Noninvasive Localization Research Articles

Application value of a new lesion positioning stickers in breast lesion surface localization.

Accurate breast lesion surface localization can guarantee accurate biopsy and local treatment. But there is no guideline to regular equipment and methods for the localization of breast lesions. The conventional non-invasive localization method is marker-based localization. The advantages of this method are simple and efficient. The disadvantages are that markers disappear easily under coupling agents; the positioning length of markers cannot last long on skin; and healthcare associated infection due to many patients using the same marker pen is potentially unavoidable. Breast lesion sticker (called sticker for short) is a new-type localization medical instrument in 2020. Our study aims to explore the clinical value of a new lesion stickers in breast lesion surface localization via comparison of the sticker and marker pen localization methods. This was a prospective cohort study. It was conducted in 67 patients who needed breast lesion surface localization before biopsy. The patients were randomly assigned into 2 groups. One group of patients used marker pen to mark breast lesion surface location by ultrasonography. The other group of patients used stickers. Patients labeled with markers on skin were swabbed agents before marking. Then the markers were checked by ultrasound scan. If the surface positions of breast lesion were not correct, the above procedure was repeated. In the sticker group, the stickers were released synchronously after the lesions were detected by ultrasound scan. Then locations were checked via scanning hole. If the surface positions of breast lesion were not correct, the above procedure was repeated. The accuracy of positioning, the length of positioning time and satisfaction of patients between the 2 groups were compared. The length of positioning time was calculated from the time when ultrasound detected the lesion to the time when the surface position of breast lesion was confirmed. The total score of patients' satisfaction was 5 points according to Service Quality Evaluation of SERVQUAL Scale, including sonographers' service attitude and their technical proficiency, other medical staffs' service attitude and their technical proficiency, hospital service procedures, positioning comfort, and positioning effects. All 67 patients were females, aged 18-66 (39.73±13.10). There were 35 patients in the marker pen group and 32 patients in the sticker group. The time length of group used marker pen to localization was 22-88 (52.20±2.90) s, and the sticker group was 3-15 (9.22±0.58) s in length. The length of positioning time for the stickers was significantly shorter than that of the marker (P<0.01). Both methods were accurate in the surface localization of lesions before operation. The total scores of patients' satisfaction was 4-5 (4.92±0.02) in the stickers group, and 1-5 (3.35±0.10) in the marker pen group. The patients' satisfaction scores with the sticker were significantly higher than those with the marker pen (P<0.01). The length of positioning time and patients' satisfication scores for sonographer with 20 years' working experience were shorter and higher than those of sonographer with 10 years' working experience, respectively (both P<0.05). The new breast lesion positioning stickers have more advantages than the marker pen in localization efficiency. It could reduce the workload of medical workers and increase patients' satisfaction to some extent. The stickers can be used not only in the breast lesions surface localization, but also in the skin location of pleural effusion and ascites, the skin location of surface masses, the skin location of thyroid nodule, and many other clinical marker areas, to further expand the scope of clinical application and value of the stickers.

Non-invasive localization of premature ventricular focus: A prospective multicenter study

BackgroundAccurate localization of premature ventricular contractions (PVC) focus is a prerequisite to successful catheter ablation. ObjectiveThe objective was to evaluate the software View Into Ventricular Onset (VIVO) accuracy at locating the anatomical origins for premature ventricular contractions. The VIVO device noninvasively creates a model of the patient's heart and torso, with exact locations of 12‑lead ECG electrodes, and applies a mathematical algorithm from surface signals to determine the origin of the arrhythmia. We sought to compare the agreement between VIVO-predicted locations to invasive electroanatomical mapping results. Methods51 consecutive patients who presented for PVC ablations at the study centers were recruited. VIVO images were collected at baseline preprocedure and all patients underwent invasive electroanatomical activation mapping of the clinical arrhythmia. Pacing was performed in pre-specified locations in the right and/or left ventricle. The successful sites of ablation and the pacing locations were compared to VIVO predicted locations. The results were adjudicated by physician experts in a blinded fashion. ResultsSeven patients were excluded from analyses. VIVO accurately identified the origin of the clinical premature ventricular contractions in 44/44 patients (100.00%). The accuracy in identifying the paced location for all patients (right and left sides of the heart) was 99.5% using the VIVO system. No adverse events were reported. ConclusionsVIVO is a novel noninvasive system that could be used to help guide ablation procedures with a high degree of accuracy. The VIVO algorithm is easy to use and may be useful in the workflow for ventricular arrhythmia ablation.

Emulation pulmonary nodules localization model:a novel non-invasive localization technique in resection of pulmonary nodules

Objective: To explore the accuracy and efficiency of a novel 3D-printed emulation localization model of small pulmonary nodules in lung surgery. Methods: From April 2020 to April 2021, a total of 66 patients were selected in the study, who underwent localization and resection of pulmonary nodules with video-assisted thoracoscopic surgery (VATS) guided by the 3D-printed emulation localization model at Department of Thoracic Surgery, West China Hospital of Sichuan University. There were 13 males and 53 females, aged from 25 to 79 (52.7±11.4) years. Of all patients, 24 (36.4%) had single pulmonary nodule, and 42 (63.6%) had synchronous multiple pulmonary nodules. The chest high-resolution CT image data were utilized for digital reconstruction and 3D printing to make a tailored life-size emulation pulmonary nodules localization model, which was used to navigate real-time intraoperative localization of nodules. Clinical data including operative parameters, localization information, resection types and pathological findings of nodules were analyzed. The pulmonary nodules that doctors planned to resect were categorized into two categories:major nodules and additional nodules, according to their presence of invasion and radiological risk factors. The accuracy of localization and resection efficiency of nodules were evaluated in accordance with the categories of the nodules respectively. Results: On the basis of preoperative evaluation, there were 71 major nodules with median maximal diameter of 0.9 (0.6-1.3) cm, and 77 additional nodules with median maximal diameter of 0.5 (0.4-0.7) cm. All patients underwent VATS surgery, 52 of them (78.8%) were treated with uniportal VATS and 14 (21.2%) with triportal VATS. Among the patients with single nodule, 18 segmentectomies and 6 wedge resections were performed; whereas among the patients with multiple nodules, 5 segmentectomies, 14 wedge resections, and 23 combined pulmonary resections (including 2 cases of lobectomy+segmentectomy, 7 cases of lobectomy+wedge resections, and 14 cases of segmentectomy+wedge resections) were achieved. The median operative time was 93 (45-240) min, and the median resection time for all nodules was 51.4 (6.7-147.0) min. All major nodules were successfully resected and visibly dissected after removal, and all additional nodules were successfully resected with 85.7%(66/77) nodules visibly dissected. The accuracy rate of localization of both types of nodules was 100%. All major nodules were malignant, and the malignancy rate of additional nodules was 21.2%(14/66). Conclusion: This novel 3D-printed emulation localization model of small pulmonary nodules proved to be a non-invasive, accurate and efficient technique. Not only that, it has a unique advantage in localization of synchronous multiple pulmonary nodules.

A Resonant Coupler for Subcutaneous Implant.

A resonator coupler for subcutaneous implants has been developed with a new impedance matching pattern added to the conventional loop antenna. The tuning element of a concentric metal pad contributes distributed capacitance and inductance to the planar inductive loop and improves resonance significantly. It provides a better qualify factor for resonant coupling and a much lower reflection coefficient for the implant electronics. Practical constraints are taken into account for designs including the requirement of operation within a regulated frequency band and the limited thickness for a monolithic implant. In this work, two designs targeting to operate in the two industrial, scientific, and medical (ISM) bands at 903 MHz and 2.45 GHz are considered. The tuning metal pad improves their resonances significantly, compared to the conventional loop designs. Since it is difficult to tune the implant antenna after implantation, the effects of tissue depth variations due to the individual’s surgery and the appropriate implant depths are investigated. Simulations conducted with the dielectric properties of human skin documented in the literature are compared to measurements done with hydrated ground pork as phantoms. Experiments and simulations are conducted to explain the discrepancies in frequency shifts due to the uses of pork phantoms. The design method is thus validated for uses on human skin. A noninvasive localization method to identify the implant under the skin has been examined and demonstrated by both simulations and measurements. It can efficiently locate the subcutaneous implant based on the high quality-factor resonance owing to the tuning elements in both implant and transmitter couplers. The planar resonant coupler for wireless power transfer shows good performance and promise in subcutaneous applications for implants.

Cardiovascular magnetic resonance of cardiac tumors and masses.

Cardiac masses diagnosis and treatment are a true challenge, although they are infrequently encountered in clinical practice. They encompass a broad set of lesions that include neoplastic (primary and secondary), non-neoplastic masses and pseudomasses. The clinical presentation of cardiac tumors is highly variable and depends on several factors such as size, location, relation with other structures and mobility. The presumptive diagnosis is made based on a preliminary non-invasive diagnostic work-up due to technical difficulties and risks associated with biopsy, which is still the diagnostic gold standard. The findings should always be interpreted in the clinical context to avoid misdiagnosis, particularly in specific conditions (e.g., infective endocarditis or thrombi). The modern multi-modality imaging techniques has a key role not only for the initial assessment and differential diagnosis but also for management and surveillance of the cardiac masses. Cardiovascular magnetic resonance (CMR) allows an optimal non-invasive localization of the lesion, providing multiplanar information on its relation to surrounding structures. Moreover, with the additional feature of tissue characterization, CMR can be highly effective to distinguish pseudomasses from masses, as well as benign from malignant lesions, with further differential diagnosis of the latter. Although histopathological assessment is important to make a definitive diagnosis, CMR plays a key role in the diagnosis of suspected cardiac masses with a great impact on patient management. This literature review aims to provide a comprehensive overview of cardiac masses, from clinical and imaging protocol to pathological findings.

Decompression of the suprascapular nerve at the suprascapular notch under combined arthroscopic and ultrasound guidance

Decompression of the suprascapular nerve (SSNe) at the suprascapular notch (SSNo) is usually performed with an arthroscopic procedure. This technique is well described but locating the nerve is complex because it is deeply buried and surrounded by soft tissue. We propose to combine ultrasound and arthroscopy (US-arthroscopy) to facilitate nerve localization, exposure and release. The main objective of this study was to assess the feasibility of this technique. This is an experimental, cadaveric study, carried out on ten shoulders. The first step of our technique is to locate the SSNo using an ultrasound scanner. Then an arthroscope is introduced under ultrasound control to the SSNo. A second portal is then created to dissect the pedicle and perform the ligament release. Ultrasound identification of the SSNo, endoscopic dissection and decompression of the nerve were achieved in 100% of cases. Ultrasound identification of the SSNo took an average of 3 min (± 4) while dissection and endoscopic release time took an average of 8 min (± 5). Ultrasound is an extremely powerful tool for non-invasive localization of nerves through soft tissues, but it is limited by the fact that tissue visualization is limited to the ultrasound slice plane, which is two-dimensional. On the other hand, arthroscopy (extra-articular) allows three-dimensional control of the surgical steps performed, but the locating of the nerve involves significant tissue detachment and a risk of damaging the nerve with the dissection. The combination of the two (US-arthroscopy) offers the possibility of combining the advantages of both techniques.

Implementation of Intraoperative Ultrasound Localization for Breast-Conserving Surgery in a Large, Integrated Health Care System is Feasible and Effective

BackgroundIntraoperative ultrasound (IUS) localization for breast cancer is a noninvasive localization technique. In 2015, an IUS program for breast-conserving surgery (BCS) was initiated in a large, integrated health care system. This study evaluated the clinical results of IUS implementation.MethodsThe study identified breast cancer patients with BCS from 1 January to 31 October 2015 and from 1 January to 31 October 2019. Clinicopathologic characteristics were collected, and localization types were categorized. Clinical outcomes were analyzed, including localization use, surgeon adoption of IUS, day-of-surgery intervals, and re-excision rates. Multivariate logistic regression analysis was performed to evaluate predictors of re-excision.ResultsThe number of BCS procedures increased 23%, from 1815 procedures in 2015 to 2226 procedures in 2019. The IUS rate increased from 4% of lumpectomies (n = 79) in 2015 to 28% of lumpectomies (n = 632) in 2019 (p < 0.001). Surgeons using IUS increased from 6% (5 of 88 surgeons) in 2015 to 70% (42 of 60 surgeons) in 2019. In 2019, 76% of IUS surgeons performed at least 25% of lumpectomies with IUS. The mean time from admission to incision was shorter with IUS or seed localization than with wire localization (202 min with IUS, 201 with seed localization, 262 with wire localization in 2019; p < 0.001). The IUS re-excision rates were lower than for other localization techniques (13.6%, vs 19.6% for seed localization and 24.7% for wire localization in 2019; p = 0.006), and IUS predicted lower re-excision rates in a multivariable model (odds ratio [OR], 0.59).ConclusionsIn a high-volume integrated health system, IUS was adopted for BCS by a majority of surgeons. The use of IUS decreased the time from admission to incision compared with wire localization, and decreased re-excision rates compared with other localization techniques.

Non-invasive localization of the ectopic foci of focal atrial tachycardia by using ECG signal based sparse decomposition algorithm

Over 95% of supraventricular tachycardia (SVT) can be treated using the electrophysiology study (EPS) and catheter ablation procedure. As The lack of accurate tools to guide electrophysiologists to find the exact location of ectopic foci, the present study was to locate ectopic foci of focal-atrial tachycardia (FAT) via information extracted from simple and non-invasive electrocardiogram (ECG) signals. For this aim, 32 ECG signals were collected from Tehran arrhythmia clinic database, and then independent features were obtained through the independent component analysis (ICA). Subsequently, the location of arrhythmia in the right and left atria was established and classified by sparse decomposition algorithm upon developing a dictionary based on these independent features. This algorithm could represent a spatial–temporal pattern of the input in the form of a combined line of basic functions existing in the dictionary. Over the past few decades, it has been also widely utilized in image compression and restoration as well as source separation and classification. The study results demonstrated that the sparse decomposition algorithm was well able to locate arrhythmias in the right and left atria with a mean accuracy of 93.27 ± 2.78. Since FAT generally emerges in certain anatomical locations, five areas in the right atrium and four areas in the left atrium, were determined as nine classifications in this respect. The accuracy of the results for different classifications was by 70.24% on average. Therefore, it was concluded that ECG signals could estimate the location ectopic foci before EPS in an accurate manner.

A method for magnetocardiography functional localization based on boundary element method and Nelder-Mead simplex algorithm.

BackgroundThe magnetocardiography (MCG) functional localization can transfer the biomagnetic signal to the electrical activity information inside the heart. The electrical activity is directly related to the physiological function of the heart.MethodsThis study proposes a practical method for MCG functional localization based on the boundary element method (BEM) and the Nelder–Mead (NM) simplex algorithm. Single equivalent moving current dipole (SEMCD) is served as the equivalent cardiac source. The parameters of SEMCD are adapted using the NM simplex algorithm by fitting the measured MCG with the calculated MCG obtained based on BEM. The SEMCD parameters are solved in the sense that the difference between measured and calculated MCG is minimized.ResultsThe factors affecting the localization accuracy of this BEM–NM method were first explored with synthetic signals. Then, the results with real MCG signals show a good agreement between the SEMCD location and the region where ventricle depolarization starts, demonstrating the feasibility of this idea.ConclusionsThis is the first three‐dimensional localization of the onset of ventricular depolarization with the BEM–NM method. The method is promising in the noninvasive localization of lesions for heart diseases.

Detrended fluctuation analysis in the presurgical evaluation of parietal lobe epilepsy patients

ObjectiveTo examine the usability of long-range temporal correlations (LRTCs) in non-invasive localization of the epileptogenic zone (EZ) in refractory parietal lobe epilepsy (RPLE) patients. MethodsWe analyzed 10 RPLE patients who had presurgical MEG and underwent epilepsy surgery. We quantified LRTCs with detrended fluctuation analysis (DFA) at four frequency bands for 200 cortical regions estimated using individual source models. We correlated individually the DFA maps to the distance from the resection area and from cortical locations of interictal epileptiform discharges (IEDs). Additionally, three clinical experts inspected the DFA maps to visually assess the most likely EZ locations. ResultsThe DFA maps correlated with the distance to resection area in patients with type II focal cortical dysplasia (FCD) (p<0.05), but not in other etiologies. Similarly, the DFA maps correlated with the IED locations only in the FCD II patients. Visual analysis of the DFA maps showed high interobserver agreement and accuracy in FCD patients in assigning the affected hemisphere and lobe. ConclusionsAberrant LRTCs correlate with the resection areas and IED locations. SignificanceThis methodological pilot study demonstrates the feasibility of approximating cortical LRTCs from MEG that may aid in the EZ localization and provide new non-invasive insight into the presurgical evaluation of epilepsy.

Neurite orientation dispersion and density imaging parameters may help for the evaluation of epileptogenic tubers in tuberous sclerosis complex patients.

To investigate the usefulness of neurite orientation dispersion and density imaging (NODDI) in evaluating cortical tubers, especially epileptogenic tubers in tuberous sclerosis complex (TSC) patients. High-resolution conventional MRI and multi-shell diffusion-weighted imaging were performed in 27 TSC patients. Diffusion images were fitted to NODDI and DTI models. Tubers were visually assessed on different image types and scored by two neuroradiologists. For 10 patients who underwent epilepsy surgery, the contrast ratios between lesion and background tissue were measured on different image types, and these were compared between 16 epileptogenic tubers and 92 non-epileptogenic tubers. There were significant differences in lesion conspicuity scores and lesion-background contrast ratios across different sequences (both p< 0.001). The post hoc analysis showed that both the conspicuity scores and contrast ratios of intracellular volume fraction (ICVF) derived from NODDI were higher than other image types. For the 16 epileptogenic tubers, lesion visibility on ICVF was better/equal in 4/12 tubers compared with conventional MRI and better/equal in 5/11 tubers compared with DTI. Significant differences were observed between epileptogenic and non-epileptogenic tubers on diffusion maps, especially on orientation dispersion index derived from NODDI (p< 0.0001). ICVF demonstrated higher contrast than conventional MRI and DTI, which helped detection of subtle epileptogenic tubers. Moreover, NODDI parameters showed the potential to identify epileptogenicity. • The noninvasive localization of epileptogenic cortical tubers is essential for the preparation of epilepsy surgery for TSC patients. • ICVF derived from NODDI showed greater contrast than conventional MRI and DTI in detecting tubers, especially subtle epileptogenic ones. • Diffusion parameters, especially ODI derived from NODDI, can support the identification of epileptogenicity.

Variability in the atrial flutter vectorcardiographic loops and non-invasive localization of circuits

Localization of atrial flutter circuits is tedious. Knowledge of this information beforehand will aid clinicians assess and plan ablation operations in advance to improve efficacy. In this article, we develop a novel classifier to determine flutter circuit localization by exploiting the variability contained in beat-to-beat series of vectorcardiographic flutter loop parameters, related to the variability of the activation circuit. Resulting classifier performance is satisfactory (maximum accuracy 0.93 for sample size of 56, sensitivity and specificity of 0.87 and 1.00 using logistic regression). Using an original method for selection of the most relevant features, it is shown that right and left AFL variability is different (right AFL has larger variability compared to left AFL) regarding higher-order statistics. On the other hand, it is hypothesized that respiratory motion alongside physical location of the two atria introduces variability in different amounts in right and left flutter circuits. This constitutes a confounding source of variability and may explain differences between right and left variability. We verify this hypothesis by removing this variability related to respiratory motion and analyzing the changes in classifier performance and variability feature values. It was concluded that respiratory motion is not the origin of discriminatory variability, and that this variability possibly originates from the AFL itself.

Clock dial integrated positioning combined with single utility port video-assisted thoracoscopic surgery: a new localization method for lung tumors.

BackgroundPreoperative localization of lung tumor mainly consisted of two methods: CT-guided percutaneous localization and electromagnetic navigation bronchoscopy-guided localization. However, these invasive methods could result in serious complications. In order to avoid the adverse effects of preoperative invasive localization, we propose a method of intraoperative noninvasive localization for lung tumors: clock dial integrated positioning (CDIP).MethodsTo retrospectively analyze the clinic data about the application of CDIP for 127 lung tumour patients in single utility port video-assisted thoracoscopic surgery (SUPVATS) between June 2017 and October 2017.ResultsOne hundred and twenty-four cases (97.64%) underwent thoracoscopic surgery, which including 14 lobectomy, 107 partial resection, 2 lobectomy plus partial resection and 1 left pneumonectomy. Three cases (2.36%) underwent thoracoscopic biopsy. The mean operation time and intraoperative bleeding were 47.9±22.1 min and 70.1±40.3 mL, respectively. The mean postoperative hospital stay and chest drain duration were 3.9±2.2 and 3.6±1.8 days, respectively. There were 118 cases of malignant tumors, including adenocarcinoma (n=101), squamous cell carcinoma (n=9), large cell carcinoma (n=2), small cell lung carcinoma (n=3), and metastatic lung carcinoma (n=3). The remaining nine cases were benign tumors, including granuloma (n=3), intrapulmonary lymph node (n=2), sclerosing hemangioma (n=2), and hamartoma (n=2). The incidence of postoperative complications was 10.2%. There was no mortality, secondary operation, or conversion to open procedure due to massive intraoperative bleeding.ConclusionsCDIP combined with SUPVATS is a safe, feasible, and effective method for the localization of lung tumors. This novel method can provide a reliable alternative technique when the marker is dislocated.

Non-invasive detection and localization of microplastic particles in a sandy sediment by complementary neutron and X-ray tomography

PurposeMicroplastics have become a ubiquitous pollutant in marine, terrestrial and freshwater systems that seriously affects aquatic and terrestrial ecosystems. Common methods for analysing microplastic abundance in soil or sediments are based on destructive sampling or involve destructive sample processing. Thus, substantial information about local distribution of microplastics is inevitably lost.MethodsTomographic methods have been explored in our study as they can help to overcome this limitation because they allow the analysis of the sample structure while maintaining its integrity. However, this capability has not yet been exploited for detection of environmental microplastics. We present a bimodal 3D imaging approach capable to detect microplastics in soil or sediment cores non-destructively.ResultsIn a first pilot study, we demonstrate the unique potential of neutrons to sense and localize microplastic particles in sandy sediment. The complementary application of X-rays allows mineral grains to be discriminated from microplastic particles. Additionally, it yields detailed information on the 3D surroundings of each microplastic particle, which supports its size and shape determination.ConclusionThe procedure we developed is able to identify microplastic particles with diameters of approximately 1 mm in a sandy soil. It also allows characterisation of the shape of the microplastic particles as well as the microstructure of the soil and sediment sample as depositional background information. Transferring this approach to environmental samples presents the opportunity to gain insights of the exact distribution of microplastics as well as their past deposition, deterioration and translocation processes.

Selective venous sampling in primary hyperparathyroidism: Is it worth doing?

Accurate preoperative localization of the culprit gland is the key point for the surgical treatment of primary hyperparathyroidism. Conventional imaging techniques (ultrasound and Tc99m sestamibi scintigraphy) are usually adequate for preoperative localization. However, in some patient groups, additional imaging modalities may be required since noninvasive techniques may fail. In this study, we aimed to evaluate the diagnostic value of selective parathyroid venous sampling in patients with unclear noninvasive localization tests. Among 513 cases who underwent parathyroidectomy due to primary hyperparathyroidism, twelve cases (2.3%) were undergone selective parathyroid venous sampling and were included in the study. Age, sex, presenting symptom, presence of a genetic disease, medical and surgical history, serum calcium (Ca)-parathormone (PTH) levels (preoperative, intraoperative, and postoperative), imaging reports (US, SM, and SVS), surgery reports, pathology reports, and complications were retrospectively reviewed. Seven cases (58.3%) had persistent primary hyperparathyroidism and one patient (8.3%) had past surgical history of total thyroidectomy. The remaining four patients (33.3%) had no previous neck surgery. T he sensitivity of selective venous sampling was 75%. According to the medical history, accurate localization was achieved in 85.7% of persistent cases and 60% of primary cases. Eight cases (66.6%) underwent unilateral neck exploration and four cases (33.3%) underwent four gland exploration. A single adenoma was detected in ten cases (90.9%) while one patient (9.1%) had double adenoma.

A comparative study of recent neuroimaging techniques to show temporal region is the most common site in focal epilepsy irrespective of age

Epilepsy is a chronic disease characterized by recurrent seizures that may affect 2% of the population classification of seizures based solely on EEG and clinical findings can result in the misclassification of some patients, particularly those individuals with partial seizures that rapidly generalize. The information provided by imaging techniques can contribute to the proper classification of certain epileptic disorders in non-invasive localisation of epileptogenic foci. Neuroimaging has an important role in the investigation, localisation and treatment of patients with epilepsy. It is presently recognized that epilepsy is often associated with gross or subtle structural or metabolic lesions of the brain. Neuroimaging is mandatory in the work-up of epilepsy for localisation of the seizure focus for possible surgical cure. In this study it was concluded that that temporal lobe is most common site as epileptic lesion by different neuroimaging techniques. Keywords: EEG, Electroencephalography, PET, Positron emission tomography, CT, Computed tomography, MRI, Magnetic resonance imaging, MRS, MR spectroscopy.

Comparing hand movement rate dependence of cerebral blood volume and BOLD responses at 7T

Functional magnetic resonance imaging (fMRI) based on the Blood Oxygenation Level Dependent (BOLD) contrast takes advantage of the coupling between neuronal activity and the hemodynamics to allow a non-invasive localisation of the neuronal activity. In general, fMRI experiments assume a linear relationship between neuronal activation and the observed hemodynamics. However, the relationship between BOLD responses, neuronal activity, and behaviour are often nonlinear. In addition, the nonlinearity between BOLD responses and behaviour may be related to neuronal process rather than a neurovascular uncoupling. Further, part of the nonlinearity may be driven by vascular nonlinearity effects in particular from large vessel contributions. fMRI based on cerebral blood volume (CBV), promises a higher microvascular specificity, potentially without vascular nonlinearity effects and reduced contamination of the large draining vessels compared to BOLD. In this study, we aimed to investigate differences in BOLD and VASO-CBV signal changes during a hand movement task over a broad range of movement rates. We used a double readout 3D-EPI sequence at 7T to simultaneously measure VASO-CBV and BOLD responses in the sensorimotor cortex. The measured BOLD and VASO-CBV responses increased very similarly in a nonlinear fashion, plateauing for movement rates larger than 1 Hz. Our findings show a tight relationship between BOLD and VASO-CBV responses, indicating that the overall interplay of CBV and BOLD responses are similar for the assessed range of movement rates. These results suggest that the observed nonlinearity of neuronal origin is already present in VASO-CBV measurements, and consequently shows relatively unchanged BOLD responses.

Contribution of Ictal Source Imaging for Localizing Seizure Onset Zone in Patients With Focal Epilepsy

To determine whether seizure onset zone (SOZ) can be localized accurately prior to surgical planning in patients with focal epilepsy, we performed noninvasive EEG recordings and source localization analyses on 39 patients. In 39 patients with focal epilepsy, we recorded and extracted 138 seizures and 1,325 interictal epileptic discharges using high-density EEG. We investigated a novel approach for directly imaging sources of seizures and interictal spikes from high-density EEG recordings, and rigorously validated it for noninvasive localization of SOZ determined from intracranial EEG findings and surgical resection volume. Conventional source imaging analyses were also performed for comparison. Ictal source imaging showed a concordance rate of 95% when compared to intracranial EEG or resection results. The average distance from estimation to seizure onset (intracranial) electrodes is 1.35 cm in patients with concordant results, and 0.74 cm to surgical resection boundary in patients with successful surgery. About 41% of the patients were found to have multiple types of interictal activities; coincidentally, a lower concordance rate and a significantly worse performance in localizing SOZ were observed in these patients. Noninvasive ictal source imaging with high-density EEG recording can provide highly concordant results with clinical decisions obtained by invasive monitoring or confirmed by resective surgery. By means of direct seizure imaging using high-density scalp EEG recordings, the added value of ictal source imaging is particularly high in patients with complex interictal activity patterns, who may represent the most challenging cases with poor prognosis.

From the Literature

From the Literature

Noninvasive Localization of Accessory Pathways in Wolff–Parkinson–White Syndrome by Two-Dimensional Speckle Tracking Echocardiography

Background: Two-Dimensional Speckle Tracking Echocardiography (2D-STE) is a non-Doppler echocardiographic modality that allow quantification of myocardial deformity and its timing in 2D grey scale images, and was proved to be beneficial in assessment of dyssynchrony (STAR trial). Objective: To investigate the capability of 2D-STE for localizing Accessory Pathways (APs) in patients with Wolf-Parkinson-White (WPW) Syndrome. Patients and Methods: The prospective study included 15 patients with manifest AP indicated for invasive endocardial mapping and ablation. All patients were assessed by twelve-lead ECG, 2D-STE for the earliest activated site and invasive Electrophysiology study (EPs). Results: Out of the 15 patients with left-sided APs, 2D-STE was able to accurately localize the site of AP in 10 patents (66.6%), while electrocardiogram (ECG) was able to localize the site of AP in 12 patients (80%). Conclusion: 2D-STE has the ability to approximate the location of AP without the pitfalls of Doppler methods. However, ECG still more accurate and reproducible tool.