Publications by authors named "Doneva M"

Purpose: This study proposes a novel, contrast-free Magnetic Resonance Fingerprinting (MRF) method using balanced Steady-State Free Precession (bSSFP) sequences for the quantification of cerebral blood volume (CBV), vessel radius (R), and relaxometry parameters (T , T , T *) in the brain.

Methods: The technique leverages the sensitivity of bSSFP sequences to intra-voxel frequency distributions in both transient and steady-state regimes. A dictionary-matching process is employed, using simulations of realistic mouse microvascular networks to generate the MRF dictionary.

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Background: Cardiovascular magnetic resonance (CMR) is an important imaging modality for the assessment of heart disease; however, limitations of CMR include long exam times and high complexity compared to other cardiac imaging modalities. Recently advancements in artificial intelligence (AI) technology have shown great potential to address many CMR limitations. While the developments are remarkable, translation of AI-based methods into real-world CMR clinical practice remains at a nascent stage and much work lies ahead to realize the full potential of AI for CMR.

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Purpose: T mapping is a widely used quantitative MRI technique, but its tissue-specific values remain inconsistent across protocols, sites, and vendors. The ISMRM Reproducible Research and Quantitative MR study groups jointly launched a challenge to assess the reproducibility of a well-established inversion-recovery T mapping technique, using acquisition details from a seminal T mapping paper on a standardized phantom and in human brains.

Methods: The challenge used the acquisition protocol from Barral et al.

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Purpose: Liver T mapping techniques typically require long breath holds or long scan time in free-breathing, need correction for inhomogeneities and process composite (water and fat) signals. The purpose of this work is to accelerate the multi-slice acquisition of liver water selective T (wT) mapping in a single breath hold, improving the k-space sampling efficiency.

Methods: The proposed continuous inversion-recovery (IR) Look-Locker methodology combines a single-shot gradient echo spiral readout, Dixon processing and a dictionary-based analysis for liver wT mapping at 3 T.

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Article Synopsis
  • MRI acquisition is prone to motion artifacts, which can cause significant scanning issues like blurring and ghosting, often requiring rescans.
  • Recent developments in AI-based reconstruction techniques aim to enhance MRI efficiency but typically assume no patient movement.
  • A new deep learning model was created to detect and quantify motion artifacts in brain MRI, achieving high accuracy rates in distinguishing between motion-corrupted and motion-free scans, and allowing adjustments in reconstruction methods based on detected motion.
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Purpose: Digital Reference Objects (DROs) are mathematical phantoms that can serve as a basis for evaluating MR image quality (IQ) in an objective way. Their main purpose is to facilitate the establishment of fully automated and perfectly reproducible IQ metrics to objectively compare different algorithms in MR image formation in a standardized manner. They also allow to re-build parts of standard phantoms.

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Managed entry agreements are applied in almost all European countries in order to improve patients' access to therapy. The current study aims to evaluate the changes in the affordability of biological medicines for patients in Bulgaria during 2019-2022. The study is a top-down macroeconomic analysis of the key economic indicators and reimbursed costs of biologic therapies.

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: The objective is to evaluate medication adherence level (MA) and the relevant determinants of MA among patients with type 2 diabetes mellitus (T2DM) monitored in ambulatory settings by general practitioners. : A cross-sectional study was conducted among patients with T2DM monitored in a GP practice in Sofia, Bulgaria (September-December 2022). All patients were interviewed according to a predesigned questionnaire after granting informed consent.

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Purpose: This work was aimed at proposing a supervised learning-based method that directly synthesizes contrast-weighted images from the Magnetic Resonance Fingerprinting (MRF) data without performing quantitative mapping and spin-dynamics simulations.

Methods: To implement our direct contrast synthesis (DCS) method, we deploy a conditional generative adversarial network (GAN) framework with a multi-branch U-Net as the generator and a multilayer CNN (PatchGAN) as the discriminator. We refer to our proposed approach as N-DCSNet.

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MR fingerprinting (MRF) enables fast multiparametric quantitative imaging with a single acquisition and has been shown to improve diagnosis of prostate cancer. However, most prostate MRF studies were performed with spiral acquisitions that are sensitive to B0 inhomogeneities and consequent blurring. In this work, a radial MRF acquisition with a novel subspace reconstruction technique was developed to enable fast T1/T2 mapping in the prostate in under 4 min.

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Central and Eastern European countries (CEEC) have among the highest rates of increase in healthcare expenditure. External reference pricing, generics and biologics price capping, regressive scale for price setting, health technology assessment (HTA), and positive drug lists for reimbursed medicines are among the variety of implemented cost-containment measures aimed at reducing and controlling the rising cost for pharmaceuticals. The aim of our study was to analyze the influence of a recently introduced measure in Bulgaria-budget capping in terms of overall budget expenditure.

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Article Synopsis
  • The study aimed to assess the effectiveness of 2D Dixon blurring-corrected MRF (2DDb-cMRF) in differentiating between breast cancer (BC) and normal fibroglandular tissue (FGT).
  • Researchers conducted a prospective study with 14 patients, measuring T1 and T2 times using MRF techniques before and after contrast enhancement, while analyzing the data statistically.
  • Results indicated significant differences in T1 values between BC and FGT, with positive correlations found in both tissue types; nonetheless, further investigations are necessary to fully establish MRF's potential in differential diagnosis.
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The myelin concentration and the degree of myelination of nerve fibers can provide valuable information on the integrity of human brain tissue. Magnetic resonance imaging (MRI) of myelin-sensitive parameters can help to non-invasively evaluate demyelinating diseases such as multiple sclerosis (MS). Several different myelin-sensitive MRI methods have been proposed to determine measures of the degree of myelination, in particular the g-ratio.

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Introduction: To develop and test the feasibility of free-breathing (FB), high-resolution quantitative first-pass perfusion cardiac MR (FPP-CMR) using dual-echo Dixon (FOSTERS; Fat-water separation for mOtion-corrected Spatio-TEmporally accelerated myocardial peRfuSion).

Materials And Methods: FOSTERS was performed in FB using a dual-saturation single-bolus acquisition with dual-echo Dixon and a dynamically variable Cartesian k-t undersampling (8-fold) approach, with low-rank and sparsity constrained reconstruction, to achieve high-resolution FPP-CMR images. FOSTERS also included automatic in-plane motion estimation and T correction to obtain quantitative myocardial blood flow (MBF) maps.

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The growth of public expenditure worldwide has set the priority on assessment of trends and establishment of factors which generate the most significant public costs. The goal of the current study is to review the tendencies in public healthcare expenditures in Bulgaria and to analyze the influence of the demographic, economic, and healthcare system capacity indicators on expenditures dynamics. A retrospective, top-down, financial analysis of the healthcare system expenditures was performed.

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Quantitative MRI methods and learning-based algorithms require exact forward simulations. One critical factor to correctly describe magnetization dynamics is the effect of slice-selective RF pulses. While contemporary simulation techniques correctly capture their influence, they only provide final magnetization distributions, require to be run for each parameter set separately, and make it hard to derive general theoretical conclusions and to generate a fundamental understanding of echo formation in the presence of slice-profile effects.

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Background: Dixon cardiac magnetic resonance fingerprinting (MRF) has been recently introduced to simultaneously provide water T , water T , and fat fraction (FF) maps.

Purpose: To assess Dixon cardiac MRF repeatability in healthy subjects and its clinical feasibility in a cohort of patients with cardiovascular disease.

Population: T1MES phantom, water-fat phantom, 11 healthy subjects and 19 patients with suspected cardiovascular disease.

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Purpose: Magnetic resonance fingerprinting (MRF) offers rapid quantitative imaging but may be subject to confounding effects (CE) if these are not included in the model-based reconstruction. This study characterizes the influence of in-plane , slice profile and diffusion effects on T and T estimation in the female breast at 1.5T.

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Objectives: This study aims to analyze the reimbursement and cost of biological therapy for severe asthma in Bulgaria during 2014-2019 from the perspective of the National Health Insurance Fund.

Methods: It is a retrospective, Marco-costing, top-down study of the expenditures for biological products for severe asthma. The changes in the cost paid by the National Health Insurance Fund per year, per product, and per patient during 2015-2020 were systematized and calculated.

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Parkinson's disease (PD) affects more than six million people, but reliable MRI biomarkers with which to diagnose patients have not been established. Magnetic resonance fingerprinting (MRF) is a recent quantitative technique that can provide relaxometric maps from a single sequence. The purpose of this study is to assess the potential of MRF to identify PD in patients and their disease severity, as well as to evaluate comfort during MRF.

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Purpose: To develop a novel respiratory motion compensated three-dimensional (3D) cardiac magnetic resonance fingerprinting (cMRF) approach for whole-heart myocardial T and T mapping from a free-breathing scan.

Methods: Two-dimensional (2D) cMRF has been recently proposed for simultaneous, co-registered T and T mapping from a breath-hold scan; however, coverage is limited. Here we propose a novel respiratory motion compensated 3D cMRF approach for whole-heart myocardial T and T tissue characterization from a free-breathing scan.

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Purpose: ESPIRiT is a parallel imaging method that estimates coil sensitivity maps from the auto-calibration region (ACS). This requires choosing several parameters for the optimal map estimation. While fairly robust to these parameter choices, occasionally, poor selection can result in reduced performance.

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Demyelination is the key pathological process in multiple sclerosis (MS). The extent of demyelination can be quantified with magnetic resonance imaging by assessing the myelin water fraction (MWF). However, long computation times and high noise sensitivity hinder the translation of MWF imaging to clinical practice.

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