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At least 271 records · Page 15Linked to original sources
PubMed2000

High-frame-rate tissue harmonic imaging enhances anatomic M-mode sections of the left ventricle in short-axis view.

BACKGROUND: High-frame-rate echocardiography (HFRE) and tissue harmonic imaging (THI) may improve image quality, thereby enabling anatomic M-mode sections of left ventricular (LV) wall segments to be visualized in various planes in the short-axis view. OBJECTIVES: The goals of this study were to compare image quality between HFRE and conventional-frame-rate echocardiography (CFRE) and between fundamental imaging (FI) and THI, and to obtain anatomic M-mode values of basal short-axis LV segments from healthy subjects for use in the evaluation of abnormal segments in patients with myocardial infarction (MI). METHODS AND RESULTS: The study included 28 healthy subjects and 15 patients with MI who underwent 2-dimensional echocardiography with an ultrasonographic system equipped with THI and anatomic M-mode. Left ventricular image cineloops at the basal short-axis view that were obtained with 3 combinations of imaging techniques (FI + CFRE, FI + HFRE, and THI + HFRE) were digitized and displayed side-by-side in random order for comparison by blinded readers. M-mode sections were done in 3 planes: anteroseptal-posterior, inferoseptal-lateral, and anterior-inferior basal segments. The THI + HFRE combination showed the best image quality with significant reduction in noise artifacts, resulting in a good signal-to-noise ratio and good tractability of all LV segments by anatomic M-mode. In healthy subjects, significant intersegmental differences existed in the diastolic and systolic thicknesses and in the percent systolic thickening of LV segments. In patients with MI, LV systolic thickening was significantly decreased in abnormal segments. No significant differences were noted in ejection fraction and fractional shortening among the 3 anatomic M-mode planes. CONCLUSION: High-frame-rate tissue harmonic imaging improved image quality, thereby allowing reproducible anatomic M-mode measurements in various planes in the short-axis view and providing a convenient objective evaluation of global and regional LV function.

Adult↗
PubMed2004

Comparison of BOLD contrast and Gd-DTPA dynamic contrast-enhanced imaging in rat prostate tumor.

The microcirculation and oxygenation of a tumor play important roles in its responsiveness to cytotoxic treatment, and noninvasive assessments of its vascular properties may have prognostic value. Dynamic contrast-enhanced (DCE) (1)H MRI based on infusion of Gd-DTPA, and blood oxygen level-dependent (BOLD) contrast based on altering inhaled gas are both sensitive to vascular characteristics. This study compares the effects observed in eight Dunning prostate R3327-AT1 rat tumors imaged sequentially at 4.7 Tesla by echo-planar imaging (EPI). Both interventions generated a significant response, and each revealed significant differences between the center and periphery of the tumors. On a voxel-by-voxel basis across the whole tumor population, there was a close correlation between the maximum rate of signal response and the magnitude of response to each intervention (R(2) >or= 0.6, P < 0.0001). However, when the data were analyzed separately for each individual tumor, some showed a weak correlation (R(2) < 0.4), particularly for DCE, and the nature (slope) varied between separate tumors. Generally, there was a weak correlation (N = 7, R(2) < 0.5) between responses to the two interventions on a tumor-by-tumor basis, which emphasizes that the techniques are not equivalent. Both techniques revealed intra- and intertumor heterogeneity, but the BOLD response was more rapidly reversible than the DCE response. This suggests that the BOLD technique may be a useful tool for investigating interventions (such as drugs) that cause vascular disruption.

Animals↗
PubMed1998

Prenatal magnetic resonance imaging enhances fetal diagnosis.

BACKGROUND: Ultrasound (US) evaluation of some fetal anomalies provides limited information. Anatomic details that affect prognosis and selection for fetal therapy, such as liver herniation and pulmonary hypoplasia in congenital diaphragmatic hernia (CDH) and airway patency in giant neck masses, may be difficult to delineate using conventional sonographic methods. The authors evaluated the utility of prenatal magnetic resonance imaging (MRI) with new ultrafast imaging sequences in the diagnosis and management of fetal anomalies. METHODS: From April 1996 to April 1997 45 MRI scans were performed in 31 pregnant women with an US diagnosis of a fetal anomaly. The US diagnoses included CDH, giant neck masses, lung masses, abdominal and pelvic abnormalities, twin anomalies, and central nervous system (CNS) anomalies. The fetuses ranged in age from 18 to 39 weeks' gestation (mean, 28.7 weeks). Using a 1.5-T magnet, a variety of ultrafast imaging sequences were performed including fast gradient-echo, half-fourier single shot turbo spin-echo (Haste) and echo-planar imaging yielding images with T1 to T2 type weighting. RESULTS: With CDH, MRI demonstrated liver herniation into the chest in 11 of 14 cases. In four cases, US findings had not been definitive. In two cases of CDH detected by MRI, the primary diagnosis by US had been congenital cystic adenomatoid malformation (CCAM). With lung masses, MRI accurately distinguished between CCAM and bronchopulmonary sequestration (BPS). For giant neck masses with potential airway obstruction, MRI scans permitted differentiation of teratoma from cystic hygroma and allowed delineation of fetal airway involvement. The accurate anatomic evaluation facilitated planning for the ex utero intrapartum treatment (EXIT) procedure, a technique for securing the airway while the term fetus is still on placental support. With huge abdominal masses such as enterogenous cyst and lymphangioma, MRI scanning clarified the diagnosis. Fourteen of the 31 (45%) patients underwent fetal treatment after US and MRI evaluation. CONCLUSIONS: Prenatal MRI enhances fetal anatomic evaluation and facilitates perinatal management and family counseling. Ultrafast imaging sequence MRI is helpful to corroborate and refine US diagnoses. Fetal MRI is a valuable adjunct to US for prenatal diagnosis before fetal surgical intervention for selected life-threatening birth defects.

Congenital Abnormalities↗
PubMed1998

Image Enhancement in a Reflection Optical Microscope by Suppression of Diffusing Photons Using Polarizing Annular Objectives.

: In this report, we describe the implementation of an angle-gating mechanism into a reflection optical microscope for imaging through a turbid medium. A significant improvement in image resolution and contrast is obtained when a polarizing annular objective is used to image a reflective test bar through various turbid media. The experimental results confirm that the improvement is caused by the efficient suppression of diffused photons scattered from the turbid medium when a polarized annular objective is employed as an angular gate.

Journal Article↗
PubMed2002

Usefulness of ultrasound contrast for image enhancement during stress echocardiography.

Although stress echocardiography has been established as a diagnostic technique for the detection and assessment of ischemia, there are still a number of limitations to the technique. These are related to suboptimal image quality with poor visualization of endocardial borders. Because assessment of wall motion is fundamental to the diagnostic value of stress echocardiography (both pharmacologic and exercise), endocardial border visualization is of utmost importance. Furthermore, interinstitutional observer agreement of 100% in highest image quality patients to a cumbersome 43% in low image quality patients is present. Therefore, improvements of image quality during stress are essential. One of the recent improvements is harmonic imaging, which improves visualization of endocardial borders at rest and during dobutamine stress. However, there is room for improvement. Since the introduction of ultrasound contrast agents, contrast has been increasingly used for better endocardial border visualization. Data from centers with a large number of stress echocardiography tests have shown that the addition of contrast agents decreases the number of more redundant diagnostic testing. Data obtained in our center in a subset of patients administered with SonoVue, a new generation contrast agent made of stabilized microbubbles containing sulfur hexafluoride, an inert gas, showed an improvement in the number of evaluable segments with fundamental and harmonic imaging and in the endocardial border detection during dobutamine stress echocardiography. Contrast also enables future quantitative analysis using acoustic quantification (AQ), and color kinesis. These studies should be carried out now that contrast has been approved for introduction to the market.

Echocardiography↗
PubMed2006

Enhanced imaging algorithm for scanning laser polarimetry with variable corneal compensation.

PURPOSE: To describe and investigate a method of improving assessment of retinal nerve fiber layer (RNFL) morphology with scanning laser polarimetry (SLP) with variable corneal compensation (VCC). METHODS: By neutralizing anterior segment birefringence with a variable compensator, the current VCC method allows direct measurement of RNFL retardation. In the new method, enhanced corneal compensation (ECC), the variable compensator was set to introduce a "bias" birefringence. This bias was removed mathematically for each individual pixel to produce the RNFL image. In 177 eyes of healthy subjects, patients with glaucoma, and subjects with ocular hypertension, retardation images were obtained with both VCC and ECC. RESULTS: In the tested eyes, images obtained with ECC showed the expected RNFL appearance better than those obtained with VCC. In addition, the typical scan score, which quantifies the amount of atypia, was higher with ECC than with VCC. The amount of residual anterior segment birefringence dropped significantly with ECC in the various groups. Measurements of peripapillary RNFL retardation showed reduced temporal and nasal values with ECC, whereas superior and inferior values were not significantly different between VCC and ECC. The dynamic range appeared to have increased with ECC. The accuracy of the TSNIT (temporal, superior, nasal, inferior, temporal) average and inferior average for detecting glaucoma was higher with ECC than with VCC. CONCLUSIONS: RNFL morphology may be better assessed with the presented ECC method than with standard VCC. ECC may be implemented in the current VCC systems by means of a software upgrade. It may enhance the clinical utility of the GDx VCC in glaucoma management.

Algorithms↗
PubMed1987

Differential effects of p-chlorophenylalanine on indoleamines in brainstem nuclei and spinal cord of rats. II. Identification of immunohistochemically stained structures using computer-assisted image enhancement techniques.

Following intraperitoneal injection of p-chlorophenylalanine (PCPA, 400 and 600 mg/kg) on 3 consecutive days, the brainstem and lumbar cord of rats were removed, frozen-sectioned and immunohistochemically stained (PAP method) for serotonin (5-HT). Using computer-assisted image analysis, the density of 5-HT staining in control, 400 and 600 mg/kg PCPA groups was determined. The mean number of pixels (representing 5-HT staining) was determined in 6 areas in the brainstem containing 5-HT cell bodies (nuclei raphe pallidus, raphe obscurus, rostral and caudal raphe magnus, raphe dorsalis and paragigantocellularis lateralis) and in the dorsal and ventral spinal cord. The results suggest a differential depletion of 5-HT within brainstem nuclei following PCPA treatment in that the most marked dose-related reductions were observed in nucleus raphe obscurus and caudal nucleus raphe magnus. Furthermore, a computer program designed to isolate terminal structures in the spinal cord identified a differential depletion of 5-HT terminals in the dorsal horn versus the ventral horn. The present study describes 3 analytical approaches combining immunohistochemistry with the computer-assisted image analysis technique and allows comparison between groups of animals which received the same or different drug treatments.

Animals↗
PubMed1991

Pitfalls of contrast-enhanced imaging in the nervous system.

This brief review covers the evolving clinical role of paramagnetic contrast agents in magnetic resonance imaging of the central nervous system, with particular emphasis on potential pitfalls. The safety and efficacy of Gd-DTPA is now well-established. Approximately 35-40% of all scans performed in this country now utilize the agent. The major pitfalls center on overinterpretation of the characterization of disease by either enhancement or lack thereof in any particular process.

Central Nervous System Diseases↗
PubMed2003

Conservative versus radical therapy of prostate cancer: how have recent advances in molecular markers and imaging enhanced our ability to prognosticate risk?

Recent results of several prospective phase II and phase III trials have reinforced the view that many patients with favorable-risk prostate cancer are over treated. The challenge is to identify those patients who require treatment at a point at which they are still amenable to cure, and to avoid treating those who have indolent disease and those who are incurable. This requires a combination of early detection, accurate imaging, and a selective approach to therapy. The accuracy of serum and tissue biomarkers and new imaging techniques in stratifying patients according to the risk of progression and metastasis is reviewed. The outcome of a strategy of selective intervention in good-risk patients based on prostate-specific antigen (PSA) doubling time is summarized.

Aged↗
PubMed2003

Near-infrared fluorescence contrast-enhanced imaging with intensified charge-coupled device homodyne detection: measurement precision and accuracy.

Fluorescence frequency-domain photon migration (FDPM) through tissue refers to the propagation of intensity-modulated fluorescent light that originates from tissue-laden fluorophores following illumination with an intensity-modulated excitation light source. FDPM measurements of modulation amplitude and phase are ultimately employed in an inversion algorithm for tomographic reconstruction of interior optical and fluorescent property maps that delineate disease enhanced with fluorescent contrast agent. Because the inverse problem is underdetermined, measurement precision and accuracy crucially impact its solution. Reported here are the precision and accuracy of FDPM measurements acquired using an intensified CCD homodyne detection system. By introducing 32 phase delays between the oscillators used to modulate the intensifier gain and light source intensity at 100 MHz, mean precision is maximized at +/-0.46% and +/-0.26 deg for measurements of modulation amplitude and phase, respectively. Measurement precision improves when the number of phase delays increases. Measurements of fluorescence modulation amplitude and phase, acquired from the surface of a tissue phantom at distances ranging between 0.71 and 3.6 cm from an incident excitation point source, exhibit a mean accuracy of 17% and 1.9 deg, respectively. Measurement accuracy deteriorates with increasing distance from the point source, but for distances up to 1.0 cm from the point source, measurements of fluorescence modulation amplitude and phase exhibit a mean accuracy of 5.4% and 0.30 deg, respectively.

Breast Neoplasms↗
PubMed2002

Automated endocardial border detection and evaluation of left ventricular function from contrast-enhanced images using modified acoustic quantification.

Automated border detection (ABD) techniques have been used for the quantitative assessment of left ventricular (LV) performance but require adequate visualization of the endocardial border to accurately track the blood-tissue interface. We sought to evaluate whether ABD could be used in conjunction with an infusion of echocardiographic contrast to objectively quantify LV systolic performance. Twenty-one subjects had LV volume and ejection fraction (EF) assessed by hand-tracing and prototype ABD software during contrast infusion. The mean hand-traced EF was 45% +/- 16%. Automatic tracking of contrast-enhanced endocardial borders with prototype ABD software was possible in all subjects. This allowed generation of signal averaged LV volume waveforms, from which quantitative LV ejection fraction was obtained. There were no significant differences in LV volumes or EF between contrast-enhanced acoustic quantification and manually traced borders. This technique has the potential of providing objective quantitation of LV volume and function in patients with technically limited echocardiograms.

Acoustics↗
PubMed2004

Simultaneous measurement of arterial input function and tumor pharmacokinetics in mice by dynamic contrast enhanced imaging: effects of transcytolemmal water exchange.

A noninvasive technique for simultaneous measurement of the arterial input function (AIF) for gadodiamide (Omniscan) and its uptake in tumor was demonstrated in mice. Implantation of a tumor at a suitable location enabled its visualization in a cardiac short axis image. Sets of gated, low-resolution saturation recovery images were acquired from each of five tumor-bearing mice following intravenous administration of a bolus of contrast agent (CA). The AIF was extracted from the signal intensity changes in left ventricular blood using literature values of the CA relaxivity and a precontrast T1 map. The time-dependent 1H2O relaxation rate constant (R1 = 1/T1) in the tumor was modeled using the BOLus Enhanced Relaxation Overview (BOLERO) method in two modes regarding the equilibrium transcytolemmal water exchange system: 1) constraining it exclusively to the fast exchange limit (FXL) (the conventional assumption), and 2) allowing its transient departure from FXL and access to the fast exchange regime (FXR), thus designated FXL/FXR. The FXL/FXR analysis yielded better fittings than the FXL-constrained analysis for data from the tumor rims, whereas the results based on the two modes were indistinguishable for data from the tumor cores. For the tumor rims, the values of Ktrans (the rate constant for CA transfer from the vasculature to the interstitium) and ve (volume fraction of the tissue extracellular and extravascular space) returned from FXL/FXR analysis are consistently greater than those from the FXL-constrained analysis by a factor of 1.5 or more corresponding to a CA dose of 0.05 mmole/kg.

Animals↗
PubMed1996

Soluble intercellular adhesion molecule-1 in serum and cerebrospinal fluid of clinically active relapsing-remitting multiple sclerosis: correlation with Gd-DTPA magnetic resonance imaging-enhancement and cerebrospinal fluid findings.

We measured soluble intercellular adhesion molecule-1 (sICAM-1) in the serum and cerebrospinal fluid (CSF) of 35 clinically active relapsing-remitting (RR) multiple sclerosis (MS) patients who underwent both lumbar puncture and gadopentetate dimeglumine (Gd-DTPA)-enhanced MRI within an interval of 1 week, and of 30 neurological controls of whom 17 had noninflammatory neurologic diseases (NIND), 8 bacterial meningitis (BM), and 5 AIDS dementia complex (ADC). Thirteen of the MS patients assumed corticosteroids at the time of the study. While sICAM-1 serum levels were highest in the BM group (p < 0.005), untreated MS patients showed levels higher (p < 0.05) than treated MS and NIND, but similar to ADC. Moreover, the untreated MS group had CSF/serum sICAM-1:CSF/serum albumin (sICAM-1 index) values higher than the treated group (p < 0.01), NIND (p < 0.005), and BM (p < 0.05); high sICAM-1 index was found also in ADC. Untreated MS patients with one or more Gd-DTPA-enhancing MRI lesions (Gd-positive) had higher mean values of CSF/serum albumin ratio (QAlbumin) and CSF mononuclear cells compared to patients without such lesions (Gd-negative). In the untreated Gd-negative patients, sICAM-1 serum levels were higher (p < 0.05) than those in Gd-positive patients. In the latter group, there were positive correlations between the number of CSF mononuclear cells and both IgG (p < 0.01) and sICAM-1 indices (p < 0.05), between QAlbumin and QsICAM-1 (p < 0.005) and between Qalbumin and the Expanded Disability Status Scale score (p = 0.05). There were no significant correlations in the Gd-negative group. These results suggest that sICAM-1 index can be a better marker of intrathecal sICAM-1 synthesis than CSF levels and provide additional insights, in vivo, into the blood-brain barrier mechanisms underlying MRI Gd-enhancement in clinically active RR MS.

Adolescent↗
PubMed2003

In vivo continuous-wave optical breast imaging enhanced with Indocyanine Green.

We investigate the uptake of a nontargeted contrast agent by breast tumors using a continuous wave diffuse optical tomography apparatus. The instrument operates in the near-infrared spectral window and employs 16 sources and 16 detectors to collect light in parallel on the surface of the tumor-bearing breast (coronal geometry). In our protocol an extrinsic contrast agent, Indocyanine Green (ICG), was injected by bolus. Three clinical scenarios with three different pathologies were investigated. A two-compartment model was used to analyze the pharmacokinetics of ICG and preprocess the data, and diffuse optical tomography was used for imaging. Localization and delineation of the tumor was achieved in good agreement with a priori information. Moreover, different dynamical features were observed for differing pathologies. The malignant cases exhibited slower rate constants (uptake and outflow) compared to healthy tissue. These results provide further evidence that in vivo pharmacokinetics of ICG in breast tumors may be a useful diagnostic tool for differentiation of benign and malignant pathologies.

Adenocarcinoma↗
PubMed1999

Fluorescent tissue site-selective lanthanide chelate, Tb-PCTMB for enhanced imaging of cancer.

In-vivo and in-vitro investigations indicate that a newly developed polyazamacrocyclic chelate of Tb(III) has superior properties for use as an abnormal tissue marker. In addition to tissue selectivity, this molecule is unique because of its low toxicity, attractive fluorescent properties, rapid pharmokinetics, and relatively high water solubility. The complex Tb-3,6,9-tris(methylene phosphonic acid n-butyl ester)-3,6,9,15-tetraazabicyclo[9.3.1]-pentadeca-1(15),11,13 -triene (Tb-PCTMB) has also been shown to exhibit strongly shifted emission (delta lambda--280 nm), moving the detection frequency away from autofluorescence backgrounds, and good quantum efficiencies (phi = 0.51), providing high brightness. Fluorescence imaging was used to quantify Tb-PCTMB at the picomolar level in tissues and to show the significant difference in affinity for the chelate by adenocarcinoma cells HT-29 versus normal epithelial cells (IEC-6). Topical application, or lavage introduction, under endoscopy was used to instill a millimolar aqueous solution of Tb-PCTMB into a dimethylhydrizene-treated Sprague Dawley rat large intestine containing a suspect growth. Subsequent in vitro fluorescence detection and standard histological evaluation confirmed enhanced uptake by adenocarcinoma tissue. Semiquantitative signal interrogation was employed to show the potential for using Tb-PCTMB as a contrast enhancement marker for disease detection.

Animals↗
PubMed1988

The clinical spectrum of cardiac fibroma with diagnostic and surgical considerations: noninvasive imaging enhances management.

A cardiac fibroma was successfully resected from the interventricular septum of a 25-year-old woman. The clinical data were correlated with a review of the data on 144 other patients, thereby providing a clinical profile and management strategy for this type of tumor. Initial manifestations of a fibroma were determined to be congestive heart failure (21%), tachyarrhythmias (13%), and chest pain (3.5%). A majority of patients were asymptomatic (36%) with abnormal physical findings or an abnormal chest roentgenogram. Finding the tumor at autopsy incidentally or on sudden death (23%) indicated the lethal potential. A few (3.5%) of the reports on patients with cardiac fibroma were without clinical data. Noninvasive imaging by echocardiography, computed tomography, and nuclear magnetic resonance improved the diagnosis. Surgical treatment was successful in 53 of the 84 patients for whom it was attempted.

Adult↗