Computed Tomography in the Evaluation of Fontan Circulation

Parveen Kumar,Mona Bhatia 한국심초음파학회 2021 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.29 No.2

The Fontan procedure is a well-established surgical technique to improve survival in patients with univentricular heart disease. The procedure reroutes the systemic venous flow to the lungs, bypassing the right ventricle. The originally proposed method involved direct anastomosis of the right atrium to the pulmonary artery. Since then, several modifications have been made in the original technique leading to the modern Fontan, or total cavopulmonary connection. The modern Fontan technique has shown improved surgical outcomes and increased life expectancy in patients with univentricular disease. Due to the increased survival of these patients, long-term complications are becoming more prevalent. Common complications of Fontan procedure include right atrial dilatation and thrombosis; conduit stenosis and thrombosis; right-to-left and left-to-right shunts; hepatic congestion and cirrhosis; and lymphovascular. Computed tomography (CT) can reliably depict the normal Fontan anatomy and various postoperative complications. A fundamental understanding of the techniques of CT, including imaging protocols and common interpretive pitfalls, allows targeted imaging and precise reporting of clinically significant findings. Radiologists should be familiar with the multiple stages of single-ventricle palliation, normal Fontan anatomy, pathophysiology, and imaging features of common Fontan-related complications.

Role of Computed Tomography in Postoperative Follow-up of Arterial Switch Operation

Parveen Kumar,Mona Bhatia 한국심초음파학회 2021 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.29 No.1

An arterial switch operation (ASO) is the standard treatment for infants and children born with D-loop transposition of the great arteries. During the ASO, the great vessels are transected from the native roots, switched and anastomosed with the opposite roots. This is accompanied by the relocation of the pulmonary artery anterior to the aorta by using the LeCompte maneuver and the translocation of coronary arteries to the neo-aorta. ASO has led to improved overall survival, and postoperative mortality is rare. Despite the improved outcomes, several postoperative sequelae may occur, and therefore patients require long-term follow-up. Computed tomography (CT) has emerged as a robust imaging modality in pre and postoperative evaluation of a variety of congenital heart disorders including ASO. Unlike echocardiography and cardiovascular magnetic resonance, CT is not hindered by a poor acoustic window, metallic devices or the need for sedation or general anesthesia. CT with advanced three-dimensional postprocessing techniques, high pitch scanning, wider detector system, electrocardiogram-dependent modulation and dose-reduction strategies is invaluable in assessing the postoperative complications after ASO.

Coronary Artery Calcium Data and Reporting System (CAC-DRS): A Primer

Parveen Kumar,Mona Bhatia 한국심초음파학회 2023 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.31 No.1

The Coronary Artery Calcium Data and Reporting System (CAC-DRS) is a standardized reporting method for calcium scoring on computed tomography. CAC-DRS is applied on a per-patient basis and represents the total calcium score with the number of vessels involved. There are 4 risk categories ranging from CAC-DRS 0 to CAC-DRS 3. CAC-DRS also provides risk prediction and treatment recommendations for each category. The main strengths of CAC-DRS include a detailed and meaningful representation of CAC, improved communication between physicians, risk stratification, appropriate treatment recommendations, and uniform data collection, which provides a framework for education and research. The major limitations of CAC-DRS include a few missing components, an overly simple visual approach without any standard reference, and treatment recommendations lacking a basis in clinical trials. This consistent yet straightforward method has the potential to systemize CAC scoring in both gated and non-gated scans.

Analysis of Device Parameter Variations in In 1-x Ga x As Based Gate Stacked Double Metal Surrounding Gate Nanowire MOSFET

Parveen Kumar,Sanjeev Kumar Sharma,Balwinder Raj 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.6

The research focuses on the design and analysis of a Gate Stacked Double Metal Surrounding Gate Nanowire MOSFET (DMSG-NWFET) using In 1-x Ga x As as the channel material. The performance of this MOSFET has been evaluated through simulations conducted using the silvaco ATLAS TCAD tool. The study examines the impact of Channel Length (L) and the ratio of L1/L on various DC characteristics, including Drain-Induced-Barrier-Leakage (DIBL), OFF-current (Ioff ), ON-current (Ion), Subthreshold Slope (SS), and threshold voltage (Vth). In-depth analysis has been performed by varying the indium portion (1-x) in the In 1-x Ga x As channel. Additionally, we investigate the radio frequency (RF) performances by considering the variation of the 'In' fraction and incorporating the cut-off frequency (f T ). The investigation demonstrates hat the In 1-x Ga x As based Gate Stacked Double Metal Surrounding-Gate Nanowire MOSFET exhibits superior DC and RF performance when an optimized fraction of In (Indium). We believe that the proposed device structure holds significant promise for low power VLSI applications.

Performance Assessment and Optimization of Vertical Nanowire TFET for Biosensor Application

Parveen Kumar,Balwinder Raj 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.6

This paper reports the performance assessment of vertical silicon nanowire TFET (V-siNWTFET) design for biosensor applications using dielectric-modulation and gate underlap technique. The sensitivity of the V-siNWTFET is recognizing by immobilizing the different biological molecules such as lipids, biotin, uricase, protein, Gox, streptavidin, uriease, zein etc. in the cavity region which is created under the gate electrode and source oxide. The performance analysis is observed by varying the relative permittivity of the different biomolecules and analyzes the parametric variation both for neutral and charged biomolecules. The sensitivity of the biosensor has been detecting in the terms of drain current (I D), threshold voltage (V TH), subthreshold slope (SS), transconductance (g m), and I ON /I OFF ratio. The proposed device structure has capable to reduce the leakage currents and high sensitivity biosensor design in the nanoscale regimes. The obtained best optimum parameters of the proposed devices are I ON (1.37E-08 A/μm), I OFF (9.44E-19 A/μm), SS (29.97 mV/dec) and I ON /I OFF (4.29E + 10) ratio with gate work-function (ϕ gate = 4.8 eV) and uniformly doped (1 × 10 -19 cm -3 ) silicon nanowire at drain to source voltage (V DS = 1.0 V). The higher sensitivity of the proposed V-siNWTFET for Biosensor is observed for Zein biomolecules (K = 5).

Hybrid porous thin films: Opportunities and challenges for sensing applications

Kumar, Pawan,Kim, Ki-Hyun,Vellingiri, Kowsalya,Samaddar, Pallabi,Kumar, Parveen,Deep, Akash,Kumar, Naresh Elsevier 2018 Biosensors & bioelectronics Vol.104 No.-

<P><B>Abstract</B></P> <P>In this paper, the scientific progress in the field of thin film materials and their associated sensing technologies are described comprehensively to address the directions for future research and developments as per the need of modern-day technologies. To begin with, we briefly discussed the fundamental synthesis approaches for advanced thin films with an emphasis on the properties necessary for controlled fabrication (e.g., the elemental ratio and spatial arrangement). Subsequently, we explored the control, characterization, and optimization of hybrid porous thin films with respect to diverse sensing applications. The application of hybrid porous thin film materials has also been discussed in relation to the mechanisms used for biological, optical, electrical, acoustic, and other advanced sensing techniques (e.g., surface-enhanced Raman scattering (SERS)). Finally, conclusions are drawn to highlight the current status of thin film-based sensing technology along with its opportunities and challenges.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fundamental synthesis approaches of advanced thin films. </LI> <LI> Here optimization of hybrid porous thin films for advanced sensing techniques is reviewed. </LI> <LI> Current status, opportunities, and challenges are discussed. </LI> </UL> </P>

Principles and Clinical Applications of Feature-Tracking Cardiac Magnetic Resonance Imaging: A Literature Review

Kumar Parveen,Chopra Rahul 아시아심장혈관영상의학회 2022 Cardiovascular Imaging Asia Vol.6 No.3

Cardiac magnetic resonance (CMR) imaging has become a major tool for assessing patients with left ventricular dysfunction. CMR-derived volume, function, and late gadolinium enhancement (LGE) are the most important components of cardiac imaging. Recently, the direct assessment of myocardial fiber deformation by strain imaging has shown promise in diagnosing ventricular dysfunction at preclinical stage. There are multiple CMR based techniques for myocardial strain imaging. CMR feature tracking (CMR-FT) is a new, readily available, and convenient technique to evaluate myocardial deformation with high spatial resolution. CMR-FT–derived parameters such as strain, strain rate, torsion, and mechanical dispersion have shown diagnostic and prognostic values in patients with ischemic and nonischemic cardiomyopathies, incremental to left ventricular ejection fraction and LGE. The article reviews the basic principles, clinical applications, strength, and limitations of CMR-FT.

Coronary Artery Disease Reporting and Data System: A Comprehensive Review

Parveen Kumar,Mona Bhatia 한국심초음파학회 2022 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.30 No.1

The Coronary Artery Disease Reporting and Data System (CAD-RADS) is a standardized reporting method for coronary computed tomography angiography (CCTA). It summarizes the findings of CCTA in 6 categories ranging from CAD-RADS 0 (complete absence of coronary artery disease) to CAD-RADS 5 (total occlusion of at least one vessel). It is applied on per patient basis for the highest grade of the stenotic lesion. The CAD-RADS also provides category-specific treatment recommendations, helping patient management. The main objectives of the CAD-RADS are to improve the consistency in reporting, facilitate the communication between interpreting and referring clinicians, recommend the best course of patient management, and produce consistent data for quality improvement, research and education. However, CAD-RADS has many limitations, resulting into the misclassification of the observed findings, misinterpretation of the final category, and misguidance for the treatment based upon the single score. In this review, the authors discuss the CAD-RADS categories and modifiers, along with the strengths and limitations of this new classification system.

Arterial Tortuosity Syndrome: A Case Report and Literature Review

Kumar Parveen 아시아심장혈관영상의학회 2021 Cardiovascular Imaging Asia Vol.5 No.1

Arterial tortuosity syndrome (ATS) is a rare genetic syndrome characterized by elongation, tortuosity, stenosis, and aneurysm formation of major arteries. A one year ten months old boy presented with a history of repeated chest infections. Cardiovascular examination was normal except for slightly increased heart rate (130 beats per minute). Echocardiography revealed situs solitus, levocardia, D-loop, and atrioventricular and ventricular-arterial concordance. Both right and left pulmonary arteries appeared mildly narrowed in caliber, measuring 7.1 and 9 mm, respectively. CT angiography was advised for detailed evaluation of branch pulmonary arteries. CT showed early branching of the main pulmonary trunk with narrowed caliber branch pulmonary arteries forming an inverted V sign on axial maximum intensity projection images and an V sign on coronal volume rendering technique images. All the three arch branches showed tortuous courses after their origin. The thoraco-abdominal aorta also appeared tortuous in course that extended beyond the normal expected course into adjacent anatomic areas. There was no evidence of any aortic aneurysm or dissection. In view of these typical imaging findings, the diagnosis of ATS was made. This case report highlights the role of radiological imaging to ascertain the diagnosis and detect the complications of ATS.

Role of Computed Tomography in Pre- and Postoperative Evaluation of a Double-Outlet Right Ventricle

Parveen Kumar,Mona Bhatia 한국심초음파학회 2021 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.29 No.3

Double-outlet right ventricle (DORV) is a type of ventriculoarterial connection in which both great arteries arise entirely or predominantly from the right ventricle. The morphology of DORV is characterized by a ventricular septal defect (location and relationship with the semilunar valve); bilateral coni and aortomitral continuity; the presence or absence of outflow tract obstruction; tricuspid-pulmonary annular distance; and associated cardiac anomalies. The surgical approach varies with the type of DORV and is based on multiple variables. Computed tomography (CT) is a robust diagnostic tool for the preoperative and postoperative assessment of DORV. Unlike echocardiography and magnetic resonance imaging (MRI), CT imaging is not limited by small acoustic window, need for anaesthesia and can be used in patients with metallic implants. Current generations CT scanners with high spatial and temporal resolution, wide detectors, high-pitch scanning mode, dose-reduction algorithms, and advanced three-dimensional post-processing tools provide a low-risk, high-quality alternative to diagnostic cardiac catheterization or MRI, and have been increasingly utilized in nearly every type of congenital heart defect, including DORV.