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PubMed1993

Spontaneous resolution of ectopic pregnancy: initial appearance and evolution at transvaginal US.

Spontaneous resolution of ectopic pregnancy (EP) diagnosed with transvaginal ultrasound (US) was confirmed in 13 patients from May 1990 to December 1991. These cases accounted for 24% of the total number of EPs seen in our institution during the same period. These EPs ranged in size from 1 to 3.5 cm, and the beta subunit of human chorionic gonadotropin (beta-hCG) level was less than 1,000 IU/L in all patients. The serum beta-hCG levels became undetectable in 3-45 days (mean, 15.8 days). All EPs had completely resolved at follow-up transvaginal US performed 10-63 days (mean, 30 days) after initial examination. A gestational sac was present in three of these patients, and various degrees of vascularity were detected in four. Four of the resolving EPs increased in size. Four of the nine EPs without detectable flow initially became mildly vascular during the course of resolution. The authors concluded that spontaneous resolution of EP is not an uncommon phenomenon and occurs more commonly in patients with less advanced and less vascular EPs and serum beta-hCG levels less than 1,000 IU/L. EPs can increase in size and become more vascular during their course of resolution.

Adult↗

PubMed1994

"Crisscross" MR imaging: improved resolution by averaging signals with swapped phase-encoding axes.

At conventional magnetic resonance imaging, the number of phase-encoding steps is often chosen to be less than the number of readout samples, resulting in reduced spatial resolution in the phase-encoding direction. Signal averaging improves the signal-to-noise ratio of the image but does not affect this asymmetry in resolution. By swapping the phase- and frequency-encoding directions between excitations and averaging the resultant data sets ("crisscross" imaging), equal spatial resolution can be obtained in both principal directions. Increased spatial resolution can be obtained with this method with no increase in imaging time, and the method can potentially be applied in echo-planar and three-dimensional Fourier transform imaging.

Brain↗

PubMed2003

High-resolution joint linkage disequilibrium and linkage mapping of quantitative trait loci based on sibship data.

This paper proposes variance component models for high resolution joint linkage disequilibrium (LD) and linkage mapping of quantitative trait loci (QTL) based on sibship data; this can include population data if independent individuals are treated as single sibships. One application of these models is late onset complex disease gene mapping, when parental data are not available. The models simultaneously incorporate both LD and linkage information. The LD information is contained in mean coefficients of sibship data. The linkage information is contained in the variance-covariance matrices of trait values for sibships with at least two siblings. We derive formulas for calculating the probability of sharing two trait alleles identical by descent (IBD) for sibpairs in interval mapping of QTL; this is the coefficient of dominant variance of the trait covariance of sibpairs on major QTL. To investigate the performance of the formulas, we calculate the numerical values via the formulas and get satisfactory approximations. We compare the power and sample sizes for both LD and linkage mapping. By simulation and theoretical analysis, we compare the results with those of Fulker and Abecasis "AbAw" approach. It is well known that the resolution of linkage analysis can be low for complex disease gene mapping. LD mapping, on the other hand, can increase mapping precision and is useful in high resolution mapping. Linkage analysis is less sensitive to population subdivisions and admixtures. The level of LD is sensitive to population stratification which may easily lead to spurious association. Performing a joint analysis of LD and linkage mapping can help to overcome the limits of both approaches. Moreover, the advantages of the two complementary strategies can be utilized maximally. In practice, linkage analysis may be performed using pedigree data to identify suggestive linkage between markers and trait loci based on a sparse marker map. In the presence of linkage, joint LD and linkage mapping can be carried out to do fine gene mapping based on a dense genetic map using both pedigree and population data. Population and pedigree data of any type can be combined to perform a joint analysis of high resolution LD and linkage mapping of QTL by generalizing the method.

Alleles↗

PubMed1996

Rapid and near-complete resolution of moyamoya vessels in a patient with moyamoya disease treated with superficial temporal artery-middle cerebral artery bypass.

Several groups have reported partial resolution of moyamoya vessels following surgical revascularization in pediatric patients, but angiographic documentation of near-complete resolution has been poor. We report here a case of a 5-year-old boy who underwent bilateral superficial temporal artery-middle cerebral artery bypass combined with unilateral encephaloduroarteriosynangiosis who demonstrated near-complete resolution of moyamoya vessels and a dramatic improvement in cerebral perfusion as measured by xenon-enhanced CT. The resolution of moyamoya networks may serve as an indicator of successful surgical revascularization.

Blood Flow Velocity↗

PubMedDate not supplied

Natural history of hydrops resolution in fetuses with tachyarrhythmias diagnosed and treated in utero.

Fetal tachyarrhythmias are life-threatening conditions for the fetus. Long-standing tachyarrhythmias often lead to fetal cardiac failure, hydrops and death. Normalization of the fetal cardiac rhythm leads to resolution of fetal hydrops. This report describes the sequence and timing of fetal hydrops resolution after successful therapy. Fetuses with a persistent heart rate over 180 beats/min with a 1:1 atrioventricular conduction (on M mode) were defined as having supraventricular tachycardia. Fetal hydrops was diagnosed if the following signs were seen: pleural and/or pericardial effusion and/or ascites or/and skin edema. Five fetuses with sustained fetal tachycardia and hydrops who converted to normal rhythm with antiarrhythmic agents treated at Stony Brook University Hospital and North Shore University Hospital between 1988 and 1995 are included. Resolution of hydrops required from 4 to 6 weeks and occurred in the following sequence: diminution of ascites; pleural and pericardial effusions, and disappearance of skin and scalp edema. Minimal signs of fluid retention (small ascites, mild hydrocele) remained in studied fetuses until term. Understanding the natural history of hydrops in cases of fetal tachyarrythmias will allow for accurate patient counseling pertaining to the expected timing of hydrops resolution after successful therapy.

Digoxin↗

PubMed1983

High-resolution sonography in experimentally induced scrotal pathology.

Benign and malignant extra- and intratesticular lesions were experimentally induced in the testes of Wistar rats so as to evaluate the significance of high-resolution ultrasonography for the early detection of intratesticular malignancy. The animals were studied using high-resolution sonography (mean frequency = 8 MHz) over 6 weeks. Walker carcinomas could be induced in the testicle in 50% of the cases; 8 of 17 showed a locally limited growth. Tumors over 2 mm in diameter showed a typical change in the normal sonographic pattern of the testes. The overall sensitivity of high-resolution sonography for intratesticular lesions was 88%, the specificity 91%. The detection of small intratesticular lesions has made high-resolution sonography superior to conventional sonographic techniques and may therefore prove to be of major clinical significance.

Animals↗

PubMed2004

Association between platelet receptor occupancy after eptifibatide (integrilin) therapy and patency, myocardial perfusion, and ST-segment resolution among patients with ST-segment-elevation myocardial infarction: an INTEGRITI (Integrilin and Tenecteplase in Acute Myocardial Infarction) substudy.

BACKGROUND: Paradoxically, fibrinolytic agents may systemically activate platelets, which in turn secrete plasminogen activator inhibitor (PAI-1), an antagonist of the fibrinolytic process in proportion to total body platelet mass. We hypothesized that improved epicardial patency, myocardial perfusion, and ST-segment resolution would be associated with higher levels of platelet receptor occupancy (RO) by a glycoprotein IIb/IIIa antagonist in ST-elevation MI (STEMI). METHODS AND RESULTS: Patients were drawn from the low-dose tenecteplase plus eptifibatide arm of the INTEGRITI study. Angiographic and platelet RO data were analyzed at 2 independent core laboratories. To take into account the absolute platelet count and receptors available for cross-linking, absolute platelet count was multiplied by percent of available receptors to obtain the index of the absolute number of receptors available (IANRA). Percent RO was higher among patients with a patent artery (TIMI flow grade 2/3; 78.2+/-9.2, n=63 versus 63.9+/-29.7, n=7; P=0.005), those with TIMI myocardial perfusion grade 2/3 (79.6+/-9.5, n=40 versus 73.0+/-16.2, n=30; P=0.036), and those with complete (> or =70%) ST-segment resolution at 60 minutes (81.3+/-8.3%, n=27 versus 73.1+/-17.4%, n=24; P=0.034). The absolute number of glycoprotein IIb/IIIa receptors available for cross-linking was reduced (ie, the IANRA was lower) among patients with a patent artery (P=0.0015), patients with TIMI myocardial perfusion grade 2/3 (P=0.026), and patients with > or =70% ST-segment resolution (P=0.029). CONCLUSIONS: This study links restoration of epicardial flow, normal myocardial perfusion, and complete ST-segment resolution with higher levels of platelet glycoprotein IIb/IIIa receptor occupancy after therapy with eptifibatide administered with tenecteplase.

Adult↗

PubMed1998

High-resolution emboli detection and differentiation by characteristic postembolic spectral patterns.

BACKGROUND AND PURPOSE: High-intensity transient signals (HITS) detected by transcranial Doppler ultrasonography correspond to microemboli in intracranial arteries. The purpose of this study was to develop new diagnostic criteria for the differentiation of these microembolic signals from artifact, based on a high-resolution analysis of Doppler power spectra in an in vitro model. METHODS: Two hundred seventy-six formed emboli, consisting of different biological and nonbiological materials and as air bubbles, were injected into a flow phantom with artificial blood vessels and perfused in a steady or a pulsatile way. Embolic passage was assessed with a modified 2.5-MHz pulsed Duplex machine and a commercial 2-MHz Doppler system. Embolic HITS were analyzed using internationally accepted criteria for the audiovisual characteristics of HITS. Doppler spectra changes associated with HITS were evaluated by means of a specially developed high-resolution analysis of Doppler raw data. RESULTS: Seventy-seven percent of all embolic events could be identified using conventional audiovisual criteria for embolic HITS. Analysis of Doppler spectra showed that all injected emboli generated high-amplitude signals with a minimum of at least 3 dB above background level. In addition, using high-resolution processing, specific changes in Doppler spectral patterns could be identified after all embolic HITS caused by solid particles. These postembolic spectral patterns were always characterized by a Doppler frequency shift decreasing in time and resembling the letter lambda (lambda). Duration and appearance of the postembolic spectral patterns were mainly influenced by the size and velocity of the embolus. Similar phenomena could not be found in case of embolism by either small air bubbles or in case of provoked artifact registration. Using a commercial Doppler system specific, we documented postembolic spectral patterns in 47% of injected emboli. CONCLUSIONS: In this study, highly specific changes in Doppler spectral patterns associated with microembolic HITS could be characterized, resulting in further criteria for the differentiation between microembolic signals and artifact in Doppler emboli detection. The sensitivity of the detection of these signals can be increased by high-resolution analysis of raw Doppler data.

Animals↗

PubMed2000

Transient and permanent resolution of ischemic lesions on diffusion-weighted imaging after brief periods of focal ischemia in rats : correlation with histopathology.

BACKGROUND AND PURPOSE: The early ischemic lesions demonstrated by diffusion-weighted imaging (DWI) are potentially reversible. The purposes of this study were to determine whether resolution of initial DWI lesions is transient or permanent after different brief periods of focal brain ischemia and to evaluate histological outcomes. METHODS: Sixteen rats were subjected to 10 minutes (n=7) or 30 minutes (n=7) of temporary middle cerebral artery occlusion or sham operation (n=2). DWI, perfusion-weighted imaging (PWI), and T(2)-weighted imaging (T(2)WI) were performed during occlusion; immediately after reperfusion; and at 0.5, 1.0, 1.5, 12, 24, 48, and 72 hours after reperfusion. After the last MRI study, the brains were fixed, sectioned, stained with hematoxylin and eosin, and evaluated for neuronal necrosis. RESULTS: No MRI or histological abnormalities were observed in the sham-operated rats. In both the 10-minute and 30-minute groups, the perfusion deficits and DWI hyperintensities that occurred during occlusion disappeared shortly after reperfusion. The DWI, PWI, and T(2)WI results remained normal thereafter in the 10-minute group, whereas secondary DWI hyperintensity and T(2)WI abnormalities developed at the 12-hour observation point in the 30-minute group. Histological examinations demonstrated neuronal necrosis in both groups, but the number of necrotic neurons was significantly higher in the 30-minute group (95+/-4%) than in the 10-minute group (17+/-10%, P<0.0001). CONCLUSIONS: Transient or permanent resolution of initial DWI lesions depends on the duration of ischemia. Transient resolution of DWI lesions is associated with widespread neuronal necrosis; moreover, permanent resolution of DWI lesions does not necessarily indicate complete salvage of brain tissue from ischemic injury.

Animals↗

PubMed2001

Evolution of visual resolution constrained by a trade-off.

The evolution of visual systems is constrained by a trade-off between spatial and temporal resolution. In this article we aim at identifying the causes of the trade-off at the retinal level in both artificial and natural visual systems. We start by selecting two factors that limit the values of spatial and temporal resolution. Then we show in two experiments on the evolution of an artificial system that the two factors induce trade-off curves connecting the evolved values of spatial and temporal resolution. A comparison of the experimental results with the resolution evolved in natural visual systems leads us to the conclusion that in natural systems the same factors are responsible for the observed trade-off.

Animals↗

PubMed1994

Radiographic resolution of community-acquired pneumonia.

Clinicians are frequently faced with patients in whom the radiographic resolution of community-acquired pneumonia seems delayed. Previous studies of radiographic resolution of the disease have yielded conflicting results. We prospectively assessed the radiographic resolution of pneumonia in 81 non-immuno-compromised patients, presenting to the emergency room and ambulatory clinics of a large university hospital, who met clinical and radiographic criteria for pneumonia. Serial chest radiographs were obtained every 2 wk for an initial period of 8 wk, and then every 4 wk until 24 wk had passed, or until all radiographic abnormalities had cleared. Forty-one of the 81 patients (50.6%) demonstrated complete clearance after 2 wk. Fifty of the 75 patients (66.7%) followed to 4 wk demonstrated complete clearance. The rate of clearance was inversely correlated with age (p < 0.001) and involvement of single versus multiple lobes (p < 0.0001) (log-rank test). Clearance was faster in those patients treated as outpatients (3.8 wk versus 9.1 wk, p = 0.03) and in patients who were nonsmokers (4.5 wk versus 8.4 wk, p = 0.05) (log-rank test). Multivariate regression analysis demonstrated that only age (relative risk for clearance, +0.79 per decade) and single versus multiple lobes involved (relative risk for clearance, 0.55 for more than one lobe) had independent predictive value (Cox proportional hazards regression model). The radiographic resolution of pneumonia occurs more rapidly in younger patients and in those with only a single lobe involved.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1998

High resolution imaging of the upper respiratory tract with optical coherence tomography: a feasibility study.

A need exists in respiratory medicine for a technology capable of identifying airway pathology on a micron scale. This study has demonstrated the feasibility of optical coherence tomography (OCT) for ultrahigh resolution imaging of the upper respiratory tract by in vitro studies of human tissue. OCT is a relatively new technique that can be used to noninvasively collect tomographic images of tissue microstructure with micron-scale resolution. OCT is analogous to ultrasound, measuring the intensity of infrared light rather than acoustical waves. Samples throughout the upper respiratory tract, from the epiglottis to the secondary bronchi, were imaged. The resulting images were compared with histopathology and verified the ability of OCT to delineate relevant structures such as the epithelium, mucosa, cartilage and its sublayers, and glands at a resolution higher than any clinical imaging technology. The ability of OCT to generate image resolution in the range close to that of histopathology in real time, as well as easy integration with small, relatively inexpensive endoscopes, low cost, and lack of a need for a transducing medium, supports the hypothesis that this optical technology could become a powerful modality in the diagnosis and management of a wide range of clinical respiratory pathology.

Feasibility Studies↗

PubMed1995

Macrophage engulfment of apoptotic neutrophils contributes to the resolution of acute pulmonary inflammation in vivo.

For resolution of inflammation to occur, it is necessary both to limit leukocyte influx and to clear now redundant cells from the tissues. Recent evidence from in vitro studies suggests that clearance may be an active process, accomplished in part by macrophage engulfment of intact cells that have undergone programmed cell death or apoptosis. However, the kinetics of these events and their association with the resolution of acute inflammatory responses in vivo remain to be elucidated. To investigate these events, we examined an animal model of acute, limited, neutrophilic pulmonary inflammation. Cells were obtained by bronchoalveolar lavage (BAL) of rats at various time points after intratracheal administration of lipopolysaccharide (LPS). Apoptotic neutrophils were rarely seen in BAL from control animals but were detected after neutrophil influx had occurred in response to LPS challenge. Macrophage engulfment of these cells was identified at light microscopy and confirmed at electron microscopy. The proportion of macrophages that had engulfed apoptotic neutrophils was maximal 24 h after LPS challenge and declined thereafter as total neutrophil numbers fell. During the resolution phase, the alveolar macrophages became positive for peroxidase, indicating the presence of neutrophil granule contents in their cytoplasm. These observations demonstrate that apoptosis of leukocytes indeed occurs during the course of an acute inflammatory response in vivo and that the emergence of apoptotic neutrophils and macrophage engulfment of these cells are temporally correlated with the resolution of acute inflammation.

Animals↗

PubMed1998

Neutrophil apoptosis during the development and resolution of oleic acid-induced acute lung injury in the rat.

The oleic acid (OA) model of acute lung injury in rats is characterized by a massive and rapid influx of polymorphonuclear neutrophils (PMN) within 1 h, with a peak inflammatory response at 4 h and resolution by 72 h. We hypothesized that PMN apoptosis is involved in the resolution of OA-induced acute lung injury. To test this hypothesis, healthy adult Fischer 344 rats were given 30 microl OA in 0.1% bovine serum albumin (BSA) intravenously; controls were given BSA alone and killed at 1, 4, 24, and 72 h after OA to obtain bronchoalveolar lavage fluid (BALF) and lung tissue. Cell pellets from BALF and formalin-fixed, paraffin-embedded tissue section samples were processed for terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) to identify apoptotic cells. Propidium iodide was used to counterstain nuclei. Percentage of nuclei undergoing apoptosis was counted under a fluorescent microscope. Control rats showed only resident alveolar macrophages (AM) in the BALF with no apoptosis. At the peak of injury, 1 h and 4 h after OA injection, we observed a massive PMN response without any evidence of apoptosis. At 24 h, when the OA injury is clinically and histologically in early resolution, we observed intense apoptosis of PMN nuclei along with evidence of apoptotic bodies in the cytoplasm of AM. Some of the AM also showed apoptotic nuclei at 72 h. Similar observations were made in the lung tissue sections. The results of the TUNEL assay were confirmed by DNA ladders and electron microscopy. We conclude that apoptosis of PMN and clearance by AM is an important mechanism in resolution of OA- induced acute lung injury.

Animals↗

PubMed2002

Covert attention increases spatial resolution with or without masks: support for signal enhancement.

Visual attention can increase spatial resolution even when it leads to a decrease in performance. Whether this effect is mediated by reduction of external noise or by signal enhancement is an unsettled question. Although we previously demonstrated that attention can improve speed and accuracy in an acuity task, those experiments made use of a local postmask, which could be considered a source of external noise. In this work, a peripheral cue improved observers' abilities to indicate which side of a Landolt-square target had a gap whether or not a local postmask was used and with both central- and spread-neutral cues. In addition, we documented the presence of visual field inhomogeneities in a resolution task. Given that these experiments presented the target alone with no external noise added (i.e., without distracters or masks), our results indicate that transient attention enhanced the quality of the stimulus representation. Furthermore, because performance in the Landolt-square task indexes resolution, this attentional benefit indicates that transient attention can produce signal enhancement through finer spatial resolution.

Attention↗

PubMed2004

Ocular tissue imaging using ultrahigh-resolution, full-field optical coherence tomography.

PURPOSE: Ultrahigh-resolution, full-field optical coherence tomography (OCT), which uses a white light source, allows bidimensional, noninvasive tomographic imaging without scanning. The goal of the present study was to apply full-field OCT to ocular tissue imaging in an attempt to explore the capabilities of the technique. METHODS: This full-field OCT system uses a Linnik-type interferometer with a tungsten-halogen source. The spatial resolution is 0.9 x 0.7 microm (transverse x axial). Unstained tissue samples (cornea, lens, retina, choroid, and sclera) and whole, unfixed eyes of rat, mouse, and pig were examined under immersion. A charge-coupled device (CCD) camera recorded a pair of interferometric images that were combined to display en face (i.e., in the x-y plane) tomographic images in real time. The acquisition time per tomographic image, which includes summation of 10 raw images, was on the order of 1 s. Postprocessing allows volumetric navigation through the image stack as well as three-dimensional (3D) imaging. RESULTS: Cellular-level resolution was achieved in isolated tissue samples. En face (x-y) images revealed corneal epithelial and stromal cells, lens fibers, nerve fibers, major vessels, and retinal pigment epithelial cells. In x-z reconstructions, cellular layers within the cornea and retina and arterioles and venules were clearly defined. Transscleral retinal imaging was achieved in albino animals. CONCLUSIONS: Ultrahigh-resolution, full-field OCT allows cellular-level imaging of unstained ocular tissues with high penetration depth. Although the current system is unsuitable for clinical use, this simple technique has potential for in vivo ocular examination, for which a new system is currently under development.

Anatomy, Cross-Sectional↗

PubMed1995

Trade-off between airway resistance and optical resolution in pediatric rigid bronchoscopy.

Contemporary pediatric rigid bronchoscopy reflects the culmination of years of work by prominent endoscopists aided by technical developments in optical physics and refinements in optical lens manufacturing. Improved neonatal and pediatric care has allowed survival of premature infants, many with bronchopulmonary diseases. Rigid bronchoscopy in these infants is demanding and has necessitated the development of miniaturized telescopic bronchoscopes. This study documents airway pressures through bronchoscopes with and without endoscopic telescopes, analyzes and quantitates optical resolution, discusses the trade-offs between these instruments in airway resistance and optical resolution, and makes recommendations regarding which combinations of endoscopes and bronchoscopes provide the best resistance and resolution profiles. We conclude that the size 1.9-mm endoscopic telescope provides the most favorable resistance and resolution profile for the size 2.5 to 3.0 bronchoscopes, the 2.8-mm telescope is ideal for the 3.5 bronchoscope, and the 4.0-mm telescope works best with the 4.0 and larger bronchoscopes. Furthermore, optical forceps and side-channel forceps used during bronchial foreign body removal cause little change in airway resistance.

Airway Resistance↗

PubMedDate not supplied

Spontaneous resolution of vitreomacular traction associated with diabetic macular edema.

PURPOSE: Little information is available about the natural history of vitreomacular traction (VMT) associated with diabetic macular edema. A few cases of spontaneous resolution of VMT associated with diabetic macular edema have been described, but have not been documented by optical coherence tomography (OCT). The authors report the spontaneous resolution of VMT associated with diabetic macular edema 1 month after the end of panretinal photocoagulation therapy (PRP). METHODS CASE REPORT: A 66-year-old woman presented with complicated proliferative diabetic retinopathy and diabetic macular edema associated with VMT, documented by OCT, in the right eye. Left eye examination showed complete PRP and ischemic maculopathy. PRP was immediately realized in the right eye in regard to the presence of complicated proliferative diabetic retinopathy. RESULTS: One month after the end of PRP, right eye visual acuity improved. OCT examination showed complete release of foveal posterior hyaloid traction, and significant reduction in foveal thickness. The follow-up was 1 year. At the end of follow-up, visual acuity slightly improved again; only a small residual foveal retinal thickening remained. CONCLUSIONS: The authors report spontaneous resolution of VMT associated with diabetic macular edema, probably facilitated by PRP, with concurrent reduction of macular thickness and visual improvement. As spontaneous resolution may occur in some eyes with diabetic macular edema associated with VMT, a period of observation after the end of the PRP may be considered prior to vitrectomy.

Aged↗