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PubMed1993

Objective response detection.

Evoked potential threshold estimation can be made truly objective by using statistically based methods. In general, time domain analysis is preferable for responses which are impulsive (temporally narrow, spectrally broad), whereas frequency-domain analysis is more appropriate for tonal responses (spectrally narrow, temporally broad). In both time and frequency domains, methods comparing evoked potential power to noise models are robust and powerful. For spectrally narrow responses such as steady-state evoked potentials, the performance of magnitude-squared coherence, the ratio of grand average power to mean subaverage power, is superior to that of other methods for objective response detection.

Acoustic Stimulation↗
PubMed2000

Objective response detection in an electroencephalogram during somatosensory stimulation.

Techniques for objective response detection aim to identify the presence of evoked potentials based purely on statistical principles. They have been shown to be potentially more sensitive than the conventional approach of subjective evaluation by experienced clinicians and could be of great clinical use. Three such techniques to detect changes in an electroencephalogram (EEG) synchronous with the stimuli, namely, magnitude-squared coherence (MSC), the phase-synchrony measure (PSM) and the spectral F test (SFT) were applied to EEG signals of 12 normal subjects under conventional somatosensory pulse stimulation to the tibial nerve. The SFT, which uses only the power spectrum, showed the poorest performance, while the PSM, based only on the phase spectrum, gave results almost as good as those of the MSC, which uses both phase and power spectra. With the latter two techniques, stimulus responses were evident in the frequency range of 20-80 Hz in all subjects after 200 stimuli (5 Hz stimulus frequency), whereas for visual recognition at least 500 stimuli are usually applied. Based on these results and on simulations, the phase-based techniques appear promising for the automated detection and monitoring of somatosensory evoked potentials.

Adult↗
PubMed1996

Hill-Sachs lesion: sonographic detection.

OBJECTIVE: To determine the value of ultrasonography (US) in the detection of Hill-Sachs lesion of the humerus in comparison with double-contrast computed tomographic arthrography (CTA) and with arthroscopy. DESIGN AND PATIENTS: US and CTA were performed on 92 patients, 86 of whom subsequently underwent arthroscopy. The findings of US, CTA and arthroscopy in these 86 patients in the diagnosis of Hill-Sachs lesion were analyzed. RESULTS AND CONCLUSIONS: In the detection of Hill-Sachs lesion US showed a sensitivity of 91% (21 of 23), a specificity of 95% (60 of 63) and an accuracy of 94% (81 of 86) when compared with CTA, and a sensitivity of 94% (18 of 19), specificity of 91% (61 of 67) and accuracy of 91% (79 of 86) when compared with arthroscopy. In only 2% (2 of 86) of patients was there reduced visualization because of restriction of movement. Hill-Sachs lesion and its relationship to the humeral head can be reliably diagnosed with US.

Adult↗
PubMed2001

Performance of a new F-speed film for caries detection.

OBJECTIVE: To compare films from three speed groups for the detection of approximal caries. STUDY DESIGN: Insight, Ektaspeed Plus and Ultra-speed (Eastman-Kodak, Rochester, NY, USA) radiographs of the proximal surfaces of 40 extracted posterior teeth were evaluated by six observers. The presence or absence of caries was scored using a 5-point confidence scale. The actual status of each surface was determined from histology of ground sections. Observer responses were evaluated using ROC analysis and areas under the ROC curves (A(Z)) assessed using ANOVA. RESULTS: Ultra-speed film had a mean A(Z) of 0.88, Ektaspeed Plus 0.85, and Insight 0.84. These differences were not statistically significant (P=0.5). Differences between observers were also not statistically significant (P=0.42). CONCLUSIONS: The performance of the new F-speed film was not statistically different from E or D speed for caries detection. This film shows promise as a means of reducing patient dose while maintaining diagnostic quality.

Analysis of Variance↗
PubMed1996

Preoperative MR imaging in hyperparathyroidism: results and factors affecting parathyroid detection.

OBJECTIVE: To determine the sensitivity of MR imaging for the detection of abnormal parathyroid glands in patients with biochemical evidence of hyperparathyroidism and to identify the factors affecting detection. SUBJECTS AND METHODS: Between 1985, 82 patients with biochemical proof of hyperparathyroidism were referred for MR imaging of the parathyroid glands prior to surgery. Axial T1- (600/20 [TR/TE]) and T2-weighted (2500/40, 80) spin-echo images were obtained using an anterior neck surface coil. The interpretation of the MR image was compared with the findings at surgery and also correlated with gland histology, volume, and weight. Cases in which a false-positive or false-negative diagnosis was made were reviewed to determine the factors affecting detection. RESULTS: MR imaging detected 71 of 92 (77%) surgically proven abnormal glands (sensitivity, 77%; 95% confidence interval (CI), 68-86%) and misdiagnosed five (1.6%) of 314 normal glands as abnormal. There was no difference in the detection of enlarged glands in patients presenting for the first time (n = 71) (sensitivity, 77%; 95% CI, 66-86%) compared with patients with recurrent hyperparathyroidism (n = 12) (sensitivity, 77%; 95% CI, 46-95%). There was no significant difference in the detection of adenomas (sensitivity, 77%; 95% CI, 65-86%) compared with hyperplasia (sensitivity, 71%; 95% CI, 42-92%). Of five patients with ectopic parathyroid glands (1.6%), four had had previous surgery. All five glands were successfully located (three mediastinal, two in the neck). Factors contributing to a false-negative MR imaging diagnosis included small gland size and thyroid disease. Four of five false-positive diagnoses were due to enlarged lymph nodes being mistaken for parathyroid glands. CONCLUSIONS: MR imaging is an accurate technique for investigation of hyperparathyroidism. Pitfalls include low sensitivity for the identification of small glands, misinterpretation of enlarged lymph nodes as parathyroid adenomas, and misinterpretation because of thyroid disease. MR imaging is particularly useful in the investigation of patients who remain hypercalcemic following initial surgery.

Adult↗
PubMed2000

[Detection of lymphatic metastasis from malignant melanoma after identification of the sentinel node by preoperative lymphoscintigraphy and intraoperative radioisotopic detection].

OBJECTIVES: The aim of this study was to evaluate the detection of the first lymph node draining the primary tumour site, using a radioisotopic mapping alone and to determine whether a preoperative lymphoscintigraphy using technetium sulfur colloid and a hand-held gamma detecting probe could improve the detection of the sentinel lymph node (SLN) in melanoma. PATIENTS AND METHOD: From January to December 1998, 36 patients with a cutaneous melanoma larger than 0.75 mm, stage I TNM were included in this prospective study. Mean Breslow was 1.85 mm. The distribution of melanoma was head and neck (n = 9), trunk (n = 7), upper extremities (n = 4), lower extremities (n = 16). Preoperative lymphoscintigram and intraoperative detection were used. The first hot lymph node was supposed to be the SLN. RESULTS: In all cases, a lymph node was found and nine patients had more than one SLN (average number of SLN per patient: 1.25). Aberrant drainages were found in seven patients (19.4%): 1 in-transit lymph node, three paradoxical bassins, three bypasses). Four out of 36 patients had lymph node metastases and underwent elective lymph node dissection. CONCLUSION: The radio-isotopic technique used alone for the identification of the SLN is efficient in melanoma with a 100% detection rate in this short series.

Adult↗
PubMed1995

An ultrasensitive immunoassay for prostate-specific antigen based on conventional colorimetric detection.

OBJECTIVE: Development of an ultrasensitive immunoassay for serum PSA involving conventional detection probes. DESIGN AND METHODS: The assay involves a polyclonal antibody immobilized in microtitration wells and a monoclonal antibody labeled with horseradish peroxidase. In a one-step assay, the enzymatic activity of the bound detection antibody is monitored by the addition of hydrogen peroxide/tetramethylbenzidine substrate reagent followed by spectrophotometric quantification of the conversion product. RESULTS: The assay has a lower detection limit of 0.003 micrograms/L, biological detection limit of 0.009 micrograms/L, and intra- and interassay CVs of 8.2% and 10.5% at PSA concentrations of 0.022 and 0.065 micrograms/L, respectively. The recovery of the assay averaged 104% and it demonstrated a dilution linearity down to at least 0.01 micrograms of PSA/L. Results of comparison data correlated well with those obtained by a well established enzyme immunoassay. The serum PSA concentrations were < 0.012 micrograms/L in the majority of patients (53.8%) who had undergone radical prostatectomy. CONCLUSIONS: This assay is well suited for post-surgical monitoring of PSA in patients with prostate cancer.

Antibodies↗
PubMed1991

Anal human papillomavirus infection: a comparative study of cytology, colposcopy and DNA hybridisation as methods of detection.

OBJECTIVE: To compare anal cytology, colposcopy and DNA hybridisation as methods of detecting anal HPV infection. SUBJECTS AND DESIGN: Patients attending: (1) a genitourinary medicine (GUM) clinic with ano-genital warts; (2) a surgical out-patient department with anal fissure or haemorrhoids were examined for evidence of anal HPV infection. RESULTS: Considering GUM clinic attenders, 17% (38/225) and 40% (90/225) had perianal or anal canal warts respectively. Colposcopic examination revealed anal acetowhite lesions without warts in 28% (63/225). Cytological evidence of HPV infection was found in 98%, 83%, and 90% of patients with anal canal warts, perianal warts and acetowhite lesions respectively. Anal intraepithelial neoplasia (AIN) was documented in 22% of patients with anal canal warts compared with 6% with perianal warts (p less than 0.01). HPV DNA was detected from the anal brushings of 71%, 50%, 32%, and 29% of patients with anal canal warts, perianal warts, acetowhite lesions and a normal anal examination respectively. HPV type 6/11 was detected in the majority of HPV positive samples. Considering surgical out-patient attenders with no history or signs of anal warts, 25% showed cytological evidence of anal HPV infection and HPV DNA was detected from anal brushings in 3% (2/71). CONCLUSION: Anal examination with the colposcope is a useful method for detecting subclinical HPV infection. Anal cytology may prove helpful for detecting AIN, however, since koilocytosis was rarely seen, the specificity of the cytological criteria for anal HPV infection in the absence of AIN is uncertain. DNA analysis of anal brushings proved only moderately sensitive.

Adult↗
PubMed2000

Culture as an influence on breast cancer screening and early detection.

OBJECTIVES: To explore how culture may play a part in breast cancer screening, early detection, and efforts to decrease breast mortality. DATA SOURCES: Journal articles published in the past 20 years on cultural aspects of cancer prevention and control. CONCLUSIONS: Research seems directed more at discovering cultural differences than at identifying similarities on how culture influences breast cancer screening and early detection. The influences of poverty and lack of educational opportunities account for much of what is termed cultural difference. IMPLICATIONS FOR NURSING PRACTICE: Improving practice through an informed understanding of culture calls for considerable self-education and a fundamental refinement of care delivery.

Adult↗
PubMedDate not supplied

Cine phase-contrast MR flow measurements: improved precision using an automated method of vessel detection.

OBJECTIVE: The purpose of this study was to construct a method of vessel edge detection that correctly identifies vessel pixels and to compare the interuser variability of cine phase contrast MR volumetric flow rates obtained with the conventional manual method and an automated method. MATERIALS AND METHODS: The automated method was developed based on a magnitude image threshold value and compared with the manual method in a flow phantom (three users) and in velocity images of the portal vein (five users). The threshold value determined from the magnitude image was applied to a region of interest surrounding the vessel of interest on the magnitude image to construct a vessel edge detection mask m(x,y). The velocity images were then multiplied by the mask m(x,y) and volumetric flow rates determined using the identified vessel pixels. RESULTS: In the flow phantom, flow measurements with the magnitude threshold method had significantly less interuser variability compared with the manual method (p < 0.01) and were within 10% (mean 6.0%) of the actual flow versus 35% (mean 18.6%) with the manual method. Regarding flow measurements in the portal vein of six volunteers, the magnitude threshold method was significantly more precise (p < 0.01) than the manual method with a mean standard deviation between the five users of 40.4 +/- 12.9 ml/min (range 22-60 ml/min) and 110.4 +/- 32.7 ml/min (range 70-155 ml/min), respectively. CONCLUSION: The magnitude threshold method of vessel edge detection developed in this study yields flow measurements that are accurate in the model system and have significantly less interuser variability than the manual method. This method shows promise for improving the precision of cine phase contrast flow measurements.

Adult↗
PubMed1995

Left atrial size and function: assessment using echocardiographic automatic boundary detection.

OBJECTIVE: To evaluate the waveforms of left atrial area changes obtained by automated boundary detection with newly developed acoustic quantification technology. DESIGN: All subjects had measurements of left atrial areas taken in the apical four chamber, parasternal long axis, and parasternal short axis views using both conventional echocardiographic methods and automatic boundary detection on two occasions separated by at least a week. On the second visit measurements were also repeated in healthy volunteers after acute intravenous volume loading with 1 litre of saline over 2-5 minutes. SETTING: A university medical school echocardiographic laboratory. SUBJECTS: 12 healthy male volunteers and 8 patients with cardiac disease (5 with congestive heart failure, 1 with mitral stenosis, and 2 with hypertensive left ventricular hypertrophy, and dilated left atria). RESULTS: There was close correlation between conventionally derived left atrial areas and those obtained by automatic boundary detection, particularly in the apical four chamber view (r = 0.98). Both inter and intra observer variabilities (coefficient of variation) for left atrial areas measured by automatic boundary detection were good (4.7-14.2% and 8.1-18.6% respectively). The reproducibility (coefficient of variation) for derived indices of left atrial function, however, was much poorer (10.4-104.8% and 12.5-88% respectively). After acute volume loading significant increases in left atrial area were observed at all stages in the cardiac cycle. CONCLUSIONS: These data demonstrate that although the reproducibility of left atrial functional indices is poor, instantaneous left atrial cavity measurements with automatic boundary detection are reproducible. This suggests that automatic boundary detection may assist in serial non-invasive measurement of left atrial size to assess disease states and treatments.

Adult↗
PubMed1982

[Total right hemispherectomy: neurophysiological study after twenty-six years].

Twenty-six years after a total right hemispherectomy for tumor when thirteen years old, a right-handed patient presented with disturbances of equilibrium, urinary incontinence, and a marked reduction in motor impulses, in spite of a subnormal intelligence quotient (0.85). Computed tomography examinations suggested the presence of a normal pressure hydrocephalus. However intracranial pressure monitoring and isotopic and cerebrospinal fluid perfusion tests showed the absence of any cerebral obstruction, and free communication between the cerebral and spinal spaces, though intracranial volume capacity accommodation was greatly reduced. Clinical examination demonstrated good quality sensory appreciation by the left half of the body, the possibility of detecting an object in the visual hemifield supposedly blind, and perfect location of a sound source. Somesthetic evoked potentials were studied by stimulating the median nerve in the left and right wrist regions. Left hemisphere evoked potentials from a contralateral stimulus, were of normal latency, amplitude and morphology, the response to an ipsilateral stimulus also presenting an early potential component (N 26 starting at N 21). This exceptional finding in a hemispherectomized patient could be related to activity of the spinoreticulothalamic tracts in the lemniscal or extralemniscal systems. Auditory function tests demonstrated perfect stereoaudiometry and the quality of perception during dichotic listening tests. Auditory evoked potentials in the brain stem included only minor functional-type anomalies, with slightly increased latencies in the pons on the left, and the mesencephalon and pons on the right. The presence of a bilateral wave VI was related to activity of the median geniculate pathway. Visual function tests showed good quality left photomotor reflexes and positive object detection in the anopsic hemifield. Results of these tests were reproducible during the same examination and after an interval of several months. The relevant literature is reviewed.

Adolescent↗
PubMed1996

An expert diagnostic system based on neural networks and image analysis techniques in the field of automated cytogenetics.

In this study, we introduce an expert system for intelligent chromosome recognition and classification based on artificial neural networks (ANN) and features obtained by automated image analysis techniques. A microscope equipped with a CCTV camera, integrated with an IBM-PC compatible computer environment including a frame grabber, is used for image data acquisition. Features of the chromosomes are obtained directly from the digital chromosome images. Two new algorithms for automated object detection and object skeletonizing constitute the basis of the feature extraction phase which constructs the components of the input vector to the ANN part of the system. This first version of our intelligent diagnostic system uses a trained unsupervised neural network structure and an original rule-based classification algorithm to find a karyotyped form of randomly distributed chromosomes over a complete metaphase. We investigate the effects of network parameters on the classification performance and discuss the adaptability and flexibility of the neural system in order to reach a structure giving an output including information about both structural and numerical abnormalities. Moreover, the classification performances of neural and rule-based system are compared for each class of chromosome.

Algorithms↗
PubMed2001

A sensor array processing approach to object region detection.

This paper presents a new approach for medical image analysis. It translates the object region-detection problem into a sensor array processing framework and detects the number of object regions based on the signal eigenstructure of the converted array system. The theoretical and experimental results obtained by using this approach on various medical images were in good agreement.

Biomedical Engineering↗
PubMed1998

A new screening protocol combining urine beta-core fragment and ultrasonography for Down syndrome detection.

OBJECTIVE: Our purpose was to ascertain the screening efficiency of a new midtrimester Down syndrome detection protocol that combines maternal urine testing and ultrasonographic examination. STUDY DESIGN: In a prospective study, beta-core fragment, the stable end product of human chorionic gonadotropin metabolism, was measured in maternal urine. The results were standardized for urine creatinine levels. The study was performed in women undergoing midtrimester genetic amniocentesis (15 to 24 weeks' gestation). Urine beta-core fragment values were expressed as multiples of the normal median for gestational age. The screening performance of a combination of ultrasonographic parameters and urine beta-core values for Down syndrome detection was determined. RESULTS: A total of 511 singleton pregnancies in women undergoing amniocentesis were studied, 18 of the women (3.5%) had a Down syndrome fetus. A urine beta-core fragment level > or = 97th percentile had a sensitivity of 61.1% and a false-positive rate of 3.2%. An abnormal prenatal screen was defined as a urine beta-core level > or = 97th percentile, increased nuchal thickness (> or = 5 mm), or the presence of gross structural defects. Corresponding values for the screening efficiency of an abnormal prenatal screen were sensitivity of 77.8% and a false-positive rate of 4.1%. With an abnormal prenatal screen the odds ratio is 82.8 (95% confidence interval 22.6 to 364.9) for having a Down syndrome fetus. CONCLUSION: The presence of an abnormal maternal urine beta-core level, a gross ultrasonographic anomaly, or increased nuchal thickness had a high detection rate and a low false-positive rate for Down syndrome. This novel screening algorithm is useful for further delineating the risk status in patients at high risk who are reluctant to undergo or decline genetic amniocentesis.

Adult↗
PubMed2002

Perianal versus anorectal specimens: is there a difference in Group B streptococcal detection?

OBJECTIVE: To investigate whether specimens obtained from the perianal area have a Group B streptococcal culture detection rate similar to anorectal specimens. METHODS: This is a prospective cohort study at a tertiary care university-affiliated teaching hospital. A total of 136 pregnant women between 33 and 40 weeks' gestation were recruited. Three samples for Group B streptococcal culture detection were obtained from each subject in the following order: perianal sample, vaginoperianal sample, and an anorectal sample. The women were asked to rank their pain or discomfort with obtaining the anorectal sample. The vaginoperianal specimen is the standard sample obtained from antepartum patients in this clinic, and, therefore, it serves as the control. RESULTS: Of the 136 subjects, 26.5% of the control, vaginoperianal samples were positive for Group B streptococcal culture. In comparison, 27.2% of the anorectal specimens and 28.7% of the perianal specimens were positive for Group B streptococcal culture. There was no statistically significant difference in the detection of Group B streptococcal culture among the three sample sites. Evaluation of the pain experienced with an anorectal sampling showed that 68% of subjects ranked their pain between mild to moderate, and 5% noted severe pain. CONCLUSION: The Group B streptococcal detection rate was not different among the three sampling sites. Therefore, pregnant women do not need to be subjected to the additional pain of anorectal sampling to detect Group B Streptococcus.

Adult↗
PubMedDate not supplied

An SV40 large T-antigen immortalized human umbilical vein endothelial cell line for anti-endothelial cell antibody detection.

OBJECTIVE: Anti-endothelial cell antibodies in serum of patients with different inflammatory diseases can be detected by a whole cell enzyme-linked immunosorbant assay, using primary cultures of human umbilical vein endothelial cells. To avoid repeated isolation, it would be of great value if an immortal endothelial cell line could be used to perform anti-endothelial cell antibody assays. METHODS: In this study endothelial cells from human umbilical and iliac veins and arteries were transfected with a plasmid containing the Simian Virus 40 large T-antigen. Endothelial cell line(s) derived from this procedure were compared with human umbilical vein endothelial cells in the anti-endothelial cell antibody assay. RESULTS: After transfection, clones of homologous cell populations showed an extended lifespan, before entering a period of crisis. In one human umbilical vein endothelial cell clone a subpopulation of cells escaped crisis and became immortal (EVLC2). Telomerase was activated in this endothelial cell line, resulting in maintenance of the telomere length. There was a significant correlation between anti-endothelial cell antibody testing on human umbilical vein endothelial cells and on the cell line EVLC2. CONCLUSION: The Simian Virus 40 large T-antigen immortalized human umbilical vein endothelial cell line EVLC2 may be useful for the detection of anti-endothelial cell antibodies.

Antigens, Polyomavirus Transforming↗
PubMed1996

The need for health promotion in oral cancer prevention and early detection.

OBJECTIVES: This review paper provides a rationale for using health promotion to help reduce morbidity and mortality due to oral cancers by identifying barriers to prevention and early detection of these cancers and discussing strategies for change. METHODS: A literature review of the following areas was conducted: epidemiology of and risk factors for oral cancers; knowledge, opinions, and practices of health care providers and the public regarding prevention, early detection, and control of oral cancers; and policies and regulations that either enhance or act as barriers to the prevention and early detection of oral cancers. RESULTS: Overall, the public is ill-informed about risk factors for and signs and symptoms of oral cancers and relatively few US adults have had an oral cancer examination. Further, health care providers are remiss in providing oral cancer examinations and detecting early oral cancers. CONCLUSIONS: To achieve the 13 oral cancer objectives contained in "Healthy People 2000," health care providers and the public must know the risk factors for these cancers as well as their signs and symptoms. Further, health care providers need to provide oral cancer examinations routinely and competently. Equally important, the public needs to know that an examination for oral cancer is available and that they can request one routinely. Thus, a vigorous agenda that includes education, policy, and research initiatives is needed to enhance oral cancer prevention and early detection.

Adolescent↗