342 research outputs found

    Diagnostic Screening of Digital Mammograms Using Wavelets and Neural Networks to Extract Structure

    Get PDF
    As the primary tool for detecting breast carcinoma, mammography provides visual images from which a trained radiologist can identify suspicious areas that suggest the presence of cancer. We describe an approach to image processing that reduces an image to a small number of values based on its structural characteristics using wavelets and neural networks. To illustrate its utility, we apply this methodology to the automatic screening of mammograms for mass lesions. Our results approach performance levels of trained human mammographers

    Fast evaluation of appointment schedules for outpatients in health care

    Get PDF
    We consider the problem of evaluating an appointment schedule for outpatients in a hospital. Given a fixed-length session during which a physician sees K patients, each patient has to be given an appointment time during this session in advance. When a patient arrives on its appointment, the consultations of the previous patients are either already finished or are still going on, which respectively means that the physician has been standing idle or that the patient has to wait, both of which are undesirable. Optimising a schedule according to performance criteria such as patient waiting times, physician idle times, session overtime, etc. usually requires a heuristic search method involving a huge number of repeated schedule evaluations. Hence, the aim of our evaluation approach is to obtain accurate predictions as fast as possible, i.e. at a very low computational cost. This is achieved by (1) using Lindley's recursion to allow for explicit expressions and (2) choosing a discrete-time (slotted) setting to make those expression easy to compute. We assume general, possibly distinct, distributions for the patient's consultation times, which allows us to account for multiple treatment types, as well as patient no-shows. The moments of waiting and idle times are obtained. For each slot, we also calculate the moments of waiting and idle time of an additional patient, should it be appointed to that slot. As we demonstrate, a graphical representation of these quantities can be used to assist a sequential scheduling strategy, as often used in practice

    Duodenal Duplicated Cyst Manifested by Acute Pancreatitis and Obstructive Jaundice in an Elderly Man

    Get PDF
    A duodenal duplication cyst is an uncommon congenital anomaly that is usually encountered during infancy or in early childhood. Duodenal duplication cysts generally appear on the first or second portion of the duodenum and may cause duodenal obstruction, hemorrhage or pancreatitis. Here, we report a case of a duodenal duplication cyst on the second and third portion of the duodenum in an old aged man with obstructive jaundice and acute pancreatitis, which was treated successfully by a surgical excision

    Contribution of magnetic resonance imaging in the diagnosis of talus skip metastases of Ewing's sarcoma of the calcaneus in a child: a case report

    Get PDF
    <p>Abstract</p> <p>Introduction</p> <p>Ewing's sarcoma of the calcaneus is rare. About thirty cases with calcaneus involvement have been reported in the literature. Talus skip metastases have rarely been described in the available literature</p> <p>Case presentation</p> <p>We report a case of a 14-year-old Moroccan boy, who presented with Ewing's sarcoma of his right calcaneus, diagnosed by swelling of the calcaneus evolving over a year. Radiography, computed tomography and magnetic resonance imaging showed an important tumoral process of the calcaneus and talus skip metastases. The diagnosis was confirmed with histology after a biopsy. In spite of amputation and postoperative chemotherapy, our patient died six months later due to secondary respiratory distress after lung metastasis.</p> <p>Conclusion</p> <p>Imaging, especially magnetic resonance, is important in the diagnosis of Ewing sarcoma and skeletal skip metastases. Treatment of Ewing's sarcoma consists of chemotherapy, radiation therapy and surgical resection depending on the stage and extent of the disease. With the exception of lesions in the calcaneus, the prognosis for disease-free survival of Ewing's sarcoma of the foot is excellent.</p

    Ewing sarcoma of the proximal phalanx of the little finger : Case report

    Get PDF
    El sarcoma de Ewing se presenta en la segunda década de la vida y tiene predilección por las diáfisis de los huesos largos y en la pelvis. Pueden existir localizaciones raras como en los en los metacarpianos. Reportamos un caso de sarcoma de Ewing localizado en la falange proximal del 5to dedo de la mano izquierda en un paciente masculino de 44 anos ˜ de edad. Ante la poca frecuencia de presentación, resulta importante considerar los diagnósticos diferenciales de otras patologías neoplásicas de la mano, como el osteosarcoma de células pequenas. ˜ Ésta es una rara pero agresiva forma de osteosarcoma cuyo diagnóstico es difícil de realizar y fue nuestra primera sospecha diagnóstica por valoración radiológica. Sin embargo, se caracterizó al sarcoma de Ewing con la ayuda de la biopsia y la histopatología. El control local de la enfermedad se logró mediante la excéresis del tumor con márgenes amplios.Reporte de caso137-142Paciente masculinoEwing’s sarcoma occurs in the second decade of life and has a predilection for thediaphysis of long bones and pelvis. There may be rare locations, such as in the metacarpals.A case is reported of Ewing’s sarcoma located in the proximal phalanx of the 5th finger of theleft hand in a male patient aged 44. Given the infrequency of presentation, it is importantto consider the differential diagnosis of other neoplastic diseases of the hand and small cellosteosarcoma. The latter is a rare but aggressive form of osteosarcoma, which is difficult to diagnose and was our first suspicion diagnosed by radiological assessment. However Ewing’ssarcoma was characterized with the help of the biopsy and histopathology. Local disease controlwas achieved by tumoral exeresis with wide margins

    Physicochemical composition of wastes and co-located environmental designations at legacy mine sites in the south west of England and Wales: Implications for their resource potential

    Get PDF
    © 2016 This work examines the potential for resource recovery and/or remediation of metalliferous mine wastes in the south west of England and Wales. It does this through an assessment of the physicochemical composition of several key metalliferous legacy mine waste piles and an analysis of their co-location with cultural, geological and ecological designations. Mine waste samples were taken from 14 different sites and analysed for metal content, mineralogy, paste pH, particle size distribution, total organic carbon and total inorganic carbon. The majority of sites contain relatively high concentrations (in some cases up to several % by mass) of metals and metalloids, including Cu, Zn, As, Pb, Ag and Sn, many of which exceed ecological and/or human health risk guideline concentrations. However, the economic value of metals in the waste could be used to offset rehabilitation costs. Spatial analysis of all metalliferous mine sites in the south west of England and Wales found that around 70% are co-located with at least one cultural, geological and ecological designation. All 14 sites investigated are co-located with designations related to their mining activities, either due to their historical significance, rare species assemblages or geological characteristics. This demonstrates the need to consider the cultural and environmental impacts of rehabilitation and/or resource recovery on such sites. Further work is required to identify appropriate non-invasive methodologies to allow sites to be rehabilitated at minimal cost and disturbance

    Choledochocele: an unusual form of choledochal cyst

    Full text link
    Choledochocele, or type III choledochal cyst, is a rare anomaly. Two children with choledochocele, both younger than any previously reported patient, were recently cared for at the University of Michigan Medical Center and prompted a literature review of this subject. Since 1974, 40 cases of choledochocele have been reported with enough clinical information for critical review. Ten of these patients were 21 years of age or younger. Presenting symptoms were not specific for choledochocele; they were generally interpreted to result from other biliary or gastrointestinal disorders that are more common for each age group. In pediatric patients the most frequent signs and symptoms of choledochocele were abdominal pain (70%), nausea and/or vomiting (60%), jaundice (30%), and acute pancreatitis (30%). While two-thirds of adult patients with choledochocele had undergone prior cholecystectomy (with stones rarely found), this was observed only once in children. Obstructive symptoms led to evaluation of the stomach and duodenum with either barium upper GI series or endoscopy in all children. These demonstrated an extrinsic mass effect in 90% of the patients. Endoscopic retrograde cholangiopancreatography identified a choledochocele in all cases in which the study was successfully executed. Intravenous cholangiography was sensitive in children, but less so in the adult patients reviewed. Other imaging efforts (computerized tomography, ultrasound, radionuclide scanning) were less dependable. Transduodenal marsupialization is the treatment of choice for patients of all ages and was provided in both of these newly reported children.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47183/1/383_2004_Article_BF00179633.pd

    Magnetic resonance imaging, magnetic resonance arthrography and ultrasonography for assessing rotator cuff tears in people with shoulder pain for whom surgery is being considered

    Get PDF
    Background Shoulder pain is a very common symptom. Disorders of the rotator cuff tendons due to wear or tear are among the most common causes of shoulder pain and disability. Magnetic resonance imaging (MRI), magnetic resonance arthrography (MRA) and ultrasound (US) are increasingly being used to assess the presence and size of rotator cuff tears to assist in planning surgical treatment. It is not known whether one imaging method is superior to any of the others.Objectives To compare the diagnostic test accuracy of MRI, MRA and US for detecting any rotator cuff tears (i.e. partial or full thickness) in people with suspected rotator cuff tears for whom surgery is being considered.Search methods We searched the Cochrane Register of Diagnostic Test Accuracy Studies, MEDLINE, EMBASE, and LILACS from inception to February 2011. We also searched trial registers, conference proceedings and reference lists of articles to identify additional studies. No language or publication restrictions were applied.Selection criteria We included all prospective diagnostic accuracy studies that assessed MRI, MRA or US against arthroscopy or open surgery as the reference standard, in people suspected of having a partial or full thickness rotator cuff tear. We excluded studies that selected a healthy control group, or participants who had been previously diagnosed with other specific causes of shoulder pain such as osteoarthritis or rheumatoid arthritis. Studies with an excessively long period (a year or longer) between the index and reference tests were also excluded.Data collection and analysis Two review authors independently extracted data on study characteristics and results of included studies, and performed quality assessment according to QUADAS criteria. Our unit of analysis was the shoulder. for each test, estimates of sensitivity and specificity from each study were plotted in ROC space and forest plots were constructed for visual examination of variation in test accuracy. Meta-analyses were performed using the bivariate model to produce summary estimates of sensitivity and specificity. We were unable to formally investigate potential sources of heterogeneity because of the small number of studies.Main results We included 20 studies of people with suspected rotator cuff tears (1147 shoulders), of which six evaluated MRI and US (252 shoulders), or MRA and US (127 shoulders) in the same people. Many studies had design flaws, with the potential for bias, thus limiting the reliability of their findings. Overall, the methodological quality of the studies was judged to be low or unclear. for each test, we observed considerable heterogeneity in study results, especially between studies that evaluated US for the detection of full thickness tears and studies that evaluated MRA for the detection of partial thickness tears. the criteria for a positive diagnostic test (index tests and reference standard) varied between studies.Meta-analyses were not possible for studies that assessed MRA for detection of any rotator cuff tears or partial thickness tears. We found no statistically significant differences in sensitivity or specificity between MRI and US for detecting any rotator cuff tears (P = 0.13), or for detecting partial thickness tears (P = 1.0). Similarly, for the comparison between MRI, MRA and US for detecting full thickness tears, there was no statistically significant difference in diagnostic performance (P = 0.7). for any rotator cuff tears, the summary sensitivity and specificity were 98% (95% CI 92% to 99%) and 79% (95% CI 68% to 87%) respectively for MRI (6 studies, 347 shoulders), and 91% (95% CI 83% to 95%) and 85% (95% CI 74% to 92%) respectively for US (13 studies, 854 shoulders). for full thickness tears, the summary sensitivity and specificity were 94% (95% CI 85% to 98%) and 93% (95% CI 83% to 97%) respectively for MRI (7 studies, 368 shoulders); 94% (95% CI 80% to 98%) and 92% (95% CI 83% to 97%) respectively for MRA (3 studies, 183 shoulders); and 92% (95% CI 82% to 96%) and 93% (95% CI 81% to 97%) respectively for US (10 studies, 729 shoulders).Because few studies were direct head-to-head comparisons, we could not perform meta-analyses restricted to these studies. the test comparisons for each of the three classifications of the target condition were therefore based on indirect comparisons which may be prone to bias due to confounding.Authors' conclusions MRI, MRA and US have good diagnostic accuracy and any of these tests could equally be used for detection of full thickness tears in people with shoulder pain for whom surgery is being considered. the diagnostic performance of MRI and US may be similar for detection of any rotator cuff tears. However, both MRI and US may have poor sensitivity for detecting partial thickness tears, and the sensitivity of US may be much lower than that of MRI. the strength of evidence for all test comparisons is limited because most studies were small, heterogeneous and methodologically flawed, and there were few comparative studies. Well designed studies that directly compare MRI, MRA and US for detection of rotator cuff tears are needed.Universidade Federal de São Paulo, BrazilParker Institute, DenmarkOak FoundationTeesside University, UKUniversidade Federal de São Paulo, Dept Orthopaed & Traumatol, BR-04038032 São Paulo, BrazilMonash Univ, Sch Publ Hlth & Prevent Med, Dept Epidemiol & Prevent Med, Monash Dept Clin Epidemiol,Cabrini Hosp, Malvern, AustraliaUniv Birmingham, Birmingham, W Midlands, EnglandUniv Teesside, Hlth & Social Care Inst, Middlesbrough, Cleveland, EnglandUniversidade Federal de São Paulo, Dept Orthopaed & Traumatol, BR-04038032 São Paulo, BrazilWeb of Scienc
    corecore