactory. The results obtained with the ANNs were further improved when signal pre-processing with wavelet transform was employed. Nevertheless, even with the ANN methodology, no sudden breakdowns in the ICP signal (which in this respect might be compared to a "catastrophe") can be forecast with any practical applicability. We therefore applied two ANN alg...
Neurologia i neurochirurgia polska
Transcranial colour-coded Doppler sonography enables estimation of blood flow parameters in the b... more Transcranial colour-coded Doppler sonography enables estimation of blood flow parameters in the basal cerebral arteries. Reference values as well as age and gender dependence of these parameters are not sufficiently established in transcranial Doppler studies. There are no reports regarding blood flow in the respective arteries of the circle of Willis. Therefore we examined 185 healthy volunteers--82 men (mean age 47, range 20-78 years old) and 103 women (mean age 47, range 22-86 years old). The subjects were divided into three age groups: 20-40 years old (group I), 41-60 years old (group II) and more than 60 years old (group III). The examinations were performed via the temporal acoustic window with a 2.5 MHz probe. Angle-corrected peak systolic, mean and end-diastolic velocities as well as impedance indices were determined in the anterior, middle and posterior cerebral arteries. In the group I mean velocity values (mean +/- SD) for the anterior, middle and posterior arteries amoun...
Klinika oczna, 1997
The authors present the "pattern" visual evoked potentials (VEP) analysis with use of t... more The authors present the "pattern" visual evoked potentials (VEP) analysis with use of the artificial neural networks (ANN). The study involved 11 patients with compressive chiasmal optic neuropathy, 20 patients with optic neuritis, 12 patients with anterior ischaemic optic neuropathy, 20 patients with optic nerve atrophy from neuritis, 8 patients with demyelinative neuropathy, 5 patients with oedema optic nerve, 20 healthy persons. The tests of visual evoked potentials were performed with the use of computer system UTAS-E1000. Classification of potentials was made by correlation of outputs of ANN with results of confirmed neuro-ophthalmology conditions. ANN of different architecture were classified correctly in 80-100% of VEP record samples. The obtained correctness of classification confirms usefulness of VEP analysis as the objective diagnostic method in some neuro-ophthalmological diseases and indicates application of ANN in multifactor analysis.
Medical & Biological Engineering & Computing, 1998
The problem of reliable detection of life-threatening situations in the neurosurgical patient und... more The problem of reliable detection of life-threatening situations in the neurosurgical patient undergoing treatment in the ICU is still far from reaching a satisfactory solution, although several methods of clinical and instrumental evaluation have recently been developed for the early detection of oncoming signs of danger. Continuous monitoring of intracranial pressure (ICP) provides neurosurgeons with valuable information about the current condition of the patient. However, it is increasingly felt that traditional methods of extracting information from the ICP signal have reached their natural limits, mostly because of difficulties in fitting the appropriate mathematical model to this nonlinear and non-stationary process. Successful implementations of artificial neural networks in many medical tasks have encouraged the application of this method to ICP processing. Two problems are considered: the prediction of trends in ICP, and recognition of the configuration of unfavourable symptoms likely to signal danger for the neurosurgical patient. The construction of neural network predictors of ICP trends is based on wavelet pre-processing of the original signal. The approach to the second task involves preprocessing of the ICP with spectral and statistical methods and classification of the extracted features of the current signal on an arbitrarily selected scale of danger.
Ultrasound in Medicine & Biology, 2010
Neuroinformatics, 2008
To determine the performance of an artificial neural network in transcranial color-coded duplex s... more To determine the performance of an artificial neural network in transcranial color-coded duplex sonography (TCCS) diagnosis of middle cerebral artery (MCA) spasm. TCCS was prospectively acquired within 2 h prior to routine cerebral angiography in 100 consecutive patients (54M:46F, median age 50 years). Angiographic MCA vasospasm was classified as mild (<25% of vessel caliber reduction), moderate (25-50%), or severe (>50%). A Learning Vector Quantization neural network classified MCA spasm based on TCCS peak-systolic, mean, and end-diastolic velocity data. During a four-class discrimination task, accurate classification by the network ranged from 64.9% to 72.3%, depending on the number of neurons in the Kohonen layer. Accurate classification of vasospasm ranged from 79.6% to 87.6%, with an accuracy of 84.7% to 92.1% for the detection of moderate-tosevere vasospasm. An artificial neural network may increase the accuracy of TCCS in diagnosis of MCA spasm.
Medical science monitor : international medical journal of experimental and clinical research, 2007
Vascular reactions after cerebral angiography have not been hitherto extensively explored due to ... more Vascular reactions after cerebral angiography have not been hitherto extensively explored due to the lack of a simple, easily available, and safe method for the measurement of cerebral circulation. We attempted to study cerebral circulation with color Doppler transcranial sonography (TCCS) in consecutive patients before and immediately after digital subtraction angiography (DSA). TCCS examination of the major cerebral arteries was carried out in 52 patients (25 females and 27 males), mean age 50.3+/-11.5 years, before and 10-20 minutes after cerebral angiography. A Toshiba Aplio SSA 770A system with a 2.5-MHz sector transducer was used. In general terms, there was a tendency after DSA towards a slight decrease in peak systolic blood velocity and an increase in mean and end-diastolic velocity in all the major cerebral arteries which, in turn, led to a decrease in the impedance index (pulsatility index, PI). In 19 patients, the impedance index as measured in the middle cerebral artery decreased after DSA, in 29 it did not change, while in 4 patients PI increased. Discriminant analysis showed that the factors predisposing individuals to these adverse reactions were a low score on the Glasgow Coma Scale, etiological diagnosis of intracerebral bleeding, and a high value of the impedance index prior to the procedure. Contrast cerebral angiography may affect the tonus of cerebral vessels. In the majority of patients it caused vasodilatation to varying degrees and in a small sub-group vasoconstriction.
Journal of Neurosurgery, 2002
The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MC... more The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MCA) spasm has been asserted. None of the published studies, however, has adequately scrutinized the overall diagnostic accuracy of this procedure. There are only sporadic reports concerning the utility of transcranial color Doppler (TCCD) ultrasonography, although this method has been proved to be more precise. In this study the authors attempted to estimate the performance of TCCD ultrasonography in detecting MCA narrowing by using receiver operating characteristic (ROC) curve analysis, based on TCCD studies obtained in a relatively large, randomly selected population of patients. Transcranial color Doppler ultrasonography studies were obtained in 100 consecutive patients (54 men and 46 women ages 18-74 years, median age 50 years) routinely referred by neurosurgeons for intraarterial angiography. The M1 segment of the MCA was insonated using a 2.5-MHz probe via a temporal acoustic window, and angle-corrected flow velocities were obtained. Angiographically depicted vasospasm was graded as none, mild (&amp;amp;amp;amp;amp;amp;amp;lt; or = 25% vessel caliber reduction), and moderate to severe (&amp;amp;amp;amp;amp;amp;amp;gt; 25% vessel caliber reduction). The effectiveness of TCCD ultrasonography in diagnosing MCA spasm was evaluated by calculating the areas under the ROC curves (Az). Of the 200 MCAs examined, 173 were successfully visualized with the aid of TCCD ultrasonography. Mild vasospasm was angiographically diagnosed in 15 arteries and moderate-to-severe vasospasm in 28. The best-performing TCCD parameter for the detection of MCA narrowing was revealed to be peak systolic velocity. The Az value for moderate-to-severe vasospasm only was 0.93 and that for all vasospasms was 0.8. The best efficiency, that is, the optimal tradeoff between sensitivity and specificity in diagnosing vasospasms, was associated with a peak systolic velocity of 182 cm/second. The performance of TCCD ultrasonography in the diagnosis of advanced MCA narrowing is very good, and is acceptable for all vasospasms. The best-performing parameter was peak systolic velocity.
Neuroinformatics, 2008
To determine the performance of an artificial neural network in transcranial color-coded duplex s... more To determine the performance of an artificial neural network in transcranial color-coded duplex sonography (TCCS) diagnosis of middle cerebral artery (MCA) spasm. TCCS was prospectively acquired within 2 h prior to routine cerebral angiography in 100 consecutive patients (54M:46F, median age 50 years). Angiographic MCA vasospasm was classified as mild (<25% of vessel caliber reduction), moderate (25-50%), or severe (>50%). A Learning Vector Quantization neural network classified MCA spasm based on TCCS peak-systolic, mean, and end-diastolic velocity data. During a four-class discrimination task, accurate classification by the network ranged from 64.9% to 72.3%, depending on the number of neurons in the Kohonen layer. Accurate classification of vasospasm ranged from 79.6% to 87.6%, with an accuracy of 84.7% to 92.1% for the detection of moderate-tosevere vasospasm. An artificial neural network may increase the accuracy of TCCS in diagnosis of MCA spasm.
Ultrasound in Medicine & Biology, 2010
The goal of the study was to compare performances of transcranial color-coded duplex sonography (... more The goal of the study was to compare performances of transcranial color-coded duplex sonography (TCCS) and transcranial Doppler sonography (TCD) in the diagnosis of the middle cerebral artery (MCA) narrowing in the same population of patients using statistical and nonstatistical intelligent models for data analysis. We prospectively collected data from 179 consecutive routine digital subtraction angiography (DSA) procedures performed in 111 patients (mean age 54.17 ± 14.4 years; 59 women, 52 men) who underwent TCD and TCCS examinations simultaneously. Each patient was examined independently using both ultrasound techniques, 267 M1 segments of MCA were assessed and narrowings were classified as #50% and .50% lumen reduction. Diagnostic performance was estimated by two statistical and two artificial neural networks (ANN) classification methods. Separate models were constructed for the TCD and TCCS sonographic data, as well as for detection of ''any narrowing'' and ''severe narrowing'' of the MCA. Input for each classifier consisted of the peak-systolic, mean and end-diastolic velocities measured with each sonographic method; the output was MCA narrowing. Arterial narrowings less or equal 50% of lumen reduction were found in 55 and .50% narrowings in 26 out of 267 arteries, as indicated by DSA. In the category of ''any narrowing'' the rate of correct assignment by all models was 82% to 83% for TCCS and 79% to 81% for TCD. In the diagnosis of .50% narrowing the overall classification accuracy remained in the range of 89% to 90% for TCCS data and 90% to 91% for TCD data. For the diagnosis of any narrowing, the sensitivity of the TCCS was significantly higher than that of the TCD, while for diagnosis of .50% MCA narrowing, sensitivity of the TCCS was similar to sensitivity of the TCD. Our study showed that TCCS outperforms conventional TCD in detection of #50% MCA narrowing, whereas no significant difference in accuracy between both methods was found in the diagnosis of .50% MCA Diagnosis of the middle cerebral artery narrowing d M. SWIERCZ et al.
Acta Neurochirurgica, 2000
ABSTRACT Intracranial pressure (ICP) is commonly used by neurosurgeons as a source of valuable in... more ABSTRACT Intracranial pressure (ICP) is commonly used by neurosurgeons as a source of valuable information about the current condition of the neurosurgical patient. Nevertheless, despite years of effort, extracting clinically valuable information from the ICP signal is still problematical. Approaches, using current values of ICP, may fail to disclose imminent risk, because unpredictable factors can rapidly change the properties of the signal. An alternative approach is to determine some global characteristics of the signal within a longer time interval and such statistical analyses have been proposed by several authors. A further, rarely considered, problem is assessment of the results obtained from the point of view of their practical utility and/or such classification of the obtained properties of the signal that they correspond to certain clinical states of the patient. While this might be a typical task for discriminant analysis, we approached the analysis using an alternative methodology, that of computational intelligence, implemented in artificial neural networks (ANN). We tested two variants of the ANN algorithms for classification and discrimination of global properties of the ICP signal. In a "dynamic pattern classification" the network was presented with several sections of ICP records together with information from the expert-neurosurgeon, classifying 4 risk groups. In this mode no data pre-processing was carried out, in contrast to our second approach, in which the signal had been pre-processed using published statistical analyses and only these intermediate coefficients were fed into the ANN classifier. The results obtained with both classification methods at their current stage of training were similar and approximated to a 70% rate of judgements consistent with the expert scoring. Nevertheless, the method based on the assessment of global parameters from the ICP record looks more promising, because it leaves the possibility for modification of the set of parameters analysed. The new parameters may include information extracted not only from the ICP signal, but also from other diagnostic modalities, like colour coded Doppler ultrasonography. The ultimate goal of this work is to build up a pseudo-intelligent computer expert system, which would be able to reason from a reduced set of input information, available from a standard monitoring modality, because it had been taught salient links between these data and higher-order data, upon which expert scoring was based.
Journal of Neuroimaging, 2001
This study was undertaken to assess the effect of ultrasound on human brain temperature in vivo. ... more This study was undertaken to assess the effect of ultrasound on human brain temperature in vivo. The investigation consisted of direct recording of intracranial temperature during color transcranial Doppler (TCD) sonography in a neurosurgical patient. The temperature was recorded from 3 thermocouples. One was implanted together with an intracranial pressure sensor into a surgically reduced intraparenchymal hematoma, the second was placed within the subdural space close to the temporal acoustic window, and the third was located extracranially at the outer surface of the temporal bone. Tympanic temperatures were also measured to give an approximation of global brain temperature. A 2.5-MHz transducer was used, and the system settings were as follows: spatial peak temporal average intensity = 234 mW/cm2 in B-mode at a maximum power of 32.3 mW and 2132 mW/cm2 in Doppler mode at a maximum power of 149.3 mW. Neither increase in the intraparenchymal brain temperature nor increase in the temperature at the bone/soft tissue interface was observed during 30 minutes of insonation. The ipsilateral tympanic temperature increased by only 0.06 degree C, and this value may be regarded as a measure of the overall increase in brain temperature. Passive cooling effect produced by the transducer, which was at ambient temperature, was found to reach the brain surface and to surpass any possible heating caused by the ultrasound. The results indicate that no noticeable increases in human brain temperature occur in response to ultrasound emitted by a color TCD device at high transmitter power settings within the diagnostic range.
Journal of neurosurgery, 2002
The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MC... more The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MCA) spasm has been asserted. None of the published studies, however, has adequately scrutinized the overall diagnostic accuracy of this procedure. There are only sporadic reports concerning the utility of transcranial color Doppler (TCCD) ultrasonography, although this method has been proved to be more precise. In this study the authors attempted to estimate the performance of TCCD ultrasonography in detecting MCA narrowing by using receiver operating characteristic (ROC) curve analysis, based on TCCD studies obtained in a relatively large, randomly selected population of patients. Transcranial color Doppler ultrasonography studies were obtained in 100 consecutive patients (54 men and 46 women ages 18-74 years, median age 50 years) routinely referred by neurosurgeons for intraarterial angiography. The M1 segment of the MCA was insonated using a 2.5-MHz probe via a temporal acoustic window...
computer.org
... Poznan University of Technology, Poznan, Poland Bartlomiej Beliczynski, Warsaw University of ... more ... Poznan University of Technology, Poznan, Poland Bartlomiej Beliczynski, Warsaw University of Technology, Poland Chng Eng SIong, Nanyang Technological University, Singapore Christine Fernandez-Maloigne, Université de Poitiers, France Dietmar Heinke, University of ...
Journal of …, Jan 1, 2002
Journal of …, Jan 1, 2002
… medical journal of …, Jan 1, 2007
Vascular reactions after cerebral angiography have not been hitherto extensively explored due to ... more Vascular reactions after cerebral angiography have not been hitherto extensively explored due to the lack of a simple, easily available, and safe method for the measurement of cerebral circulation. We attempted to study cerebral circulation with color Doppler transcranial sonography (TCCS) in consecutive patients before and immediately after digital subtraction angiography (DSA). TCCS examination of the major cerebral arteries was carried out in 52 patients (25 females and 27 males), mean age 50.3+/-11.5 years, before and 10-20 minutes after cerebral angiography. A Toshiba Aplio SSA 770A system with a 2.5-MHz sector transducer was used. In general terms, there was a tendency after DSA towards a slight decrease in peak systolic blood velocity and an increase in mean and end-diastolic velocity in all the major cerebral arteries which, in turn, led to a decrease in the impedance index (pulsatility index, PI). In 19 patients, the impedance index as measured in the middle cerebral artery decreased after DSA, in 29 it did not change, while in 4 patients PI increased. Discriminant analysis showed that the factors predisposing individuals to these adverse reactions were a low score on the Glasgow Coma Scale, etiological diagnosis of intracerebral bleeding, and a high value of the impedance index prior to the procedure. Contrast cerebral angiography may affect the tonus of cerebral vessels. In the majority of patients it caused vasodilatation to varying degrees and in a small sub-group vasoconstriction.
Studies in Fuzzines and Soft Computing,(ed.) PS …, Jan 1, 1998