Noninvasive Tool (noninvasive + tool)

Distribution by Scientific Domains
Distribution within Medical Sciences

Selected Abstracts

Cardiac Magnetic Resonance (CMR) Imaging: A Noninvasive Tool for Functional and Morphological Assessment of Coronary Artery Disease:

Current Clinical Applications, Potential Future Concepts
(J Interven Cardiol 2003;16:457,463) [source]

Virtual Laryngoscopy: a Noninvasive Tool for the Assessment of Laryngeal Tumor Extent

Yuling Yan PhD
Abstract Objectives: Present a clinical application of virtual laryngoscopy (VL) in the assessment of laryngeal tumor and its extent. Study Design: CT data from two subjects are acquired for this preliminary study. One subject is a healthy volunteer and the other is a patient with laryngeal tumor. The laryngeal framework and upper airway are reconstructed using CT data, which allows for computer-aided internal and external anatomical views and interactive fly-through. Methods: These CT data are reconstructed into 0.5 mm slice images, resulting in a total of 200,300 image slices. An advanced commercial visualization software (AMIRA) is used for 3D image segmentation, reconstruction and surface rendering of laryngeal anatomical structures. Results: The 3D laryngeal framework and upper airway are reconstructed for both the tumor patient and the healthy subject. The conventional views of the reconstructed vocal folds are compared with those obtained from fiber-optic laryngoscope. Additionally, unique views of the vocal folds obtained from retrograde visualization and fly-through are presented, which are not possible to obtain using conventional endoscope imaging. The segmented anatomical model and the tumor from the patient's CT images were displayed individually to show the distribution of the tumor and its extent as well as spatial and contextual relationships to the larynx and airway anatomical structures. Conclusions: This study demonstrated the potential application of VL as a noninvasive clinical diagnostic tool for the assessment of laryngeal tumor and its extent. Our preliminary results demonstrated that the VL may provide valuable insights for the diagnosis and treatment planning for laryngeal and airway tumors. The noninvasive VL may complement the invasive laryngoscopic examinations for the staging of tumors and follow-ups on surgical interventions. [source]

Magnetic resonance spectroscopy (MRS) and its application in Alzheimer's disease

Pravat K. Mandal
Abstract Magnetic resonance spectroscopy (MRS) is a noninvasive tool to measure the chemical composition of tissues (in vivo) and characterize functional metabolic processes in different parts of the human organs. It provides vital biological information at the molecular level. Combined with magnetic resonance imaging (MRI), an integrated MRI/MRS examination provides anatomical structure, pathological function, and biochemical information about a living system. MRS provides a link between the biochemical alterations and the pathophysiology of disease. This article provides a comprehensive description of the MRS technique and its application in Alzheimer's disease (AD) research. This review is a primer for students and researchers seeking a firm theoretical understanding of MRS physics as well as its application in clinical AD research. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part A 30A: 40,64, 2007. [source]

REVIEW: Aortic Atheromas: Current Concepts and Controversies,A Review of the Literature

Thenappan Thenappan M.D.
The frequent use of transesophageal echocardiogram (TEE) has led to the increased recognition of aortic atheromas. Retrospective and prospective follow-up studies have reported an association between aortic atheromas and stroke in the high-risk patient population, with complex plaques being more likely to embolize than simple plaques. However, TEE-based studies in the low-risk cohorts have failed to show a similar association. There is growing body of evidence suggesting that aortic atheroma is a marker of generalized atherosclerosis. Although magnetic resonance (MR) imaging and computed tomography (CT) scan are emerging as a powerful noninvasive tool for characterization of aortic atheromas, TEE is the imaging modality of choice. Currently, treatment of aortic atheromas is not well defined, and mixed outcomes have been reported for anticoagulation therapy with warfarin. Statins appear promising based on their plaque stabilization properties. However, there are no randomized control trials to establish the role of both anticoagulation and statins in patients with aortic atheromas, and are warranted in the future. [source]

Infarct Size Assessment in Mice

Marielle Scherrer-Crosbie M.D., Ph.D.
Genetically modified mice are used extensively in models of ischemia reperfusion (I/R) and nonreperfused myocardial infarction (MI) to gain insights into pathways involved in these pathologies. Echocardiography is an ideal noninvasive tool to serially monitor the cardiac murine phenotype. The present review details the surgical aspects of I/R and MI models and the measurement of MI size by pathology techniques and the input of echocardiographic techniques including the extent of wall motion abnormality and of perfusion defects using myocardial contrast echocardiography in the assessment of murine area at risk and MI size. [source]

Oxygen-enhanced MR imaging of mice lungs

K.N. Watt
Abstract Inhaled molecular oxygen has been widely used in humans to evaluate pulmonary ventilation using MRI. MR imaging has recently played a greater role in examining the morphologic and physiologic characteristics of mouse models of lung disease where structural changes are highly correlated to abnormalities in respiratory function. The motivation of this work is to develop oxygen-enhanced MR imaging for mice. Conventional human MR techniques cannot be directly applied to mouse imaging due to smaller dimensions and faster cardiac and respiratory physiology. This study examines the development of oxygen-enhanced MR as a noninvasive tool to assess regional ventilation in spontaneously breathing mice. An optimized cardiac-triggered, respiratory-gated fast spin-echo imaging sequence was developed to address demands of attaining adequate signal from the parenchyma, maintaining practical acquisition times, and compensating for rapid physiological motion. On average, a 20% T1 -shortening effect was observed in mice breathing 100% oxygen as compared to air. The effect of ventilation was shown as a significant signal intensity increase of 11% to 16% in the mouse parenchyma with 100% oxygen inhalation. This work demonstrates that adequate contrast and resolution can be achieved using oxygen-enhanced MR to visualize ventilation, providing an effective technique to study ventilation defects in mice. Magn Reson Med, 2008. © 2008 Wiley-Liss, Inc. [source]

Coronary Flow Reserve by Contrast-Enhanced Echocardiography: A New Noninvasive Diagnostic Tool for Cardiac Allograft Vasculopathy

F. Tona
Noninvasive tests have proven unsatisfactory in cardiac allograft vasculopathy (CAV) diagnosis. We assessed coronary flow reserve (CFR) by contrast-enhanced transthoracic echocardiography (CE-TTE) in heart transplantation (HT). CFR was assessed in the left anterior descending coronary artery in 73 HT recipients (59 male, aged 50 ± 12 years at HT), at 8 ± 4.5 years post-HT. CFR measurements were taken blindly from coronary angiographies. CFR cut points were the standard value of ,2 and those defined by receiver operating characteristics (ROC) curve analysis. CFR was lower in patients with CAV (2.3 ± 0.7 vs. 3.2 ± 0.5, p < 0.0001). The ,2 cut point was 100% specific and 38% sensitive. The ,2.7 cut point, optimal by ROC analysis, was 87% specific and 82% sensitive. Accuracy rose from 71% with the standard ,2 cut point to 85% with the optimal cut point of ,2.7. CFR by CE-TTE may offer promise as a novel, easily repeatable and accurate noninvasive tool in CAV detection. However, further longitudinal studies in larger patient cohorts are warranted before widespread adoption can be advocated. [source]

Impact of Preceding Ventricular Premature Beats on Heart Rate Turbulence

Hung Yi Chen M.D.
Background: Heart rate turbulence (HRT) has recently been introduced as a noninvasive tool for studying autonomic dysfunction. It presented short time fluctuation of sinus cycle length following single ventricular premature contraction (VPC). However, HRT parameters may be influenced by different factors. This study aimed to evaluate the possible influence of VPC frequency on HRT. Methods: 24-h Holter recording was performed in patients with VPCs initially detected by 12-lead electrocardiography (ECG) in the outpatient department. The numbers of VPCs in 2- and 5-minute durations preceding each VPC tachogram were calculated. The HRT parameters and the numbers of the VPCs preceding VPC tachograms were analyzed. Results: There were 23,122 available VPC tachograms from 107 healthy subjects included in the study. The turbulence onset (TO) value increased and the turbulence slope (TS) value decreased as VPC's frequency increased. The TO values rapidly increased when the number of VPCs was >15 beats in the 2-minute and >35 beats in the 5-minute durations. There was also a prominent decrease in TS values when the VPCs reached 14 and 30 beats in the 2- and 5-minute durations, respectively. Conclusion: Physiologic baroreflex may be attenuated under intensive stimulation, which is evidenced by blunted HRT parameters by frequent VPCs. Physiologic response to VPC's frequency may be related to baroreflex fatigue and is demonstrated as a sigmoid curve. [source]

Usefulness of Nonlinear Analysis of ECG Signals for Prediction of Inducibility of Sustained Ventricular Tachycardia by Programmed Ventricular Stimulation in Patients with Complex Spontaneous Ventricular Arrhythmias

Ornella Durin M.D.
Introduction: The aim of our study was to assess the effectiveness of the nonlinear analysis (NLA) of ECG in predicting the results of invasive electrophysiologic study (EPS) in patients with ventricular arrhythmias. Methods: We evaluated 25 patients with history of cardiac arrest, syncope, sustained, or nonsustained ventricular tachycardia (VT). All patients underwent electrophysiologic study (EPS) and nonlinear analysis (NLA) of ECG. The study group was compared with a control group of 25 healthy subjects, in order to define the normal range of NLA. ECG was processed in order to obtain numerical values, which were analyzed by nonlinear mathematical functions. Patients were classified through the application of a clustering procedure to the whole set of functions, and the correlation between the results of nonlinear analysis of ECG and EPS was tested. Results: NLA assigned all patients with negative EPS to the same class of healthy subjects, whereas the patients in whom VT was inducible had been correctly and clearly isolated into a separate cluster. In our study, the result of NLA with application of the clustering technique was significantly correlated to that of EPS (P < 0.001), and was able to predict the result of EPS, with a negative predictive value of 100% and a positive predictive value of 100%. Conclusions: NLA can predict the results of EPS with good negative and positive predictive value. However, further studies are needed in order to verify the usefulness of this noninvasive tool for sudden death risk stratification in patients with ventricular arrhythmias. [source]

Inflammatory cytokine gene expression in the urinary sediment of patients with lupus nephritis

Rebecca Wing-Yan Chan
Objective Lupus nephritis is characterized by intrarenal inflammation and lymphocyte activation. In the present study, the expression of cytokine genes in the urinary sediment of patients with systemic lupus erythematosus (SLE) was examined. Methods We studied 3 SLE patient groups (25 with active lupus nephritis [active group], 25 with inactive SLE and previous renal involvement [remission group], 20 with inactive SLE and no history of renal involvement [nonrenal SLE group]) and 2 control groups (10 patients with noninflammatory renal diseases [non-SLE group] and 10 healthy volunteers [healthy group]). Cytokine gene expression in the urinary sediment was studied by real-time quantitative polymerase chain reaction. Results Expression of interferon-, (IFN,) in urinary sediment was significantly higher in the active group than in all other groups (P < 0.001 by Kruskal-Wallis test). Among the SLE patient groups, there was a close correlation between IFN, expression and the overall SLE Disease Activity Index (SLEDAI) score (Spearman's r = 0.590, P < 0.001) and the SLEDAI renal score (r = 0.642, P < 0.001). Urinary expression of interleukin-2 (IL-2) in the active group was significantly higher than that in the healthy group (P = 0.046) but not in the remission or nonrenal SLE groups. There was no difference in the levels of IL-4 expression among the SLE groups. Conclusion We found a predominance of Th1 cytokine in the urinary sediment of patients with active lupus nephritis. Measurement of cytokine gene expression in urinary sediment may be a useful noninvasive tool for assessing the severity of renal involvement in SLE. [source]

In Vivo Determination of Bone Structure in Postmenopausal Women: A Comparison of HR-pQCT and High-Field MR Imaging,

Galateia J Kazakia PhD
Abstract Bone structural measures obtained by two noninvasive imaging tools,3T MRI and HR-pQCT,were compared. Significant but moderate correlations and 2- to 4-fold discrepancies in parameter values were detected, suggesting that differences in acquisition and analysis must be considered when interpreting data from these imaging modalities. Introduction: High-field MRI and high resolution (HR)-pQCT are currently being used in longitudinal bone structure studies. Substantial differences in acquisition and analysis between these modalities may influence the quantitative data produced and could potentially influence clinical decisions based on their results. Our goal was to compare trabecular and cortical bone structural measures obtained in vivo by 3T MRI and HR-pQCT. Materials and Methods: Postmenopausal osteopenic women (n = 52) were recruited for this study. HR-pQCT imaging of the radius and tibia was performed using the XtremeCT scanner, with a voxel size of 82 × 82 × 82 ,m3. MR imaging was performed on a 3T Signa scanner using SSFP imaging sequences, with a pixel size of 156 × 156 ,m2 and slice thickness of 500 ,m. Structure parameters were calculated using standard HR-pQCT and MRI analysis techniques. Relationships between measures derived from HR-pQCT, MRI, and DXA were studied. Results: Significant correlations between HR-pQCT and MRI parameters were found (p < 0.0001) and were strongest for Tb.N (r2 = 0.52), Ct.Th (r2 = 0.59), and site-specific Tb.Sp (r2 = 0.54,0.60). MRI and HR-pQCT provided statistically different values of structure parameters (p < 0.0001), with BV/TV and Tb.Th exhibiting the largest discrepancies (MR/HR-pQCT = 3,4). Although differences in the Tb.N values were statistically significant, the mean differences were on the order of our reproducibility measurements. Systematic differences between MRI and HR-pQCT analysis procedures leading to discrepancies in cortical thickness values were observed, with MRI values consistently higher. Minimal correlations were found between MRI or HR-pQCT parameters and DXA BMD or T-score, except between HR-pQCT measures at the radius and the ultradistal radius T-scores, where moderate correlations were found (r2 = 0.19,0.58). Conclusions: This study provides unique insight into two emerging noninvasive tools for bone structure evaluation. Our findings highlight the significant influence of analysis technique on results of in vivo assessment and underscore the importance of accounting for these differences when interpreting results from these modalities. [source]

Geographic variation in loud calls of sportive lemurs (Lepilemur ssp.) and their implications for conservation

Maria Méndez-Cárdenas
Abstract Bioacoustical studies in nonhuman primates have shown that loud calls can be reliably used as a noninvasive diagnostic tool for discriminating cryptic taxa, for their monitoring in the field as well as for the reconstruction of their phylogeny. To date, it is unknown, whether loud calls can be used for these purposes in sportive lemurs, for which current genetic studies suggest the existence of at least 24 cryptic species. The aim of this study was to compare the structure of loud calls of populations of sportive lemurs to characterize informative acoustic traits for taxa discrimination and to establish a phylogenetic tree based on acoustic structure. We have based our study on Inter-River-Systems (IRSs) as operational taxonomic units. Samples were collected from nine different localities of four IRSs along a transect from northwestern to northern Madagascar. Two call types, the ouah and the high-pitched call, were present in almost all IRSs. Six temporal and eight spectral parameters were measured in 196 calls of the best quality given by 21 different males. Variation within and between IRSs was assessed by multivariate statistics. Loud calls differed significantly among the different IRSs. The IRSs varied most in spectral parameters, whereas temporal parameters were less variable. Phylogenetic analysis using parsimony yielded 11 out of 17 acoustic characters as phylogenetically informative. The acoustic tree had an average branch support of 78%. Its topology coincided less with geographic distances than with genetic tree topology. Altogether our findings revealed that loud calls separated geographically isolated populations of sportive lemurs specifically. Based on these results, noninvasive tools for diagnosis and monitoring of cryptic species in nature can be developed for conservation management. Am. J. Primatol. 70:828,838, 2008. © 2008 Wiley-Liss, Inc. [source]