Zahari Zahariev - Academia.edu (original) (raw)

Papers by Zahari Zahariev

Journal of Radioanalytical and Nuclear Chemistry

Folia Medica

The ultrasound fusion imaging (UFI) system is a new promising imaging modality that combines live... more The ultrasound fusion imaging (UFI) system is a new promising imaging modality that combines live ultrasound investigations with preregistered CT, MRI, or PET images. In this study, we want to present our initial experience with the new method that combines the transcranial color-coded sonography (TCCS) in different insonation planes and the 3T-weighted MRI cerebral images. The study validates the diagnostic capabilities of the system to detect different normal cerebral structures in healthy volunteers. In the present paper, we also discuss the advantages of US fusion imaging technology and its clinical applications in Neurology.

Journal of Endourology and Minimally Invasive Surgery

Introduction: Prostate cancer is the most common malignancy in men in Europe. One of the importan... more Introduction: Prostate cancer is the most common malignancy in men in Europe. One of the important clinical problems is the early detection and visualization of recurrence after radical prostatectomy, radiation therapy or other radical topical treatment, in patients with PSA values above 0.2 ng/ml. With the introduction of molecular highly sensitive imaging methods after administration of radiolabeled prostate-specific membrane antigen (PSMA), it became possible to detect early functional changes associated with the development of a metastatic process in this disease, with a negative CT or MRI result. 99mTc-PSMA is a new radiopharmaceutical and is a small ligand that binds to the active core of PSMA. The aim of our study was to evaluate the clinical role of 99mTc-PSMA in imaging local recurrence and/or loco-regional and distant metastases in patients with recurrent prostate cancer and biochemical disease progression. Material and methods: A cohort of 36 prostate cancer patients was ...

2019 X National Conference with International Participation (ELECTRONICA)

There are a lot of mobile robot application, when the people interact with mobile robots. The nat... more There are a lot of mobile robot application, when the people interact with mobile robots. The natural way of interaction are voice commands send for navigate mobile robot motion. To do this in this article is proposed to create a LabVIEW model for receiving and recognizing voice commands send from a person to the robot. For the experiments and tests the LabVIEW model is implemented in an Internet of Thinks module mounted on mobile robot platform.

2017 40th International Spring Seminar on Electronics Technology (ISSE), 2017

There are many methods for controlling the movement of mobile robots. Some of them are based on r... more There are many methods for controlling the movement of mobile robots. Some of them are based on received information from the audio and video sensors of the robot. Some methods are using separately the audio or the video information, but the purpose of the current article is to combine both, using audio and video input in parallel, and by this to increase the effectiveness of controlling the movement of the mobile robot. This is very important in the cases when the human operator using both gestures and voice commands to navigate and control the robot.

2019 X National Conference with International Participation (ELECTRONICA), 2019

The proliferation of mobile robots in a wide range of professional and home applications is a rea... more The proliferation of mobile robots in a wide range of professional and home applications is a real stimulus of researches for more convenient natural ways and communication skills of mobile robots to interact with human. Voice communicating with mobile robots is always preferable but in many cases is inappropriate due to technical complexity, not enough accuracy and inability of real time of voice recognition. That is why voice communications with mobile robots are often replaced or combined with human interaction by hand gestures. Therefore, this is the goal of this article, with proposition of realization based on artificial intelligence and deep learning.

Neurologia i Neurochirurgia Polska, 2021

Aim. This study aimed to explore associations between fibrinogen and acute ischaemic stroke, neur... more Aim. This study aimed to explore associations between fibrinogen and acute ischaemic stroke, neurological impairment, cerebral ischaemia, and clinical evaluation of stroke patients. Materials and methods. The study involved 153 patients categorised into two groups: patients with acute ischaemic stroke, and patients with risk factors but who had not had a stroke. Blood samples were collected to analyse the serum level of fibrinogen. The time from stroke onset to blood test was noted. The National Institutes of Health Stroke Scale was used to determine the neurological disability of the stroke patients upon hospital admission and upon discharge. Cerebral CT was performed on the same group of patients during the first 24 h after stroke onset and evidence of early ischaemic lesions was recorded. The stroke cases were divided into subgroups according to the TOAST classification. Results. Patients with ischaemic stroke had a significantly increased mean level of fibrinogen (> 4g/l). Analysis of stroke subtypes shows that patients with undetermined cause of stroke and patients with atherosclerotic stroke had a significantly higher median level of fibrinogen compared to patients with some other types of stroke. No significant connection was found between fibrinogen level and neurological deficit. A positive linear relationship was established between fibrinogen and blood sample time. A negative relation was established between the clinical evolution of ischaemic stroke patients and fibrinogen level. A significant relation between fibrinogen level and the presence of ischaemic lesions on cerebral CT was observed: patients with a fibrinogen level > 3.41g/l showed a 3.29-times increased risk of ischaemic lesions. Conclusion. Fibrinogen is a reliable biomarker that could characterise acute ischaemic stroke.

Folia Medica, 2019

We present a case report of a 32-year-old woman diagnosed with opticomyelitis of Devic (OMD) and ... more We present a case report of a 32-year-old woman diagnosed with opticomyelitis of Devic (OMD) and systemic lupus erythematosus (SLE). The onset of neurological symptoms was with optic neuritis. Five months later the neurological deficit progressed within a few days to lower paraplegia and upper paraparesis, retention of urine and faeces, impaired somatic and deep sensation below the level of Th1 dermatome. The results from laboratory investigations confirmed anaemic syndrome, increased urea and creatinine, hypoproteinemia and severe proteinuria. The results from CSF investigations demonstrated hyperproteinorachia with extremely high Ig fractions. Serum and CSF oligoclonal bands and positive serum Aquaporin IgG 32 times higher than the upper referent limit were found. The association with SLE was confirmed by the increased levels of total ANA and anti-ds-DNA ANA. MRT visualized the spinal cord as non-homogenously hypointense on T1 and extremely hyperintense on FLAIR sequences through ...

2019 16th Conference on Electrical Machines, Drives and Power Systems (ELMA), 2019

Voice commands recognition tasks used limited sets of words in comparison of universal speech rec... more Voice commands recognition tasks used limited sets of words in comparison of universal speech recognition systems dedicated to work with the whole set of words of one or more that one natural languages. Today these universal speech recognition systems are usually based on cloud technologies, artificial intelligence and probably on neural networks with deep learning. The main drawback of using these universal speech recognition systems in tasks like voice commands recognition is the need of unnecessary search the limited set of words (a few words of voice commands) in the databases, containing very large set of words of a chosen natural language. Therefore, the proposition as the goal of this article is to combine the advantages of universal speech recognition systems using cloud technologies, artificial intelligence and neural networks with deep learning in voice commands recognition tasks, but creating and using the reduced database as an appropriate subset of the large speech recognition database existing as cloud databases.

2018 International Conference on High Technology for Sustainable Development (HiTech), 2018

One of the main tasks in development of intelligent mobile robots is motion control. Some of them... more One of the main tasks in development of intelligent mobile robots is motion control. Some of them are based on the existing and mounted on the mobile robot different sensors, suitable to self-mobile robots control during their motion within outdoor or indoor environments. There are others applications and tasks, where the mobile robot interacts with person or people. For these situations is needed to arrange the so called "human-mobile robot interface", from which is possible to establish mobile robot motion control via human voice or gesture commands. Therefore, the goal in this article is to develop the speech recognition algorithm and model, based on myRIO embedded device and LabView graphical programming language, for audio control of mobile robot motion with voice commands.

Annals of Oncology, 2020

and on the information campaign This study has been approved by all Ethical Commettees of the cen... more and on the information campaign This study has been approved by all Ethical Commettees of the centers. Results: The first survey was conducted between March 16th and April 30th. 1027 questionnaires were collected. Mean age was 64 yrs (SD 11.7), 58% were women, 49% had low educational level. 80% and 20% received i.v. and oral treatment, respectively. As for pts feelings, 45.5% indicated that their fears related to cancer increased because hope in recovery diminished (23%). Courage of coping with tumor was increased in 26%, unchanged in 64%; 95% perceived a high availability of healthcare facilities and 97.6% declared confidence in the treating teams, while 65.3% stated that the information received from the Government and local bodies was confusing. Conclusions: Although half of the pts had more fears and concerns about the epidemic, they feel reassured, maintain trust in healthcare facilities and a good communication with doctors and nurses. Due to the epidemic course, the second survey could not yet be performed and data will be available by June.

Japan Journal of Research, 2020

Comparative dosimetric analysis of the left breast carcinoma radiotherapy irradiation techniques ... more Comparative dosimetric analysis of the left breast carcinoma radiotherapy irradiation techniques with deep inspiration breathing and free breathing

Current Cancer Reports, 2020

The Primary Mediastinal Seminoma (PMS) is a rare extragonadal malignant germ-cell tumor. We repor... more The Primary Mediastinal Seminoma (PMS) is a rare extragonadal malignant germ-cell tumor. We report a clinical case of our practice, which is the reason for this literature review and try to find the optimal multimodal therapeutic option and the role of radiotherapy.

Physica Medica, 2019

Introduction: Xoft Ò Axxent Ò Electronic Brachytherapy (eBx Ò) System Ò is balloon-based techniqu... more Introduction: Xoft Ò Axxent Ò Electronic Brachytherapy (eBx Ò) System Ò is balloon-based technique for intraoperative radiotherapy (IORT) that uses a tungsten target to generate low energy X-ray beam (50 kV, tube current 0.3 mA and half-value layer of 0.5 mmAl). This system is available in 11 countries around Europe and the published data regarding its application is very limited. We report the first results of IORT with this system in Bulgaria. Material and Methods: This is a prospective case series of 12 early breast cancer patients fulfilling the GEC-ESTRO low risk group criteria for partial breast irradiation and treated with IORT at Alexandrovska University Hospital, Sofia, Bulgaria. For intraoperative evaluation (IOE) of resection margins, rapid frozen section examination was performed. For IOE of sentinel node, marked with 99mTc-MIBI, the College of American Pathologists protocol was followed. Results: The median values of patients, tumors and irradiation characteristics are as follows: age 59.5 (55-73); tumor size-14.5 mm (8-24); balloon applicator size À47.5 cc (30-70); time of irradiation-12.75 min (8.38-18.02); skin dose-7.5 Gy (6-10). In all patients distance from the skin was more than 7 mm (7-11). No radiation-induced skin reactions were observed and the cosmetic results were excellent. With median follow up of 15 months no recurrence was observed. Conclusions: Four hospitals in Bulgaria have Axxent Ò eBx Ò. We report the results of the center with biggest experience with this system. The small number of patients treated is due to the additional expenses for payment of the applicator's price, which are not covered by the National Health Insurance Fund. The first Bulgarian results prove that this system is effective and convenient for patients, significantly shortening the irradiation time and is less aggressive to the skin. Longer follow up is necessary to confirm the low recurrence rate, comparable to other techniques.

GSC Biological and Pharmaceutical Sciences, 2019

The study purpose was to perform an open, prospective study on various aspects of Lamotrigine (LT... more The study purpose was to perform an open, prospective study on various aspects of Lamotrigine (LTG) effectiveness in Bulgarian patients with drug-resistant epilepsy. The study was performed with the participation of patients with epilepsy who attended the Clinic of Neurology at the University Hospital in Plovdiv, Bulgaria. The patients completed diaries about seizure frequency, severity, and adverse events. There were regular documented visits at 3 or 6 months during the first year of treatment with LTG and at 6 months afterwards, with dynamic assessment of seizure frequency, severity, adverse events, and EEG recordings. LTG was applied as add-on treatment in 73 patients (47 males, mean age 36 years). There was a relatively mild and stable dynamic improvement of seizure severity, a satisfactory seizure frequency reduction in 39.7% of participants, a stable mean seizure frequency reduction (43-59%) from the 6 th to the 36 th month of treatment and a stable responder rate (55.7-59.4%) during the same period. There were adverse events (dizziness/vertigo, generalized edema, irritability, aggressiveness, speech disturbances, visual hallucinations, sleepiness, insomnia, headache, diplopia, nystagmus, impaired balance, muscle cramps, gastrointestinal discomfort, generalized rash, fatigue, nausea) in 12.3% of patients. In conclusion, LTG treatment is associated with: a low and stable improvement of seizure severity, a good and stable improvement of seizure frequency, a possible worsening of seizure control, a good safety and tolerability.

Folia Medica, 2018

Ischemic stroke is a socially significant health problem due to high mortality and disability. On... more Ischemic stroke is a socially significant health problem due to high mortality and disability. One of the leading causes for cerebrovascular accidents is the carotid atherosclerosis. The mechanism of its formation presents not only lipid accumulation in the arterial wall but a complex inflammatory disease. The aims of this review are to point the new methods and approaches for diagnostic of the unstable and high-risk carotid plaques. The old plaque imaging modalities emphasized mainly to the degrees of luminal stenosis. The new possibilities reveal plaque morphology so detailed even compared to histological verification. Recent techniques as Shear wave elastography, optical coherence tomography, Superb microvascular imaging, USPIO MRI give information about the pathological mechanisms of carotid atherosclerosis. The efforts are directed to predict the atherosclerotic burden, plaque instability and the occurrence of cerebrovascular events for each patient and to optimize personal man...

Česká a slovenská neurologie a neurochirurgie, 2018

Bulharská rodina s epileptickými záchvaty jako prvním projevem familiárních cerebrálních kavernóz... more Bulharská rodina s epileptickými záchvaty jako prvním projevem familiárních cerebrálních kavernózních malformací The authors declare they have no potential confl icts of interest concerning drugs, products, or services used in the study. Autoři deklarují, že v souvislosti s předmětem studie nemají žádné komerční zájmy. The Editorial Board declares that the manu script met the ICMJE "uniform requirements" for biomedical papers. Redakční rada potvrzuje, že rukopis práce splnil ICMJE kritéria pro publikace zasílané do biomedicínských časopisů.

Journal of Translational Science, 2016

Multiple sclerosis (MS) is an autoimmune disease of unknown etiology whose treatment is of limite... more Multiple sclerosis (MS) is an autoimmune disease of unknown etiology whose treatment is of limited efficiency and therefore has a high social burden. As it has been suggested that myelin destruction model, the clinical manifestation and the potential of therapeutic response in MS are correlated, it is quite justifiable that we study various factors (genetic, hormonal, environmental) that take part in the autoimmune process in order to improve the control over the disrupted immune regulation. Results from epidemiological and clini¬cal studies clearly suggest that changes in vitamin D serum concentrations are correlated with the magnitude of the risk of developing MS, the phases of relapse and remittance and with gender differences in vitamin D metabolism. Experimental and clinical studies also have established that 25-hydroxy vitamin D (25(OH)D) and 1,25-dihydroxy vitamin D (1,25(OH)2D) exert an immunomodulatory effect in the central nervous system and peripheral organs of the immune system. The standard reference range of vitamin D con¬centration in serum is 50-80 nmol/l-it provides normal calcium metabolism. Issues that are discussed include the vitamin D serum concentration needed to suppress the aberrant immune response in MS patients; a subgroup of MS patients suitable for vitamin D treat¬ment, the vitamin D being applied in optimally effective and safe dosage. MS prevalence rate in Bulgaria has increased twofold in 17 years but this is a rather short interval to be able to assume that the gene pool of the population changes. Thus further studies on pos¬sible interactions between different environmental factors and these factors' role in the disease pathogenesis are justified and necessary.

Neurology. Clinical practice, 2016

Delayed-release dimethyl fumarate (DMF), indicated for the treatment of patients with relapsing-r... more Delayed-release dimethyl fumarate (DMF), indicated for the treatment of patients with relapsing-remitting multiple sclerosis (MS), is a disease-modifying therapy with potential immunomodulatory and neuroprotective effects. In clinical trials, DMF was associated with reduced white blood cell and absolute lymphocyte counts. Current US prescribing information recommends obtaining a complete blood count, including absolute lymphocyte count (ALC), before initiating and during DMF treatment. We conducted an integrated analysis of phase 2b/3/long-term extension studies of DMF in MS (N = 2,470) to characterize ALC profiles. Mean ALCs decreased by 30% during the first year and then plateaued, remaining above the lower limit of normal (LLN). Among patients treated ≥6 months (N = 2,099), 2.2% experienced ALCs <500 mm(3) persisting ≥6 months. ALCs remained ≥LLN in 84% and 76% of patients during the first 6 and 12 months, respectively; of these, 0.1% and 0%, respectively, developed ALCs <5...