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PubMed1997

Differentiation of hepatocellular adenoma and focal nodular hyperplasia of the liver: comparison of power Doppler imaging and conventional color Doppler sonography.

The aim of our study was to compare the diagnostic efficacy of power Doppler imaging and conventional color Doppler sonography for differentiating between hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH) of the liver. Thirty-one focal liver lesions (in 29 patients) with histologic proof of HCA (n = 9) or FNH (n = 22) were studied with power and color Doppler sonography according to a standardized examination protocol. The size of the lesions ranged between 1.5 and 14.5 cm (HCA, 3.5-14.5 cm, mean +/- SD 7.3 +/- 3.3 cm; FNH, 1.5-9.1 cm, mean +/- SD 5.1 +/- 2.1 cm). Intratumoral vessels with a venous Doppler spectrum, associated with either pulsatile or continuous peripheral flow, were detected in HCA (eight of nine lesions by power Doppler imaging and six of nine by color Doppler imaging) but not in FNH. In contrast, color signals with an arterial Doppler spectrum, radiating from the center to the periphery of the lesion, were depicted in FNH (20 of 22 cases by power Doppler imaging and 15 of 22 by color Doppler sonography) but not in HCA. Differentiation of HCA and FNH was achieved in 28 of 31 cases (90 %) by power Doppler imaging and in 21 of 31 (68 %) by color Doppler sonography (p < 0.01). Power Doppler imaging is superior to conventional color Doppler sonography in the depiction of the intratumoral flow characteristics of HCA and FNH, and enables a more accurate differential diagnosis than color Doppler sonography.

Adenoma, Liver Cell↗

PubMed2005

Generalization and categorization of spectral colors in goldfish I. Experiments with one training wavelength.

Goldfish have a tetrachromatic color vision with a high discrimination ability for spectral colors as well as for object colors. We investigate the question whether goldfish organize the high number of discriminable colors in terms of color categories, i.e. in a few larger groups of colors independent of wavelength discrimination. Twenty-four goldfish were trained with food reward, each fish on one out of 13 wavelengths between 371 nm and 630 nm. In transfer tests two different wavelengths were presented, one shorter and one longer than the training wavelength, and the choice behavior was determined. Choice frequencies of >or=50% were assumed to indicate similarity to the training color. The wavelength ranges >or=50% were about 100 nm and twice as large as the just noticeable differences measured in wavelength discrimination tests (Fig. 7). The ranges were surprisingly about the same for all training wavelengths, provided the data were plotted on a wavelength scale weighted according to discrimination ability (Fig. 4). Thus, with the training method chosen goldfish showed a kind of categorization which, however, depends on training wavelength and discrimination ability. Generalization tests in which training wavelength and test wavelengths were shown separately for 2 min each gave the same results as wavelength discrimination tests (Figs. 5 and 6) and are, therefore, not indicative for color categories.

Animals↗

PubMed1994

Color Doppler flow patterns and flow velocity waveforms of the intraplacental fetal circulation in growth-retarded fetuses.

OBJECTIVE: We examined intraplacental color Doppler flow patterns and spectral Doppler flow velocity waveforms of villous arteries in pregnancies with intrauterine growth retardation. STUDY DESIGN: A total of 192 uncomplicated pregnancies and 29 pregnancies with intrauterine growth retardation between 26 and 41 weeks' gestation were examined in this cross-sectional study. Intraplacental color Doppler flow findings and pulsatility indexes of umbilical and villous arteries were correlated with the presence of intrauterine growth retardation and multiple outcome variables. Villous arteries were identified by their intraplacental color Doppler flow image, and flow velocity waveforms were obtained by superimposition of pulse-wave Doppler. RESULTS: (1) Intraplacental color Doppler flow signals from two or more villous arteries were detected in all 192 normal pregnancies but were undetectable in 8 of 29 fetuses with intrauterine growth retardation (27.6%, p < 0.0001). Absence of intraplacental color Doppler flow signals was associated with fetal distress in 6 of 8 cases (87.5%) and perinatal death in two cases (25.0%), compared with 3 of 21 (14.2%, p < 0.005) and 0 of 21 (not significant) cases of intrauterine growth retardation with detectable intraplacental color Doppler flow. Median Apgar scores at 1 minute were 5 and 8 (p < 0.05), respectively, and at 5 minutes were 8 and 8 (not significant), respectively. (2) Umbilical artery flow velocity waveforms were abnormal (> 95th percentile) in 8 of 21 cases of intrauterine growth retardation (38.0%) with detectable intraplacental color Doppler flow, including two cases with reversed end-diastolic flow. In contrast, the corresponding villous artery flow velocity waveforms were abnormal in only 1 of 21 cases (p < 0.04). CONCLUSION: (1) Failure to detect intraplacental color Doppler flow signals is associated with intrauterine growth retardation and fetal distress. (2) Flow velocity waveforms of detectable villous arteries are usually normal in intrauterine growth retardation, even in the presence of extremely abnormal umbilical artery flow velocity waveforms.

Blood Circulation↗

PubMed1979

Color perception and deafness: college-level comparisons.

The performance of three groups of college-level subjects, deaf students, normal-hearing students, and Art students, were compared on nine tests involving color perception and color-verbal materials including (a) Color-Form Sorting, (b) Color-Form Pointing, (c) Color-Word Meaning, (d) Color-Pair Preferences (N=3), and (e) Color-Word Interference (N=3). Color perception differences between the deaf and the hearing groups were not substantiated: deaf and hearing groups differed only on tests involving verbal materials. The Deaf differed more from the Art students than from the Hearing.

Adolescent↗

PubMed1995

The use of color Doppler ultrasound to identify fetuses at increased risk for trisomy 21: an alternative for high-risk patients who decline genetic amniocentesis.

OBJECTIVE: To compare color Doppler ultrasound with real-time ultrasound to determine whether it increased the identification of fetuses with trisomy 21. METHODS: Consecutive fetuses with a second trimester risk greater than 1:270 for trisomy 21 were examined with real-time ultrasound (n = 1028) or real-time plus color Doppler ultrasound (n = 1028) before second trimester genetic amniocentesis. The type of abnormal ultrasound findings were compared between fetuses with normal and abnormal chromosomes. Using the Bayes theorem, the ultrasound-adjusted maternal age-related risk (posterior risk) for trisomy 21 was computed after a normal or abnormal real-time plus color Doppler examination. RESULTS: A significantly greater number of fetuses with trisomy 21 (87% [13 of 15] versus 29% [5 of 17], P < .002) were identified with real-time plus color Doppler than with real-time ultrasound. Color Doppler ultrasound identified a significantly higher rate of cardiovascular abnormalities in fetuses with trisomy 21 (60% [9 of 15] versus 12% [2 of 17], P < .008) than did real-time ultrasound. Identification of abnormal fetal anatomy using real-time plus color Doppler in patients 35 years and older increases the likelihood of detecting trisomy 21. A normal real-time plus color Doppler examination of the fetus decreases the risk for trisomy 21 to less than 1:270 until the maternal age of 42, above which the risk for trisomy 21 is greater than 1:270. CONCLUSION: Real-time plus color Doppler ultrasound examination of the fetus is an alternative for the identification of trisomy 21 for patients who may decline genetic amniocentesis based on their age-related risk.

Adult↗

PubMed1993

Simultaneous luminance contrast with chromatic colors.

The variations in the color of a test field of constant luminance during changes in the luminance of a contiguous inducing field was measured psychophysically. The fields had the same hue (red, green, or blue). The colors induced in the test field could be specified by the strength of a chromatic quality, and by the strength of the opponent qualities luminous/black. The psychophysical relationship between the two kinds of perceptive variables and test and inducing luminance followed distinctly different functions. The luminous/black variable varied linearly with contrast over a large range, as previously found for achromatic colors. The contrast gain of the luminous/black variable for the red and green colors was the same as for achromatic colors. The gain for the blue colors was twice the gain for the other colors. The chromatic variables were primarily related to the local luminance. For a given test luminance they were maximal near zero contrast. They followed the same function as the white component of achromatic colors. It is suggested that the luminous/black variable is related to spectrally broadband cells with a strong center/surround antagonism, while the chromatic variables and white are related to cells that lack a spectrally broadband surround in their receptive field.

Color Perception↗

PubMed1996

Color constancy under natural and artificial illumination.

Color constancy was studied under conditions simulating either natural or extremely artificial illumination. Four test illuminants were used: two broadband phases of daylight (correlated color temperatures 4000 and 25,000 K) and two spectrally impoverished metamers of these lights, each consisting of only two wavelengths. A computer controlled color monitor was used for reproducing the chromaticities and luminances of an array of Munsell color samples rendered under these illuminants. An asymmetric haploscopic matching paradigm was used in which the same stimulus pattern, either illuminated by one of the test illuminants, or by a standard broadband daylight (D65), was alternately presented to the left and right eye. Subjects adjusted the RGB settings of the samples seen under D65 (match condition), to match the appearance of the color samples seen under the test illuminant. The results show the expected failure of color constancy under two-wavelengths illumination, and approximate color constancy under natural illumination. Quantitative predictions of the results were made on the basis of two different models, a computational model for recovering surface reflectance, and a model that assumes the color response to be determined by cone-specific contrast and absolute level of stimulation (Lucassen & Walraven, 1993). The latter model was found to provide somewhat more accurate predictions, under all illuminant conditions.

Color Perception↗

PubMed1991

Sources of color variation on firing porcelain.

The final color matching of porcelain crowns depends upon the accuracy of the original shade matching by the dentist and variables introduced during processing. Possible sources of processing variables include thickness and color of the opaque, thickness, color, and translucency of the body and enamel layers, firing temperature, and number of firings (Miller, 1987). These processing variables can lead to an error in shade match. The purpose of this study was to quantify, in CIE delta E units: (1) the shade variations when the same batches are fired, (2) the shade variations between different batches, and (3) the differences in color produced by the multiple firing. Three lots of six shades of four commercial brands were included in this study. The color variation of the opaque samples (mean delta E was 0.46) was generally lower than that of the body/opaque samples (mean delta E was 0.86). The average color variation for three different batches of the body/opaque samples was 1.44. The average color difference produced as a result of multiple firings was 1.00 after six firings, compared with the color after three firings.

Analysis of Variance↗

PubMed1995

Transesophageal color Doppler evaluation of obstructive lesions using the new "Quasar" technology.

Due to the unavoidable problem of aliasing, color flow signals from high blood flow velocities cannot be measured directly by conventional color Doppler. A new technology termed Quantitative Un-Aliased Speed Algorithm Recognition (Quasar) has been developed to overcome this limitation. Employing this technology, we used transesophageal color Doppler echocardiography to investigate whether the velocities detected by the Quasar would correlate with those obtained by continuous-wave Doppler both in vitro and in vivo. In the in vitro study, a 5.0 MHz transesophageal transducer of a Kontron Sigma 44 color Doppler flow system was used. Fourteen different peak velocities calculated and recorded by color Doppler-guided continuous-wave Doppler were randomly selected. In the clinical study, intraoperative transesophageal echocardiography was performed using the same transducer 18 adults (13 aortic valve stenosis, 2 aortic and 2 mitral stenosis, 2 hypertrophic obstructive cardiomyopathy and 1 mitral valve stenosis). Following each continuous-wave Doppler measurement, the Quasar was activated, and a small Quasar marker was placed in the brightest area of the color flow jet to obtain the maximum mean velocity readout. The maximum mean velocities measured by Quasar closely correlated with maximum peak velocities obtained by color flow guided continuous-wave Doppler in both in vitro (0.53 to 1.65 m/s, r = 0.99) and in vivo studies (1.50 to 6.01 m/s, r = 0.97). We conclude that the new Quasar technology can accurately measure high blood flow velocities during transesophageal color Doppler echocardiography. This technique has the potential of obviating the need for continuous-wave Doppler.

Adult↗

PubMed1996

Endosonographic and color Doppler flow imaging alterations observed within irradiate rectal cancer.

PURPOSE: To correlate the endosonographic and color Doppler flow imaging alterations observed in irradiated rectal cancers with the pathologic features of radiation response, and to evaluate the potential impact of altered blood flow on the integrity of the surgical anastomosis. METHODS AND MATERIALS: Endosonography with color and pulsed wave Doppler was performed on 20 rectal cancer masses before and after high dose preoperative radiation (XRT). Pre- and post-XRT observations included comparing alterations in tumor size, sonographic echotexture, color Doppler flow, and pulsatility indices. Comparisons were made with pathologic findings in the irradiated specimens and with the incidence of anastomotic failure. RESULTS: Compared to pre-XRT observations, irradiated rectal cancers decreased in size and became either mixed in echogenicity with less apparent color Doppler flow (16 of 20) or unchanged in color Doppler flow and echotexture (4 of 20). Those with less flow (16 of 20) were imaged later (mean = 90.2 +/- 12.1 days) than those without change in color Doppler flow (mean = 21.7 +/- 2.7 days). Pathologically, the group of four without change in color Doppler signal had features of acute inflammation which were not observed in 16 of 20 imaged later. Based on pulsatility index measurements, both high and low resistance vessels were detected and confirmed by immunohistochemical staining, and features of postradiation obliterative vasculitis were observed. Only one primary anastomosis in 14 patients with decreased flow failed. CONCLUSIONS: The sonographic and color Doppler flow imaging alterations observed within irradiated rectal cancer correlated with changes of postradiation obliterative vasculitis. The apparent diminished local blood flow within high and low resistance vessels post-XRT did not result in an increased incidence of anastomotic failures.

Aged↗

PubMedDate not supplied

An automatic color segmentation algorithm with application to identification of skin tumor borders.

A principal components transform algorithm for automatic color segmentation of images is described. This color segmentation algorithm was used to find tumor borders in six different color spaces including the original red, green, and blue (RGB) color space of the digitized image, the intensity/hue/saturation (IHS) transform, the spherical transform, chromaticity coordinates, the CIE transform and the uniform color transform designated CIE-LUV. Five hundred skin tumor images were separated into a training set and a test set for comparison of the different color spaces. Automatic induction was applied to dynamically determine the number of colors for segmentation. Ninety-one percent of image variance was contained in the image component along the principal axis (also containing the most image information). When compared to a luminance radial search method, the principal components color segmentation border method performed equally well by one measure and 10% better by another measure, including more near border points outside the tumor. The spherical transform provides the highest success rate and the chromaticity transform the lowest error rate, although large variances in the data preclude definitive statistical comparisons.

Algorithms↗

PubMed2006

Color naming universals: the case of Berinmo.

Proponents of a self-identified 'relativist' view of cross-language color naming have confounded two questions: (1) Is color naming largely subject to local linguistic convention? and (2) Are cross-language color naming differences reflected in comparable differences in color cognition by their speakers? The 'relativist' position holds that the correct answer to both questions is Yes, based on data from the Berinmo language of Papua New Guinea. It is shown here that the Berinmo facts instead support a more complex view -- that cross-language color naming follows non-trivial universal tendencies, while cross-language color-naming differences do indeed correlate with differences in color cognition. The rhetoric of 'relativity' versus 'universalism' impedes understanding of cross-language color naming and cognition.

Cognition↗

PubMed2004

Color and opacity variations in three different resin-based composite products after water aging.

OBJECTIVES: Correct shade selection and clinical procedures may be invalidated as a result of intrinsic color shifting with time. The aim of this study was to test the influence of exposure to water on the color stability of three structurally different resin-based composites. METHODS: Six comparable Vita shades of three different resin-based composite systems were selected. For each product at each shade, three disks were made, 1 mm in thickness and 15 mm in diameter. The samples were studied with a spectrophotometer equipped with an integrating sphere. For color determinations, a 50% gray card was used as background, and the data were recorded in the CIE L*a*b* system. Opacity was calculated as the ratio of the reflectance of a specimen disk when backed by a black standard that when backed by a white standard. After the initial measurements, the samples were stored for 30 days in a 60 degrees C water bath and then measured again under the same conditions. The color shifts were calculated using the formula: delta E = [(L1 - L2)2 + (a1 - a2)2 + (b1 - b2)2]1/2. RESULTS: If the standard of delta E < 3.3 as clinically acceptable was taken into consideration, one of the three materials involved in the study showed an unacceptable color shift for all shades. Only one of the three materials remained completely within an acceptable shade shift (delta E < 3.3) after aging. The difference in the color stability between products was significant (p < 0.001). The differences may be due to the different nature of the matrix and could also be correlated with filler particles dimensions. With reference to opacity; the results showed a similar pattern as that of the color and the statistical analysis also correlated. SIGNIFICANCE: From this work, it can be concluded that for some products, aging of composites in water leads to color instability and opacity variation.

Analysis of Variance↗

PubMed2005

Color accuracy of commercial digital cameras for use in dentistry.

OBJECTIVES: The use of calibrated, commercial digital cameras for dental applications is promising. The color accuracy of various calibration models were evaluated as applied to three commercial digital cameras for use in dental color matching. METHODS: CIE LAB values of 264 color patches and 65 shade tabs were measured with a spectroradiometer. Digital images of the samples were taken with the Nikon D100, Canon D60 and Sigma SD9 cameras. Four regression models were formulated from the color patch CIE LAB and the digital image values. Shade tab CIE LAB colors were predicted by applying the digital image values into the calibration models and were compared to the measured CIE LAB values. The Wilcoxon Rank-Sum test determined if the 12 camera/calibration models differed significantly from the color measurement setup. RESULTS: Every camera/calibration model (DeltaE's ranging from 1.79 to 5.25) showed a statistically significant difference from the color measurement setup. SIGNIFICANCE: Commercial SLR digital cameras when combined with the appropriate calibration protocols showed potential for use in the color replication process of clinical dentistry.

Calibration↗

PubMed2006

Reactivation of medial temporal lobe and occipital lobe during the retrieval of color information: A positron emission tomography study.

It is widely accepted that memory traces of an event include various types of information about the content of the event and about the circumstances in which the individual experienced it. However, how these various types of information are stored and later retrieved is poorly understood. One hypothesis postulates that the retrieval of specific event information reactivates regions that were active during the encoding of this information, with the aid of binding functions of the medial temporal lobe (MTL) structures. We used positron emission tomography to identify the brain regions related to the encoding and retrieval of color information. Specifically, we assessed whether overlapping activity was found in both the MTL structures and color-related cortical regions during the encoding and retrieval of color information attached with meaningless shapes. During the study, subjects were asked to encode colored (red or green) and achromatic random shapes. At subsequent testing, subjects were presented with only achromatic shapes, which had been presented with or without colors during encoding, and were engaged in retrieval tasks of shapes and colors. Overlapping activity was found in the MTL and occipital lobe (the lingual and inferior occipital gyri) in the right hemisphere during the encoding and retrieval of meaningless shapes with color information compared with those without color information. Although there are some limitations to be considered, the present findings seem to support the view that the retrieval of specific event information is associated with reactivation of both the MTL structures and the regions involved during encoding of the information.

Adult↗

PubMed2006

Color blindness and contrast perception in cuttlefish (Sepia officinalis) determined by a visual sensorimotor assay.

We tested color perception based upon a robust behavioral response in which cuttlefish (Sepia officinalis) respond to visual stimuli (a black and white checkerboard) with a quantifiable, neurally controlled motor response (a body pattern). In the first experiment, we created 16 checkerboard substrates in which 16 grey shades (from white to black) were paired with one green shade (matched to the maximum absorption wavelength of S. officinalis' sole visual pigment, 492 nm), assuming that one of the grey shades would give a similar achromatic signal to the tested green. In the second experiment, we created a checkerboard using one blue and one yellow shade whose intensities were matched to the cuttlefish's visual system. In both assays it was tested whether cuttlefish would show disruptive coloration on these checkerboards, indicating their ability to distinguish checkers based solely on wavelength (i.e., color). Here, we show clearly that cuttlefish must be color blind, as they showed non-disruptive coloration on the checkerboards whose color intensities were matched to the Sepia visual system, suggesting that the substrates appeared to their eyes as uniform backgrounds. Furthermore, we show that cuttlefish are able to perceive objects in their background that differ in contrast by approximately 15%. This study adds support to previous reports that S. officinalis is color blind, yet the question of how cuttlefish achieve "color-blind camouflage" in chromatically rich environments still remains.

Animals↗

PubMed1997

Color processing in object verification.

This study examined the effect of different object verification tasks on perceptual and conceptual color processing. Participants decided whether two successively presented stimuli (two pictures or a word then a picture) referred to the same object. Although the task did not require object-color processing, prototypical object-color was semantically activated and influenced verification decisions. This automatic conceptual color processing was more powerful than perceptual processing of the surface color presented in the picture. Moreover, conceptual color processing occurred in tasks involving only two pictures, implying that activation of prototypical color does not depend on verbal processing. Rather, activation of prototypical color depends on whether pictures are semantically encoded during verification, which in turn, occurs when verification cannot proceed from structural object information.

Cognition↗

PubMed1998

Validation of color Doppler measurements of minimum patent ductus arteriosus diameters: significance for coil embolization.

BACKGROUND: Echocardiography is sometimes performed to identify candidates for coil embolization of patent ductus arteriosus (PDA). Therefore we attempted to determine the validity of color Doppler echocardiography to accurately determine the minimum PDA diameter. METHODS AND RESULTS: We reviewed data from 27 children (median 3.8 years, range 1 to 15 years) with PDAs and measured their minimum ductal diameters by color flow Doppler echocardiography and by angiography. We found that there were significant mean differences between the color Doppler and angiographic measurements (2.7+/-0.8 vs 1.6+/-0.7 mm, P< .001) with color Doppler exceeding angiographic measurements by > or = 1.0 mm in 15 (56%) of 27 patients. More importantly, color Doppler measured a PDA > or = 4.0 mm (usually greater than that recommended for coiling) in 3 (11%) patients in whom the angiographic measurement was <4.0 mm. Correlation analysis demonstrated no correlation between the color Doppler and angiographic measurements (r2 = 0.17, P= .04, SEE = 0.2 mm). CONCLUSIONS: These data suggest that color Doppler echocardiography often overestimates the true minimum PDA diameter, therefore we recommend that a color Doppler-based recommendation that a PDA is too large for transcatheter coil occlusion not be used exclusively to exclude a patient from this treatment modality.

Adolescent↗