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PubMedDate not supplied

Accuracy of object depiction and opacity transfer function optimization in CT volume-rendered images.

Volume rendering is a visualization technique that has important applications in diagnostic radiology and radiotherapy. A methodology is presented for (a) evaluation of the quantitative accuracy of representation of known objects in volume-rendered scenes and for (b) optimization of the opacity transfer function to achieve the most accurate representation of a particular structure. Results using this methodology are shown for structures representing each of the major tissue interfaces and are discussed.

Algorithms↗

PubMedDate not supplied

Noninvasive diagnosis of coronary artery disease in women.

Cardiovascular disease is the leading cause of mortality and significant morbidly among women in the United States. The frequent absence of antecedent symptoms, the potential for an initial fatal cardiac event and the limitations of currently available noninvasive diagnostic tests pose challenges to healthcare practitioners as they try to optimally risk stratify patients. Therefore, the purpose of this article is to discuss the accuracy of noninvasive tests for CAD diagnosis in women.

Coronary Disease↗

PubMed1987

Computer-assisted subtraction radiography in periodontal diagnosis.

In the diagnosis of periodontal disease radiography serves as an adjunct to clinical methods to determine the extent of bone involvement. At subsequent examinations radiography is used to e.g. evaluate the course of disease and the effect of treatment. Differences between examinations due to biological changes often occur against a complex background of stationary anatomical structures and the signals of diagnostic interest are therefore often concealed in structured noise. This imposes severe constraints on the radiographic diagnosis of changes in the periodontal bone over time. A method was developed to reduce the amount of structured noise by subtracting identical image features in serial radiographs which had been digitized, using a high quality TV-camera interfaced with an analog to digital converter and a computer. When the technique was applied to standardized radiographs taken before and after small lesions had been made in the marginal crest of dry human mandibles, observers were able to detect those lesions more accurately than in the conventional radiographs from which the computer-assisted subtraction images were produced. The sensitivity increased from 51% to 91% while the specificity remained unchanged at about 95-96% High geometric reproducibility between radiographs to be subtracted is essential, but serial radiographs taken with angulation differences of 3 degrees yielded a higher degree of diagnostic accuracy, evaluated by the ROC-curve technique, than optimally taken conventional radiographs. Defects, slightly less than a mm wide, made in the marginal crest of dry human mandibles and with a depth in the direction of the radiation beam corresponding to 0.49 mm of compact bone could be detected with a close to perfect accuracy (ROC-evaluation) in subtraction images. Conventional radiographs required lesions more than three times as deep to render a similar degree of diagnostic accuracy. The actual lesion depths were assessed by the Iodine-125 absorptiometry technique. To standardized serial radiographs, taken before and after small marginal defects were induced, various amount of random noise was superimposed by adding to the existing grey-level of each picture element in the digitized radiographs a Poisson random deviate. Resultant noise-degraded images correspond to images produced by from faster imaging systems and it was shown that the application of computer-assisted subtraction yielded a high degree of diagnostic accuracy even when severely noise-degraded images were used. This indicates the potential usefulness of much faster imaging technology than presently used.(ABSTRACT TRUNCATED AT 400 WORDS)

Alveolar Process↗

PubMed1989

Carcinoma of the anal region.

Preservation of anorectal function makes chemoradiotherapy attractive as the primary treatment in patients with squamous cell carcinoma of the anal region. Despite variations in techniques of chemoradiotherapy administration, the accumulated experience of a number of institutions indicates substantial improvement over previous approaches, which included surgery or radiation therapy individually. Although no longer providing the definitive therapeutic role in this disease, the surgeon is frequently asked to evaluate lesions suspected of being anal malignancies. In addition, it is the surgeon who most often performs the diagnostic biopsy, consults on local complications of chemoradiotherapy, and manages complications of local recurrence. In this context, optimal care includes early organization of the medical oncologist, radiation therapist, and surgeon to participate in the initial diagnostic evaluations, examinations with the patient under anesthesia, and follow-up during therapy. A complete response is often not evident until 2 to 3 months after treatment. We recommend a follow-up schedule of monthly visits for the first 6 months, examinations every 3 months for the next 2 years, and assessment every 6 months thereafter. Evaluation during early routine visits includes manual and proctoscopic examination of the perineum and rectum and review of the hemogram and liver enzyme levels in the serum. CT, MRI, or lower endoscopy procedures are performed only if clinical examination or studies suggest the possibility of recurrence or a second primary tumor. Patients with an incomplete response to therapy after 3 months often undergo examination under anesthesia with biopsy of suspect areas. Chronic inflammatory changes in the area of previous carcinoma may be interpreted as persistent disease. Thus histologic proof of recurrent malignancy must be obtained before considering surgical or chemoradiotherapy salvage treatment.

Anus Neoplasms↗

PubMed2001

Diagnostic performance of an expert system for the interpretation of myocardial perfusion SPECT studies.

UNLABELLED: An expert system (PERFEX) developed for the computer-assisted interpretation of myocardial perfusion SPECT studies is now becoming widely available. To date, a systematic validation of the diagnostic performance of this expert system for the interpretation of myocardial perfusion SPECT studies has not been reported. METHODS: To validate PERFEX's ability to detect and locate coronary artery disease (CAD), we analyzed 655 stress/rest myocardial perfusion prospective SPECT studies in patients who also underwent coronary angiography. The patient population comprised CAD patients (n = 480) and healthy volunteers (n = 175) (449 men, 206 women). Data from 461 other patient studies were used to implement and refine 253 heuristic rules that best correlated the presence and location of left ventricular myocardial perfusion defects on SPECT studies with angiographically detected CAD and with human expert visual interpretations. Myocardial perfusion defects were automatically identified as segments with counts below sex-matched normal limits. PERFEX uses the certainty of the location, size, shape, and reversibility of the perfusion defects to infer the certainty of the presence and location of CAD. The visual interpretations of tomograms and polar maps, vessel stenosis from coronary angiography, and PERFEX interpretations were all accessed automatically from databases and were used to automatically generate comparisons between diagnostic approaches. RESULTS: Using the physician's reading as a gold standard, PERFEX's sensitivity and specificity levels for detection and localization of disease were, respectively, 83% and 73% for CAD, 76% and 66% for the left anterior descending artery, 90% and 70% for the left circumflex artery, and 74% and 79% for the right coronary artery. These results were extracted from a receiver operating characteristic curve using the average optimal input certainty factor. CONCLUSION: This study shows that the diagnostic performance of PERFEX for interpreting myocardial perfusion SPECT studies is comparable with that of nuclear medicine experts in detecting and locating CAD.

Adult↗

PubMed1995

Clinical Utility of Electrocardiographic ST-Segment Area for Predicting Unsatisfactory Outcomes Following Thrombolytic Therapy.

The bedside surface 12-lead electrocardiogram is a mainstay in the early diagnostic evaluation of patients with suspected acute myocardial infarction. The presence of ST-segment elevation exceeding 1.0 mm in two or more anatomically associated leads is a reliable marker of myocardial injury and, when considered along with concomitant ST-segment depression, reflects the extent of myocardial injury. Mounting evidence also suggests that prolonged repolarization is a marker of injury and predicts the likelihood of malignant ventricular arrhythmias. We questioned whether a measure of both ST-segment duration and deviation (ST-deviation area) would offer additional prognostic information. Methods/Results: Admission electrocardiograms from 200 consecutive patients with ischemic chest pain accompanied by ST-segment elevation in whom thrombolytic therapy was given within 6 hours from symptom onset were analyzed. The sum of ST-segment elevation (Sigma ST elevation) and ST-segment deviation (Sigma ST deviation) were calculated, as was the sum of ST-segment deviation area (Sigma ST deviation area). All ST measurements were performed 60 msec after the J point. Computerized planimetry was used to calculate ST-segment area. Sigma ST deviation and Sigma ST deviation area remained constant over time. Patients with large deviations (Sigma ST elevation > 20 mm (odds ratio 2.14, p = 0.02) and Sigma ST deviation area > 150 (odds ratio 1.92, p = 0.02) had a higher incidence of in-hospital unsatisfactory clinical outcome (defined as death, congestive heart failure, cardiogenic shock, recurrent myocardial infarction, or the need for coronary revascularization). These relationships were present for both inferior and anterior infarctions. Sigma ST deviation area correlated closely with Sigma ST elevation (r = 0.92; p = 0.0001) and significantly but much less strongly with the sum of Q waves (r = 0.18; p = 0.01). By univariate analysis, only site of infarction (p = 0.01), Sigma ST deviation area (p = 0.04), and the sum of Q waves (p = 0.005) were identified as predictors of a poor clinical outcome. The sum of Q waves was identified by multivariate analysis as the best independent predictor of an unsatisfactory clinical outcome. Conclusions: A clinician's ability to provide optimal care is influenced strongly by the availability of diagnostic and prognostic information. In the evaluation of patients with acute myocardial infarction, ST-segment deviation area derived from the admission surface electrocardiogram can be used to risk-stratify patients. The full clinical potential of this measure is unknown and will require further evaluation.

Journal Article↗

PubMed1989

[Intramuscular hemangioma: problems of differential diagnosis from angiosarcoma].

Despite recent technical advances in diagnostic imaging (computerised tomography, magnetic resonance), intramuscular haemangiomas are relatively uncommon and often difficult to diagnose. Angiosarcomas are probably the most important tumour to be differentiated from hemangiomas, in order to define the optimal therapeutic approach. Only biopsy allows a proper preoperative diagnosis, although this diagnostic technique involves some risks. Total excision is the treatment of choice. Radiotherapy has been employed without substantial results. A review of the literature and a case report are presented here.

Adult↗

PubMed2002

[Blunt isolated pancreatic trauma. Diagnostic problems--a clinical and radiological challenge].

INTRODUCTION: Blunt isolated pancreas trauma is rare, but it is a very serious condition. Diagnosis and treatment are often delayed, which considerably increases morbidity. The delay is caused by uncharacteristic symptomatology and the application of paraclinical and radiological diagnostic methods of low initial sensitivity and specificity. The aim of this study was to describe the diagnostic difficulties and the applicability of the various radiological modalities. MATERIAL AND METHODS: During the period 1995-2000, three patients with blunt isolated pancreas trauma were treated, and the case reports were examined retrospectively. RESULTS: All three showed classical mechanisms of injury, and a characteristic delay in diagnosis and treatment of 24 to 48 hours was seen. DISCUSSION: The frequent delay in diagnosis and subsequent treatment of the blunt pancreas trauma requires a more optimal strategy for handling such traumas. We recommend the following diagnostic algorithm: Repeated measurements of serum amylase initially. Image diagnostics with a dynamic spiral CT-scan with both oral and intravenous contrast. The CT scan is to be repeated or supplemented by MRCP on continued suspicion of pancreas injury, even when the initial CT scan shows normal findings.

Adult↗

PubMed1997

Coarse blobs or fine edges? Evidence that information diagnosticity changes the perception of complex visual stimuli.

Efficient categorizations of complex visual stimuli require effective encodings of their distinctive properties. However, the question remains of how processes of object and scene categorization use the information associated with different perceptual spatial scales. The psychophysics of scale perception suggests that recognition uses coarse blobs before fine scale edges, because the former is perceptually available before the latter. Although possible, this perceptually determined scenario neglects the nature of the task the recognition system must solve. If different spatial scales transmit different information about the input, an identical scene might be flexibly encoded and perceived at the scale that optimizes information for the considered task-i.e., the diagnostic scale. This paper tests the hypothesis that scale diagnosticity can determine scale selection for recognition. Experiment 1 tested whether coarse and fine spatial scales were both available at the onset of scene categorization. The second experiment tested that the selection of one scale could change depending on the diagnostic information present at this scale. The third and fourth experiments investigated whether scale-specific cues were independently processed, or whether they perceptually cooperated in the recognition of the input scene. Results suggest that a mandatory low-level registration of multiple spatial scales promotes flexible scene encodings, perceptions, and categorizations.

Adult↗

PubMed2002

[Metachronous tumor of the small intestine--rare cause of ileus in a patient after resection of colon cancer].

Neoplastic metastases in the small intestine are rare--only 2% of the metastases are localized in the small intestine. It is important to remember that colorectal metastases are the most frequent, though metachronous cancer of the small intestine is the rare cause of ileus or bleeding in patients who underwent resection of the colorectal cancer. The challenge is to select among those patients, the ones with metachronous tumor in the other parts of the small and large bowel. The diagnostics in these situations is often difficult and only the operative management is an optimal way of treatment. We present the case of the patient with metachronous cancer of the small intestine after the sigmoid resection and the diagnostic difficulties concerned.

Adenocarcinoma↗

PubMed2006

Optimal duration of event recording for diagnosis of arrhythmias in patients with palpitations and light-headedness in the general practice.

BACKGROUND: Patient-activated continuous-loop event recorders (CER) are useful as a diagnostic tool in new episodes of palpitations and/or dizziness. So far, no analysis of optimal duration for monitoring in unselected patients has been published. METHODS: During a period of 30 days, we prospectively evaluated the time until diagnosis using CER in patients with symptoms of palpitations and/or dizziness in general practice. RESULTS: In total, 127 patients received an event recorder for a maximum duration of 30 days. Events were recorded by 104 patients (82%), of whom 83 (78%) showed an arrhythmia. After 2 weeks, 75% of all diagnoses and 83.3% of all clinically relevant diagnoses could be established. CONCLUSION: The yield of event recording in general practice diminishes with recording time. A minimum recording time of 2 weeks seems necessary.

Adolescent↗

PubMed2006

Fluorescence detection of pleural malignancies using 5-aminolaevulinic acid.

STUDY OBJECTIVE: Although the use of video-assisted thoracoscopy has improved the diagnostic accuracy in patients presenting with pleural diseases, not all biopsies performed are conclusive and staging of the disease is not always optimal. Fluorescence diagnosis (FD) with 5-aminolaevulinic acid (5-ALA) has been used in the diagnostic workup for various malignancies. The impact of 5-ALA-mediated FD on diagnosis and staging during video-assisted thoracoscopy was examined. DESIGN: Prospective, single-center study. SETTING: National cancer center. PATIENTS: Twenty-six patients with nonconclusive pleural effusions who were scheduled for video-assisted thoracoscopy. INTERVENTION: Eligible patients were administered 1,500 to 2,500 mg po of 5-ALA before video-assisted thoracoscopy. After conventional inspection with white light, fluorescence inspection of the pleural cavity was performed (D-LIGHT Auto Fluorescent System; Karl Storz; Tuttlingen, Germany). Biopsy specimens of both normal and abnormal sites, as determined from white light and FD inspection, were obtained for histologic examination. RESULTS: One patient was ineligible, and two patients were not evaluable because of equipment failure. One postoperative death occurred due to preexisting myocardial disease. In another patient, an empyema developed; in another patient, a postoperative infection of the lung developed. Other toxicities were minimal. A definitive diagnosis was obtained in 24 of 25 cases, with malignant mesothelioma in 15 cases, other malignancies in 5 cases, one infection, and three benign diseases. Upstaging occurred in four patients (unsuspected tumor deposits) due to FD examination. In 23 patients, a total of 111 biopsy specimens could be analyzed. When correct findings of white light and FD were compared, FD had an additional value in 21 of 111 biopsies, compared to white light with 16 of 111 biopsies. CONCLUSIONS: FD using 5-ALA in the pleural cavity is feasible with limited side effects when used in addition to white light inspection. It improved visualization of abnormal lesions and led to upstaging in 4 of 15 mesothelioma patients.

Adult↗

PubMedDate not supplied

Growth of mycobacteria in relation to the pH of the medium.

The influence of pH on the growth of mycobacteria on Loewenstein and Dubos OAA media was studied with 56 strains belonging to 10 species of rapidly growing and 16 species of slowly growing mycobacteria. pH gradients were obtained by the use of McIlvaine's citrate and Sörensen's citrate buffer. The sensitivity of mycobacteria at different pH values of the medium was independent of the culture medium and buffer used. Minimal, maximal and optimal pH values were specific for each species, all strains of the same species producing identical results. Some slowly growing mycobacteria such as Mycobacterium lepraemurium developed within a very narrow optimal pH range: between 5.8 and 6.1. Other species developed over a wide optimal pH range, e.g. M. nonchromogenicum: from 5 to greater than 7.4. For slow growers, in general, with the exception of M. lepraemurium, optimal pH was between 5.8 and 6.5. In general, rapidly growing mycobacteria developed over a wider pH range of more than 2 units. All strains, with the exception of M. chelonei, developed optimally between pH 7 and 7.4. For M. chelonei, as for slower growing species, the optimal pH was between 5.4 and 6.5. Taxonomically related species such as M. tuberculosis and M. bovis, M. kansasii and M. gastri, M. microti and M. bovis BCG, and M. vaccae and M. parafortuitum, were inhibited or stimulated at identical pH values. This specificity constitutes a supplementary taxonomic character. At certain pH values, some species otherwise difficult to separate may be differentiated: e.g. M. avium, not growing at pH 4.6, is distinguished from M. scrofulaceum which does grow at pH 4.6. For routine diagnostic purposes, Loewenstein Jensen medium at pH 7 is not optimal; Ogawa medium, with its pH of 6, is more appropriate.

Culture Media↗

PubMed2002

Fluorescence spectral imaging for characterization of tissue based on multivariate statistical analysis.

A novel spectral imaging method for the classification of light-induced autofluorescence spectra based on principal component analysis (PCA), a multivariate statistical analysis technique commonly used for studying the statistical characteristics of spectral data, is proposed and investigated. A set of optical spectral filters related to the diagnostically relevant principal components is proposed to process autofluorescence signals optically and generate principal component score images of the examined tissue simultaneously. A diagnostic image is then formed on the basis of an algorithm that relates the principal component scores to tissue pathology. With autofluorescence spectral data collected from nasopharyngeal tissue in vivo, a set of principal component filters was designed to process the autofluorescence signal, and the PCA-based diagnostic algorithms were developed to classify the spectral signal. Simulation results demonstrate that the proposed spectral imaging system can differentiate carcinoma lesions from normal tissue with a sensitivity of 95% and specificity of 93%. The optimal design of principal filters and the optimal selection of PCA-based algorithms were investigated to improve the diagnostic accuracy. The robustness of the spectral imaging method against noise in the autofluorescence signal was studied as well.

Algorithms↗

PubMed2002

Diagnostic value of CRP and Lp(a) in coronary heart disease.

OBJECTIVES: Increased lipoprotein (a) [Lp(a)] concentration was reported to be an independent risk factor for coronary heart disease (CHD). Recent epidemiological studies affirmed the value of C-reactive protein (CRP) as the strongest, univariate predictor of the cardiovascular events. We decided to establish cut-off levels providing maximum diagnostic efficiency for CHD. METHODS: In this study we measured CRP and Lp(a) concentrations in patients with angiographically demonstrated CHD (group A, n: 120), patients without any angiographically demonstrable lesion (group B, n: 62) and a group of healthy subjects (group C, n: 41). Data were evaluated correcting for lipid and lipoprotein concentrations, diabetes mellitus, hypertension, smoking, age, and body mass index in men and women. ROC curve based cut-off values (comparing group A versus groups B and C) and associated diagnostic performances of the assays were evaluated. RESULTS: Significant increases were noted in serum CRP concentrations in men and women, in groups A vs. B,A vs. C, B vs. C. Lp(a) concentrations were not different among groups in men but were higher in group A vs. B and C in women. Optimal cut-off levels for CRP in women and men were found as 2.1 and 3.0 mg/l with the diagnostic values of 0.792 and 0.770, respectively. For Lp(a) optimal cut-off levels were found as 22.6 and 9.8 mg/dl with the diagnostic values of 0.612 and 0.596 in women and men, respectively. CONCLUSION: The CRP level is quite efficient for separation of patients from controls. Therefore keeping in mind the lack of specificity, the CRP level may be a useful tool in the diagnosis of coronary heart disease. However, the Lp(a) level is not efficient enough to support the use of Lp(a) measurement for management of coronary heart disease.

C-Reactive Protein↗

PubMed2005

Compliance with European guidelines for diagnostic mammography in a decentralized health-care setting.

PURPOSE: To evaluate the compliance of Danish mammography clinics with requirements concerning organization, activity volume, and assessment procedures from two European guidelines for quality assurance in diagnostic mammography (EUSOMA and EUREF). MATERIAL AND METHODS: We used individual records on all diagnostic mammographies performed in Denmark in 2000, and questionnaires given to Danish mammography clinics in 2000, 2002, and 2004. RESULTS: The study showed a marked centralization of the diagnostic activity from 2000 to 2004 to a smaller number of public breast assessment centers with full multidisciplinary breast assessment. However, a relatively large number of these centers did not comply with the activity volume requirement of 2000 mammograms per clinic per year. The number of private diagnostic mammography clinics performing basic diagnostic mammography has remained fairly stable in the period 2000 to 2004. Compared with public breast assessment centers, the private diagnostic mammography clinics had a lower compliance with activity volume requirements. CONCLUSION: A marked proportion of Danish public breast assessment centers operate with less than optimal activity volume, suggesting that further centralization would be appropriate. The situation in private diagnostic mammography clinics may cause concern, as our study showed that the majority of these clinics did not meet the activity volume requirements.

Ambulatory Care Facilities↗

PubMed1999

Standardization of a PCR-ELISA in serum samples: diagnosis of active parvovirus B19 infection.

To standardize a PCR assay for the detection of parvovirus B19 DNA in serum samples three different sample treatments were evaluated on the basis of the efficiency of recovery, reproducibility, convenience of sample handling, and presence of PCR inhibitors. Moreover, the presence of an internal standard competitor as the working reagent at one defined concentration in a competitive PCR-ELISA has been suggested as a valid tool to standardize and validate the assay. The results indicated that serum sample treatment by rapid heating fulfilled the criteria for a routine practice in the diagnostic laboratory. Titration experiments carried out to define the optimal amount of the internal standard competitor to use in PCR-ELISA showed that at 2 x10(2) competitor copies, any amplification interferences between target and competitor sequences were avoided. The internal standard competitor in a competitive PCR-ELISA allows the detection of false-negative results due to PCR inhibitors in the samples or large amounts of target DNA. Heating treatment and competitive PCR-ELISA for the detection of parvovirus B19 DNA were applied to the testing of 347 serum samples, which were submitted to the laboratory for B19 investigation. Of the 34 serum samples that were positive for B19 DNA, 15 were from adult patients and 19 from pediatric subjects. B19 infection was associated with haematological disorders, nonimmunological foetal hydrops, atypical rash, arthropathies, hepatic dysfunction, nonspecific symptoms, and congenital infections.

Adolescent↗

PubMed1990

Direct chromosome preparation and culture using chorionic villi: an evaluation of the two techniques.

We present a comparison between direct chromosome preparation and cell culture for first trimester fetal chromosome study using chorionic villi. The 2 techniques have advantages and disadvantages and are demonstrated to be appropriate for routine diagnostic work. The combined use of both methods may optimize the quality of the chromosome study and minimize the possibility of false-positive and false-negative findings.

Cells, Cultured↗