Nikolay Sirakov

Dr. Nikolay Sirakov

orcid

Research Focus & Metrics

Academic Career Length

29Years (1998-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 May 2023 in World Journal of Radiology
Verified
Journal Article
Open access
LCLyubomir Chervenkov
Lyubomir Chervenkov
NSNikolay Sirakov
Nikolay Sirakov
GKGancho Kostov
Gancho Kostov
Tsvetelina VelikovaTsvetelina Velikova
Tsvetelina Velikova
GHGeorge V Hadjidekov
George V Hadjidekov
Future of prostate imaging: Artificial intelligence in assessing prostatic magnetic resonance imaging

24 January 2025 in Medicina
Verified
Journal Article
Open access
PDF file
KGKaterina Gaberova
Katerina Gaberova
IPIliyana Pacheva
Iliyana Pacheva
NSNikolay Sirakov
Nikolay Sirakov
ETElena Timova
Elena Timova
ИИИван Иванов
Иван Иванов
Background and Objectives: Hemiplegic or unilateral cerebral palsy (UCP) is primarily characterized by motor impairment, mainly affecting the upper limb. Research has centered on factors influencing the varying degrees of motor deficit in UCP, using neuroscience advancements for in vivo exploration of brain structure (morphometry) and cortical reorganization (functional magnetic resonance imaging (fMRI)). This study aims to evaluate functional activation in the motor cortex in UCP and to explore how lesion characteristics and timing affect neuroplasticity and motor function. Materials and Methods: Between 2017 and 2021, structural and functional MRIs were performed on 44 UCP patients (mean age 15.5 years, 24 males, 20 females), all with Manual Ability Classification System (MACS) levels I-III and Intelligence Quotient (IQ) ≥ 50. The lesion characteristics of size, type, and time of occurrence (ante-, peri-, or early postnatal) were analyzed. An association was sought between the characteristics of the lesion and the degree of motor deficit of the upper limb, as determined by the MACS level. fMRI assessed cortical activation during a finger-tapping task for the paretic hand and compared activation patterns based on lesion characteristics. Results: Six lesion types were identified, with arterial ischemic stroke being the most common and largest in volume. Lesion size strongly correlated with patients’ MACS levels, while lesion type and timing showed no association with the severity of motor impairment classified by MACS. Motor reorganization varied, with activation occurring ipsi-, contra-, or bilaterally to the affected hand, depending on lesion size and type. Smaller, subcortical lesions primarily showed ipsilesional activation, while larger, cortical lesions did not exhibit a specific group activation, possibly due to varying individual reorganization. No association was found between the lesion timing and the reorganization model. Conclusions: Motor functional reorganization in UCP is closely linked to lesion characteristics, with smaller, subcortical lesions favoring typical organization in the contralateral motor cortex. The timing of the lesion does not significantly affect cortical reorganization. Lesion size was a key determinant of motor function, whereas lesion type (e.g., ischemic stroke) and timing (early vs. late occurrence) were less critical for predicting functional outcome.

13 September 2023 in Life
Verified
Journal Article
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LCLyubomir Chervenkov
Lyubomir Chervenkov
NSNikolay Sirakov
Nikolay Sirakov
AGAleksandar Georgiev
Aleksandar Georgiev
Dimitrina Georgieva MitevaDimitrina Georgieva Miteva
Dimitrina Georgieva Miteva
MGMilena Gulinac
Milena Gulinac
Tsvetelina VelikovaTsvetelina Velikova
Tsvetelina Velikova
(1) Although new imaging methods for examining the GIT with high diagnostic capabilities were introduced, the improvement and implementation of safe, efficient, and cost-effective approaches continue, and GIT diseases are still challenging to diagnose; (2) Methods: We aim to show the possibilities of computed tomography (CT) colonography for early diagnosis of colon diseases using a multidetector 32-channel CT scanner after appropriate preparation; (3) Results: After a colonoscopy was performed earlier, 140 patients were examined with CT colonography. Complete colonoscopy was performed in 80 patients (57.1%) out of 140 who underwent CT colonography. Incomplete colonoscopy was observed in 52 patients (37.2%); in 5 patients (3.6%), it was contraindicated, and in 3 patients (2.1%), it was not performed because of patients’ refusal. We determined that in cases of complete FCS in 95% of patients, CT colonography established the same clinical diagnosis as FCS. In cases of incomplete, refused, or contraindicated FCS in 32.7% (17 patients), FCS failed to diagnose correctly. The main reasons for incomplete colonoscopy were: intraluminal obturation of tumor nature-17 patients (33%), extraluminal obturation (compression) from a tumor formation-4 patients (8%), stenotic changes of non-tumor nature-11 patients (21%), congenital diseases with changes in the length of the lumen of the intestinal loops-7 patients (13%), and subjective factors (pain, poor preparation, contraindications) in 13 patients (25%); (4) Conclusions: Our results confirmed that CT colonography is a method of choice in cases of negative FCS results accompanied by clinical data for the neoplastic process and in cases of incomplete and contraindicated FCS. Also, the insufflation system we developed optimizes the method by improving the quality of the obtained images and ensuring good patient tolerance.

23 March 2018 in Journal of Evaluation in Clinical Practice
Verified
Journal Article
Closed access
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Ferihan Ahmed-PopovaFerihan Ahmed-Popova
Ferihan Ahmed-Popova
AKAntoaneta Kovacheva
Antoaneta Kovacheva
PGPetar Garov
Petar Garov
SSStefan Sivkov
Stefan Sivkov
SKSevdalina Kandilarova
Sevdalina Kandilarova
KVKichka G. Velkova
Kichka G. Velkova

1 January 1998
Verified
Journal Article
Closed access
PZPlamen Zagorchev
Plamen Zagorchev
VSV Sirakov
V Sirakov
AUA Uchikov
A Uchikov
NSNikolay Sirakov
Nikolay Sirakov

1 April 2011 in Open Medicine
Verified
Journal Article
Open access
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AKAthanas Kristev
Athanas Kristev
NSNikolay Sirakov
Nikolay Sirakov
DGDamianka Getova
Damianka Getova
VKVasil Katcarov
Vasil Katcarov
VSVladimir Sirakov
Vladimir Sirakov
KVKichka Velkova
Kichka Velkova
Hyoscine and drotaverine effectiveness was compared for the purposes of achieving optimum distension following insufflation in CT colonography. The in vitro effects of hyoscine and drotaverine on tone and contractility of SM preparations isolated from different areas of human colon were studied by isometric registration of contractile activity. Both medications have a relaxing effect on SM preparations and inhibit their spontaneous contractions. The drotaverine-induced effects were reliably more marked than the hyoscine-induced ones. CT colonography was performed in 70 patients who were injected with equal doses of either hyoscine (n=32) or drotaverine (n=38). The degree of drug-induced distension in both groups was determined by measuring the lumen of the colon on a 2D reconstruction. In most colon areas the width of the distended lumen was greater in the drotaverine-treated patients. We concluded that drotaverine can be used as a means to facilitate colonic distension.