Noninvasive Assessment (noninvasive + assessment)

Distribution by Scientific Domains
Distribution within Medical Sciences


Selected Abstracts


Noninvasive Assessment of Coronary Flow Reserve in the Left Anterior Descending Artery by Transthoracic Echocardiography before and after Stenting

ECHOCARDIOGRAPHY, Issue 8 2007
Elie Chammas M.D., F.E.S.C.
Background: Noninvasive assessment of coronary flow reserve in the left anterior descending artery (LAD) by transthoracic Doppler echocardiography (TTDE) has been already validated as a new method for determining the degree of stenosis over the proximal flow. Objectives: The aim of the study is to determine, by TTDE, the feasibility and the value of the coronary flow reserve (CFR) (defined as the maximal increase in coronary blood flow above its basal pressure for a given perfusion pressure when coronary circulation is maximally dilated) in the mid-to-distal LAD before and after percutaneous angioplasty and to demonstrate the early recovery of microvascular tone immediately after stenting. Methods: The study population consisted of 36 patients with significant isolated LAD stenosis (70,90%) identified by coronary angiography. CFR was recorded in the mid-to-distal LAD at rest and during hyperemia obtained after adenosine intravenous infusion before and after stenting. Results: Adequate visualization of the LAD was obtained in 25 out of 36 patients (70%). At rest the mean CFR was 1.5132 ± 0.33 (1.1,2.58). However, after stenting the mean CFR was significantly higher: 2.18 ± 0.55 (1.3,3.8), with P <0.01. Conclusions: CFR can be easily determined by TTE in approximately 70% of patients. Noninvasive Doppler echocardiography shows impaired CFR in patients with LAD disease. After stenting CFR is restored, demonstrating early recovery of microvascular tone. These results are comparable to those published in the same conditions. Larger series with a long-term follow-up may allow identifying patients at high risk for restenosis after stenting. [source]


Comparison of Coronary Flow Velocities Between Patients with Obstructive and Nonobstructive Type Hypertrophic Cardiomyopathy: Noninvasive Assessment by Transthoracic Doppler Echocardiography

ECHOCARDIOGRAPHY, Issue 1 2005
Seden Celik M.D.
Background: We aimed to compare coronary flow velocity (CFV) measurements of patients with nonobstructive (NHCM) and obstructive hypertrophic cardiomyopathy (HOCM) by using transthoracic Doppler echocardiography (TTDE). Methods and Results: In 11 patients with NHCM and 26 with HOCM, CFV in the distal left anterior descending (LAD) coronary was measured by TTDE (3.5 MHz) under the guidance of color Doppler flow mapping in addition to standard 2D and Doppler echocardiography. The results were compared with 24 normal participants who had no evidence of cardiac disease. Peak diastolic velocity of LAD was also higher in NHCM and HOCM than controls (52 ± 14 cm/sec and 54 ± 20 cm/sec vs 41 ± 11 cm/sec, respectively, P < 0.01). The analysis of systolic velocities revealed abnormal flow patterns in 16 (61%) patients with HOCM (12 systolic-reversal flow and 4 no systolic flow) and 6 (54%) (5 reversal flow and 1 zero flow) patients with NHCM (,11 ± 30 cm/sec and ,13 ± 38 cm/sec, vs 24 ± 9 cm/sec, respectively, P < 0.001). Linear regression analysis demonstrated no correlation between intraventricular pressure gradient and coronary flow velocities in HOCM patients. However, there were significant positive and negative correlations between septal thickness and diastolic and systolic velocities, respectively (r = 0.50, P < 0.002, and r =,0.43, P < 0.005). Conclusion: We conclude that the coronary flow velocity abnormalities are independent from the type of hypertrophic cardiomyopathy. [source]


Noninvasive Assessment of Influence of Resistant Respiration on Blood Flow Velocities Across the Cardiac Valves in Humans,A Quantification Study by Echocardiography

ECHOCARDIOGRAPHY, Issue 5 2004
Lijun Yuan M.D.
The aim of our study is to quantitatively investigate influence of the intrathoracic pressure change on the four cardiac valves' velocities and further verify a new proposal of the mechanism of respiratory influence on hemodynamics. Methods: Thirty healthy volunteers with no cardiopulmonary diseases were included. The intrathoracic pressure changes were measured with self-designed device. The velocity across the four cardiac valves during spontaneous respiration and with the intrathoracic pressure change at ,4, ,8, and ,12 mmHg, respectively, were recorded simultaneously with the electrocardiogram and respiratory curve. The respiratory variation indices (RVIs) were calculated. The average RVIs of mitral, aortic, tricuspid, and pulmonary valves were 12.54%, 13.19%; 6.23%, 8.27%; 20.27%, 24.36%; and 6.45%, 7.69% with intrathoracic pressure change at ,8 mmHg and ,12 mmHg, respectively. All the above parameters have a significant difference from those during spontaneous respiration (P < 0.01 or P < 0.001). We concluded that it might be the respiratory intrathoracic pressure change that causes the change of the velocity across the valves. (ECHOCARDIOGRAPHY, Volume 21, July 2004) [source]


Noninvasive Assessment of Significant Right Coronary Artery Stenosis Based on Coronary Flow Velocity Reserve in the Right Coronary Artery by Transthoracic Doppler Echocardiography

ECHOCARDIOGRAPHY, Issue 6 2003
M.D., Yoshiki Ueno
Background: Coronary flow velocity reserve (CFVR) measured by transthoracic Doppler echocardiography (TTDE) has been reported to be useful for the noninvasive assessment of coronary stenosis in the left anterior descending artery. However, the measurement of CFVR in the right coronary artery by TTDE has not yet been validated in a clinical study. Objective: The aim of this study was to evaluate whether CFVR by TTDE can detect significant stenosis in the right coronary artery. Methods: We studied 50 patients who underwent coronary angiography. Coronary flow velocity in the posterior descending branch of the right coronary artery (PD) was measured by TTDE both at baseline and during hyperemia induced by the intravenous infusion of adenosine triphosphate. CFVR was calculated as the hyperemia/baseline (average diastolic peak velocity). Results: Adequate spectral Doppler recordings in the PD were obtained in 36 patients including 26 patients who were given an echocardiographic contrast agent to improve Doppler spectral signals. The study population was divided into 2 groups with (Group A;n = 11) and without (Group B;n = 25) significant stenosis in the right coronary artery. CFVR in Group A was significantly smaller than that in Group B (1.6±0.3versus2.5±0.4; P < 0.0001). The sensitivity of a CFVR of <2.0 for predicting the presence of significant stenosis in the right coronary artery was 91%, and the specificity was 88%. Conclusions: The measurement of CFVR in the PD by TTDE is useful for the noninvasive assessment of significant stenosis in the right coronary artery. (ECHOCARDIOGRAPHY, Volume 20, August 2003) [source]


Noninvasive Assessment of Cardiac Resynchronization Therapy for Congestive Heart Failure Using Myocardial Strain and Left Ventricular Peak Power as Parameters of Myocardial Synchrony and Function

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 12 2002
Ph.D., ZORAN B. POPOVI
Resynchronization Therapy for Heart Failure.Introduction: Although invasive studies have shown that cardiac resynchronization therapy by biventricular pacing improves left ventricular (LV) function in selected heart failure patients, it is impractical to apply such techniques in the clinical setting. The aim of this study was to assess the acute effects of cardiac resynchronization therapy by noninvasive techniques. Methods and Results: Twenty-two patients enrolled in the InSync trial (age 64 ± 9 years, 18 men and 4 women; all with ejection fraction <35% and QRS >130 msec) were studied 1 to 12 months after pacemaker implantation during pacing, and while ventricular pacing was inhibited. Regional myocardial strains of the interventricular septum, LV free wall, and right ventricular free wall were derived from color Doppler tissue echocardiography. Peak power index was calculated as a product of simultaneously recorded noninvasive blood pressure and pulse-wave (PW) Doppler velocity of the LV outflow tract. The Z ratio (sum of LV ejection and filling times divided by RR interval) and tei index were calculated from PW Doppler data. During pacing, overall regional strain improved (P = 0.01), while the LV strain coefficient of variation decreased from 2.7 ± 2.4 to 1.3 ± 0.7 (P = 0.009). Additionally, peak power index improved from 84 ± 24 to 94 ± 27 cm· mmHg/sec (P = 0.004). The Z ratio increased from 0.71 ± 0.08 to 0.78 ± 0.07 (P = 0.0005), while the tei index decreased from 0.86 ± 0.33 to 0.59 ± 0.16 (P = 0.0002). Conclusion: Using novel noninvasive indices, we demonstrated that cardiac resynchronization therapy improves LV performance. [source]


Diffusion tensor magnetic resonance imaging in spinal cord injury

CONCEPTS IN MAGNETIC RESONANCE, Issue 3 2008
Benjamin M. Ellingson
Abstract Noninvasive assessment of spinal cord integrity following injury is critical for precise diagnosis, prognosis, and surgical intervention strategies. Diffusion weighted imaging and diffusion tensor imaging are more sensitive to the underlying spinal cord microstructure than traditional imaging techniques. As a result, diffusion imaging is emerging as the clinical technique for imaging the spinal cord after trauma, surgery or during progressive degenerative diseases. This review describes the basic physics of diffusion imaging using magnetic resonance, techniques used to visualize diffusion measurements, and expected changes in diffusion measurements following spinal cord injury. © 2008 Wiley Periodicals, Inc.Concepts Magn Reson Part A 32A: 219,237, 2008. [source]


Noninvasive Assessment of Coronary Flow Reserve in the Left Anterior Descending Artery by Transthoracic Echocardiography before and after Stenting

ECHOCARDIOGRAPHY, Issue 8 2007
Elie Chammas M.D., F.E.S.C.
Background: Noninvasive assessment of coronary flow reserve in the left anterior descending artery (LAD) by transthoracic Doppler echocardiography (TTDE) has been already validated as a new method for determining the degree of stenosis over the proximal flow. Objectives: The aim of the study is to determine, by TTDE, the feasibility and the value of the coronary flow reserve (CFR) (defined as the maximal increase in coronary blood flow above its basal pressure for a given perfusion pressure when coronary circulation is maximally dilated) in the mid-to-distal LAD before and after percutaneous angioplasty and to demonstrate the early recovery of microvascular tone immediately after stenting. Methods: The study population consisted of 36 patients with significant isolated LAD stenosis (70,90%) identified by coronary angiography. CFR was recorded in the mid-to-distal LAD at rest and during hyperemia obtained after adenosine intravenous infusion before and after stenting. Results: Adequate visualization of the LAD was obtained in 25 out of 36 patients (70%). At rest the mean CFR was 1.5132 ± 0.33 (1.1,2.58). However, after stenting the mean CFR was significantly higher: 2.18 ± 0.55 (1.3,3.8), with P <0.01. Conclusions: CFR can be easily determined by TTE in approximately 70% of patients. Noninvasive Doppler echocardiography shows impaired CFR in patients with LAD disease. After stenting CFR is restored, demonstrating early recovery of microvascular tone. These results are comparable to those published in the same conditions. Larger series with a long-term follow-up may allow identifying patients at high risk for restenosis after stenting. [source]


Capillarization of the sinusoids in liver fibrosis: Noninvasive assessment with contrast-enhanced MRI in the rabbit

MAGNETIC RESONANCE IN MEDICINE, Issue 4 2003
Bernard E. Van Beers
Abstract Sinusoidal capillarization induces microcirculatory changes in liver cirrhosis and fibrosis. The purpose of this study was to assess whether contrast-enhanced MRI can be used to demonstrate the effects of sinusoidal capillarization in liver fibrosis. Dynamic MRI after injection of a low-molecular-weight contrast agent of 0.56 kDa (Gd-DOTA), and two high-molecular-weight contrast agents of 6.47 kDa and 52 kDa (P792 and P717) was performed in rabbits with liver fibrosis induced by cholesterol and diethylstilbestrol. The hepatic distribution volume accessible to the high-molecular-weight agents decreased in the rabbits with liver fibrosis (P792: 7.8% ± 1.7% vs. 10.1% ± 1.8% in normal rabbits, P = .038; P717: 6.2% ± 2.1% vs. 9.7% ± 1.6% in normal rabbits, P = .007), whereas the hepatic mean transit time (MTT) of the low-molecular-weight agent was increased (15.9 ± 8.0 s vs. 8.8 ± 2.6 s in normal rabbits, P = .015). In rabbits with liver fibrosis, the clearance of indocyanine green (ICG) was correlated with the volume accessible to the high-molecular-weight agents (P792: r = 0.810, P = .015; P717: r = 0.857, P = .007). The collagen content of the liver was inversely correlated with the distribution volume of P717 (r = ,.833, P = .010) and with the ICG clearance (r = ,.810, P = .015). It was concluded that the microcirculatory changes induced by sinusoidal capillarization in liver fibrosis can be demonstrated noninvasively with MRI. Magn Reson Med 49:692,699, 2003. © 2003 Wiley-Liss, Inc. [source]


Noninvasive assessment of energy expenditure in children

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2006
Isabelle Sarton-Miller
This study establishes an affordable, simple, and noninvasive method to assess energy expenditure (EE) in children, an underrepresented group. The method is based on regression modeling, where prediction of oxygen consumption (VO2), a proxy of EE, was deduced from heart rate (HR) and several variables that adjusted for interindividual variability. Limb activities (arms vs. legs) and posture (sitting vs. standing) were represented in the regression as dichotomous covariates. The order of activities and intensities was randomized. Seventy-four children (aged 7,10 years), raised at sea-level (Seattle, WA), comprised the sample. Anthropometric measures were taken, and VO2 and HR were measured for activities using the arms in sitting and standing positions (mixing and punching), as well as walking at different velocities on a treadmill. Repeated measures and least square regression estimation were used. HR, body mass, number of hours of physical activity per week (HPA), an interaction term between sitting and standing resting HR, and the two dichotomous variables, sex and limbs, were significant covariates; posture was not. Several equations were developed for various field uses. The equations were built from sea-level data, but ultimately this method could serve as a baseline for developing a similar approach in other populations, where noninvasive estimation of EE is imperative in order to gain a better understanding of children's energetic issues. Am. J. Hum. Biol. 18:600,609, 2006. © 2006 Wiley-Liss, Inc. [source]


Noninvasive assessment of liver fibrosis in thalassaemia major patients by transient elastography (TE) , lack of interference by iron deposition

BRITISH JOURNAL OF HAEMATOLOGY, Issue 3 2010
Vito Di Marco
Summary The correlation between liver stiffness, measured by transient elastography, liver fibrosis, using the histological METAVIR score, and iron overload, measured by atomic absorption spectrometry was evaluated in 56 homozygous-,-thalassaemics. Liver stiffness increased proportionally to liver fibrosis staging (r = 0·70; P > 0·001) independently of liver iron concentration (r = 0·01; P = 0·932). The area under the receiver-operating characteristic curve for prediction of cirrhosis was 0·997 (95% confidence interval [CI]: 0·925,1·000) with cut-off of 13 kPa with 100% sensitivity (95% CI: 69·0,100·0) and 95% specificity (95% CI: 84·2,99·3). Transient elastography is a reliable non-invasive tool for diagnosing advanced liver fibrosis in homozygous-,-thalassaemics, regardless of the degree of iron overload. [source]


Noninvasive Assessment of Significant Right Coronary Artery Stenosis Based on Coronary Flow Velocity Reserve in the Right Coronary Artery by Transthoracic Doppler Echocardiography

ECHOCARDIOGRAPHY, Issue 6 2003
M.D., Yoshiki Ueno
Background: Coronary flow velocity reserve (CFVR) measured by transthoracic Doppler echocardiography (TTDE) has been reported to be useful for the noninvasive assessment of coronary stenosis in the left anterior descending artery. However, the measurement of CFVR in the right coronary artery by TTDE has not yet been validated in a clinical study. Objective: The aim of this study was to evaluate whether CFVR by TTDE can detect significant stenosis in the right coronary artery. Methods: We studied 50 patients who underwent coronary angiography. Coronary flow velocity in the posterior descending branch of the right coronary artery (PD) was measured by TTDE both at baseline and during hyperemia induced by the intravenous infusion of adenosine triphosphate. CFVR was calculated as the hyperemia/baseline (average diastolic peak velocity). Results: Adequate spectral Doppler recordings in the PD were obtained in 36 patients including 26 patients who were given an echocardiographic contrast agent to improve Doppler spectral signals. The study population was divided into 2 groups with (Group A;n = 11) and without (Group B;n = 25) significant stenosis in the right coronary artery. CFVR in Group A was significantly smaller than that in Group B (1.6±0.3versus2.5±0.4; P < 0.0001). The sensitivity of a CFVR of <2.0 for predicting the presence of significant stenosis in the right coronary artery was 91%, and the specificity was 88%. Conclusions: The measurement of CFVR in the PD by TTDE is useful for the noninvasive assessment of significant stenosis in the right coronary artery. (ECHOCARDIOGRAPHY, Volume 20, August 2003) [source]


Dynamic T1-weighted monitoring of vascularization in human carcinoma heterotransplants by magnetic resonance imaging,

INTERNATIONAL JOURNAL OF CANCER, Issue 1 2003
Fabian Kiessling
Abstract Studies on tumor angiogenesis and antiangiogenic therapies are commonly performed with tumor heterotransplants in nude mice. To monitor therapeutic effects, improved noninvasive analyses of functional data are required, in addition to the assessment of tumor volume and histology. Here, we report on sequential monitoring of vascularization of human squamous cell carcinomas growing as heterotransplants in nude mice using MRI. Using a custom-developed animal coil in a conventional whole-body 1.5 T MRI scanner, dynamic T1w sequences were recorded after i.v. injection of Gd-DTPA in tumors grown for 17, 21, 25, 29 and 33 days. Amplitude and the exchange rate constant (kep) were calculated according to a 2-compartment model, discriminating intravascular and interstitial spaces, and correlated with tumor size and histology. High-resolution imaging of small heterotransplants from 100 to 1,000 mm3 was achieved, clearly discriminating vital and necrotic areas. Preceding the development of necroses, which were hyperintense in T2w images and confirmed with histology, a local decrease of amplitude and kep values was observed. Significantly higher amplitudes were found in tumor periphery than in central parts, correlating well with the vascular pattern obtained by immunocytochemistry. Tumor size correlated negatively with amplitude, probably as a result of increasing necrotic areas, whereas the reason for the observed increase of kep value with tumor size remains unclear. These data demonstrate that dynamic MRI is an excellent method for noninvasive assessment of tumor vascularization in small animals using a clinical whole-body scanner with little technical modifications. This technique provides functional data characterizing essential features of tumor biology and is thus appropriate for monitoring antiangiogenic therapies. © 2002 Wiley-Liss, Inc. [source]


Prevalence, risk factors and causes of discordance in fibrosis staging by transient elastography and liver biopsy

LIVER INTERNATIONAL, Issue 10 2010
Robert P. Myers
Abstract Background and aims: Liver stiffness measurement (LSM) by transient elastography (TE) is widely used for the noninvasive assessment of fibrosis. Our objectives were to examine the prevalence, risk factors and causes of discordance between fibrosis estimated by TE and liver biopsy. Methods: Two hundred and fifty-one patients with hepatitis B, C and nonalcoholic fatty liver disease underwent LSM by TE and liver biopsy. Predictors of discordance (,2 fibrosis stages) between measures, which occurred in 14% of patients (n=35), were identified by comparing patient, TE and biopsy characteristics of discordant and nondiscordant cases. Results: According to predefined criteria, 40% of discordances were attributed to TE error and 23% to biopsy error; 37% were indeterminate. In multivariate analysis, mild fibrosis (F0,2 vs. F3,4), and higher body mass index (BMI), ALT and LSM variability [assessed by the ratio of the interquartile range to median LSM (IQR/M)] were independently associated with discordance. Discordance was three-fold more common in patients with obesity (28 vs. 9%), ALT,60 U/L (20 vs. 7%) and IQR/M ,0.17 (22 vs. 7%; all P<0.005). Based on these variables, a discordance risk score assigning 1 point to each factor was developed. The prevalence of discordance in patients with 0, 1, 2 and 3 factors were 2, 7, 20, and 55% respectively (P<0.0005). Conclusions: Discordance between liver fibrosis estimated by TE and biopsy occurs in one in seven patients. In assessing the validity of TE results, clinicians must recognize risk factors for discordance and in at-risk patients, consider alternative measures including biomarkers and possibly biopsy. [source]


Functional colonography of Min mice using dark lumen dynamic contrast-enhanced MRI

MAGNETIC RESONANCE IN MEDICINE, Issue 3 2008
C. Chad Quarles
Abstract Dark lumen MRI colonography detects colonic polyps by minimization of the intestinal lumen signal intensity. Here we validate the use of perfluorinated oil as an intestinal-filling agent for dark lumen MRI studies in mice, enabling the physiological characterization of colonic polyps by dynamic contrast-enhanced MRI. In control and Min (multiple intestinal neoplasia) mice with and without pretreatment with oral dextran sodium sulfate (DSS), polyps as small as 0.94 mm diameter were consistently identified using standard 2D gradient echo imaging (voxel size, 0.23 × 0.16 × 0.5 mm). In serial studies, polyp growth rates were heterogeneous with an average ,5% increase in polyp volume per day. In DSS-treated control mice the colon wall contrast agent extravasation rate constant, Ktrans, and extravascular extracellular space volume fraction, ve, values were measured for the first time and found to be 0.10 ± 0.03 min,1 and 0.23 ± 0.09, respectively. In DSS-treated Min mice, polyp Ktrans values (0.09 ± 0.04 min,1) were similar to those in the colon wall but the ve values were substantially lower (0.16 ± 0.03), suggesting increased cellular density. The functional dark-lumen colonography approach described herein provides new opportunities for the noninvasive assessment of gastrointestinal disease pathology and treatment response in mouse models. Magn Reson Med 60:718,726, 2008. © 2008 Wiley-Liss, Inc. [source]


MRI of muscular fat

MAGNETIC RESONANCE IN MEDICINE, Issue 4 2002
Fritz Schick
Abstract An MRI technique with high selectivity and sensitivity to the signal components in the chemical shift range of methylene and methyl protons of fatty acids has been developed for noninvasive assessment of muscular fat in vivo. A spoiled gradient-echo sequence with spatial-spectral excitation by six equidistant pulses with 2°-(,9°)-17°-(,17°)-9°-(,2°) and a multi-echo train (TE = 16, 36, 56, 76, 96, and 116 ms) allowed a series of images to be recorded with a receiver bandwidth of 78 Hz per pixel. SIs from phantoms with lipid contents between 0.1% and 100% were compared to those from pure water. Thirty healthy volunteers underwent fat-selective imaging of their lower leg, and parallel localized proton spectroscopy of the tibialis anterior and the soleus muscle by a single-voxel stimulated echo acquisition mode (STEAM) technique (TR = 2 s, TE = 10 ms, TM = 15 ms). Results show a high correlation (r = 0.91) between fat imaging and the spectroscopic approach in the soleus muscle, considering the percentage total fat content of musculature. The correlation coefficient was clearly lower (r = 0.55) in the tibialis anterior muscle due to signal contaminations from adjacent subcutaneous fat in the images, inhomogeneous fat distribution, and generally lower lipid content in this muscle. Applications of the new imaging technique showed marked intra- and interindividual variability in the spatial distribution of lipids in the musculature of the lower leg. No significant correlation of the muscular fat with the thickness of the subcutaneous fat layer was found. In addition, the body mass index does not appear to determine muscular fat content, except in very obese cases. Magn Reson Med 47:720,727, 2002. © 2002 Wiley-Liss, Inc. [source]


The urinary proteome in diabetes and diabetes-associated complications: New ways to assess disease progression and evaluate therapy

PROTEOMICS - CLINICAL APPLICATIONS, Issue 7-8 2008
Kasper Rossing
Abstract Diabetes represents one of the main chronic diseases worldwide. Diabetes and its associated complications may be detectable even at early stages in the urinary proteome. In this article we review the current literature on urinary proteomics applied to the study of diabetes and diabetic complications. Further, we present recent data that strongly indicate urinary proteome analysis may be a valuable tool in detecting diabetes-associated pathophysiological changes at an early stage, and also may enable assessment of disease progression and efficacy of therapy. Current data indicate that collagen-derived peptides represent one of the main peptidic components in urine, which are consistently found at reduced levels in diabetes. It is tempting to speculate that this decrease in urinary collagen-derived peptides is related to an increase in extracellular matrix deposition which is a major complication in diabetes. Therefore, urinary proteome analysis might enable noninvasive assessment of this process at an early stage via determination of specific collagen fragments. This may open an avenue towards targeted therapeutic intervention. [source]


The Complexity of External Acoustic Detection of Defects in Björk-Shiley Convexoconcave Heart Valves

ARTIFICIAL ORGANS, Issue 1 2001
Bas A. De Mol
Abstract: Fractures in Björk-Shiley convexoconcave (BScc) heart valves have raised questions about the feasibility of early diagnosis of technical defects by means of acoustic assessment. Three laboratory tests were conducted. To establish acoustic fingerprints, 66 valves with a defect, such as single-leg fracture (SLF) or single-leg separation (SLS), or without a defect were connected with a contact sensor and excited by dropping a small metal ball onto the outlet strut. In the second test, we simulated the valve sound propagation within the thorax. In the third test, intact, SLF, and SLS valves were placed in a mock heart immersed in a large water tank. We observed a resonance frequency corresponding with valve size and presence of defects. The second test showed that both the chest wall and the lungs created numerous reflections. This led to a substantial overlap of the original pulse frequencies and the frequencies measured. The third test confirmed that submersion of the chest in water can significantly reduce chest wall reflections. Reliable noninvasive assessment of BScc valve clicks for the presence of defects of the outlet strut is hampered by complex sound propagation within the thorax and variability of valve excitation. Acoustic fingerprints to diagnose mechanical defects should be integrated in valve design. [source]


Sensitivity and specificity of confocal laser-scanning microscopy for in vivo diagnosis of malignant skin tumors

CANCER, Issue 1 2006
Armin Gerger M.D.
Abstract BACKGROUND Melanoma and nonmelanoma skin cancer are the most frequent malignant tumors by far among whites. Currently, early diagnosis is the most efficient method for preventing a fatal outcome. In vivo confocal laser-scanning microscopy (CLSM) is a recently developed potential diagnostic tool. METHODS One hundred seventeen melanocytic skin lesions and 45 nonmelanocytic skin lesions (90 benign nevi, 27 malignant melanomas, 15 basal cell carcinomas, and 30 seborrheic keratoses) were sampled consecutively and were examined using proprietary CLSM equipment. Stored images were rated by 4 independent observers. RESULTS Differentiation between melanoma and all other lesions based solely on CLSM examination was achieved with a positive predictive value of 94.22%. Malignant lesions (melanoma and basal cell carcinoma) as a group were diagnosed with a positive predictive value of 96.34%. Assessment of distinct CLSM features showed a strong interobserver correlation (, >0.80 for 11 of 13 criteria). Classification and regression tree analysis yielded a 3-step algorithm based on only 3 criteria, facilitating a correct classification in 96.30% of melanomas, 98.89% of benign nevi, and 100% of basal cell carcinomas and seborrheic keratoses. CONCLUSIONS In vivo CLSM examination appeared to be a promising method for the noninvasive assessment of melanoma and nonmelanoma skin tumors. Cancer 2006. © 2006 American Cancer Society. [source]


PATIENT AGE IS A STRONG INDEPENDENT PREDICTOR OF 13C-AMINOPYRINE BREATH TEST RESULTS: A COMPARATIVE STUDY WITH HISTOLOGY, DUPLEX-DOPPLER AND A LABORATORY INDEX IN PATIENTS WITH CHRONIC HEPATITIS C VIRUS INFECTION

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2006
Arne RJ Schneider
SUMMARY 1Noninvasive tests for the staging of chronic hepatitis C virus (HCV) infection would be an attractive alternative to liver biopsy. The 13C-aminopyrine breath test (ABT) has been proposed for the noninvasive assessment of hepatic function and partly correlates with fibrosis. We aimed to investigate causes for the lack of discriminatory power for different degrees of hepatic fibrosis. 2Eighty-three patients (median age 49 years (28,78 years)) with chronic HCV infection underwent the ABT after an oral load of 75 mg N,N-dimethyl- 13C-aminopyrine. Portal vein flow was assessed by duplex-Doppler and a laboratory index (aspartate aminotransferase to platelet ratio index or APRI) was calculated. Parameters were compared with liver histology. 3The cumulative 13C-recovery differed significantly between patients without relevant fibrosis (fibrosis score 0,2) and cirrhosis (5,6), beginning after 30 min of sampling (P < 0.05). The ABT did not discriminate patients with fibrosis scores 3,4 from the remaining two patient groups. Sensitivity and specificity for the prediction of cirrhosis was 73.4,82.8% and 63.2,68.4%, depending on the sampling time. Compared with the fibrosis score (P = 0.04), patient age was a highly significant independent predictor for the 13C-recovery (P < 0.0001). Aspartate aminotransferase to platelet ratio index and duplex-Doppler predicted cirrhosis with 76.6%vs. 87.5% sensitivity and 63.2%vs. 68.4% specificity. 4Our data suggest an age-dependent decrease of cytochrome P450 activity which probably accounts for the large overlap of ABT results that preclude clear differentiation. This is also consistent with former pharmacodynamic trials. Age-adapted reference ranges could improve ABT results. [source]