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PubMed2004

In vivo study of human skin using pulsed terahertz radiation.

Studies in terahertz (THz) imaging have revealed a significant difference between skin cancer (basal cell carcinoma) and healthy tissue. Since water has strong absorptions at THz frequencies and tumours tend to have different water content from normal tissue, a likely contrast mechanism is variation in water content. Thus, we have previously devised a finite difference time-domain (FDTD) model which is able to closely simulate the interaction of THz radiation with water. In this work we investigate the interaction of THz radiation with normal human skin on the forearm and palm of the hand in vivo. We conduct the first ever systematic in vivo study of the response of THz radiation to normal skin. We take in vivo reflection measurements of normal skin on the forearm and palm of the hand of 20 volunteers. We compare individual examples of THz responses with the mean response for the areas of skin under investigation. Using the in vivo data, we demonstrate that the FDTD model can be applied to biological tissue. In particular, we successfully simulate the interaction of THz radiation with the volar forearm. Understanding the interaction of THz radiation with normal skin will form a step towards developing improved imaging algorithms for diagnostic detection of skin cancer and other tissue disorders using THz radiation.

Algorithms↗
PubMed2004

[Diagnostic utility of capsule endoscopy in occult gastrointestinal bleeding].

BACKGROUND AND OBJECTIVE: The video-capsule endoscopy (CE) of the small intestine is a novel innovative procedure for outpatient use that can detect even small lesions of the mucosa of the small intestine. Aim of this retrospective clinical study was to evaluate the diagnostic value of CE in a clinical routine setting. PATIENTS AND METHODS: Between July 2001 and October 2002 we investigated 42 patients with suspected gastrointestinal bleeding by CE. In all patients, the previous upper and lower endoscopy work-up was normal. In some cases additional procedures such as bloodpool scintigraphy, angiography, small-bowel enteroclysis or push-enteroscopy were performed. RESULTS: CE detected relevant pathological findings in 23 out of 42 Patients (55 %). The majority of findings in the CE consisted of angiodysplasia (n = 16), ulcer and haemorrhagical erosions (n = 10), one Ulcus Dieulafoy and additional polyps of the small intestine (n = 2). In 4 cases an inflammatory small-bowel disease was detected. These findings could be confirmed by Re-endoscopy. The information provided was helpful to direct further diagnostic and treatment options. In 14 cases (33 %) CE-findings steered additional diagnostic and therapeutic steps. We conclude that CE is safe and has a high diagnostic yield. CONCLUSION: M2A video CE is likely to become an integral part of the algorithm of diagnostic of occult gastrointestinal bleeding after exclusion of other causes of anemia and negative upper and lower endoscopy work-up.

Adult↗
PubMed1992

An evaluation of maximum likelihood-expectation maximization reconstruction for SPECT by ROC analysis.

A ROC study was performed in order to evaluate whether the maximum likelihood expectation maximization (ML-EM) reconstruction algorithm improves diagnostic performance compared to the conventional filtered backprojection method in SPECT. Several implementations of the algorithm were tested including 25 and 50 iteration stopping points, with and without nonuniform attenuation compensation, and with and without Metz filtering. Filtered backprojection was with Metz filter and without attenuation compensation. The test data were computer simulated to model cardiac 201Tl SPECT. The data incorporated the effects of nonuniform attenuation, distance-dependent collimator response, and scatter. Patient CT images provided realistic anatomy and attenuation information for the data simulation. Four observers each viewed 120 images for each of the reconstruction methods. Lesion detectability with ML-EM increased with Metz filtering and decreased with nonuniform attenuation compensation. The best MIL-EM implementation, 50 iterations with Metz filtering and without attenuation compensation, was not statistically better than filtered backprojection.

Algorithms↗
PubMed2005

Cost-effectiveness of 18F-fluorodeoxyglucose positron emission tomography in the assessment of early dementia from a Belgian and European perspective.

(18)F-fluoro-deoxyglucose positron emission tomography (FDG PET) can aid to predict AD in an early stage. The aim of this study was to estimate the economic effects of incorporating FDG PET in the diagnostic work-up of AD in a Belgian and European setting. A decision tree analysis was followed comparing a conventional algorithm using diagnostic clinical criteria and one that also incorporates PET. Major outcome terms were overall cost per patient in either strategy; diagnostic accuracy and cost per accurate diagnosis. A sensitivity analysis was performed for four critical variables: cost of PET, sensitivity and specificity of PET and delay in cognitive decline because of appropriate medication. Cost-savings per accurate diagnosis ranged from 623-6110 Euro in favour of the proposed algorithm with PET. For the same cost, more accurate diagnoses were made, resulting in benefit for patients and society. The positive results were maintained over a wide range of values for the critical variables and were expandable to other European countries with a similar health system. Therefore, incorporation of FDG PET into the clinical diagnostic work up of patients with early symptoms of cognitive decline can be advocated.

Algorithms↗
PubMed2000

Oculographic and clinical characterization of thirty-seven children with anomalous head postures, nystagmus, and strabismus: the basis of a clinical algorithm.

BACKGROUND AND PURPOSE: We studied children with nystagmus who also had anomalous head postures and strabismus to determine the etiology of the conditions and present a diagnostic clinical algorithm. METHODS: The patients for this study were among the 560 patients evaluated in the ocular motor neurophysiology laboratory between the years 1991 and 1997. Clinical characteristics, infrared oculography data, and medical and surgical treatments were entered into a database for analysis. Oculography was performed on all patients according to a standard protocol, and data were stored and analyzed off-line. Etiology of anomalous head posture was determined with both clinical and oculography information. RESULTS: Thirty-seven children are the subjects of this report. The etiology of anomalous head posture was a "gaze null" due to congenital nystagmus in 23 (62%) patients, an "adduction null" due to manifest latent nystagmus in 12 (32%) patients, spasmus nutans in 1 (3%) patient, and strabismus in 1 (3%) patient. The patients' ages ranged from 9 months to 12 years and averaged 4.4 years. Sixty-nine percent were male patients. Nineteen (63%) of 30 patients had abnormal recognition (linear optotype) acuity in at least 1 eye on monocular cover; the recognition remained abnormal in 5 (17%) of 30 patients under binocular conditions. Thirty percent of patients had amblyopia, 16% had some structural disease of the eyes, 22% had some systemic syndrome or abnormality, 57% had a significant refractive error, and 27% had some ability to fuse. CONCLUSIONS: The major etiology for anomalous head posture in these patients was to adopt a gaze null due to congenital nystagmus (62% of patients) regardless of the direction of their anomalous head posture or type of strabismus. Moving the fixing eye as the first step for the anomalous head posture, combined with moving the nonfixing eye for the resulting strabismus may help treat these patients.

Algorithms↗
PubMed2001

Infectious diarrhea in human immunodeficiency virus.

Chronic HIV-associated diarrhea is currently a field in flux. Improved noninvasive diagnostic tests, improved pathogen-specific regimens, and better empiric therapies may change some of the assumptions used to select algorithms for diagnostic evaluation and management. Any shift in the cause of diarrhea from pathogen-associated to idiopathic or a reduction in the overall incidence of diarrhea would have considerable impact. It is unclear how significant the problem of pathogen relapse in previous responders will become. Existing studies reviewed in this article show that the high diagnostic yield of endoscopy when stool tests are negative, coupled with significantly better outcomes when pathogens are identified, support the current practice of routine endoscopic evaluation. There currently are scant data on the economic impact of HIV-associated diarrhea as it relates to pathogen-specific and empiric therapy in the era of protease inhibitors. Such data would be integral to future evaluation of the impact of diagnostic and therapeutic strategies.

AIDS-Related Opportunistic Infections↗
PubMed1998

Aspects of diagnosis of acute otitis media.

BACKGROUND: Acute otitis media is a common disease, particularly among children. The importance of a correct diagnosis is crucial, especially as unjustified prescription of antibiotics has become a major problem in clinical praxis. OBJECTIVES: Our aim was to evaluate the predictive value of different otological findings in diagnostics and treatment of acute otitis media among GPs and ear specialists and to investigate if the diagnosis could be improved by the use of an ear microscope instead of an otoscope. Furthermore, we aimed to test the value of following an algorithm, METHODS: Thirty-one patients with otalgia at the Emergency Department at the Karolinska Hospital in Stockholm were examined by both a GP and an ear specialist. The GP used an otoscope, whereas the ear specialist first used an otoscope and then an ear microscope. The doctors registered their findings and their proposal for treatment in questionnaires. The ability among participating ear specialists to give a correct diagnosis was confirmed by the use of 12 video-taped selected cases of aural diseases. An algorithm for diagnostics, based on medical facts, was formulated and tested. RESULTS: In general, the concordance between ear specialists and GPs was satisfactory with regard to establishing the diagnosis acute otitis media. The diagnostics were not improved by use of an ear microscope. The algorithm identified most patients with acute otitis media. Conclusion. The results indicate that the following of a simple algorithm may simplify the CONCLUSION: and lead to a correct diagnosis of acute otitis media.

Acute Disease↗
PubMed1990

Tapetool: a software tool for importing image data from image acquisition computers to image processing computers.

Currently, the image distribution gap between image acquisition computers and image processing computers is bridged through magnetic tapes. The tape formats used by the manufacturers of the image acquisition computers are idiosyncratic and fairly complex. A general purpose window based software tool is herein described, which frees the clinical and research sectors of the responsibility of understanding and decoding these complex formats in order to import image databases from acquisition computers to image processing computers. This software tool provides a cornerstone for developing image processing software for diagnostic, therapeutic and surgical planning purposes.

Algorithms↗
PubMed1999

[Low back pain].

Many people suffer from low back pain in the course of their life, of whom not all seek health care. In the majority of patients who seek care and refrain from work, the problem of pain resolves within a few weeks. It is reason that chronic pain syndromes such as chronic back pain are responsible for enormous costs for health care and society. Also, many diagnostics procedures and durability of rehabilitation makes low back pain as a very expensive disease. All of that are good reasons to make algorithm for diagnostic and treatment of low back pain in Croatian Society for Rheumatology.

Humans↗
PubMed2005

[A new view of approaches to diagnostics and treatment of Kaposi's sarcoma].

The paper contains literature data and the results of author's own observations, devoted to the clinical manifestations, ethiology and pathogenesis of Kaposi's sarcoma. An algorithm of diagnostics of the disease and methods of treatment are offered, which are developed taking into account the type of the disease, its form, the extent of the pathologic process and immunological parameters.

Biopsy↗
PubMed1983

Ready! Fire! . . . Aim! An inquiry into laboratory test ordering.

Informal test-ordering protocols that do not follow a physiological rationale are common in teaching hospitals and represent part of the folklore of resident practice. Such faulty test-ordering routines increase the cost of care, waste resources, may fail to answer diagnostic questions, or may generate false leads. They prove to be part of a broader set of issues in information management not restricted to medicine. Clinically appropriate algorithms for diagnostic testing can be constructed to replace folkloric protocols. This should represent a major area of professional concern in clinical pathology.

Clinical Laboratory Techniques↗
PubMed2004

Diagnostic fidelity of the Z-buffer segmentation algorithm: preliminary assessment based on intracranial aneurysm detection.

We have developed an algorithm known as the Z-buffer segmentation (ZBS) algorithm for segmenting vascular structures from 3D MRA images. Previously we evaluated the accuracy of the ZBS algorithm on a voxel level in terms of inclusion and exclusion of vascular and background voxels. In this paper we evaluate the diagnostic fidelity of the ZBS algorithm. By diagnostic fidelity we mean that the data preserves the structural information necessary for diagnostic evaluation. This evaluation is necessary to establish the potential usefulness of the segmentation for improved image display, or whether the segmented data could form the basis of a computerized analysis tool. We assessed diagnostic fidelity by measuring how well human observers could detect aneurysms in the segmented data sets. ZBS segmentation of 30 MRA cases containing 29 aneurysms was performed. Image display used densitometric reprojections with shaded surface highlighting that were generated from the segmented data. Three neuroradiologists independently reviewed the generated ZBS images for aneurysms. The observers had 80% sensitivity (90% for aneurysms larger than 2mm) with 0.13 false positives per image. Good agreement with the gold standard for describing aneurysm size and orientation was shown. These preliminary results suggest that the segmentation has diagnostic fidelity with the original data and may be useful for improved visualization or automated analysis of the vasculature.

Algorithms↗
PubMed2004

[Methodical and practical approaches to the management of health care quality control in a large military polyclinic].

The experience of creation and practical use of the medical care quality (MCQ) control system in the Diagnostic center N 52 is summarized. The measures realizing the functions of planning, motivation and organization during MCQ control are described. The goals, objects and system elements, functional duties and algorithm of officials' actions during the continuous MCQ support are substantiated. Introduction of some elements of MCQ control system caused the decrease in the number of patients' complaints, defects in rendering of medical care and complications.

Algorithms↗
PubMed1989

The clinical utility of renal concentrating capacity in polycystic kidney disease.

We studied 177 adult nonazotemic subjects with autosomal dominant polycystic kidney disease (ADPKD) and 123 unaffected family members (NADPKD). In order to assess the factors influencing renal concentrating capacity maximal urinary osmolality (UOsm) after overnight water deprivation and vasopressin was measured. UOsm was reduced in ADPKD (680 +/- 14) compared to NADPKD subjects (812 +/- 13 mOsm/kg). A greater severity of the architectural abnormality as assessed by cyst number and size and remaining volume of normal parenchyma was associated with a greater impairment of renal concentrating capacity. The concentrating defect was present in the youngest ADPKD subjects and the rate of decline of concentrating capacity with age in ADPKD paralleled that in NADPKD subjects. Based on the initial 135 subjects studied, we developed an algorithm for diagnostic screening for ADPKD utilizing blood pressure, serum creatinine and UOsm designed to maximize sensitivity. When applied to a subsequent population of 165 adults, 121 with ADPKD and 44 unaffected relatives, this algorithm would have spared 20% of unaffected subjects from the cost of ultrasound while failing to detect less than 2% of affected subjects. This simple protocol thus offers a rapid and inexpensive way to screen for ADPKD.

Adult↗
PubMed2004

Characterization of small pulmonary nodules by CT.

Small pulmonary nodules with diameters </=10 mm are very frequent findings at CT examinations. Despite the traditional opinion that every pulmonary nodule should be considered malignant until proven otherwise, the vast majority of small lesions are benign, and therefore biopsy may not be necessary in all cases. During the last few years, several CT-based methods have been developed to differentiate between benign and malignant lesions non-invasively. A negative quantitative contrast-enhanced CT is a strong predictor for benignity. Repeat nodule volume measurements at short-term follow-up CT examinations can detect growth suggesting malignancy. Limitations and potential pitfalls of these methods must be observed to avoid false negative test results leading to delayed diagnosis and treatment of malignant tumours. An algorithm for diagnostic workup of incidentally detected small pulmonary nodules in subjects without known malignancy is proposed in this article.

Algorithms↗