In surgical practice, small metallic instruments are frequently used to perform various tasks inside the human body. We address the problem of their accurate localization in the tissue. Recent experiments using medical ultrasound have shown that this modality is suitable for real-time visualization of anatomical structures as well as the position of surgical instruments. We propose an image-processing algorithm that permits automatic estimation of the position of a line-segment-shaped object. This method was applied to the localization of a thin metallic electrode in biological tissue. We show that the electrode axis can be found through maximizing the parallel integral projection transform that is a form of the Radon transform. To accelerate this step, hierarchical mesh-grid algorithm is implemented. Once the axis position is known, localization of the electrode tip is performed. The method was tested on simulated images, on ultrasound images of a tissue mimicking phantom containing a metallic electrode, and on real ultrasound images from breast biopsy. The results indicate that the algorithm is robust with respect to variations in electrode position and speckle noise. Localization accuracy is of the order of hundreds of micrometers and is comparable to the ultrasound system axial resolution.

• MeSH
• fantomy radiodiagnostické MeSH
• implantace protézy metody   MeSH
• implantované elektrody * MeSH
• interpretace obrazu počítačem metody   MeSH
• intervenční ultrasonografie přístrojové vybavení   metody   MeSH
• lidé MeSH
• reprodukovatelnost výsledků MeSH
• senzitivita a specificita MeSH
• vylepšení obrazu metody   MeSH
• zobrazování trojrozměrné metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Tools for post-operative localization of deep brain stimulation (DBS) electrodes may be of major benefit in the evaluation of the stimulation area. However, little is known about their precision. This study compares 3 different software packages used for DBS electrode localization. T1-weighted MRI images before and after the implantation of the electrodes into the subthalamic nucleus for DBS in 105 Parkinson's disease patients were processed using the pipelines implemented in Lead-DBS, SureTune4, and Brainlab. Euclidean distance between active contacts determined by individual software packages and in repeated processing by the same and by a different operator was calculated. Furthermore, Dice coefficient for overlap of volume of tissue activated (VTA) was determined for Lead-DBS. Medians of Euclidean distances between estimated active contact locations in inter-software package comparison ranged between 1.5 mm and 2 mm. Euclidean distances in within-software package intra- and inter-rater assessments were 0.6-1 mm and 1-1.7 mm, respectively. Median intra- and inter-rater Dice coefficients for VTAs were 0.78 and 0.75, respectively. Since the median distances are close to the size of the target nucleus, any clinical use should be preceded by careful review of the outputs.

• Klíčová slova
• Deep brain stimulation, Electrode localization, Magnetic resonance imaging, Neuroimaging, Parkinson’s disease, Software comparison, Subthalamic nucleus,
• MeSH
• hluboká mozková stimulace * metody   přístrojové vybavení   MeSH
• implantované elektrody * MeSH
• lidé středního věku MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• nucleus subthalamicus chirurgie   MeSH
• Parkinsonova nemoc * terapie   MeSH
• senioři MeSH
• software MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

OBJECTIVE: When considering all patients with focal drug-resistant epilepsy, as high as 40-50% of patients suffer seizure recurrence after surgery. To achieve seizure freedom without side effects, accurate localization of the epileptogenic tissue is crucial before its resection. We investigate an automated, fast, objective mapping process that uses only interictal data. METHODS: We propose a novel approach based on multiple iEEG features, which are used to train a support vector machine (SVM) model for classification of iEEG electrodes as normal or pathologic using 30 min of inter-ictal recording. RESULTS: The tissue under the iEEG electrodes, classified as epileptogenic, was removed in 17/18 excellent outcome patients and was not entirely resected in 8/10 poor outcome patients. The overall best result was achieved in a subset of 9 excellent outcome patients with the area under the receiver operating curve = 0.95. CONCLUSION: SVM models combining multiple iEEG features show better performance than algorithms using a single iEEG marker. Multiple iEEG and connectivity features in presurgical evaluation could improve epileptogenic tissue localization, which may improve surgical outcome and minimize risk of side effects. SIGNIFICANCE: In this study, promising results were achieved in localization of epileptogenic regions by SVM models that combine multiple features from 30 min of inter-ictal iEEG recordings.

• Klíčová slova
• Connectivity, Drug resistant epilepsy, Epileptogenic zone localization, High frequency oscillations, Machine learning, Multi-feature approach,
• MeSH
• dospělí MeSH
• elektroencefalografie přístrojové vybavení   metody   MeSH
• epilepsie parciální diagnóza   patofyziologie   MeSH
• implantované elektrody MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• retrospektivní studie MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

In a group of 24 healthy people acoustic brain stem responses (ABR) were simultaneously recorded from different regions of the scalp. Evaluation of latencies and amplitudes individual ABR waves has shown that their average latency is longer and the amplitude is higher in records from electrodes above the right half of the scalp, regardless of which ear was stimulated.

• MeSH
• dospělí MeSH
• elektrody MeSH
• lidé MeSH
• mozkový kmen fyziologie   MeSH
• sluchové evokované potenciály * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

This note discusses the effects of the electrode position scaling on the realistic Laplacian (RL) computation. It is shown that when the RL is estimated with the help of Tikhonov regularization and the generalized cross-validation (GCV) criterion, improper electrode position scaling may influence the GCV criterion, which results in the decrease of RL precision. We identify what the proper scaling should be, and we provide a closer examination of how the GCV criterion is affected by the electrode position scaling.

• MeSH
• algoritmy * MeSH
• diagnóza počítačová metody   MeSH
• elektrody * MeSH
• elektroencefalografie přístrojové vybavení   metody   MeSH
• lidé MeSH
• mapování mozku přístrojové vybavení   metody   MeSH
• modely neurologické * MeSH
• počítačová simulace MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH

We present a custom-made multielectrode array for the recording of evoked potentials during acute experiments in rats, which offers a quick and reliable estimation of the cortical tonotopy. The array consists of electrodes represented by insulated copper wires of 0.09 mm diameter fixed in epoxy resin in a 3 x 5 arrangement, with final impedances of 410-800 kOhm. The array was placed on the brain surface of anesthetized rats approximately at the location of the auditory cortex (AC) and the cortical evoked potentials (middle-latency responses, MLR) were elicited by a series of tone pips of different frequencies at 50 dB of sound pressure level (SPL) intensity. The frequency that evoked the highest MLR amplitude (best frequency, BF) was identified for each electrode. The obtained distribution of the BFs characterized the cortical tonotopy, and it correlated with the frequency selectivity of neurons recorded at the same positions by an extracellular microelectrode. Although the space resolution of the array did not allow for the identification of AC sub regions, the array proved to be a reliable tool for a quick estimation and prediction of areas of interest for the subsequent measurements of neurons by more precise techniques.

• MeSH
• akustická stimulace metody   MeSH
• časové faktory MeSH
• implantované elektrody * MeSH
• krysa rodu Rattus MeSH
• mapování mozku přístrojové vybavení   metody   MeSH
• potkani Long-Evans MeSH
• sluchové evokované potenciály fyziologie   MeSH
• sluchové korové centrum fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Electrically evoked hippocampal afterdischarges are used as a model of partial epileptic seizures with a complex symptomatology and for testing anticonvulsants and toxic substances. Stimulating electrodes were implanted in the dorsal hippocampus of 16 laboratory rats and when the animals had recovered they were stimulated (15-s series, 8 Hz, pulse length 1 ms) with a voltage double the threshold value for a tissue response. The following features of the evoked afterdischarge were evaluated: the duration of the first phase of the afterdischarge, the duration of the non-active interphase, the duration of the second phase and the number of "wet dog shakes" (a constant accompaniment of hippocampal afterdischarges). Localization of the electrodes in the CA1 (n = 7) and CA3 (n = 7) region of the hippocampus made no difference to these parameters and in both cases the measured and evaluated data were the same. The afterdischarges were always accompanied by a marked orientation reaction. The study showed that when using macroelectrodes to stimulate the dorsal hippocampus, their localization in the CA1/CA3 is not of critical importance.

• MeSH
• časové faktory MeSH
• chování zvířat MeSH
• elektrická stimulace MeSH
• elektrody MeSH
• elektrofyziologie MeSH
• hipokampus fyziologie   MeSH
• inbrední kmeny potkanů MeSH
• krysa rodu Rattus MeSH
• modely neurologické MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

OBJECTIVE: Intracranial recordings were taken from the basal ganglia (BG) in order to explore the possible role of the BG in the cognitive processing of sensory information. METHODS: Ten patients with intractable temporal lobe epilepsy, who were candidates for epilepsy surgery, underwent intracranial recordings with depth electrodes. A frontal approach was used for the insertion of diagonal depth electrodes into the amygdalo-hippocampal complex (AH complex). These electrodes passed through the BG. The putamen was explored in 8 patients; the nucleus caudatus and pallidum were explored in two patients. The contingent negative variation (CNV) paradigm was tested using auditory warning stimuli and visual imperative stimuli followed by a hand flexion. The auditory and visual middle and late latency potentials evoked by the warning and imperative stimuli were analyzed. RESULTS: (1) Auditory evoked potentials (EPs): the amplitude potential gradient was observed with latencies of (a) 150-195ms (9 patients); (b) 215-290ms (9 patients); and (c) 350-600ms (10 patients). Negative potentials, with latencies of 100 and 110ms were observed in two patients. (2) Visual EPs: (a) 160-195ms (9 patients); (b) 210-295ms (9 patients); and (c) 330-550ms (7 patients). Negative potentials with latencies between 100 and 120ms were observed in 4 patients. CNV was obtained from the BG in 8 patients; a phase reversal was observed twice. CONCLUSIONS: (1) The BG generate middle and late latency EPs in a cognitive paradigm linked to the motor task. (2) The BG generate CNV. (3) The BG could play an integrative role in the processing of sensory, cognitive, and motor information.

• MeSH
• akustická stimulace MeSH
• bazální ganglia fyziologie   MeSH
• čití, cítění fyziologie   MeSH
• dospělí MeSH
• elektroencefalografie MeSH
• elektrofyziologie MeSH
• epilepsie temporálního laloku patofyziologie   MeSH
• implantované elektrody MeSH
• kognice fyziologie   MeSH
• kontingentní negativní variace fyziologie   MeSH
• lidé MeSH
• mapování mozku MeSH
• podněty MeSH
• pohyb fyziologie   MeSH
• reakční čas fyziologie   MeSH
• sluchové evokované potenciály fyziologie   MeSH
• světelná stimulace MeSH
• zrakové evokované potenciály fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

We present a method for automatic surgical tool localization in 3D ultrasound images based on line filtering, voxel classification and model fitting. This could possibly provide assistance for biopsy needle or micro-electrode insertion, or a robotic system performing this insertion. The line-filtering method is first used to enhance the contrast of the 3D ultrasound image, then a classifier is chosen to separate the tool voxels, in order to reduce the number of outliers. The last step is Random Sample Consensus (RANSAC) model fitting. Experimental results on several different polyvinyl alcohol (PVA) cryogel data sets demonstrate that the failure rate of the method proposed herein is improved by at least 86% compared to the model-fitting RANSAC algorithm with axis accuracy better than 1mm, at the expense of only a modest increase in computational effort. The results of this experiment show that this system could be useful for clinical applications.

• Klíčová slova
• 3D ultrasound, Biopsy, Line filtering, RANSAC, Tool localization,
• MeSH
• lidé MeSH
• ultrasonografie metody   MeSH
• zobrazování trojrozměrné metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

INTRODUCTION: Precise localization of the epileptogenic zone is critical for successful epilepsy surgery. However, imbalanced datasets in terms of epileptic vs. normal electrode contacts and a lack of standardized evaluation guidelines hinder the consistent evaluation of automatic machine learning localization models. METHODS: This study addresses these challenges by analyzing class imbalance in clinical datasets and evaluating common assessment metrics. Data from 139 drug-resistant epilepsy patients across two Institutions were analyzed. Metric behaviors were examined using clinical and simulated data. RESULTS: Complementary use of Area Under the Receiver Operating Characteristic (AUROC) and Area Under the Precision-Recall Curve (AUPRC) provides an optimal evaluation approach. This must be paired with an analysis of class imbalance and its impact due to significant variations found in clinical datasets. CONCLUSIONS: The proposed framework offers a comprehensive and reliable method for evaluating machine learning models in epileptogenic zone localization, improving their precision and clinical relevance. SIGNIFICANCE: Adopting this framework will improve the comparability and multicenter testing of machine learning models in epileptogenic zone localization, enhancing their reliability and ultimately leading to better surgical outcomes for epilepsy patients.

• Klíčová slova
• Binary classification, Class imbalance, Epilepsy, Epileptogenic tissue localization, Epileptogenic zone, Evaluation metrics, Intracranial electroencephalography, Machine learning, Seizure onset zone,
• MeSH
• dospělí MeSH
• elektrokortikografie metody   normy   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• refrakterní epilepsie * chirurgie   patofyziologie   MeSH
• strojové učení * MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH