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1.
Bratisl Lek Listy ; 120(5): 362-367, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31113199

RESUMO

BACKGROUND: The goal of this study was to show the importance of the identifying potential carotid and vertebrobasilar stenosis with Computed Tomography Angiography (CTA) in severe coronary artery disease. METHODS: In 109 patients, CTA of the carotid and the vertebrobasilar system were taken in the six months following the Coronary Angiography (CA). Coronary arteries and carotid vertebrobasilar system stenosis were considered significant at more than ≥ 50 %. RESULTS: A significant statistical relationship was found between a coronary artery group of three-vessel disease (3-VD) and stenosis of the cervical segments of the right (p = 0.022) and left internal carotid artery (ICA) (p = 0.001); intracranial segments of the right (p = 0.007) and left ICA (p = 0.020), and the right vertebral artery (VA) (p = 0.008). There was a significant statistical relationship between Gensini score and stenosis of both the right (p = 0.030) and the left ICA cervical segments (p = 0.003). CONCLUSION: In patients with severe coronary artery disease especially in 3-VD, CTA scan may be useful diagnostic tool for identifying stenosis of the carotid arteries, particularly in the intracranial segments of the ICA and in the preforaminal (V1) segment of the VA (Tab. 4, Fig. 3, Ref. 22).


Assuntos
Estenose das Carótidas , Doença da Artéria Coronariana , Artéria Carótida Interna , Estenose das Carótidas/complicações , Constrição Patológica , Doença da Artéria Coronariana/complicações , Humanos , Tomografia Computadorizada por Raios X
2.
J Antimicrob Chemother ; 71 Suppl 1: i71-83, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27048584

RESUMO

OBJECTIVES: Data are presented from the Survey of Antibiotic Resistance (SOAR) for respiratory tract infection pathogens collected in 2011-13 from Turkey. METHODS: MICs were determined using Etest(®). Susceptibility was assessed using CLSI, EUCAST and pharmacokinetic/pharmacodynamic (PK/PD) interpretive criteria. RESULTS: Rates of antibiotic susceptibility were very low among 333 isolates of Streptococcus pneumoniae tested: penicillin 38% using CLSI (oral) and EUCAST breakpoints; erythromycin 51% using CLSI and EUCAST criteria; and cefuroxime 64.6% using CLSI and PK/PD and 46.9% using EUCAST. Of the isolates, >90% were susceptible to amoxicillin/clavulanic acid, ceftriaxone (except using EUCAST criteria: 76%), levofloxacin and high-dose intravenous penicillin. Among 339 Haemophilus influenzae isolates, 6.8% were ß-lactamase positive while 9.1% were ß-lactamase negative but ampicillin resistant (BLNAR) by CLSI (14.7% by EUCAST) criteria. Amoxicillin/clavulanic acid susceptibility was ∼90% by CLSI (with or without BLNAR adjustment, EUCAST and high-dose PK/PD) but lower, at 82.9%, by EUCAST with BLNAR adjustment. Levofloxacin susceptibility was 96% using all three breakpoints. Dramatic differences in rates of susceptibility, depending on the breakpoints used, were seen for cefaclor [94% by CLSI (86.4% BLNAR adjusted), 23% by PK/PD] and cefuroxime [97% by CLSI (89.1% BLNAR adjusted), 85% by PK/PD, 15% by EUCAST (13.0% BLNAR adjusted)]. Streptococcus pyogenes (n = 222) and Moraxella catarrhalis (n = 40) isolates remained highly susceptible to amoxicillin/clavulanic acid, cephalosporins and levofloxacin, with only erythromycin susceptibility dropping below 95% for S. pyogenes. CONCLUSIONS: Overall, amoxicillin/clavulanic acid and levofloxacin were the most active antibiotics based on all three breakpoints against these pathogens. Although susceptibility was not universally low in Turkey, high resistance rates were found in S. pneumoniae and, when using PK/PD and EUCAST breakpoints, in other respiratory pathogens.


Assuntos
Antibacterianos/farmacologia , Bactérias/classificação , Bactérias/efeitos dos fármacos , Infecções Bacterianas/microbiologia , Farmacorresistência Bacteriana , Infecções Respiratórias/microbiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Bactérias/isolamento & purificação , Infecções Bacterianas/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Macrolídeos/farmacologia , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Infecções Respiratórias/epidemiologia , Turquia/epidemiologia , Adulto Jovem , beta-Lactamas/farmacologia
3.
J Antimicrob Chemother ; 71 Suppl 1: i85-91, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27048585

RESUMO

OBJECTIVES: To investigate changes in antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae from the Survey of Antibiotic Resistance (SOAR) in community-acquired respiratory tract infections (CA-RTIs) between 2002 and 2009 in Turkey. METHODS: Previously published SOAR data were used for this analysis. MICs were determined using Etest(®) gradient strips or disc diffusion. Susceptibility against a range of antimicrobial agents was assessed using CLSI breakpoints. RESULTS: A total of 900 S. pneumoniae isolates were analysed: 2002-03 (n = 75), 2004-05 (n = 301) and 2007-09 (n = 524). Four antibiotics were tested consistently throughout and three showed a statistically significant decrease in susceptibility (P < 0.0001): penicillin (74.7% susceptible in 2002-03; 67.8% in 2004-05; and 47.2% in 2007-09); cefaclor (85.3% in 2002-03; 78.7% in 2004-05; and 53.5% in 2007-09) and clarithromycin (85.3% in 2002-03; 82.7% in 2004-05; and 61.9% in 2007-09). Susceptibility to amoxicillin/clavulanic acid did not significantly change (100% in 2002-03; 98.7% in 2004-05; and 97.7% in 2007-09). A total of 930 H. influenzae isolates were analysed: 2002-03 (n = 133), 2004-05 (n = 379) and 2007-09 (n = 418). Four antibiotics were also consistently tested: ampicillin, amoxicillin/clavulanic acid, clarithromycin and cefaclor. All showed >90% susceptibility, but only cefaclor susceptibility significantly reduced (P < 0.0001) over time (99.2% in 2002-03; 96.3% in 2004-05; and 90.4% in 2007-09). CONCLUSIONS: In S. pneumoniae from Turkey, there has been a clear statistically significant reduction in susceptibility to key antibiotics since 2002, but not to amoxicillin/clavulanic acid (or amoxicillin). However, susceptibility in H. influenzae remained stable. Continued surveillance is required to monitor future changes in antibiotic susceptibility for CA-RTI bacteria.


Assuntos
Antibacterianos/farmacologia , Infecções Comunitárias Adquiridas/microbiologia , Farmacorresistência Bacteriana , Haemophilus influenzae/efeitos dos fármacos , Infecções Respiratórias/microbiologia , Streptococcus pneumoniae/efeitos dos fármacos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Infecções Comunitárias Adquiridas/epidemiologia , Feminino , Infecções por Haemophilus/epidemiologia , Infecções por Haemophilus/microbiologia , Haemophilus influenzae/isolamento & purificação , Humanos , Lactente , Recém-Nascido , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Infecções Pneumocócicas/epidemiologia , Infecções Pneumocócicas/microbiologia , Infecções Respiratórias/epidemiologia , Streptococcus pneumoniae/isolamento & purificação , Turquia/epidemiologia , Adulto Jovem
4.
Clin Radiol ; 70(5): e14-9, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25703460

RESUMO

AIM: To investigate the underlying relationship between obesity and the extent of emphysema depicted at CT. METHODS AND MATERIALS: A dataset of 477 CT examinations was retrospectively collected from a study of chronic obstructive pulmonary disease (COPD). The low attenuation areas (LAAs; ≤950 HU) of the lungs were identified. The extent of emphysema (denoted as %LAA) was defined as the percentage of LAA divided by the lung volume. The association between log-transformed %LAA and body mass index (BMI) adjusted for age, sex, the forced expiratory volume in one second as percent predicted value (FEV1% predicted), and smoking history (pack years) was assessed using multiple linear regression analysis. RESULTS: After adjusting for age, gender, smoking history, and FEV1% predicted, BMI was negatively associated with severe emphysema in patients with COPD. Specifically, one unit increase in BMI is associated with a 0.93-fold change (95% CI: 0.91-0.96, p<0.001) in %LAA; the estimated %LAA for males was 1.75 (95% CI: 1.36-2.26, p<0.001) times that of females; per 10% increase in FEV1% predicated is associated with a 0.72-fold change (95% CI: 0.69-0.76, p<0.001) in %LAA. CONCLUSION: Increasing obesity is negatively associated with severity of emphysema independent of gender, age, and smoking history.


Assuntos
Obesidade/complicações , Enfisema Pulmonar/complicações , Enfisema Pulmonar/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Idoso , Índice de Massa Corporal , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pennsylvania , Testes de Função Respiratória , Fatores de Risco , Fatores Sexuais , Inquéritos e Questionários
5.
Euro Surveill ; 16(11)2011 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-21435327

RESUMO

Based on data collected by the European Antimicrobial Resistance Surveillance Network (EARS-Net) and the former EARSS, the present study describes the trends in antimicrobial susceptibility patterns and occurrence of invasive infections caused by Escherichia coli and Staphylococcus aureus in the period from 2002 to 2009. Antimicrobial susceptibility results from 198 laboratories in 22 European countries reporting continuously on these two microorganisms during the entire study period were included in the analysis. The number of bloodstream infections caused by E. coli increased remarkably by 71% during the study period, while bloodstream infections caused by S. aureus increased by 34%. At the same time, an alarming increase of antimicrobial resistance in E. coli was observed, whereas for S. aureus the proportion of meticillin resistant isolates decreased. The observed trend suggests an increasing burden of disease caused by E. coli. The reduction in the proportion of meticillin-resistant S. aureus and the lesser increase in S. aureus infections, compared with E. coli, may reflect the success of infection control measures at hospital level in several European countries.


Assuntos
Anti-Infecciosos/uso terapêutico , Farmacorresistência Bacteriana , Infecções por Escherichia coli/microbiologia , Escherichia coli/efeitos dos fármacos , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/sangue , Infecções por Escherichia coli/tratamento farmacológico , Infecções por Escherichia coli/epidemiologia , Europa (Continente)/epidemiologia , Humanos , Testes de Sensibilidade Microbiana , Vigilância da População/métodos , Infecções Estafilocócicas/sangue , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/epidemiologia , Staphylococcus aureus/isolamento & purificação
6.
Science ; 215(4537): 1267-8, 1982 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-7058347

RESUMO

A noninvasive technique has been developed to measure and display local cerebral blood flow (LCBF) in vivo. In this procedure, nonradioactive xenon gas is inhaled and the temporal changes in radiographic enhancement produced by the inhalation are measured by sequential computerized tomography. The time-dependent xenon concentrations in various anatomical units in the brain are used to derive both the local partition coefficient and the LCBF. Functional mapping of blood flow with excellent anatomical specificity has been obtained in the baboon brain. The response of LCBF to stimuli such as changes in carbon dioxide concentrations as well as the variability in LCBF in normal and diseased tissue can be easily demonstrated. This method is applicable to the study of human physiology and pathologic blood flow alterations.


Assuntos
Circulação Cerebrovascular , Tomografia Computadorizada por Raios X/métodos , Xenônio , Animais , Papio
7.
J Hosp Infect ; 71(1): 36-42, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19013679

RESUMO

The Mediterranean region has been identified as an area of hyper-endemicity for multi-resistant hospital pathogens. To better understand potential drivers behind this situation, we attempted to correlate already published meticillin-resistant Staphylococcus aureus (MRSA) data from 27 hospitals, participants in the Antibiotic Resistance Surveillance & Control in the Mediterranean Region (ARMed) project, with responses received from the same institutions to questionnaires which dealt with various aspects of infection control and antibiotic stewardship. No difference could be ascertained between high and low prevalence hospitals in terms of scores from replies to structured questions regarding infection control set-up, hand hygiene facilities and antibiotic stewardship practices. However, we did identify differences in terms of bed occupancy and isolation facilities. Hospitals reporting frequent episodes of overcrowding, particularly involving several departments, and which found regular difficulties sourcing isolation beds, had significantly higher MRSA proportions. This suggests that infrastructural deficits related to insufficient bed availability and compounded by inadequate isolation facilities could potentiate MRSA hyper-endemicity in south-eastern Mediterranean hospitals.


Assuntos
Infecção Hospitalar/epidemiologia , Controle de Infecções/métodos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Infecções Estafilocócicas/epidemiologia , Ocupação de Leitos , Infecção Hospitalar/prevenção & controle , Coleta de Dados , Humanos , Região do Mediterrâneo/epidemiologia , Prevalência , Vigilância de Evento Sentinela
8.
J Hosp Infect ; 70(3): 228-34, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18783850

RESUMO

The prevalence of multiply resistant organisms (MROs) reported from south-eastern Mediterranean hospitals highlights the need to identify possible contributory factors to help design control interventions. This was investigated through a structured questionnaire, which examined infection control and antibiotic stewardship practices in hospitals participating or collaborating with the Antibiotic Resistance SurveilLance & Control in the Mediterranean Region (ARMed) project. A total of 45 hospitals (78.9% of invited institutions) responded to the questionnaire; 60% indicated that they faced periods of overcrowding when available bed complement was insufficient to cope with hospital admissions and 62% reported difficulties in isolating patients with MROs due to lack of available beds. Most hospitals relied mainly on washing to achieve hand hygiene, whether by non-medicated or disinfectant soaps. Dependence on solid bars of soap (28.9%) and cloth towels (37.8%) were among the problems identified as well as inconvenient distances of sinks from patient beds (66.6%). Alcohol hand rub was the predominant hand hygiene product in only 7% of hospitals. Programmes for better antibiotic use were mostly limited in scope; 33.3% reported having antibiotic prescribing guidelines and 53.3% of hospitals fed back resistance rates to prescribers. Auditing of antibiotic consumption, whether institution- or unit-based, was carried out in 37.8% of responding hospitals. Multi-faceted approaches aimed at improving isolation of patients with MROs, increasing the emphasis on hand hygiene by encouraging greater use of alcohol hand rubs and introducing effective antibiotic stewardship programmes should be encouraged in south-eastern Mediterranean hospitals.


Assuntos
Antibacterianos/uso terapêutico , Comportamento Cooperativo , Infecção Hospitalar/prevenção & controle , Controle de Infecções/métodos , Relações Interprofissionais , Farmacorresistência Bacteriana , Resistência a Múltiplos Medicamentos , Uso de Medicamentos , Hospitais , Humanos , Região do Mediterrâneo , Inquéritos e Questionários
9.
Clin Microbiol Infect ; 12(2): 150-5, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16441453

RESUMO

Sequence analysis of the pbp genes from 20 Streptococcus pneumoniae isolates from Turkey (eight with high-level penicillin-resistance, nine with low-level penicillin-resistance, and three that were penicillin-susceptible) was performed and phylogenetic trees were constructed. Most isolates clustered together within a single branch that was distinct from sequences deposited previously in GenBank, which suggests that these isolates have probably evolved following new recombination events. The most prominent active-site mutations, which have also been associated previously with resistance, were T371A in PBP1a, E481G followed by T451A in PBP2b, and T338A in PBP2x. All isolates also possessed a (570)SVES/TK(574) block in the PBP2b sequence, instead of the QLQPT sequence of R6, which is fairly uncommon in GenBank sequences. This is the first study to analyse alterations in the pbp sequences of pneumococci isolated in Turkey.


Assuntos
Proteínas de Bactérias/genética , Mutação , Resistência às Penicilinas/genética , Proteínas de Ligação às Penicilinas/genética , Streptococcus pneumoniae/genética , Sítios de Ligação/genética , DNA Bacteriano/química , DNA Bacteriano/genética , Evolução Molecular , Humanos , Dados de Sequência Molecular , Filogenia , Infecções Pneumocócicas/microbiologia , Recombinação Genética , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/isolamento & purificação , Turquia
10.
Euro Surveill ; 11(7): 164-7, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16966796

RESUMO

Sporadic reports from centres in the south and east of the Mediterranean have suggested that the prevalence of antibiotic resistance in this region appears to be considerable, yet pan-regional studies using comparable methodology have been lacking in the past. Susceptibility test results from invasive isolates of Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Enterococcus faecium and faecalis routinely recovered from clinical samples of blood and cerebrospinal fluid within participating laboratories situated in Algeria, Cyprus, Egypt, Jordan, Lebanon, Malta, Morocco, Tunisia and Turkey were collected as part of the ARMed project. Preliminary data from the first two years of the project showed the prevalence of penicillin non-susceptibility in S. pneumoniae to range from 0% (Malta) to 36% (Algeria) [median: 29%] whilst methicillin resistance in Staphylococcus aureus varied from 10% in Lebanon to 65% in Jordan [median: 43%]. Significant country specific resistance in E. coli was also seen, with 72% of isolates from Egyptian hospitals reported to be resistant to third generation cephalosporins and 40% non-susceptible to fluoroquinolones in Turkey. Vancomycin non-susceptibility was only reported in 0.9% of E. faecalis isolates from Turkey and in 3.8% of E. faecium isolates from Cyprus. The preliminary results from the ARMed project appear to support previous sporadic reports suggesting high antibiotic resistance in the Mediterranean region. They suggest that this is particularly the case in the eastern Mediterranean region where resistance in S. aureus and E. coli seems to be higher than that reported in the other countries of the Mediterranean.


Assuntos
Farmacorresistência Bacteriana , Vigilância da População , Farmacorresistência Bacteriana/fisiologia , Humanos , Região do Mediterrâneo/epidemiologia , Resistência a Meticilina/fisiologia , Testes de Sensibilidade Microbiana , Resistência às Penicilinas/fisiologia , Vigilância da População/métodos
11.
Euro Surveill ; 11(7): 11-12, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29208166

RESUMO

Sporadic reports from centres in the south and east of the Mediterranean have suggested that the prevalence of antibiotic resistance in this region appears to be considerable, yet pan-regional studies using comparable methodology have been lacking in the past. Susceptibility test results from invasive isolates of Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Enterococcus faecium and faecalis routinely recovered from clinical samples of blood and cerebrospinal fluid within participating laboratories situated in Algeria, Cyprus, Egypt, Jordan, Lebanon, Malta, Morocco, Tunisia and Turkey were collected as part of the ARMed project. Preliminary data from the first two years of the project showed the prevalence of penicillin non-susceptibility in S. pneumoniae to range from 0% (Malta) to 36% (Algeria) [median: 29%] whilst methicillin resistance in Staphylococcus aureus varied from 10% in Lebanon to 65% in Jordan [median: 43%]. Significant country specific resistance in E. coli was also seen, with 72% of isolates from Egyptian hospitals reported to be resistant to third generation cephalosporins and 40% non-susceptible to fluoroquinolones in Turkey. Vancomycin non-susceptibility was only reported in 0.9% of E. faecalis isolates from Turkey and in 3.8% of E. faecium isolates from Cyprus. The preliminary results from the ARMed project appear to support previous sporadic reports suggesting high antibiotic resistance in the Mediterranean region. They suggest that this is particularly the case in the eastern Mediterranean region where resistance in S. aureus and E. coli seems to be higher than that reported in the other countries of the Mediterranean.

12.
Int J Antimicrob Agents ; 26(1): 33-7, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15953709

RESUMO

Fifty-three Salmonella enterica group C isolates obtained from various human samples (47 stool, 4 blood and 2 urine) in ten provinces of Turkey between 1 July 2000 and 30 June 2002 were serotyped and resistance to antimicrobials was investigated by agar dilution tests. The isolates were identified as S. Choleraesuis (11), S. Hadar (7), S. Irumu (4), S. Virchow (3), S. Tallahassee (3), S. Paratyphi C (2), S. Braenderup (2), S. Othmarschen (2), S. Menston (2), S. Concord (2), S. Infantis (2), S. Kottbus (2), S. Edinburg (1), S. Oranienburg (1), S. Muenchen (1) and S. Malmoe (1). Antimicrobial resistance rates of S. enterica groups C1 and C2 were high for ampicillin (26% and 60%, respectively), amoxicillin/clavulanic acid (11% and 40%), chloramphenicol (16% and 27%) and tetracycline (3% and 40%). The percentages of strains sensitive to all antimicrobials were 58% and 33%, respectively. Multiresistance was not observed in group C1 isolates, but the rate of multiresistant isolates was 13% in group C2. The rate of decreased ciprofloxacin susceptibility (CipL) was 61% in serogroup C1 and 20% in serogroup C2. These results indicated that S. enterica group C infections in humans were not infrequent in Turkey and that multiple antimicrobial resistance was common within these strains.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Salmonella enterica/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Infecções por Salmonella/epidemiologia , Infecções por Salmonella/microbiologia , Salmonella enterica/classificação , Turquia/epidemiologia
13.
J Chemother ; 17(1): 31-5, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15828441

RESUMO

Macrolide resistance in Streptococcus pneumoniae is usually caused by the presence of the erm(B) or mef(A) resistance determinants. The aim of the present study was to identify the predominant macrolide resistance mechanisms among erythromycin-resistant S. pneumoniae isolated in a university hospital, Ankara, Turkey. A total of 669 S. pneumoniae strains were isolated from clinical specimens of patients admitted to the hospital between 1994--2002. The minimum inhibitory concentrations (MICs) of penicillin G, erythromycin A and clindamycin were determined by the agar dilution method according to NCCLS guidelines. Ninety-one (13.6%) isolates were resistant to erythromycin. Erythromycin-resistant isolates were examined for their macrolide resistance phenotypes by a triple disc diffusion assay. It assigned 57 (62.6%) of the 91 erythromycin-resistant pneumococci to cMLS(B) phenotype, 19 (20.9%) to iMLS(B) phenotype and 15 (16.5%) to M phenotype. All erythromycin-resistant isolates were analyzed by PCR for the presence of erm(B) and mef(A) determinants. The isolates were characterized for the underlying resistance genotype, with 83.5% having erm(B), 16.5% having the mef(A) genotypes. This study provides further evidence of the dissemination of macrolide-resistant mutants in pneumococci as the use of new, long-acting macrolides increases. This is the first article about MLS(B) resistance phenotypes and genotypes of S. pneumoniae from Turkey and it emphasizes the need for future epidemiological monitoring of macrolide-resistant pneumococci.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Streptococcus pneumoniae/efeitos dos fármacos , Clindamicina/farmacologia , Eritromicina/farmacologia , Genótipo , Hospitais Universitários , Humanos , Testes de Sensibilidade Microbiana , Penicilina G/farmacologia , Fenótipo , Infecções Pneumocócicas/epidemiologia , Infecções Pneumocócicas/microbiologia , Streptococcus pneumoniae/genética , Streptococcus pneumoniae/isolamento & purificação , Turquia/epidemiologia
14.
Arch Neurol ; 44(5): 551-4, 1987 May.
Artigo em Inglês | MEDLINE | ID: mdl-3579669

RESUMO

The absence of cerebral blood flow is a valuable adjunct confirming clinical criteria of brain death. However, current methods to confirm absent cerebral blood flow have problems that limit their clinical use. We reviewed cerebral blood flow data obtained with xenon-enhanced computed tomography in nine patients who were being evaluated for brain death. In eight patients who met clinical criteria for brain death, mean cerebral blood flow was 1.6 +/- 2.0 mL X 100 g X min. This value was within the range of error inherent in the method, and therefore represented absent flow. In a patient with persistent respiratory efforts, flow values compatible with absent flow were obtained in the supratentorial compartment, while mean flows as high as 24 mL X 100 g X min were measured in selected regions of interest in the infratentorial compartment, correlating with the clinical evidence of residual function of the brain stem. Xenon-enhanced computed tomography may be a useful test to confirm the absence of cerebral blood flow in patients being evaluated for brain death.


Assuntos
Morte Encefálica , Circulação Cerebrovascular , Tomografia Computadorizada por Raios X/métodos , Xenônio , Adulto , Feminino , Humanos , Lactente , Masculino
15.
Int J Radiat Oncol Biol Phys ; 17(6): 1337-40, 1989 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-2513293

RESUMO

Portal verification images were generated by the photon contamination in electron beams produced by a linear accelerator during treatment of patients receiving high-energy electron radiation therapy. Both conventional and storage phosphor methods yielded projection radiographs in which anatomy of the irradiated and surrounding tissue was demonstrated. Exposed phantoms were used to confirm that the images represent a true projection of the radiation field. A preliminary series of 22 cases was evaluated by two radiotherapists and judged subjectively to be of clinical value. Geometric error, or more importantly, the lack thereof, during high-energy electron treatments was easily confirmed with this method. In three cases, the treatment protocol was corrected based on the images obtained. Because the readout process of storage phosphor images allows for gain adjustments and post-processing, the images obtained with this method were found to delineate anatomy in the treated and surrounding tissues somewhat more consistently than could conventional images.


Assuntos
Elétrons , Medições Luminescentes , Radioterapia de Alta Energia , Humanos , Aceleradores de Partículas , Tecnologia Radiológica
16.
Invest Radiol ; 31(3): 146-53, 1996 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8675422

RESUMO

RATIONALE AND OBJECTIVES: A simple and effective computerized detection scheme was developed to identify suspicious mass regions in digitized mammograms. METHODS: This method identifies a maximum of five suspicious mass regions per image and was tested with a database of 510 images, including 162 verified masses. It includes a series of five rule-based processes that select one region with each of the following characteristics: 1) a global minimum of optical density in a smoothed image; 2) a local minimum of optical density in the original image; 3) a local minimum of optical density in a filtered image; 4) a small "mass" of low contrast; and 5) a small "mass" of high contrast. RESULTS: This multi-stage process achieved a sensitivity of 95% while limiting false-positive detection rates to below an average of two per image. CONCLUSION: Because this method limits the initial number of suspicious mass regions while retaining high sensitivity, it may be applicable to clinically usable computer-aided diagnosis schemes.


Assuntos
Processamento de Imagem Assistida por Computador , Mamografia/métodos , Intensificação de Imagem Radiográfica , Doenças Mamárias/diagnóstico por imagem , Neoplasias da Mama/diagnóstico por imagem , Diagnóstico por Computador , Reações Falso-Positivas , Feminino , Humanos , Sensibilidade e Especificidade
17.
Invest Radiol ; 29(6): 636-42, 1994 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8088973

RESUMO

INTRODUCTION: With ever-increasing interest in bedside radiography using digital imaging techniques, one question often asked is whether and which antiscatter grid should be used to reduce the effects of scattered radiation. In this article, the authors quantitatively analyze and compare images obtained with a flexible circular hole (FCH) grid, a conventional 6:1 focused grid, or without a grid. METHODS: Scatter-to-primary ratios (SPRs), contrast signals, and contrast-to-noise ratios (CNRs) were measured for fixed patient exposure and were compared at various locations in the images of an anthropomorphic chest phantom. RESULTS: Although both grids resulted in greater contrast signals, a significant improvement of the CNR was achieved only in the upper and middle mediastinum regions when the conventional grid was used. With the FCH grid, the CNR is degraded at most locations in the chest image. DISCUSSION: Our results indicate that at fixed exposure level, the use of either grid yields only marginal improvement, at best, in bedside digital chest radiography.


Assuntos
Intensificação de Imagem Radiográfica/instrumentação , Radiografia Torácica/instrumentação , Humanos , Modelos Estruturais , Espalhamento de Radiação , Tecnologia Radiológica
18.
Invest Radiol ; 27(2): 169-72, 1992 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-1601610

RESUMO

Virtually all receiver operating characteristic (ROC) studies of medical imaging methods have involved data collected on a discrete confidence-rating scale, though in principle ROC studies can be conducted with either discrete or continuous scales. Continuous scales provide potential advantages in medical applications of ROC analysis, but the possible dependence of ROC results on the kind of scale used in an observer-performance experiment has not been investigated empirically. The authors conducted a multi-observer ROC study in which radiologists read abdominal computed tomography (CT) examination results displayed on a workstation with a high-resolution video monitor. Ninety-five examinations were evaluated by five radiologists who reported their confidence concerning the presence of abdominal masses on a conventional five-category discrete scale and, in a separate reading session, on a continuous subjective-probability scale. ROC analysis showed no statistically significant difference between the detection accuracies (Az) achieved with the two scales by any reader. Accuracies averaged over all readers were identical with the two scales. The results of this study suggest that discrete or continuous scales often can be used interchangeably in image-evaluation studies. However, the authors recommend continuous scales for routine use in radiologic ROC studies because of their potential advantages in some situations.


Assuntos
Diagnóstico por Imagem/estatística & dados numéricos , Intervalos de Confiança , Humanos , Curva ROC , Interpretação de Imagem Radiográfica Assistida por Computador , Radiografia Abdominal , Tomografia Computadorizada por Raios X/estatística & dados numéricos
19.
Invest Radiol ; 31(9): 563-8, 1996 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8877493

RESUMO

RATIONALE AND OBJECTIVES: The authors assess the robustness of a computer-aided diagnosis (CAD) scheme with five rule-based stages to identify regions suspicious for mass in digitized mammograms. METHODS: With a database of 428 mammograms, 234 of which had not been analyzed by this scheme before, the authors evaluated the performance robustness of their CAD scheme. The following four issues were investigated to assess the variability of the scheme's performance due to: (1) the maximum permissible number of "masses" detected at each stage; (2) exclusion of selected individual rule-based stages; (3) added image noise; and (4) repeated digitizations of the same image. RESULTS: Enabling the CAD scheme to select a maximum of two suspicious mass regions at any one stage increased sensitivity by as much as 4% (from 93% to 97%), but it increased the false-positive detection rate by as much as 1.2 per image (from 1.7 to 2.9). Eliminating any individual stage decreased sensitivity by as much as 6%, but this reduced the false-positive detection rate by as much as 0.4 per image (from 1.7 to 1.3). The addition of reasonable noise levels decreased sensitivity by as much as 4% without substantially affecting the false-positive detections. Repeated digitizations of selected images demonstrated a scheme sensitivity of 93% +/- 1.8% with more than a 90% overlap of the false-positive regions. CONCLUSIONS: The results of this preliminary study clearly indicate that this scheme is reasonably robust to the variables investigated here.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Diagnóstico por Computador , Mamografia/métodos , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Intensificação de Imagem Radiográfica , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
20.
Invest Radiol ; 25(7): 835-7, 1990 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-2391200

RESUMO

Maximum likelihood estimation, assuming a binormal model, has been used extensively to estimate the area under receiver operating characteristic (ROC) curves and thus provide an index of diagnostic accuracy for the comparison of two imaging systems. However, in some instances, a degenerate data set results in a fitted ROC curve of inappropriate shape. In those instances, a nonparametric Wilcoxon statistic may be used to compare the areas under two ROC curves. Simulation of this approach indicates that the procedure has relatively high statistical power and its use in specific degenerate data sets shows its applications potential.


Assuntos
Interpretação Estatística de Dados , Diagnóstico por Imagem/estatística & dados numéricos , Curva ROC , Humanos
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