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PubMed2004

Unconscious perception: the need for a paradigm shift.

According to Snodgrass, Bernat, and Shevrin (2004), unconscious perception can be demonstrated convincingly only at the objective detection threshold, provided that the conditions of their objective detection/strategic model are met, whereas both the subjective threshold model of Cheesman and Merikle (1984, 1986) and the objective threshold/rapid decay model of Greenwald, Draine, and Abrams (1996) are inconclusive. We argue on theoretical, metatheoretical, and empirical grounds that all three dual-process models, which are based on both conscious and unconscious perception, should be rejected in favor of the single-process conscious perception model.

Humans↗
PubMedDate not supplied

Gd-DTPA MR detection of blood-brain barrier opening in rats after hyperosmotic shock.

OBJECTIVE: Detection of blood-brain barrier (BBB) opening in neonates has required invasive methods not clinically applicable. We set out to develop a noninvasive approach to detect such opening. MATERIALS AND METHODS: Wistar rats were studied using MRI with Gd-DTPA contrast before and after injection of hyperosmotic solutions known to produce barrier opening. Arabinose was given via right carotid artery to produce unilateral barrier opening; urea was given via tail vein to produce bilateral opening; controls received normal saline. Next, all animals received Gd-DTPA via tail vein. RESULTS: Animals receiving carotid hyperosmotic injections showed increased signal in the ipsilateral brain hemisphere; those receiving venous hyperosmotic injections showed increased signal bilaterally. Similar increases were not found prior to administration of hyperosmotic agent or in saline controls. In both cases, barrier opening was detectable using the relative partitioning of Gd-DTPA between intrabarrier and extrabarrier structures, even in the absence of a hemispheric control. CONCLUSION: We conclude that MRI with Gd-DTPA contrast allows noninvasive detection of BBB opening in the rat.

Animals↗
PubMed2005

Magnetic resonance imaging of pelvic and femoral bones for detection of bone marrow infiltration in patients with non-Hodgkins lymphoma.

OBJECTIVE: Detection of the residual bone marrow (BM) involvement is essential in treatment of patients with non-Hodgkin's lymphoma (NHL). Bilateral iliac crest BM biopsies appear to have low sensitivity for BM infiltration, while magnetic resonance imaging (MRI) presents more global view of BM. This study was conducted to determine the advantage of femoral marrow MRI as a non-invasive technique over bilateral iliac crest BM biopsies in detecting BM infiltration before treatment and residual disease after completion of treatment. METHODS: Over a period of 27 months from January 2002 to March 2004, a total of 30 patients with newly diagnosed NHL were included in the study. Magnetic resonance imaging of 26 patients were conducted in King Fahd Hospital of the University, Al-Khobar, Kingdom of Saudi Arabia. Magnetic resonance imaging of 4 patients were referred from different hospitals in the Eastern Province. Twenty-five patients were of B-cell type and 5 patients were of T-cell type. Coronal MRI of the pelvis and femoral marrow were obtained by the T1, T2-weighted spin echo sequences and short TI inversion recovery technique. RESULTS: Magnetic resonance images showed BM infiltration in 17 cases (56.7%) before treatment and positive biopsy results were found in 9 cases (30%); all had abnormal MR images. There was a significant difference between both methods in the detection of infiltration (p=0.037). Magnetic resonance imaging showed that 58.8% of cases have scattered pattern, 23.5% were uniform and 17.6% of cases have nodular patterns. Magnetic resonance images after completion of treatment showed residual BM infiltration in 6 out of 17 cases who previously had positive MR images and only one case of them had a positive BM biopsy with a significant difference between both methods and all of them relapsed within 6 months (p=0.034). CONCLUSION: Magnetic resonance images of the pelvis and femoral marrow were superior than BM biopsy on detection of BM infiltration before treatment and residual infiltration after treatment.

Adolescent↗
PubMed1994

Lyme disease: a search for a causative agent in ticks in south-eastern Australia.

Attempts were made to identify the causative organism of Lyme disease in Australia from possible tick vectors. Ticks were collected in coastal areas of New South Wales, Australia, from localities associated with putative human infections. The ticks were dissected; a portion of the gut contents was examined for spirochaetes by microscopy, the remaining portion inoculated into culture media. The detection of spirochaetes in culture was performed using microscopy, and immunochemical and molecular (PCR) techniques. Additionally, whole ticks were tested with PCR for spirochaetes. From 1990 to 1992, approximately 12,000 ticks were processed for spirochaetes. No evidence of Borrelia burgdorferi or any other spirochaete was recovered from or detected in likely tick vectors. Some spirochaete-like objects detected in the cultures were shown to be artifacts, probably aggregates of bacterial flagellae. There is no definitive evidence for the existence in Australia of B. burgdorferi the causative agent of true Lyme disease, or for any other tick-borne spirochaete that may be responsible for a local syndrome being reported as Lyme disease.

Animals↗
PubMed2002

A support vector machine approach for detection of microcalcifications.

In this paper, we investigate an approach based on support vector machines (SVMs) for detection of microcalcification (MC) clusters in digital mammograms, and propose a successive enhancement learning scheme for improved performance. SVM is a machine-learning method, based on the principle of structural risk minimization, which performs well when applied to data outside the training set. We formulate MC detection as a supervised-learning problem and apply SVM to develop the detection algorithm. We use the SVM to detect at each location in the image whether an MC is present or not. We tested the proposed method using a database of 76 clinical mammograms containing 1120 MCs. We use free-response receiver operating characteristic curves to evaluate detection performance, and compare the proposed algorithm with several existing methods. In our experiments, the proposed SVM framework outperformed all the other methods tested. In particular, a sensitivity as high as 94% was achieved by the SVM method at an error rate of one false-positive cluster per image. The ability of SVM to out perform several well-known methods developed for the widely studied problem of MC detection suggests that SVM is a promising technique for object detection in a medical imaging application.

Algorithms↗
PubMed1995

A microwave method that enhances detection of aberrant p53 expression in formalin-fixed, paraffin-embedded tissues.

OBJECTIVE: Detection of aberrantly accumulated p53 protein by immunohistochemistry may have prognostic significance in many human neoplasms. We wished to identify a technique applicable to formalin-fixed, paraffin-embedded sections that would reliably yield results equivalent to frozen-section immunohistochemistry. DESIGN: We compared the frequency of p53 immunostaining obtained by applying monoclonal antibodies PAb1801, DO7, or DO1, a 1:1 PAb1801-DO7 cocktail, and a 1:1 PAb1801-DO1 cocktail to fresh-frozen and formalin-fixed, paraffin-embedded tissues from 36 lung and upper aerodigestive-tract carcinomas. With the formalin-fixed tissues, we compared pepsin predigestion with microwave irradiation in citrate buffer as means of enhancing the sensitivity of p53 detection. SETTING AND PATIENTS: All tissues were obtained from surgical resections of tumors, from patients who underwent surgery at the Minneapolis Department of Veterans Affairs Medical Center between 1990 and 1992. MAIN OUTCOME MEASURES: The sensitivity of different paraffin section techniques for immunohistochemical detection of accumulated p53 protein was determined in reference to the optimal frozen section method (defined as the method that yielded the greatest number of p53-positive cases in frozen tissue). RESULTS: Microwave antigen retrieval markedly enhanced staining with PAb1801 and DO7 in paraffin sections, as compared with pepsin predigestion and no pretreatment. This technique was 100% sensitive relative to the optimal frozen tissue method. In contrast, staining with DO1 alone was not enhanced by microwaving. CONCLUSIONS: Microwave pretreatment in conjunction with the use of either PAb1801 or DO7 is highly efficacious in the immunohistochemical detection of aberrant p53 expression in formalin-fixed, paraffin-embedded tissues.

Antibodies, Monoclonal↗
PubMed2006

Computerized evaluation of echocardiographic stress tests in patients with poorly visualized endocardium using analysis of color-encoded contrast-enhanced images.

AIMS: We hypothesized that real-time color encoding of contrast-enhanced images would allow objective detection of stress-induced wall motion abnormalities (WMA). METHODS: We studied 117 patients with poorly visualized endocardium undergoing dobutamine stress tests. Color-encoded images (Philips, color kinesis) were obtained at rest and peak stress in four standard views during i.v. infusion of Definity. Images were reviewed without color overlays by two expert readers, who graded regional wall motion as normal or abnormal. In 101/117 patients (86%), in whom contrast enhancement allowed endocardial tracking, regional fractional area changes were calculated from the color overlays, and thresholds for calling a stress-induced WMA were optimized in a randomly selected subgroup of 34 patients (ROC analysis) to achieve maximum agreement with expert grades. This computerized detection of stress-induced WMA was then tested prospectively in the remaining 67 patients, using the expert grades as a "gold standard". RESULTS: 20/67 patients had resting WMA and 13/67 patients developed WMA at peak stress. The automated technique detected stress-induced WMA in at least one vascular territory with a sensitivity, specificity and accuracy of 0.80, 0.65 and 0.69, while the level of agreement between the two experts was 0.62, 0.91 and 0.85, respectively. CONCLUSION: Analysis of color-encoded, contrast-enhanced images allows objective, accurate, automated detection of stress-induced WMA in patients with poor acoustic windows.

Cardiotonic Agents↗
PubMed2004

Levels of minimal residual disease detected by quantitative molecular monitoring herald relapse in patients with multiple myeloma.

BACKGROUND AND OBJECTIVES: Detection of minimal residual disease (MRD) has helped to improve the treatment of patients with leukemia. At present MRD testing in patients with multiple myeloma (MM) is not applied as a standard diagnostic or prognostic method. DESIGN AND METHODS: Immunoglobulin heavy chain (IgH) polymerase chain reaction (PCR) using patient-specific TaqMan probes together with LightCycler technology was performed to quantify minimal residual disease in MM. Relative levels of clonotypic cells were assessed as IgH/2beta-actin ratios with a sensitivity of 10(-4) to 10(-5). RESULTS: Following stem cell transplantation, a significant reduction of clonotypic cells was observed in bone marrow (BM) and peripheral blood (PB) samples of 11 patients, comparing pre-treatment values with those of best response (median: 13% to 0.09% and 0.03% to 0%, respectively). In 5 patients with ongoing clinical remission IgH/2beta-actin ratios remained stable at a low level, while in 6 patients an increase to 2% in BM and 0.4% in PB was associated with progression of the disease. In 4 of these 6 patients the increase of clonotypic cells in PB was detectable a median of 3 months (range: 0.5-6) before relapse. Furthermore, time-to-progression of patients with pre-transplantation IgH/2b-actin ratios > 0.03% in BM was significantly shorter than that of patients with lower MRD levels. INTERPRETATION AND CONCLUSIONS: MRD in patients with MM can be quantified reliably using TaqMan chemistry adapted to the LightCycler system. Residual tumor cell levels before transplantation as well as results of sequential molecular monitoring are predictive of relapse.

Actins↗
PubMed1997

Computerised prostate boundary estimation of ultrasound images using radial bas-relief method.

A new method is presented for automatic prostate boundary detection in ultrasound images taken transurethrally or transrectally. This is one of the stages in the implementation of a robotic procedure for prostate surgery performed by a robot known as the robot for urology (UROBOT). Unlike most edge detection methods, which detect object edges by means of either a spatial filter (such as Sobel, Laplacian or something of that nature) or a texture descriptor (local signal-to-noise ratio, joint probability density function etc.), this new approach employs a technique called radial bas-relief (RBR) to outline the prostate boundary area automatically. The results show that the RBR method works well in the detection of the prostate boundary in ultrasound images. It can also be useful for boundary detection problems in medical images where the object boundary is hard to detect using traditional edge detection algorithms, such as ultrasound of the uterus and kidney.

Humans↗
PubMed2003

Quantitative echocardiographic assessment of regional wall motion and left ventricular asynchrony with color kinesis in cardiac surgery patients.

UNLABELLED: Conventional echocardiographic interpretation of regional wall motion abnormalities is subjective and experience dependent. Delayed contraction in the ejection phase (tardokinesis) and regional systolic asynchrony, sensitive markers of myocardial ischemia, cannot be accurately assessed visually. We used color kinesis (CK), a technique that evaluates spatiotemporal patterns of endocardial motion, to objectively detect regional wall motion abnormalities in patients undergoing coronary bypass surgery, and we compared it with conventional assessment of grayscale images by less experienced reviewers; we used expert grading as the gold standard for comparisons. Quantitative CK analysis agreed more closely with expert grading than less experienced reviewers (kappa coefficients, 0.74 versus 0.52 and 0.5). Global tardokinesis, identified in 9 of 26 patients (2 with normal fractional area change), was associated with an increased index of systolic asynchrony. Regional tardokinesis was identified in 48 of 150 segments: 27 segments had a normal magnitude of wall motion, 18 were hypokinetic, and 3 were severely hypokinetic/akinetic. Mildly hypokinetic segments showed delayed systolic motion, whereas residual motion of severely hypokinetic/akinetic segments occurred in early systole, reflecting passive effects produced by adjacent myocardial contraction. Quantitative CK may be a useful supplement to visual assessment, particularly for less experienced readers. By diagnosing tardokinesis, common among cardiac surgical patients even with normal standard ejection phase indices, quantitative CK may improve the intraoperative detection of regional ischemic changes. IMPLICATIONS: Quantitative color kinesis allows for objective and sensitive intraoperative echocardiographic assessment of abnormal spatial and temporal patterns of regional ventricular wall motion, with potentially important implications for improving myocardial ischemia detection in patients undergoing cardiac surgery.

Cardiac Surgical Procedures↗
PubMed2005

Visual recognition: as soon as you know it is there, you know what it is.

What is the sequence of processing steps involved in visual object recognition? We varied the exposure duration of natural images and measured subjects' performance on three different tasks, each designed to tap a different candidate component process of object recognition. For each exposure duration, accuracy was lower and reaction time longer on a within-category identification task (e.g., distinguishing pigeons from other birds) than on a perceptual categorization task (e.g., birds vs. cars). However, strikingly, at each exposure duration, subjects performed just as quickly and accurately on the categorization task as they did on a task requiring only object detection: By the time subjects knew an image contained an object at all, they already knew its category. These findings place powerful constraints on theories of object recognition.

Adult↗
PubMedDate not supplied

Microwave time delay spectroscopic imagery of isolated canine kidney.

A method for producing microwave images that are improved through the reduction of multipath propagation effects is described. This method employs water immersed antennas and microwave time delay spectroscopy (TDS) at S-band. It is shown that objects as small as 6 mm in diameter can be detected. Objects 10 mm apart appear as separate responses on the image. It is also shown that is possible to generate a physiologically and anatomically relevant image of an isolated canine renal specimen.

Animals↗
PubMed1994

Detection of bilateral symmetry using spatial filters.

When bilaterally symmetric images are spatially filtered and thresholded, a subset of the resultant 'blobs' cluster around the axis of symmetry. Consequently, a quantitative measure of blob alignment can be used to code the degree of symmetry and to locate the axis of symmetry. Four alternative models were tested to examine which components of this scheme might be involved in human detection of symmetry. Two used a blob-alignment measure, operating on the output of either isotropic or oriented filters. The other two used similar filtering schemes, but measured symmetry by calculating the correlation of one half of the pattern with a reflection of the other. Simulations compared the effect of spatial jitter, proportion of matched to unmatched dots and width or location of embedded symmetrical regions, on models' detection of symmetry. Only the performance of the oriented filter + blob-alignment model was consistent with human performance in all conditions. It is concluded that the degree of feature co-alignment in the output of oriented filters is the cue used by human vision to perform these tasks. The broader computational role that feature alignment detection could play in early vision is discussed, particularly for object detection and image segmentation. In this framework, symmetry is a consequence of a more general-purpose grouping scheme.

Computer Simulation↗
PubMed1991

A high galactic latitude survey of far-ultraviolet excess objects.

Optical spectra have been obtained for a selection of objects included in a catalog of far ultraviolet bright, high galactic latitude objects detected with a balloon-borne survey telescope. The observed objects provide a sample of subdwarf O and B stars, white dwarfs, and binary systems including a hot subluminous member. Model atmospheres analysis of the subdwarf sample is used to determine the temperature, gravity, and helium to hydrogen ratio of the individual objects. A smooth distribution of objects is found on the gravity versus temperature diagram near the theoretical location of the extended horizontal branch. A break between the helium rich and helium poor objects occurs at 40,000 K. Suspected binary objects were found and analyzed to determine the temperature and gravity of the hot subluminous member in each system. The number of subdwarf stars contained in binaries is determined to be from 65% to 100%. The number versus ultraviolet magnitude distribution of the subdwarf B sample is modeled to obtain a midplane density of 3.3 10(-6) pc-3 and a population scale height of 240 pc. The proportion of white dwarfs that experience the subdwarf phase of evolution is found to be 0.94%.

Astronomy↗
PubMed2005

Recursive neural networks for processing graphs with labelled edges: theory and applications.

In this paper, we introduce a new recursive neural network model able to process directed acyclic graphs with labelled edges. The model uses a state transition function which considers the edge labels and is independent both from the number and the order of the children of each node. The computational capabilities of the new recursive architecture are assessed. Moreover, in order to test the proposed architecture on a practical challenging application, the problem of object detection in images is also addressed. In fact, the localization of target objects is a preliminary step in any recognition system. The proposed technique is general and can be applied in different detection systems, since it does not exploit any a priori knowledge on the particular problem. Some experiments on face detection, carried out on scenes acquired by an indoor camera, are reported, showing very promising results.

Computer Simulation↗
PubMed1994

A method for automatic edge detection and volume computation of the left ventricle from ultrafast computed tomographic images.

RATIONALE AND OBJECTIVES: Detection of endocardial and epicardial borders of the left ventricle (LV) using various imaging modalities is time-consuming and prone to interpretive error. An automatic border detection algorithm is presented that is used with ultrafast computed tomographic images of the heart to compute cavity volumes. METHODS: The basal-level slice is identified, and the algorithm automatically detects the endocardial and epicardial borders of images from the basal to the apical levels. From these, the ventricular areas and chamber volumes are computed. The algorithm uses the Fuzzy Hough Transform, region-growing schemes, and optimal border-detection techniques. The cross-sectional areas and the chamber volumes computed with this technique were compared with those from manually traced images using canine hearts in vitro (n = 8) and studies in clinical patients (n = 27). RESULTS: Though the correlation was good (r = .88), the algorithm overestimated the LV epicardial area by 4.8 +/- 6.4 cm2, though this error was not statistically different from zero (P > .05). There was no difference in endocardial areas (r = .95, P > .05). The algorithm tended to underestimate the end-diastolic volume (r = .94) and the end-systolic volume (r = .94), although these errors were not statistically different from zero (P > .05). The algorithm tended to underestimate the ejection fraction (r = .80), although this error was not statistically different from zero (P > .05). CONCLUSIONS: Automatic detection of myocardial borders provides the clinician with a useful tool for calculating chamber volumes and ejection fractions. The algorithm, with the corrections suggested, provides an accurate estimation of areas and volumes. This algorithm may be useful for contour border identification with ultrasound, positron-emission tomography, magnetic resonance imaging, and other imaging modalities in the heart, as well as other structures.

Algorithms↗
PubMed2004

[Detection of chlamydia antibodies in non-standard biological fluids in women with fertility disorders].

OBJECTIVE: Detection of IgA and IgG antibodies against Chlamydia trachomatis in various biological materials in patients with fertility disorders. DESIGN: Retrospective study. SETTING: Department of Gynecology and Obstetrics, Medical Faculty of Charles University and Faculty Hospital, Plzen. METHODS: Antichlamydial antibodies IgA and IgG were detected in 73 patients. Examination of sera was performed in all 73 women, peritoneal fluid was examined in 20 patients who underwent diagnostic laparoscopy, follicular fluid samples in 22 women from IVF programme and antibodies in cervical ovulatory mucus were examined in 31 patients of the Division of Immunology of Reproduction. Results were compared with clinical findings and data of personal histories. Blood donors sera examination were used as a control group. RESULTS: High number of chlamydial antibody positivity was found in follicular fluid--in IgA (18/22, 82%) and IgG (16/22, 73%) and also in ovulatory cervical mucus in IgA (13/31, 42%). Examinations of sera did not differ significantly from the control group. CONCLUSION: High levels of chlamydial antibodies in follicular fluid samples could display connection between chlamydia infection and infertility, mainly as its organic cause (adhesions, tubal factor). IgA positivity in cervical ovulatory mucus is caused by local antibody production. Serologic examination of chlamydial antibodies is one of the most suitable examinations of entry in infertile patients as well as in pregnant women.

Adult↗
PubMed2007

[Detection and significance of APC gene promoter hypermethylation in serum of breast cancer patients].

BACKGROUND & OBJECTIVE: Detection of circulating tumor markers is one of current hot spots in tumor research. Free tumor DNA may exist in the peripheral blood of malignant tumor patients. Identical DNA mutations existing in both peripheral serum and primary tumor are found in many kinds of malignant tumors. This study used adenomatous polyposis coli (APC) gene promoter hypermethylation as a tumor marker to investigate the correlations of free tumor DNA to primary tumor and clinicopathologic features of breast cancer. METHODS: The methylation status of APC gene in tumor tissue, paracancer normal tissue, and paired peripheral serum from 84 patients with breast cancer and 10 patients with benign breast diseases were detected by methylation-specific polymerase chain reaction (MSP). RESULTS: The detection rate of APC gene promoter hypermethylation was 45.2% in tumor tissues and 31.0% in paired peripheral sera. APC gene hypermethylation in peripheral serum was significantly correlated to that in tumor tissue (r=0.977, P=0.002). The sensitivity of detecting APC gene hypermethylation in peripheral serum was 68.4%; the specificity was 97.8%. The aberrant methylation of APC gene in tumor tissue and peripheral serum had no correlation to patients' age, tumor stage, tumor size, histological type, and receptor status (P>0.05). No aberrant methylation of APC gene was found in the serum samples from healthy control and the patients without gene methylation in tumor tissue. CONCLUSION: The aberrant tumor gene methylation in peripheral serum of breast cancer patients is significantly correlated to that in primary tumor.

Adult↗