Biomedical subjects

Ruchira Garg

Publications and source records attributed to Ruchira Garg.

4 recordsLinked to original sources

PubMed2006

Faster flow quantification using sensitivity encoding for velocity-encoded cine magnetic resonance imaging: in vitro and in vivo validation.

PURPOSE: To test the agreement between conventional and sensitivity-encoded (SENSE) velocity encoded cine (VEC) MRI in a flow phantom and in subjects with congenital and acquired heart disease. MATERIALS AND METHODS: Flow measurements were performed in a 1.5 T scanner using a segmented k-space VEC MRI sequence and then repeated with a SENSE factor of 2. The flow phantom used a piston pump to generate physiologic arterial waveforms (0.5-4.9 L/min). In the subjects, flow measurements were performed in the ascending aorta (N = 33) and/or the main pulmonary artery (N = 24). RESULTS: Utilization of SENSE reduced the scan time by 50%. In the phantom, measurements without and with SENSE agreed closely with a mean difference of 0.01 +/- 0.08 L/min or 0.12% +/- 3.8% (P = 0.68). In the subjects, measurements without and with SENSE also agreed closely with a mean difference of 0.08 +/- 0.36 L/min or 1.3% +/- 7.2% (P = 0.08). Compared with standard imaging, the use of SENSE reduced the signal-to-noise ratio (SNR) by 28% in the phantom (N = 10) and 27% in vivo (N = 22). CONCLUSION: VEC MRI flow measurements with a SENSE factor of 2 were twice as fast and agreed closely with the conventional technique in vitro and in vivo. VEC MRI with SENSE can be used for rapid and reliable quantification of blood flow.

Adolescent↗

PubMed2006

Simulations of congenital septal defect closure and reactivity testing in patient-specific models of the pediatric pulmonary vasculature: A 3D numerical study with fluid-structure interaction.

Clinical imaging methods are highly effective in the diagnosis of vascular pathologies, but they do not currently provide enough detail to shed light on the cause or progression of such diseases, and would be hard pressed to foresee the outcome of surgical interventions. Greater detail of and prediction capabilities for vascular hemodynamics and arterial mechanics are obtained here through the coupling of clinical imaging methods with computational techniques. Three-dimensional, patient-specific geometric reconstructions of the pediatric proximal pulmonary vasculature were obtained from x-ray angiogram images and meshed for use with commercial computational software. Two such models from hypertensive patients, one with multiple septal defects, the other who underwent vascular reactivity testing, were each completed with two sets of suitable fluid and structural initial and boundary conditions and used to obtain detailed transient simulations of artery wall motion and hemodynamics in both clinically measured and predicted configurations. The simulation of septal defect closure, in which input flow and proximal vascular stiffness were decreased, exhibited substantial decreases in proximal velocity, wall shear stress (WSS), and pressure in the post-op state. The simulation of vascular reactivity, in which distal vascular resistance and proximal vascular stiffness were decreased, displayed negligible changes in velocity and WSS but a significant drop in proximal pressure in the reactive state. This new patient-specific technique provides much greater detail regarding the function of the pulmonary circuit than can be obtained with current medical imaging methods alone, and holds promise for enabling surgical planning.

Blood Flow Velocity↗

PubMed2005

Effects of metallic implants on magnetic resonance imaging evaluation of Fontan palliation.

This study examined the effects of endovascular metallic implants on the ability of magnetic resonance imaging to evaluate cardiovascular anatomy and to assess ventricular size and function in 101 consecutive patients with Fontan palliation. Compared with studies in patients without implants, in whom 100% of anatomic segments were adequately visualized and the median image quality grade for ventricular function assessment was 5 of 5, the presence of any implant (54% of studies) reduced the proportion of adequately imaged anatomy to 77% (p <0.001) and the median image quality grade for ventricular function assessment to 3 of 5 (p <0.001).

Adolescent↗

PubMedDate not supplied

Hyperglycemia and retinopathy of prematurity in very low birth weight infants.

OBJECTIVE: Retinopathy of prematurity (ROP) remains a leading cause of morbidity in the very low-birth-weight (VLBW) infant. This study investigates a possible association between serum/blood glucose and the development of ROP. METHODS: A retrospective case-control study of all infants born between 1992 and 1997 at the Johns Hopkins Hospital with birth weights less than 1000 g who developed Stage 3 or 4 ROP was conducted. Controls either had Stage 1 ROP or no eye disease and were matched 2:1 with ROP patients for gestational age, birth weight and year of birth. Odds ratios (ORs) of ROP were calculated for multiple exposures over the first month after birth, including oxygen concentration (FiO(2)), blood glucose levels, vitamin E, mean airway pressure and mean blood pressure. RESULTS: In a simple logistic regression analysis, we found an increased ROP risk for: (1) each 10 mg/dl increase of mean glucose (OR 1.96; 95% CI 1.13 to 3.42), (2) each 1% increase of mean FiO(2) (OR 1.06; 95% CI 1.004 to 1.13), (3) history of dopamine infusion (OR 5.4; 95% CI 1.16 to 25.2) and (4) intraventricular hemorrhage Grade 3 or 4 (OR 7.3; 95% CI 1.53 to 34.7). Using a multiple regression model, we found an increased ROP risk for each 10 mg/dl increase of mean glucose (OR 2.7; 95% CI 1.003 to 7.27). Each IU/kg/day of vitamin E supplementation reduced ROP risk (OR 0.37; 95% CI 0.16-0.86). CONCLUSION: In this study, we could demonstrate that glucose levels in the first month of life are associated with the development of ROP. Further studies have to determine if this association is causal or if hyperglycemia is just an expression of severity of illness.

Case-Control Studies↗