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At least 1,279 records · Page 71Linked to original sources
PubMed2001

Entropy, entropy rate, and pattern classification as tools to typify complexity in short heart period variability series.

An integrated approach to the complexity analysis of short heart period variability series (approximately 300 cardiac beats) is proposed and applied to healthy subjects during the sympathetic activation induced by head-up tilt and during the driving action produced by controlled respiration (10, 15, and 20 breaths/min, CR10, CR15, and CR20 respectively). The approach relies on: 1) the calculation of Shannon entropy (SE) of the distribution of patterns lasting three beats; 2) the calculation of a regularity index based on an entropy rate (i.e., the conditional entropy); 3) the classification of frequent deterministic patterns (FDPs) lasting three beats. A redundancy reduction criterion is proposed to group FDPs in four categories according to the number and type or of heart period changes: a) no variation (0V); b) one variation (1V); and c) two like variations (2LV); 4) two unlike variations (2UV). We found that: 1) the SE decreased during tilt due to the increased percentage of missing patterns; 2) the regularity index increased during tilt and CR10 as patterns followed each other according to a more repetitive scheme; and 3) during CR10, SE and regularity index were not redundant as the regularity index significantly decreased while SE remained unchanged. Concerning pattern analysis we found that: a) at rest mainly three classes (0V, 1V, and 2LV) were detected; b) 0V patterns were more likely during tilt; c) 1V and 2LV patterns were more frequent during CR10; and d) 2UV patterns were more likely during CR20. The proposed approach based on quantification of complexity allows a full characterization of heart period dynamics and the identification of experimental conditions known to differently perturb cardiovascular regulation.

Analysis of Variance↗
PubMedDate not supplied

An O(N2) algorithm for discovering optimal Boolean pattern pairs.

We consider the problem of finding the optimal combination of string patterns, which characterizes a given set of strings that have a numeric attribute value assigned to each string. Pattern combinations are scored based on the correlation between their occurrences in the strings and the numeric attribute values. The aim is to find the combination of patterns which is best with respect to an appropriate scoring function. We present an O(N2) time algorithm for finding the optimal pair of substring patterns combined with Boolean functions, where N is the total length of the sequences. The algorithm looks for all possible Boolean combinations of the patterns, e.g., patterns of the form p and not q, which indicates that the pattern pair is considered to occur in a given string s, if p occurs in s, AND q does NOT occur in s. An efficient implementation using suffix arrays is presented, and we further show that the algorithm can be adapted to find the best k-pattern Boolean combination in O(Nk) time. The algorithm is applied to mRNA sequence data sets of moderate size combined with their turnover rates for the purpose of finding regulatory elements that cooperate, complement, or compete with each other in enhancing and/or silencing mRNA decay.

3' Untranslated Regions↗
PubMed2006

A system for learning statistical motion patterns.

Analysis of motion patterns is an effective approach for anomaly detection and behavior prediction. Current approaches for the analysis of motion patterns depend on known scenes, where objects move in predefined ways. It is highly desirable to automatically construct object motion patterns which reflect the knowledge of the scene. In this paper, we present a system for automatically learning motion patterns for anomaly detection and behavior prediction based on a proposed algorithm for robustly tracking multiple objects. In the tracking algorithm, foreground pixels are clustered using a fast accurate fuzzy K-means algorithm. Growing and prediction of the cluster centroids of foreground pixels ensure that each cluster centroid is associated with a moving object in the scene. In the algorithm for learning motion patterns, trajectories are clustered hierarchically using spatial and temporal information and then each motion pattern is represented with a chain of Gaussian distributions. Based on the learned statistical motion patterns, statistical methods are used to detect anomalies and predict behaviors. Our system is tested using image sequences acquired, respectively, from a crowded real traffic scene and a model traffic scene. Experimental results show the robustness of the tracking algorithm, the efficiency of the algorithm for learning motion patterns, and the encouraging performance of algorithms for anomaly detection and behavior prediction.

Algorithms↗
PubMed2005

Pattern-sensitive epilepsy: electroclinical characteristics, natural history, and delineation of the epileptic syndrome.

PURPOSE: To elucidate the electroclinical features and long-term outcome of patients with pattern-sensitive epilepsy. METHODS: We reviewed the clinical and electroencephalographic (EEG) findings of 73 (43 female and 30 male) patients in whom pattern-sensitive epilepsy was diagnosed at Mayo Clinic (Rochester, Minnesota, U.S.A.) from 1950 through 1999. We contacted patients and their relatives by letter or telephone to obtain the latest seizure and quality-of-life outcomes. RESULTS: The median age at onset of seizures was 12.8 years (range, 0.6-32.9 years). Most patients had absence, myoclonic, or generalized tonic-clonic seizures. Interictal epileptiform discharges in the EEG were detected in 61 (83.6%) patients and were generalized in 54 (74%). Paroxysmal epileptiform discharges in the EEG elicited with standard patterns were all generalized in two thirds of patients but were restricted to the posterior head region in one-third. Eight (11%) patients did not exhibit photosensitivity. Television was the most common precipitant [30 patients (41%)]. Twenty-nine patients gave a clear history of one or more seizures precipitated while viewing environmental patterns such as window screens, garments, tablecloths, and ceiling tiles; the rest of the patients admitted that they preferred to avoid looking at patterned objects because these objects made them uncomfortable. The electroclinical features suggested juvenile myoclonic epilepsy in 14 patients, progressive myoclonus epilepsy in three, progressive familial cerebellar ataxia with myoclonus in two, and severe myoclonic epilepsy of infancy in one. During a median follow-up period of 15.7 years, 25 (45.5%) of 55 patients who were followed up for > or =5 years achieved complete seizure remission. The median age at remission was 24.4 years. The absence of progressive neurologic disease was correlated significantly with remission; a family history of seizures showed a trend in favor of remission. More than two thirds of the patients did not consider the seizures an impediment to their family life or to educational and occupational achievements. CONCLUSIONS: Although pattern sensitivity as a trait occurs in various epileptic syndromes, pattern-sensitive epilepsy is a readily distinguishable subtype of the visually provoked reflex epilepsies. In our opinion, the location and extent of the excitable region or regions within the visual cortex concerned with different attributes of visual function dictate susceptibility to a specific trigger (intermittent light, pattern, or color) or closely related multiple triggers and the resultant electroclinical phenomenon.

Adolescent↗
PubMed1975

Pattern and flicker detection analysed by subthreshold summation.

1. We confirm Keesey's (1972) observation that, when a flickering line is viewed, there are distinct thresholds for detecting flicker (or movement) and for detecting a well localized line (pattern detection). Our measurements of the temporal sensitivity of these two mechanisms are similar to Keesey's. 2. The flicker and pattern detection mechanism have been analysed using subthreshold summation, i.e. by observing the effect of subthreshold flickering stimuli (lines and gratings) on the contrast threshold for a flickering test line. 3. The pattern detector shows linear spatial summation of contrast while the flicker detector is non-linear in this respect. 4. The receptive field of the (most sensitive) flicker detector is about two to four times broader than that of the pattern detector. 5. The flicker detector has relatively weak surround inhibition and so, unlike the pattern detector, it is sensitive to a uniform flickering field. 6. The spatial arrangement of the pattern detector is the same at all temporal frequencies (including steady presentation); for flicker detection, the width of the receptive field increases with temporal frequency and the strength of lateral inhibition decreases at high frequencies. 7. Flicker detectors of various widths were demonstrated by using different test stimuli (for 12 Hz modulation); surround ingibition was relatively weak for the broadest detector. 8. There is a delay of surround inhibition of about 3 ms for both flicker and pattern detection. 9. By using a broad test stimulus modulated at a high frequency, a detector can be found with no significant surround inhibition. At threshold, this stimulus produces a sensation of flicker without the appearance of lateral motion observed for finer test lines at lower frequencies. 10. The characteristics of pattern and flicker (movement) detection are compared to electrophysiological studies on X (sustained) and Y (transient) neurones respectively, and correlations are described for studies of temporal frequency response, non-linearity, width of receptive field, strength of the inhibitory surround and motion sensitivity.

Animals↗
PubMed1979

Responses of striate cortex cells to grating and checkerboard patterns.

1. Cells in visual cortex have been alternately considered as bar and edge detectors, or as spatial-frequency filters responding to the two-dimensional Fourier component of patterns. 2. The responses to gratings and to checkerboards allow one to test these alternate models: the Fourier components of a checkerboard pattern do not occur at the same orientation as the edges, nor do the checkerboard spatial frequencies correspond to the check widths. 3. Knowing the orientation tuning of a cell for gratings, one can precisely predict its orientation tuning to checkerboards from the orientation of the fundamental Fourier components of the patterns, not from the orientation of their edges. This was found for both square and rectangular checkerboards, and held for both simple and complex cortical cells. 4. Knowing the spatial tuning of a cell for sine-wave gratings, one can precisely predict its spatial tuning to square and rectangular checkerboards from the spatial frequencies of the fundamental Fourier components of the patterns, not from the widths of their checks. 5. When presented with checkerboards in which not the fundamental but the upper harmonics were within its spatial bandpass, a cell's orientation tuning was found to be predictable from the (quite different) orientation of the higher Fourier harmonic components, but not from the orientation of the edges. 6. Knowing a cell's contrast sensitivity for gratings, one can predict the cell's contrast sensitivity for checkerboards much more accurately from the amplitudes of the two-dimensional Fourier components of the patterns than from the contrasts of the patterns. 7. The orientation tuning, spatial-frequency tuning and responsiveness of cells to a plaid pattern were also found to be predictable from the pattern's two-dimensional Fourier spectrum. 8. Both simple and complex striate cortex cells can thus be characterized as two-dimensional spatial-frequency filters. Since different cells responsive to the same region in the visual field are tuned to different spatial frequencies and orientations, the ensemble of such cells would fairly precisely encode the two-dimensional Fourier spectrum of a patch of visual space.

Action Potentials↗
PubMed1994

Pattern electroretinogram and automated perimetry in patients with glaucoma and ocular hypertension.

To determine whether the pattern electroretinogram can improve the objectivity of visual field assessment, 39 patients with glaucoma and ocular hypertension were studied. This was to establish whether there is a correlation between the pattern electroretinogram and the global indices (mean deviation and corrected pattern standard deviation) provided by automated perimetry using the Humphrey visual field analyser. A significant correlation was found between the amplitude of the P50 + N95 wave of the pattern electroretinogram and the mean deviation and corrected pattern standard deviation components of the visual field. The larger the deviation from normal of these indices, particularly the corrected pattern standard deviation, the smaller the amplitude of the pattern electroretinogram. This correlation between the pattern electroretinogram and visual field indices provides an additional measure of confidence when interpreting equivocal results of automated perimetry.

Adult↗
PubMed1992

The effects of background pattern and contrast on prey discrimination by the praying mantis Sphodromantis lineola (Burr.).

Tethered, adult female Sphodromantis lineola (Burr.) were presented with two groups of two-dimensional stimuli (i.e., 2-D lures) against various backgrounds. Lure Group 1 comprised various black rectangles in three different size arrays: each size array included a 2, 6, or 12 mm square, respectively, several 'worm' lures of a constant width (l2, edge perpendicular to the direction of movement, 3-30 mm), but varying in length (l1, parallel to the direction of movement, 6-114 mm), and several 'antiworm' lures of a constant length but varying width. Group 1 lures were presented against patterned backgrounds of similar luminance: one natural pattern mimicking foliage and the other a random geometric pattern of rectangles. Group 2 lures comprised various configurations and combinations of black and white lures which were presented against white, black, and natural pattern backgrounds. The appetitive behaviors of approaching and striking at a lure were dependent measures indicating that a stimulus was categorized as prey. For Group 1 lures, overall response rates to lures of the same size were enhanced by the natural pattern background rather than the geometric pattern background. Against the natural pattern background, worm lures were stronger releasers of predatory behavior than antiworm lures of the same size. Lure configuration (especially for the smallest array) was masked by the geometric pattern background, although worm versus antiworm discrimination was apparent with the largest size array. For Group 2 lures, lure-to-background contrast, as well as configuration, effected prey recognition. For instance, lures with low lure-to-background contrast ratios were weaker releasers than those with high ratios, and lures that were darker (versus lighter) than the background were stronger releasers. In addition, particular stimulus properties interacted to effect lure strength. For instance, a weak or strong releaser became stronger or weaker, respectively, when a more or less, respectively, preferred releaser was super-imposed. The results also suggest that S. lineola attends preferentially to the leading edge of a moving stimulus. These findings are in agreement with predatory behavior of praying mantises in the wild.

Animals↗
PubMed1994

An examination of colour-contingent pattern aftereffects.

The McCollough effect (ME) is an example of a pattern-contingent colour aftereffect. This study describes some characteristics of another visual aftereffect linking pattern and colour here called a colour-contingent pattern aftereffect (CCPA). After inducing with, for example, a magenta and black radial pattern and a green and black pattern of concentric circles, presentation of a green homogeneous field evoked a faint image of a radial pattern superimposed on the field, whereas presentation of a magenta homogeneous field produced a faint image of concentric circles. The pattern was blurred and fleeting, occurring with the onset of the homogeneous field, but nevertheless was evoked reliably. Various properties of these colour-contingent pattern aftereffects are reported. Although the aftereffects have some of the characteristics of the ME, the CCPA is not as long lasting as the ME, and, unlike the usual ME, it is abolished if eye-movements are made during induction.

Color Perception↗
PubMed1999

Factors limiting peripheral pattern discrimination.

Previous reports indicate that some foveally discriminable compound gratings are indiscriminable in peripheral vision, even when they are scaled by the ratio of peripheral to foveal grating acuity. To determine the stimulus properties that limit peripheral discrimination, we used Gaussian derivatives of various orders. These patterns are spatially localized and have intrinsic even or odd symmetry. Our results show that certain odd symmetric patterns are discriminable in the periphery, while others are not. Furthermore, certain even symmetric patterns are not peripherally discriminable. These data are consistent with three limitations on peripheral pattern discrimination: (1) Patterns that produce different maximum neural responses will be peripherally discriminable. (2) Positional uncertainty and undersampling degrade discrimination of high spatial frequency patterns in the periphery. (3) Patterns generating substantial neural activity within a constrained region are processed as textures in peripheral vision so that pattern details within that region are no longer available for discrimination. A neural model incorporating inhibition of simple cells by complex cells implements a transition between contour analysis and texture analysis in peripheral vision and explains the experimental data.

Fovea Centralis↗
PubMed2004

The neural tube patterns vessels developmentally using the VEGF signaling pathway.

Embryonic blood vessels form in a reproducible pattern that interfaces with other embryonic structures and tissues, but the sources and identities of signals that pattern vessels are not well characterized. We hypothesized that the neural tube provides vascular patterning signal(s) that direct formation of the perineural vascular plexus (PNVP) that encompasses the neural tube at mid-gestation. Both surgically placed ectopic neural tubes and ectopic neural tubes engineered genetically were able to recruit a vascular plexus, showing that the neural tube is the source of a vascular patterning signal. In mouse-quail chimeras with the graft separated from the neural tube by a buffer of host cells, graft-derived vascular cells contributed to the PNVP, indicating that the neural tube signal(s) can act at a distance. Murine neural tube vascular endothelial growth factor A (VEGFA) expression was temporally and spatially correlated with PNVP formation, suggesting it is a component of the neural tube signal. A collagen explant model was developed in which presomitic mesoderm explants formed a vascular plexus in the presence of added VEGFA. Co-cultures between presomitic mesoderm and neural tube also supported vascular plexus formation, indicating that the neural tube could replace the requirement for VEGFA. Moreover, a combination of pharmacological and genetic perturbations showed that VEGFA signaling through FLK1 is a required component of the neural tube vascular patterning signal. Thus, the neural tube is the first structure identified as a midline signaling center for embryonic vascular pattern formation in higher vertebrates, and VEGFA is a necessary component of the neural tube vascular patterning signal. These data suggest a model whereby embryonic structures with little or no capacity for angioblast generation act as a nexus for vessel patterning.

Angiogenesis Inhibitors↗
PubMed2005

Slow muscle regulates the pattern of trunk neural crest migration in zebrafish.

In avians and mice, trunk neural crest migration is restricted to the anterior half of each somite. Sclerotome has been shown to play an essential role in this restriction; the potential role of other somite components in specifying neural crest migration is currently unclear. By contrast, in zebrafish trunk neural crest, migration on the medial pathway is restricted to the middle of the medial surface of each somite. Sclerotome comprises only a minor part of zebrafish somites, and the pattern of neural crest migration is established before crest cells contact sclerotome cells, suggesting other somite components regulate the pattern of zebrafish neural crest migration. Here, we use mutants to investigate which components regulate the pattern of zebrafish trunk neural crest migration on the medial pathway. The pattern of trunk neural crest migration is aberrant in spadetail mutants that have very reduced somitic mesoderm, in no tail mutants injected with spadetail morpholino antisense oligonucleotides that entirely lack somitic mesoderm and in somite segmentation mutants that have normal somite components but disrupted segment borders. Fast muscle cells appear dispensable for patterning trunk neural crest migration. However, migration is abnormal in Hedgehog signaling mutants that lack slow muscle cells, providing evidence that slow muscle cells regulate the pattern of trunk neural crest migration. Consistent with this idea, surgical removal of adaxial cells, which are slow muscle precursors, results in abnormal patterning of neural crest migration; normal patterning can be restored by replacing the ablated adaxial cells with ones transplanted from wild-type embryos.

Animals↗
PubMed2000

Expression of achaete-scute homologues in discrete proneural clusters on the developing notum of the medfly Ceratitis capitata, suggests a common origin for the stereotyped bristle patterns of higher Diptera.

The stereotyped positioning of sensory bristles in Drosophila has been shown to result from complex spatiotemporal regulation of the proneural achaete-scute genes, that relies on an array of cis-regulatory elements and spatially restricted transcriptional activators such as Pannier. Other species of derived schizophoran Diptera have equally stereotyped, but different, bristle patterns. Divergence of bristle patterns could arise from changes in the expression pattern of proneural genes, resulting from evolution of the cis-regulatory sequences and/or altered expression patterns of transcriptional regulators. Here we describe the isolation of achaete-scute homologues in Ceratitis capitata, a species of acalyptrate Schizophora whose bristle pattern differs slightly from that of Drosophila. At least three genes, scute, lethal of scute and asense have been conserved, thus demonstrating that gene duplication within the achaete-scute complex preceded the separation of the families Drosophilidae and Tephritidae, whose common ancestor goes back more than 100 million years. The expression patterns of these genes provide evidence for conservation of many cis-regulatory elements as well as a common origin for the stereotyped patterns seen on the scutum of many Schizophora. Some aspects of the transcriptional regulation have changed, however, and correlate in the notum with differences in the bristle pattern. The Ceratitis pannier gene was isolated and displays a conserved expression domain in the notum.

Amino Acid Sequence↗
PubMed1992

The effects of pharmaceutical firm enticements on physician prescribing patterns. There's no such thing as a free lunch.

We examined the impact on physician prescribing patterns of pharmaceutical firms offering all-expenses-paid trips to popular sunbelt vacation sites to attend symposia sponsored by a pharmaceutical company. The impact was assessed by tracking the pharmacy inventory usage reports for two drugs before and after the symposia. Both drugs were available only as intravenous preparations and could be used only on hospitalized patients. The usage patterns were tracked for 22 months preceding each symposium and for 17 months after each symposium. Ten physicians invited to each symposium were interviewed about the likelihood that such an enticement would affect their prescribing patterns. A significant increase in the prescribing pattern of both drugs occurred following the symposia. The usage of drug A increased from a mean of 81 +/- 44 units before the symposium to a mean of 272 +/- 117 after the symposium (p less than 0.001). The usage of drug B changed from 34 +/- 30 units before the symposium to 87 +/- 24 units (p less than 0.001) after the symposium. These changed prescribing patterns were also significantly different from the national usage patterns of the two drugs by hospitals with more than 500 beds and major medical centers over the same period of time. These alterations in prescribing patterns occurred even though the majority of physicians who attended the symposia believed that such enticements would not alter their prescribing patterns.

Conflict of Interest↗
PubMed2005

The rod photoreceptor pattern is set at the optic vesicle stage and requires spatially restricted cVax expression.

How and when positional identities in the neural retina are established have been addressed primarily with respect to the topographic projections of retinal ganglion cells onto their targets in the brain. Although retinotectal map formation is a prominent manifestation of retinal patterning, it is not the only one. Photoreceptor subtypes are arranged in distinct, species-specific patterns. The mechanisms used to establish photoreceptor patterns have been relatively unexplored at the mechanistic level. We performed ablations of the eye anlage in chickens and found that removal of the anterior or dorsal optic vesicle caused loss of the area centralis, which is a rod-free central area of the retina, and severely disorganized other aspects of the rod pattern. These observations indicate that the anteroposterior and dorsoventral distribution of rods is determined by the optic vesicle stage. To investigate the molecular mechanisms involved, the rod distribution was analyzed after viral misexpression of several patterning genes that were previously shown to be important in positional specification of retinal ganglion cells. Ectopic expression of FoxG1, SOHo1,or GH6 transcription factors expressed in the anterior optic vesicle and/or optic cup, respectively, did not affect the rod pattern. This pattern therefore appears to be specified by an activity acting before, or in parallel with, these factors. In contrast, misexpression of the ventrally restricted transcription factor, cVax, severely disturbed the rod pattern.

Animals↗
PubMed2005

Dermatoglyphic pattern types in subjects with nonsyndromic cleft lip with or without cleft palate (CL/P) and their unaffected relatives in the Philippines.

OBJECTIVE: To investigate dermatoglyphic patterns in 95 nonsyndromic Filipino subjects with nonsyndromic cleft lip with or without cleft palate (CL/P) and 90 of their unaffected relatives. DESIGN: Retrospective study of dermatoglyphic pattern types. SETTING: Negros Occidental and Cavite in the Philippines. PARTICIPANTS: Nonsyndromic subjects with CL/P and their unaffected relatives. METHODS: Dermatoglyphic patterns were categorized as arch, ulnar loop, radial loop, whorl, or other by three independent raters. Pattern data from the subjects, the unaffected relatives, and an unaffected control population (from the literature) were compared using chi-square tests. As a measure of asymmetry, dissimilarity between pattern types on homologous fingers was quantified and compared using Student's t tests. RESULTS: The frequency of arches (p = .016) and ulnar loops (p = .04) were significantly increased, and whorls decreased in the affected group (p = .0015), compared with the unaffected group. Affected female subjects had significantly more ulnar loops and arches (p = .009 and p = .023, respectively) and fewer whorls (p < .0001) than the unaffected female subjects. There were no significant differences between affected and unaffected male subjects. Dissimilarity scores were significantly different between male and female subjects and between subjects with CL/P and unaffected relatives. Additionally, pattern type frequencies for the relatives fell in between the frequencies for the CL/P group and the controls. CONCLUSIONS: In this Filipino population, differences in frequency of dermatoglyphic pattern types and pattern dissimilarity exist between individuals with orofacial clefts and their unaffected relatives and between both groups and controls, with the major effect seen in female subjects.

Case-Control Studies↗
PubMed2005

A multiple-pattern biosequence analysis method for diverse source association mining.

BACKGROUND: In order to understand the intricacy of biomolecules more comprehensively, significant patterns extracted from related data collected from diverse sources must be integrated. These data sources may be local or distributed, possibly with different representation schemes. Often, related data from different sources correspond only with respect to some of their values. METHODS: In biological sequence analysis, a goal is to identify new, previously unknown, relevant patterns, to obtain additional insights into the biomolecule. This is known as a pattern discovery task, rather than a pattern matching task. In this research, we present a method to tackle this problem typically found in molecular sequence analysis when the alignment of the sequences is represented as a relation. In this article, we propose an information measure to select attribute values that reflect multiple patterns of significant interdependence information. Based on these selected values, the patterns are evaluated with data values from other sources. RESULTS: In the experiments, a cancer-suppressor gene known as TP53 (encoding tumour protein p53) is analysed with the mutation records of patients. The experiments identify previously unknown points in the molecule that have patterns negatively associated with the occurrence of cancer. CONCLUSION: Since the evaluated interdependence pattern is a global property of the molecule, we conjecture that the identified points might also be a reflection of the molecule's cancer-suppressor characteristics. The experiments also confirm the usefulness of the proposed method.

Amino Acid Sequence↗
PubMed1986

Sonography of diffuse benign liver disease: accuracy of pattern recognition and grading.

Sonograms of 110 patients were compared to recently performed liver biopsies for evaluation of the accuracy of sonography in predicting the type (pattern) of pathology and its grade of severity (mild, moderate, or severe) in a wide variety of diffuse liver processes. There are two distinct, abnormal sonographic patterns: the fatty-fibrotic pattern seen primarily with cirrhosis, chronic hepatitis, and/or fatty infiltration, and the centrilobular pattern seen primarily with acute hepatitis. Sonography was 88% accurate in assigning the correct pattern to the corresponding pathology (sensitivity 89%, specificity 86%, p less than 0.001). The degree of accuracy was dependent on the grade of pathologic severity, with mild disease offering the greatest difficulty; moderate and severe diseases were accurately detected and placed in the correct pattern in all cases. Sonographic grading of the severity of disease was far less precise (63% overall). This study showed that sonography can distinguish between two abnormal sonographic patterns of diffuse benign liver disease as well as between normal and abnormal patterns.

Biopsy↗