Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 61
Filtrar
1.
Neurosurg Rev ; 47(1): 76, 2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38324094

RESUMO

Intracranial aneurysms (IAs) located in the anterior and posterior circulations of the Circle of Willis present differential rupture risks. This study aimed to compare the rupture risk and clinical outcomes of anterior communicating artery aneurysms (AcomA) and basilar tip aneurysms (BAs); two IA types located along the midline within the Circle of Willis. We retrospectively collected data from 1026 patients presenting with saccular IAs. Only AcomA and BAs with a 3D angiography were included. Out of 186 included IAs, a cohort of 32 BAs was matched with AcomA based on the patients' pre-existing conditions and morphological parameters of IAs. Clinical outcomes, including rupture risk, hydrocephalus development, vasospasm incidence, and patients' outcome, were compared. The analysis revealed no significant difference in rupture risk, development of hydrocephalus, need for ventricular drainage, or vasospasm incidence between the matched AcomA and BA cohorts. Furthermore, the clinical outcomes post-rupture did not significantly differ between the two groups, except for a higher Fisher Grade associated with BAs. Once accounting for morphological and patient factors, the rupture risk between AcomA and BAs is comparable. These findings underscore the importance of tailored management strategies for specific IA types and suggest that further investigations should focus on the role of individual patient and aneurysm characteristics in IA rupture risk and clinical outcomes.


Assuntos
Hidrocefalia , Aneurisma Intracraniano , Humanos , Estudos Retrospectivos , Angiografia
2.
Magn Reson Med ; 90(5): 2175-2189, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37496183

RESUMO

PURPOSE: To estimate relative transvalvular pressure gradient (TVPG) noninvasively from 4D flow MRI. METHODS: A novel deep learning-based approach is proposed to estimate pressure gradient across stenosis from four-dimensional flow MRI (4D flow MRI) velocities. A deep neural network 4D flow Velocity-to-Presure Network (4Dflow-VP-Net) was trained to learn the spatiotemporal relationship between velocities and pressure in stenotic vessels. Training data were simulated by computational fluid dynamics (CFD) for different pulsatile flow conditions under an aortic flow waveform. The network was tested to predict pressure from CFD-simulated velocity data, in vitro 4D flow MRI data, and in vivo 4D flow MRI data of patients with both moderate and severe aortic stenosis. TVPG derived from 4Dflow-VP-Net was compared to catheter-based pressure measurements for available flow rates, in vitro and Doppler echocardiography-based pressure measurement, in vivo. RESULTS: Relative pressures calculated by 4Dflow-VP-Net and in vitro pressure catheterization revealed strong correlation (r2 = 0.91). Correlations analysis of TVPG from reference CFD and 4Dflow-VP-Net for 450 simulated flow conditions showed strong correlation (r2 = 0.99). TVPG from in vitro MRI had a correlation coefficient of r2 = 0.98 with reference CFD. 4Dflow-VP-Net, applied to 4D flow MRI in 16 patients, showed comparable TVPG measurement with Doppler echocardiography (r2 = 0.85). Bland-Altman analysis of TVPG measurements showed mean bias and limits of agreement of -0.20 ± 2.07 mmHg and 0.19 ± 0.45 mmHg for CFD-simulated velocities and in vitro 4D flow velocities. In patients, overestimation of Doppler echocardiography relative to TVPG from 4Dflow-VP-Net (10.99 ± 6.77 mmHg) was observed. CONCLUSION: The proposed approach can predict relative pressure in both in vitro and in vivo 4D flow MRI of aortic stenotic patients with high fidelity.


Assuntos
Estenose da Valva Aórtica , Imageamento Tridimensional , Humanos , Constrição Patológica/diagnóstico por imagem , Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética , Estenose da Valva Aórtica/diagnóstico por imagem , Redes Neurais de Computação , Velocidade do Fluxo Sanguíneo
3.
GeoJournal ; 88(2): 2121-2136, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36035321

RESUMO

The water crisis is the main stress in arid and semi-arid areas, especially in rural areas where agriculture is the main livelihood. This study assessed vulnerability to water scarcity in six rural regions of Isfahan, Iran. These areas have lost their primary water source of agriculture, the Zayandeh Rud River, since 2006. They have confronted many socio-ecological problems which threatened their existence. A mixed methodology was used to assess vulnerability as a function of exposure, sensitivity, and adaptive capacity. Structured questionnaires and in-depth interviews were conducted with key informants and 266 households. The method of Multidimensional Poverty Index was applied to calculate the sensitivity index, which has not been used for sensitivity assessment yet. The results showed that the leading cause of water scarcity is poor water governance. The three districts that had direct access to the Zayandeh Rud river were more vulnerable to water scarcity (scores of 0.35, 0.39, and 0.44) than those that had never had direct access to the river (scores of 0.19, 0.21, and 0.23) due to the more exposure and less adaption to water shortage. Inappropriate financial resilience (from 0.24 to 0.41) and living standards (from 0.19 to 0.36) have made more contributions to creating sensitivity than socioeconomic factors (from 0.14 to 0.28). Different natural capitals have mainly created differences in adaptive capacity across rural areas. Villages located downstream have lost their natural capital due to water-quality degradation caused by river drying up and groundwater overexploitation. Supplementary Information: The online version contains supplementary material available at 10.1007/s10708-022-10726-0.

4.
MAGMA ; 35(5): 733-748, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35175449

RESUMO

OBJECTIVE: Arterial stenosis is a significant cardiovascular disease requiring accurate estimation of the pressure gradients for determining hemodynamic significance. In this paper, we propose Generalized Bernoulli Equation (GBE) utilizing interpolated-based method to estimate relative pressures using streamlines and pathlines from 4D Flow MRI. METHODS: 4D Flow MRI data in a stenotic phantom model and computational fluid dynamics simulated velocities generated under identical flow conditions were processed by Generalized Bernoulli Equation (GBE), Reduced Bernoulli Equations (RBE), as well as the Simple Bernoulli Equation (SBE) which is clinically prevalent. Pressures derived from 4D flow MRI and noise corrupted CFD velocities were compared with pressures generated directly with CFD as well as pressures obtained using Millar catheters under identical flow conditions. RESULTS: It was found that SBE and RBE methods underestimated the relative pressure for lower flow rates while overestimating the relative pressure at higher flow rates. Specifically, compared to the reference pressure, SBE underestimated the maximum relative pressure by 22[Formula: see text] for a pulsatile flow data with peak flow rate [Formula: see text] and overestimated by around 40[Formula: see text] when [Formula: see text]. In contrast, for GBE method the relative pressure values were overestimated by 15[Formula: see text] with [Formula: see text]and around 10[Formula: see text] with [Formula: see text]. CONCLUSION: GBE methods showed robust performance to additive image noise compared to other methods. Our findings indicate that GBE pressure estimation over pathlines attains the highest level of accuracy compared to GBE over streamlines, and the SBE and RBE methods.


Assuntos
Imageamento por Ressonância Magnética , Doenças Vasculares , Constrição Patológica/diagnóstico por imagem , Hemodinâmica , Humanos , Hidrodinâmica , Fluxo Pulsátil
5.
J Magn Reson Imaging ; 52(1): 117-128, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-31850597

RESUMO

BACKGROUND: Single Venc 4D flow MRI with Cartesian readout is hampered by poor velocity resolution and noise when imaging during diastole. Dual Venc acquisitions typically require the acquisition of two distinct datasets, which leads to longer scan times. PURPOSE/HYPOTHESIS: To design and develop a 4D Spiral Dual Venc sequence. The sequence allows for separate systolic and diastolic Venc s as part of a single acquisition with a prescribed switch time. The implemented sequence was hypothesized to be comparable to Cartesian 4D flow, but with increased velocity resolution in the diastolic phase and with better scan efficiency and reduced noise. STUDY TYPE: Prospective. POPULATION: The studied populations were two phantoms-a straight pipe with a stenotic narrowing and a phantom of the aortic arch which included a calcific polymeric valve-under both steady and pulsatile flows, six healthy volunteers, and eight patients with severe aortic stenosis (AS). FIELD STRENGTH/SEQUENCE: 1.5T, Dual Venc 4D flow with spiral readouts. ASSESSMENT: Data from the proposed sequence were compared with data from 4D Cartesian Dual Venc and Single Venc acquisitions. Noise was assessed from the acquired velocity data with the pump turned off and by varying Venc . Steady acquisitions were compared to the proximal slice of the lowest Single Venc acquisition. STATISTICAL TESTS: Steady flows were compared using relative-root-mean-squared-error (RRMSE). For in vivo flows and pulsatile in vitro flows, net flow for corresponding timepoints were compared with the Pearson correlation test (P < 0.01). RESULTS: For steady flows, RRMSEs for Single Venc s ranged from 17.6% to 19.4%, and 9.6% to 16.5% for Dual Venc s. The net flow correlation coefficient for the aortic arch phantom was 0.975, and 0.995 for the stenotic phantom. Normal volunteer and patient comparisons yielded a correlation of 0.970 and 0.952, respectively. in vitro and in vivo pulsatile flow waveforms closely matched. DATA CONCLUSION: The Dual Venc offers improved noise properties and velocity resolution, while the spiral trajectory offers a scan efficient acquisition with short echo time yielding reduced flow artifacts. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2020;52:117-128.


Assuntos
Estenose da Valva Aórtica , Imageamento Tridimensional , Estenose da Valva Aórtica/diagnóstico por imagem , Velocidade do Fluxo Sanguíneo , Humanos , Imageamento por Ressonância Magnética , Imagens de Fantasmas , Estudos Prospectivos , Reprodutibilidade dos Testes
6.
Hum Mutat ; 40(11): 1968-1984, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31343797

RESUMO

Considering the application of human genome variation databases in precision medicine, population-specific genome projects are continuously being developed. However, the Middle Eastern population is underrepresented in current databases. Accordingly, we established Iranome database (www.iranome.com) by performing whole exome sequencing on 800 individuals from eight major Iranian ethnic groups representing the second largest population of Middle East. We identified 1,575,702 variants of which 308,311 were novel (19.6%). Also, by presenting higher frequency for 37,384 novel or known rare variants, Iranome database can improve the power of molecular diagnosis. Moreover, attainable clinical information makes this database a good resource for classifying pathogenicity of rare variants. Principal components analysis indicated that, apart from Iranian-Baluchs, Iranian-Turkmen, and Iranian-Persian Gulf Islanders, who form their own clusters, rest of the population were genetically linked, forming a super-population. Furthermore, only 0.6% of novel variants showed counterparts in "Greater Middle East Variome Project", emphasizing the value of Iranome at national level by releasing a comprehensive catalog of Iranian genomic variations and also filling another gap in the catalog of human genome variations at international level. We introduce Iranome as a resource which may also be applicable in other countries located in neighboring regions historically called Greater Iran (Persia).


Assuntos
Biologia Computacional/métodos , Bases de Dados Genéticas , Etnicidade/genética , Genoma Humano , Genômica , Navegador , Variação Genética , Genética Populacional , Genômica/métodos , Genótipo , Geografia , Humanos , Irã (Geográfico) , Oriente Médio , Anotação de Sequência Molecular
7.
Am J Physiol Regul Integr Comp Physiol ; 317(3): R470-R484, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31242020

RESUMO

We studied relationships of cerebral spinal fluid (CSF) pulsatile flow at cervical, thoracic, and lumbar levels using phase-contrast cine MRI (PCCMRI) to determine the following: 1) instantaneous and average net flows at cervical, thoracic, and lumbar levels, 2) stochastic correlations of CSF flow with major arterial supplies and major draining veins, and 3) whether adjustments of cord-flow curves-using cord cross-sectional areas, caudal lengths, and caudal volumes-would normalize flow curves from different levels. We scanned 15 healthy volunteers without anesthesia, ages 23-46 yr, using external, retrocardiac-gated, two-dimensional PCCMRI at 3T. Transverse scans of the subarachnoid space, arteries, and veins were acquired and analyzed at cervical, thoracic, and lumbar levels. Instantaneous CSF flow decreased craniocaudally along the full time course of a cardiac cycle. Downward net flow generally increased craniocaudally. During diastole, instantaneous CSF flow decreased proportionally to cross-sectional area, caudal residual length, and caudal residual volume of the cord. The proportionalities were less consistent during systole. CSF, internal carotid artery (ICA), vertebral artery, and lower aorta temporal correlations were highest in systole and decreased craniocaudally. CSF flow temporally correlated better with lower aorta flow than with the ICA at T7 and L2 during systole but not diastole. Inferior vena cava temporal correlation increased craniocaudally. We conclude that whereas instantaneous flow is attenuated cranial caudally, net downward flow, per cardiac cycle, increases caudally, becoming statistically significant at T7 and below the conus medullaris. We can explain the results with the assumption of cord CSF production and peripheral-dominated CSF absorption.


Assuntos
Líquido Cefalorraquidiano/fisiologia , Fluxo Pulsátil/fisiologia , Medula Espinal/anatomia & histologia , Adulto , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Medula Espinal/irrigação sanguínea
8.
Mikrochim Acta ; 186(4): 254, 2019 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-30903376

RESUMO

An ultrasensitive electrochemiluminescence (ECL) disposable aptamer sensor (aptasensor) is presented for detection of myocardial infarction biomarker by quantification of troponin I in blood serum. A screen-printed electrode was modified with (a) aptamer-modified gold nanoparticles, (b) cyclometallated iridium(III)-poly-4-vinylpyridine nanoparticles, and (c) nitrogen-doped graphene in order to increase the loading capacity and conductivity of the aptasensor. If the aptasensor is exposed to troponin I, it will bind to the aptamer and desorb the aptamer from gold nanoparticles and the surface of the electrode. This generates an enhancement in ECL emission depending on troponin I concentration. ECL emission is strongly improved by aggregation-induced phenomenon, which is caused by inhibition of the water and oxygen quenching effect on the iridium complex ECL in aqueous media. Under optimum conditions, the aptasensor has a wide dynamic range that extends from 0.1 pM to 10 nM, with a 20 fM detection limit (S/N = 3) and a relative standard deviation of 3.1%. The ECL aptasensor was successfully applied to 20 individual human serum for the detection of troponin I biomarker. Graphical abstract Schematic presentation of electrochemiluminescence aptamer assay fabrication for detection of Troponin I. Carbon screen printed electrode (CSPE) was modified with nitrogen doped graphene (NG), gold nanoparticles (AuNPs), cyclometallated iridium(III)-polyvinylpyridine polymer nanoparticles, ionic liquid and bovine serum albumin.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Complexos de Coordenação/química , Grafite/química , Nanopartículas Metálicas/química , Poliestirenos/química , Polivinil/química , Troponina I/sangue , Sequência de Bases , Técnicas Eletroquímicas/métodos , Ouro/química , Humanos , Irídio/química , Limite de Detecção , Medições Luminescentes/métodos , Infarto do Miocárdio/diagnóstico , Nitrogênio/química
10.
Magn Reson Med ; 75(3): 1018-29, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25914199

RESUMO

PURPOSE: The utility of four-dimensional (4D) spiral flow in imaging of stenotic flows in both phantoms and human subjects with aortic stenosis is investigated. METHODS: The method performs 4D flow acquisitions through a stack of interleaved spiral k-space readouts. Relative to conventional 4D flow, which performs Cartesian readout, the method has reduced echo time. Thus, reduced flow artifacts are observed when imaging high-speed stenotic flows. Four-dimensional spiral flow also provides significant savings in scan times relative to conventional 4D flow. RESULTS: In vitro experiments were performed under both steady and pulsatile flows in a phantom model of severe stenosis (one inch diameter at the inlet, with 87% area reduction at the throat of the stenosis) while imaging a 6-cm axial extent of the phantom, which included the Gaussian-shaped stenotic narrowing. In all cases, gradient strength and slew rate for standard clinical acquisitions, and identical field of view and resolution were used. For low steady flow rates, quantitative and qualitative results showed a similar level of accuracy between 4D spiral flow (echo time [TE] = 2 ms, scan time = 40 s) and conventional 4D flow (TE = 3.6 ms, scan time = 1:01 min). However, in the case of high steady flow rates, 4D spiral flow (TE = 1.57 ms, scan time = 38 s) showed better visualization and accuracy as compared to conventional 4D flow (TE = 3.2 ms, scan time = 51 s). At low pulsatile flow rates, a good agreement was observed between 4D spiral flow (TE = 2 ms, scan time = 10:26 min) and conventional 4D flow (TE = 3.6 ms, scan time = 14:20 min). However, in the case of high flow-rate pulsatile flows, 4D spiral flow (TE = 1.57 ms, scan time = 10:26 min) demonstrated better visualization as compared to conventional 4D flow (TE = 3.2 ms, scan time = 14:20 min). The feasibility of 4D spiral flow was also investigated in five normal volunteers and four subjects with mild-to-moderate aortic stenosis. The approach achieved TE = 1.68 ms and scan time = 3:44 min. The conventional sequence achieved TE = 2.9 ms and scan time = 5:23 min. In subjects with aortic stenosis, we also compared both MRI methods with Doppler ultrasound (US) in the measurement of peak velocity, time to peak systolic velocity, and eject time. Bland-Altman analysis revealed that, when comparing peak velocities, the discrepancy between Doppler US and 4D spiral flow was significantly less than the discrepancy between Doppler and 4D Cartesian flow (2.75 cm/s vs. 10.25 cm/s), whereas the two MR methods were comparable (-5.75 s vs. -6 s) for time to peak. However, for the estimation of eject time, relative to Doppler US, the discrepancy for 4D conventional flow was smaller than that of 4D spiral flow (-16.25 s vs. -20 s). CONCLUSION: Relative to conventional 4D flow, 4D spiral flow achieves substantial reductions in both the TE and scan times; therefore, utility for it should be sought in a variety of in vivo and complex flow imaging applications.


Assuntos
Estenose da Valva Aórtica/fisiopatologia , Imageamento Tridimensional/métodos , Angiografia por Ressonância Magnética/métodos , Adulto , Idoso , Humanos , Masculino , Modelos Cardiovasculares , Imagens de Fantasmas , Fluxo Pulsátil/fisiologia
11.
Magn Reson Med ; 73(3): 939-50, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24604617

RESUMO

PURPOSE: Inaccuracy of conventional four-dimensional (4D) flow MR imaging in the presence of random unsteady and turbulent blood flow distal to a narrowing has been an important challenge. Previous investigations have revealed that shorter echo times (TE) decrease the errors, leading to more accurate flow assessments. METHODS: In this study, as part of a 4D flow acquisition, an Ultra-Short TE (UTE) method was adopted. UTE works based on a center-out radial k-space trajectory that inherently has a short TE. By employing free induction decay sampling starting from read-out gradient ramp-up, and by combining the refocusing lobe of the slice select gradient with the bipolar flow encoding gradient, TEs of ≈1 msec may be achieved. RESULTS: Both steady and pulsatile flow regimes, and in each case a range of Reynolds numbers, were studied in an in-vitro model. Flow assessment at low and medium flow rates demonstrated a good agreement between 4D UTE and conventional 4D flow techniques. However, 4D UTE flow significantly outperformed conventional 4D flow, at high flow rates for both steady and pulsatile flow regimes. Feasibility of the method in one patient with Aortic Stenosis was also demonstrated. CONCLUSION: For both steady and pulsatile high flow rates, the measured flow distal to the stenotic narrowing using conventional 4D flow revealed more than 20% error compared to the ground-truth flow. This error was reduced to less than 5% using the 4D UTE flow technique.


Assuntos
Estenose da Valva Aórtica/fisiopatologia , Velocidade do Fluxo Sanguíneo , Interpretação de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Angiografia por Ressonância Magnética/métodos , Reologia/métodos , Algoritmos , Estenose da Valva Aórtica/diagnóstico , Estudos de Viabilidade , Humanos , Aumento da Imagem/métodos , Angiografia por Ressonância Magnética/instrumentação , Imagens de Fantasmas , Fluxo Pulsátil , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
12.
J Food Sci Technol ; 52(4): 1872-80, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25829568

RESUMO

Dramatic growth in date (Phoenix dactylifera L.) production, makes it clear to apply proper methods to preserve this nutritious fruit for a long time. Numerous methods have been used to gain this goal in recent years that can be classified into non-thermal (fumigation, ozonation, irradiation, and packaging) and thermal (heat treatment, cold storage, dehydration, jam etc.) processing methods. In this paper these methods were reviewed and novel methods for date preservation were presented.

13.
Tumour Biol ; 35(7): 6763-8, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24722823

RESUMO

C-kit receptor (CD117) and its ligand, stem cell factor, play a key role in normal hematopoiesis. It has been demonstrated that its expression extremely increases in leukemias with myeloid commitment. We analyzed findings on CD117 expression together with other myeloid related markers in 203 de novo acute leukemias, referred to Iranian immunophenotyping centers: Iranian Blood Transfusion Organization (IBTO) and Baghiatallah Hospital (BH). All cases were characterized based on the French American British cooperative group (FAB) and European Group for Immunological Classification of Leukemias (EGIL). The cases comprised of 111 acute myeloblastic leukemia (AML), 86 acute lymphoblastic leukemia (ALL), and 6 acute undifferentiated leukemia (AUL). CD117 was positive in 75 % of AML and 50 % of AUL, whereas none of the ALL cases was positive for this marker. Although CD117 was positive in 100 % of M5a cases, no M5b positive was found (p = 0.036). The calculated specificity for myeloid involvement was 100 % for CD117 and CD33, and 98 % for CD13 and CD15 (p < 0.001). The calculated sensitivity for myeloid involvement was 83, 76, 64, and 41 % for CD13, CD117, CD33, and CD15, respectively (p < 0.001). We concluded that CD117 expression is a specific and rather sensitive marker for differential diagnosis between AML and ALL, and except for M5 subtypes, it fails to determine FAB subtypes; lack of expression in M5 can identify M5b. Therefore, it should be included in the routine primary panel for diagnosis of acute leukemias.


Assuntos
Leucemia Mieloide Aguda/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Proteínas Proto-Oncogênicas c-kit/sangue , Fator de Células-Tronco/sangue , Diagnóstico Diferencial , Regulação Neoplásica da Expressão Gênica , Humanos , Leucemia Mieloide Aguda/sangue , Leucemia Mieloide Aguda/patologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/sangue , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia
14.
J Magn Reson Imaging ; 39(6): 1477-85, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24123721

RESUMO

PURPOSE: To validate conventional phase-contrast MRI (PC-MRI) measurements of steady and pulsatile flows through stenotic phantoms with various degrees of narrowing at Reynolds numbers mimicking flows in the human iliac artery using stereoscopic particle image velocimetry (SPIV) as gold standard. MATERIALS AND METHODS: A series of detailed experiments are reported for validation of MR measurements of steady and pulsatile flows with SPIV and CFD on three different stenotic models with 50%, 74%, and 87% area occlusions at three sites: two diameters proximal to the stenosis, at the throat, and two diameters distal to the stenosis. RESULTS: Agreement between conventional spin-warp PC-MRI with Cartesian read-out and SPIV was demonstrated for both steady and pulsatile flows with mean Reynolds numbers of 130, 160, and 190 at the inlet by evaluating the linear regression between the two methods. The analysis revealed a correlation coefficient of > 0.99 and > 0.96 for steady and pulsatile flows, respectively. Additionally, it was found that the most accurate measures of flow by the sequence were at the throat of the stenosis (error < 5% for both steady and pulsatile mean flows). The flow rate error distal to the stenosis was primarily found to be a function of narrowing severity including dependence on proper Venc selection. CONCLUSION: SPIV and CFD provide excellent approaches to in vitro validation of new or existing PC-MRI flow measurement techniques.


Assuntos
Hidrodinâmica , Imageamento por Ressonância Magnética/métodos , Fluxo Pulsátil , Reologia/métodos , Velocidade do Fluxo Sanguíneo , Constrição Patológica , Técnicas In Vitro , Magnetismo , Imagens de Fantasmas , Reprodutibilidade dos Testes
15.
J Neurosurg Case Lessons ; 7(9)2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38408336

RESUMO

BACKGROUND: Perivascular spaces (PVSs) are spaces in brain parenchyma filled with interstitial fluid surrounding small cerebral vessels. Massive enlargements of PVSs are referred to as "giant tumefactive perivascular spaces" (GTPVSs), which can be classified into three types depending on their localization. These lesions are rare, predominantly asymptomatic, and often initially misinterpreted as cystic tumor formations. However, there are several reported cases in which GTPVSs have induced neurological symptoms because of their size, mass effect, and location, ultimately leading to obstructive hydrocephalus necessitating neurosurgical intervention. Presented here are three diverse clinical presentations of GTPVS. OBSERVATIONS: Here, the authors observed an asymptomatic case of type 1 GTPVS and two symptomatic cases of type 3 GTPVS, one causing local mass effect and the other hydrocephalus. LESSONS: GTPVSs are mostly asymptomatic lesions. Patients without symptoms should be closely monitored, and biopsy is discouraged. Hydrocephalus resulting from GTPVS necessitates surgical intervention. In these cases, third ventriculostomy, shunt implantation, or direct cyst fenestration are surgical options. For patients presenting with symptoms from localized mass effect, a thorough evaluation for potential neurosurgical intervention is imperative. Follow-up in type 3 GTPVS is recommended, particularly in untreated cases. Given the infrequency of GTPVS, definitive guidelines for neurosurgical treatment and subsequent follow-up remain elusive.

16.
Artigo em Inglês | MEDLINE | ID: mdl-38847530

RESUMO

BACKGROUND AND OBJECTIVES: Traditional neurosurgical education has relied heavily on the Halstedian "see one, do one, teach one" approach which is increasingly perceived as inefficient in contemporary settings marked by a steady decline in surgical caseload. In recent years, simulation training has emerged as an effective and accessible training alternative. To date, however, there is no standardized criterion pertaining to the quality and implementation of simulators in neurosurgical education and training. This research aims to compare the efficacy of virtual reality (VR) and Phantom-based simulation training in the context of neurosurgical skill acquisition, with a focus on middle cerebral artery aneurysm clipping. METHODS: An immersive VR clipping tool and a haptic clipping simulator incorporating 3-dimensional printing, additive manufacturing, and rheological analyses were developed. Twenty-two participants, comprising 12 medical students, 6 neurosurgical residents, and 4 experienced neurosurgeons, tested and evaluated both simulators for face and content validity. Construct and predictive validity of the simulators were assessed using an objective structured assessment scale for aneurysm clipping, measuring participants' performances and progress. RESULTS: Both modalities were deemed highly advantageous for educational purposes. Objective evaluations, however, revealed measurable differences in usability, efficacy, and transferability of the learned skills with VR excelling in procedural planning and visualization while Phantom simulation being noticeably superior in conveying surgical skills. CONCLUSION: Simulation training can accelerate the neurosurgical learning curve. The results of this study highlight the importance of establishing standardized criteria for the implementation and assessment of simulation modalities, ensuring consistent quality and efficacy in neurosurgical education.

17.
Prog Cardiovasc Dis ; 2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38925255

RESUMO

Cardiovascular magnetic resonance (CMR) imaging is the gold standard test for myocardial tissue characterization and chamber volumetric and functional evaluation. However, manual CMR analysis can be time-consuming and is subject to intra- and inter-observer variability. Artificial intelligence (AI) is a field that permits automated task performance through the identification of high-level and complex data relationships. In this review, we review the rapidly growing role of AI in CMR, including image acquisition, sequence prescription, artifact detection, reconstruction, segmentation, and data reporting and analysis including quantification of volumes, function, myocardial infarction (MI) and scar detection, and prediction of outcomes. We conclude with a discussion of the emerging challenges to widespread adoption and solutions that will allow for successful, broader uptake of this powerful technology.

18.
Pathog Dis ; 812023 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-37286796

RESUMO

Bacterial vaginosis, a type of vaginal inflammation, can be considered the main reason for abnormal discharges of the vagina and vaginal dysbiosis during reproductive years. Epidemiological investigations of females suffering from vaginitis demonstrated that at least 30% to 50% of all women had Bacterial vaginosis (BV). One of the fields of treatment is the use of probiotics, probiotics are commonly defined as viable microorganisms (yeasts or bacteria) that can positively affect the health of their hosts. They are used in foods, notably fermented milk products, and medicine-related products. The development of new probiotic strains is aimed at more active advantageous organisms. Lactobacillus species are the dominant bacteria in a normal vagina that can decrease the pH of the vagina by the production of lactic acid. A number of lactobacilli types can produce hydrogen peroxide as well. The presence of hydrogen peroxide-induced low pH can prevent the growth of several other microorganisms. The vaginal flora of BV cases can modify by replacing the Lactobacillus species with a high density of anaerobic bacteria (i.e. Mobiluncus sp. Bacteroides sp.), Mycoplasma hominis, and Gardnerella vaginalis. More vaginal infections are treated with medications, while there is a possibility of recurrence and chronic infection because of the adverse effects on the indigenous lactobacilli. Probiotics and prebiotics have shown capacities for optimizing, maintaining, and restoring the vaginal microflora. Therefore, biotherapeutics can offer alternative approaches to reduce infections of the vagina and thus promote consumers' health.


Assuntos
Probióticos , Vaginose Bacteriana , Feminino , Humanos , Vaginose Bacteriana/tratamento farmacológico , Peróxido de Hidrogênio/uso terapêutico , Vagina/microbiologia , Gardnerella vaginalis , Lactobacillus , Probióticos/uso terapêutico
19.
Int J STD AIDS ; 34(4): 214-228, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36630307

RESUMO

Penile cancer is a rare malignancy which HIV infection appears to increase the risk of. The magnitude of this risk and the pathogenesis remain unclear. A comprehensive review of the literature was undertaken using conventional search strategies. Twenty-four publications were identified by this methodology, of which nine were case reports and 15 were observational studies. These studies were highly heterogeneous, with varying study designs, populations, and objectives. The risk of penile cancer within HIV-positive individuals is significantly greater than in those without HIV (RR = 3 .7 to 5.8, 3 studies; SIR = 3.8 to 11.1, 4 studies). HIV is also shown to influence disease characteristics, with a four-fold increased risk of death from penile cancer. Moreover, progression from intraepithelial neoplasia occurs earlier in HIV, six years sooner than in HIV-negative men. HIV-positive men have a higher prevalence of HPV infection. Ethnicity is also shown to modulate the relationship between HIV and penile carcinoma, with a higher risk of cancer in Hispanic, compared with Caucasian, HIV-positive men. This review has collated data from diverse sources to improve understanding of the relationship between HIV and penile cancer. This relationship has been quantitatively and qualitatively characterised and highlights areas deserving further enquiry.


Assuntos
Infecções por HIV , Infecções por Papillomavirus , Neoplasias Penianas , Masculino , Humanos , Infecções por HIV/epidemiologia , Neoplasias Penianas/patologia , Infecções por Papillomavirus/epidemiologia , Papillomaviridae , Prevalência
20.
Prog Cardiovasc Dis ; 81: 54-77, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37689230

RESUMO

Artificial Intelligence (AI) is a broad discipline of computer science and engineering. Modern application of AI encompasses intelligent models and algorithms for automated data analysis and processing, data generation, and prediction with applications in visual perception, speech understanding, and language translation. AI in healthcare uses machine learning (ML) and other predictive analytical techniques to help sort through vast amounts of data and generate outputs that aid in diagnosis, clinical decision support, workflow automation, and prognostication. Coronary computed tomography angiography (CCTA) is an ideal union for these applications due to vast amounts of data generation and analysis during cardiac segmentation, coronary calcium scoring, plaque quantification, adipose tissue quantification, peri-operative planning, fractional flow reserve quantification, and cardiac event prediction. In the past 5 years, there has been an exponential increase in the number of studies exploring the use of AI for cardiac computed tomography (CT) image acquisition, de-noising, analysis, and prognosis. Beyond image processing, AI has also been applied to improve the imaging workflow in areas such as patient scheduling, urgent result notification, report generation, and report communication. In this review, we discuss algorithms applicable to AI and radiomic analysis; we then present a summary of current and emerging clinical applications of AI in cardiac CT. We conclude with AI's advantages and limitations in this new field.


Assuntos
Inteligência Artificial , Reserva Fracionada de Fluxo Miocárdico , Humanos , Coração , Algoritmos , Tomografia Computadorizada por Raios X , Angiografia por Tomografia Computadorizada
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa