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1.
Phys Rev Lett ; 129(8): 083602, 2022 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-36053693

RESUMEN

Exceptional points (EPs), singularities of non-Hermitian physics where complex spectral resonances degenerate, are one of the most exotic features of nonequilibrium open systems with unique properties. For instance, the emission rate of quantum emitters placed near resonators with EPs is enhanced (compared to the free-space emission rate) by a factor that scales quadratically with the resonance quality factor. Here, we verify the theory of spontaneous emission at EPs by measuring photoluminescence from photonic-crystal slabs that are embedded with a high-quantum-yield active material. While our experimental results verify the theoretically predicted enhancement, they also highlight the practical limitations on the enhancement due to material loss. Our designed structures can be used in applications that require enhanced and controlled emission, such as quantum sensing and imaging.

2.
J Hum Hypertens ; 29(4): 247-53, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25273858

RESUMEN

Germany was reported to have higher blood pressure (BP) and lower awareness, treatment and control of BP than other western countries based on 1998 data. BP distribution and hypertension management were examined for 1998 and 2008-11 in 7108 adult participants of the German National Health Interview and Examination Survey 1998 (GNHIES98) and in 7095 adult participants the German Health Interview and Examination Survey for Adults 2008-11 (DEGS1) aged 18-79 years. Age- and sex-standardized mean systolic BP (SBP) dropped from 129.0 to 124.1 mm Hg (women 127.3-120.8, men 130.7-127.4), mean diastolic BP (DBP) from 78.3 to 73.2 mm Hg (women 78.0-71.2, men 78.5-75.3). Mean SBP and DBP decreased most in treated hypertensives but were also lower in participants without hypertension. The overall prevalence of hypertension, including controlled hypertension, remained almost unchanged (30% vs 32%). Uncontrolled hypertension (BP⩾140/90 mm Hg) decreased from 23% to 15% (women 22-13%, men 24-18%). Among hypertensives, awareness increased from 69% to 82% (women 74-87%, men 65-78%), treatment increased from 55% to 72% (women 62-79%, men 48-65%) and control increased from 23% to 51% (women 25-58%, men 20-45%). However, men aged 18-29 years had an opposite trend with 1.5 mm Hg higher SBP and increased prevalence of hypertension, which was mostly uncontrolled. These findings suggest that BP has decreased substantially in Germany, while leaving a persistent gender gap in management and room for further improvement of prevention and treatment, particularly in men.


Asunto(s)
Antihipertensivos/uso terapéutico , Actitud del Personal de Salud , Concienciación , Presión Sanguínea/efectos de los fármacos , Conocimientos, Actitudes y Práctica en Salud , Hipertensión/tratamiento farmacológico , Hipertensión/epidemiología , Pautas de la Práctica en Medicina/tendencias , Adolescente , Adulto , Factores de Edad , Anciano , Estudios Transversales , Femenino , Alemania/epidemiología , Encuestas de Atención de la Salud , Disparidades en el Estado de Salud , Disparidades en Atención de Salud , Humanos , Hipertensión/diagnóstico , Hipertensión/fisiopatología , Masculino , Persona de Mediana Edad , Prevalencia , Factores Sexuales , Factores de Tiempo , Resultado del Tratamiento , Adulto Joven
3.
Phys Rev Lett ; 113(5): 057402, 2014 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-25126935

RESUMEN

At low temperature the photoluminescence of single-wall carbon nanotubes show a large variety of spectral profiles ranging from ultranarrow lines in suspended nanotubes to broad and asymmetrical line shapes that puzzle the current interpretation in terms of exciton-phonon coupling. Here, we present a complete set of photoluminescence profiles in matrix embedded nanotubes including unprecedented narrow emission lines. We demonstrate that the diversity of the low-temperature luminescence profiles in nanotubes originates in tiny modifications of their low-energy acoustic phonon modes. When low-energy modes are locally suppressed, a sharp photoluminescence line as narrow as 0.7 meV is restored. Furthermore, multipeak luminescence profiles with specific temperature dependence show the presence of confined phonon modes.

4.
Trop Med Int Health ; 18(3): 377-84, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23294376

RESUMEN

OBJECTIVES: In 2010-2011, recent graduates (2008 or earlier) of the Masters in International Health (MIH) (as offered by over 30 universities and institutions collaborating in the tropEd network) were surveyed. We aimed to examine whether the competencies gained proved appropriate for alumni's current positions and to develop the programme according to alumni's needs. METHODS: An online questionnaire was sent to 327 alumni. One hundred and seventy-seven responded and 99 met the inclusion criteria. We calculated frequency distributions of the answers and performed a bivariate analysis of certain variables. RESULTS: Alumni feel confident in all areas covered by the MIH. Most competencies acquired are perceived as essential or very relevant to their current position. Many respondents (77%) changed jobs after graduation, mostly from curative care to public health. More African and Asian alumni work in their country of origin (66% and 63%, respectively) than alumni from other continents (42%). The respondents had mostly worked at a national or provincial level, but after graduating mostly worked at international or national level. Alumni said that the network's mobility and flexibility had important advantages and disadvantages. CONCLUSIONS: This is the first alumni survey of the MIH programme offered through the international network tropEd. The results suggest that competencies gained by graduates are relevant for their current careers. We recommend offering better guidance to students planning modules and to improve administration.


Asunto(s)
Educación de Postgrado , Educación en Salud Pública Profesional , Salud Global , Adulto , Competencia Clínica , Femenino , Encuestas de Atención de la Salud , Humanos , Masculino , Ubicación de la Práctica Profesional , Evaluación de Programas y Proyectos de Salud , Clima Tropical
5.
Phys Rev Lett ; 108(5): 057401, 2012 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-22400960

RESUMEN

We report on the resonant emission in coherently driven single semiconductor quantum dots. We demonstrate that an ultraweak nonresonant laser acts as an optical gate for the quantum dot resonant response. We show that the gate laser suppresses Coulomb blockade at the origin of a resonant emission quenching, and that the optically gated quantum dots systematically behave as ideal two-level systems in both regimes of coherent and incoherent resonant emission.

6.
Artículo en Alemán | MEDLINE | ID: mdl-21800246

RESUMEN

Multimorbidity is defined as the coexistence of two or more chronic diseases. However, this complex health status, which primarily affects elderly, is still insufficiently understood. One reason is the underrepresentation of older, multimorbid people in studies. Another reason is that there is no agreement on the number and type of diseases, which have to be considered in the assessment of multimorbidity. Therefore, this article provides an overview on the status quo of research on multimorbidity indices and describes in detail, what kind of methodological challenges have to be faced regarding the development of a standardized index. Finally, recommendations are made for criteria, which can be used for the selection of diseases relevant for multimorbidity.


Asunto(s)
Enfermedad Crónica/epidemiología , Comorbilidad , Encuestas Epidemiológicas/métodos , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Estudios Transversales , Femenino , Alemania , Humanos , Masculino , Persona de Mediana Edad , Factores Sexuales , Adulto Joven
7.
Z Gerontol Geriatr ; 44(2): 115-20, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21161244

RESUMEN

BACKGROUND: Multimorbidity, the concurrent manifestation or presence of multiple chronic conditions, poses huge challenges to affected patients, their relatives, physicians, and practitioners alike. The growing number of affected persons and the complexity of their needs places just as much of a burden on the health care system as does the plethora of often poorly coordinated interventions. The Chronic Care Model developed for different chronic diseases is suited for improving medical care. The PRISCUS research consortium was established to create the prerequisites for a new care model for multimorbid, elderly patients oriented along those lines. METHODS: The research consortium utilizes data gathered in a large-scale epidemiological study on peripheral arterial disease (getABI study) and from the Dortmund and Münster stroke registries, by extracting epidemiologic and health economic data, quality-of-life parameters, and data on the extent and quality of medication. Additional projects evaluate the implementation of a multidimensional geriatric assessment in primary care, the functional consequences of multimorbidity in stroke patients along with options for prevention and therapy afforded by physical activity. Systematic reviews of the literature are used to describe quality of life and patient preferences. Experts will work on an initial draft treatment standard for patients with multimorbidity and a list of potentially inappropriate medication for the elderly in Germany. CONCLUSION: The results of the PRISCUS research consortium will enable an epidemiologic characterization and description of consequences of multimorbidity, while illustrating new approaches towards prevention, diagnosis, and management of multimorbid patients. With this, some prerequisites for a new health care model for patients with multimorbidity comparable to the Chronic Care Model will be fulfilled.


Asunto(s)
Enfermedad Crítica/rehabilitación , Atención a la Salud/organización & administración , Servicios de Salud para Ancianos/organización & administración , Modelos Organizacionales , Comorbilidad , Alemania , Humanos
8.
Artículo en Alemán | MEDLINE | ID: mdl-20354668

RESUMEN

Scientific studies often exclude institutionalized people. Thus, there is insufficient information about the percentage of older people, who are living in nursing homes. Furthermore, when they move to a care facility, it is questionable whether their new address is officially registered. This is a major prerequisite for their accessibility in studies. By using a standardized questionnaire, the number of nursing home residents in Dortmund was anonymously recorded. Their percentage of the population was determined separately for gender and age. This information was then compared to the official registry. Of those 65 years and older, 5.0% of women and 1.8% of men lived in long-term nursing homes. The percentage of institutionalized people of both genders increases with age; however, the correlation is stronger for women. Overall, 79.5% of the residents are female. To some extent, there were large differences between the information from the care facilities and the official registry concerning the number of residents.


Asunto(s)
Enfermedad Crónica/epidemiología , Personas con Discapacidad/estadística & datos numéricos , Hogares para Ancianos/estadística & datos numéricos , Casas de Salud/estadística & datos numéricos , Población Urbana/estadística & datos numéricos , Factores de Edad , Anciano , Anciano de 80 o más Años , Planificación en Salud Comunitaria , Estudios Transversales , Femenino , Alemania , Humanos , Masculino , Vigilancia de la Población , Sistema de Registros , Factores Sexuales , Revisión de Utilización de Recursos
9.
Artículo en Alemán | MEDLINE | ID: mdl-18696145

RESUMEN

Starting with the 19th century, the following article provides a short overview on the reform history of health care in Germany. The focus is on the influence of predominant societal values, structures and medical concepts as well as pressing social problems on the development of the German social insurance system. As a consequence of industrialization, the 19th century was shaped by the impoverishment of a large part of the population. Domestically pressured by the growing organization of the workforce, the first nationwide health insurance was founded in 1883. After this, national associations of physicians were established to counterbalance the dominating position of the health insurance companies. After the abolition of self-government during the period of National Socialism, health politics in western Germany after 1945 was shaped by medical practices run by individual physicians and free self-government by organizations and corporations. Since the 1980s, on the one hand, the self-determination and responsibility of patients has been growing. On the other hand, health care is increasingly influenced by the standardization of medical processes and products and evidence based decision-making processes. Today the health care sector is perceived as a stand-alone economic sector, in which the patient as a consumer is becoming a central figure. Overall it is outlined that the health care sector was less influenced by the conceptions of medical and other health care professionals, but it was shaped by the economic, political and societal context and the resultant concepts. This is still valid today.


Asunto(s)
Atención a la Salud/historia , Reforma de la Atención de Salud/historia , Medicina Social/historia , Alemania , Historia del Siglo XIX , Historia del Siglo XX , Historia del Siglo XXI
10.
Nature ; 440(7086): 904-7, 2006 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-16612377

RESUMEN

Optical parametric oscillation is a nonlinear process that enables coherent generation of 'signal' and 'idler' waves, shifted in frequency from the pump wave. Efficient parametric conversion is the paradigm for the generation of twin or entangled photons for quantum optics applications such as quantum cryptography, or for the generation of new frequencies in spectral domains not accessible by existing devices. Rapid development in the field of quantum information requires monolithic, alignment-free sources that enable efficient coupling into optical fibres and possibly electrical injection. During the past decade, much effort has been devoted to the development of integrated devices for quantum information and to the realization of all-semiconductor parametric oscillators. Nevertheless, at present optical parametric oscillators typically rely on nonlinear crystals placed into complex external cavities, and pumped by powerful external lasers. Long interaction lengths are typically required and the phase mismatch between the parametric waves propagating at different velocities results in poor parametric conversion efficiencies. Here we report the demonstration of parametric oscillation in a monolithic semiconductor triple microcavity with signal, pump and idler waves propagating along the vertical direction of the nanostructure. Alternatively, signal and idler beams can also be collected at finite angles, allowing the generation of entangled photon pairs. The pump threshold intensity is low enough to envisage the realization of an all-semiconductor electrically pumped micro-parametric oscillator.

11.
Am J Surg ; 182(3): 243-9, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11587685

RESUMEN

BACKGROUND: Multimodality staging is recommended in patients with periampullary tumors to optimize preoperative determination of resectability. We investigated the potency of currently used diagnostic procedures in order to determine resectability. METHODS: Ninety-five consecutive patients with periampullary tumors prehospitally staged resectable underwent preoperative diagnostic tests: helical-computed tomography (CT) with maximum intensity projection of arterial vessels (MIP), magnetic resonance imaging (MRI), magnetic resonance cholangiopancreaticography (MRCP), endoscopic ultrasonography (EUS), endoscopic retrograde cholangiopancreaticography (ERCP), digital subtraction angiography (DSA), and positron emission tomography (PET). Diagnoses were verified by surgery and histopathology. RESULTS: In 45 patients with benign and 50 patients with malignant periampullary tumors sensitivity for tumor diagnosis was 89% to 96% in CT, MRI, EUS, and PET. Small tumors were best diagnosed by EUS (100%). Diagnosis of malignancy was made with 85% (EUS), 83% (CT), 82% (PET), and 72% (MRI) accuracy. Arterial vessel infiltration was best predicted by CT/MIP with an accuracy of 85%. For venous vessel infiltration MRI reached 85% accuracy. Accuracy rates for local nonresectability were 93% (EUS), 92% (MRI), and 90% (CT). Two and 4 of 8 patients with distant metastases were identified by CT and PET, respectively. The correct diagnosis of malignancy and determination of resectability was made by CT in 71% and by MRI in 70%. Biliary stenting reduced accuracy of CT diagnosis of malignancy from 88% to 73%. CONCLUSIONS: CT obtained before stenting was the single most useful test, providing correct diagnosis in 88% and resectability in 71% of patients. If no tumor is depicted in CT, EUS should be added. Uncertain venous vessel infiltration can be verified by MRI or EUS. Angiography should no longer be a routine diagnostic procedure. Equivocal tumors or possible metastasis may be further examined with PET.


Asunto(s)
Neoplasias del Conducto Colédoco/diagnóstico , Neoplasias del Conducto Colédoco/cirugía , Neoplasias Duodenales/diagnóstico , Neoplasias Duodenales/cirugía , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/cirugía , Ampolla Hepatopancreática , Angiografía de Substracción Digital , Colangiopancreatografia Retrógrada Endoscópica , Endosonografía , Humanos , Imagen por Resonancia Magnética , Cuidados Preoperatorios , Sensibilidad y Especificidad , Tomografía Computarizada de Emisión , Tomografía Computarizada por Rayos X
12.
Obstet Gynecol ; 98(3): 427-33, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11530124

RESUMEN

OBJECTIVE: To assess the impact of antihypertensive therapy initiated early in pregnancy on maternal and fetal outcomes. METHODS: A retrospective review of patients treated in early pregnancy with atenolol was conducted. Therapy was directed by measurements of cardiac output. Fetal growth was analyzed with reference to prior pregnancy outcome, treatment inconsistent with standards present at the end of the study period, and year of treatment. Data were analyzed by paired and unpaired t-test, analysis of variance for multiple comparisons, and linear regression. RESULTS: Two hundred thirty-five pregnancies at risk for preeclampsia were studied. Ten percent (n = 22) received additional therapy with furosemide; 20% (n = 48) with hydralazine. Six and one half percent had treatment inconsistencies. Fifty-five percent had greater than 100 mg of proteinuria at baseline. One patient developed severe preeclampsia. Only 2.1% delivered before 32 weeks; 4.7% delivered before 34 weeks. Low percentile birth weight was strongly associated with a prior pregnancy with intrauterine growth restriction (P = 0.001), treatment inconsistency (P <.001), and a pregnancy earlier in our treatment experience (P <.001). Percentile birth weight increased from the 20th at the beginning of the study period to the 40th by the end (P = 0.002). CONCLUSION: Early intervention with antihypertensive therapy was associated with a low rate of severe maternal hypertension and preterm delivery. The failure to adjust therapy in response to an excessive fall in cardiac output or increase in vascular resistance was associated with reduced fetal growth.


Asunto(s)
Antihipertensivos/uso terapéutico , Atenolol/uso terapéutico , Desarrollo Embrionario y Fetal/efectos de los fármacos , Complicaciones Cardiovasculares del Embarazo/tratamiento farmacológico , Resultado del Embarazo , Adulto , Gasto Cardíaco , Desarrollo Embrionario y Fetal/fisiología , Femenino , Edad Gestacional , Hemodinámica , Humanos , Trabajo de Parto Prematuro/etiología , Embarazo , Complicaciones Cardiovasculares del Embarazo/fisiopatología , Estudios Retrospectivos
13.
J Nucl Med ; 42(5): 721-5, 2001 May.
Artículo en Inglés | MEDLINE | ID: mdl-11337566

RESUMEN

UNLABELLED: PET with 18F-FDG has been shown to be useful in the detection and staging of pancreatic cancer. However, whether FDG uptake is dependent on proliferative activity is still unclear. The aim of this prospective study was to evaluate a probable correlation between FDG uptake and proliferative activity in benign and malignant pancreatic tumors. METHODS: Our series consisted of 23 patients with pancreatic cancer and 9 patients with chronic active pancreatitis (CAP). FDG PET was performed within 2 wk before surgery, and standardized uptake values (SUVs) were calculated for benign and malignant pancreatic tumors. Patients were selected when focally increased FDG uptake in previously known pancreatic tumors was present. Proliferation fraction was measured in tissue specimens using the anti-Ki-67 antibody MIB-1. A computer-assisted imaging system was used for quantification of nuclear Ki-67 immunostaining. Immunohistochemical findings were correlated to SUVS: RESULTS: Pancreatic cancer showed both intense nuclear staining of Ki-67 (39% +/- 16%) and high FDG uptake (SUV = 3.6 +/- 1.6). However, no significant correlation was found between in vivo FDG uptake and Ki-67 immunoreactivity (P = 0.65). By contrast, Ki-67 nuclear staining was significantly lower (3.8% +/- 2.7%, P < 0.05) in CAP, whereas FDG uptake was in the same range as for pancreatic cancer (SUV = 3.5 +/- 1.8). CONCLUSION: FDG uptake did not correlate with proliferative activity in pancreatic cancer. Proliferative activity was tenfold higher in malignant pancreatic tumors than in benign tumors associated with CAP, whereas FDG uptake in vivo did not differ significantly. Thus, a PET tracer indicating cellular proliferation should better differentiate between cancer and inflammatory lesions than do metabolic markers such as FDG.


Asunto(s)
Carcinoma/diagnóstico por imagen , Fluorodesoxiglucosa F18 , Antígeno Ki-67/análisis , Neoplasias Pancreáticas/diagnóstico por imagen , Radiofármacos , Tomografía Computarizada de Emisión , Adenocarcinoma/química , Adenocarcinoma/diagnóstico por imagen , Adenocarcinoma/patología , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma/química , Carcinoma/patología , División Celular , Núcleo Celular/química , Enfermedad Crónica , Femenino , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Neoplasias Pancreáticas/química , Neoplasias Pancreáticas/patología , Pancreatitis/diagnóstico por imagen , Estudios Prospectivos
14.
Obstet Gynecol ; 96(6): 956-61, 2000 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11084185

RESUMEN

OBJECTIVE: To assess the risks and potential benefits of low-dose angiotensin-converting enzyme (ACE) inhibitor treatment in pregnancies complicated by severe hypertension. METHODS: A retrospective review of pregnant women treated with ACE inhibitors was conducted. Hemodynamics before and after treatment were assessed by using Doppler technique to measure cardiac output. Data were analyzed by using the Wilcoxon signed-rank test. Maternal and neonatal outcomes were assessed by chart review and phone interview. RESULTS: Ten pregnancies were identified in which ACE inhibitor therapy was initiated in pregnancy for severe, unresponsive vasoconstricted hypertension; three were complicated by severe chronic hypertension, 4 by renal insufficiency, and 3 by severe preeclampsia. Treatment was limited to a low-dose, short-acting ACE inhibitor (captopril, 12.5 to 25 mg/day). Treatment was associated with an increase in cardiac output from 5.7 +/- 1.5 L/minute to 7.4 +/- 1.4 L/minute (P<.01) and a reduction in total peripheral resistance from 1770 +/- 670 to 1222 +/- 271 dyne. sec. cm(-5) (P =.005). No fetal or neonatal complications were observed. The probability of observing one or more adverse neonatal outcome in this sample, based on an assumed true risk of 5% and 10%, was calculated to be 12% and 50%, respectively. CONCLUSION: Low-dose captopril therapy was associated with improvement in maternal hemodynamics and, in cases complicated by severe hypertension and renal insufficiency, successful continuation of pregnancy. Fetal and neonatal complications were not experienced, but complication rates of 5-10% could have been missed because of the small number of exposed pregnancies.


Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/administración & dosificación , Captopril/administración & dosificación , Hipertensión/tratamiento farmacológico , Preeclampsia/tratamiento farmacológico , Complicaciones del Embarazo/tratamiento farmacológico , Adulto , Inhibidores de la Enzima Convertidora de Angiotensina/efectos adversos , Captopril/efectos adversos , Gasto Cardíaco/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Esquema de Medicación , Femenino , Edad Gestacional , Humanos , Hipertensión/etiología , Preeclampsia/etiología , Embarazo , Complicaciones del Embarazo/etiología , Estudios Retrospectivos , Resistencia Vascular/efectos de los fármacos
15.
J Nucl Med ; 41(10): 1695-701, 2000 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-11038000

RESUMEN

UNLABELLED: Clinical diagnosis of skeletal tumors can be difficult, because such lesions compose a large, heterogeneous group of entities with different biologic behaviors. The aim of this prospective study was to assess the value of PET in grading tumors and tumorlike lesions of bone. METHODS: Two hundred two patients with suspected primary bone tumors were investigated using FDG PET. Uptake of FDG was evaluated semiquantitatively by determining the tumor-to-background ratio (T/B). All patients underwent biopsy, resulting in the histologic detection of 70 high-grade sarcomas, 21 low-grade sarcomas, 40 benign tumors, 47 tumorlike lesions, 6 osseous lymphomas, 6 plasmacytomas, and 12 metastases of an unknown primary tumor. RESULTS: All lesions, with the exception of 3 benign tumors, were detected by increased FDG uptake. Although sarcomas showed significantly higher T/Bs than did latent or active benign lesions (P < 0.001), aggressive benign lesions could not be distinguished from sarcomas. Using a T/B cutoff level for malignancy of 3.0, the sensitivity of FDG PET was 93.0%, the specificity was 66.7%, and the accuracy was 81.7%. CONCLUSION: FDG PET provides a promising tool for estimating the biologic activity of skeletal lesions, implicating consequences for the choice of surgical strategy.


Asunto(s)
Neoplasias Óseas/diagnóstico por imagen , Fluorodesoxiglucosa F18 , Radiofármacos , Tomografía Computarizada de Emisión , Adulto , Huesos/diagnóstico por imagen , Huesos/metabolismo , Femenino , Fluorodesoxiglucosa F18/farmacocinética , Humanos , Masculino , Valor Predictivo de las Pruebas , Estudios Prospectivos , Radiofármacos/farmacocinética , Sarcoma/diagnóstico por imagen , Sensibilidad y Especificidad
16.
Pancreas ; 20(2): 109-16, 2000 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10707924

RESUMEN

The aim of this study was to determine the value and limitations of 18F-fluorodeoxyglucose (FDG)-position-emission tomography (PET) for differentiating benign and malignant pancreatic disease and for staging malignant disease. One hundred fifty-nine patients with 89 malignant and 70 benign pancreatic lesions all received PET, computed tomography (CT), and endoscopic retrograde cholangiopancreatography (ERCP) before pancreatic surgery. The original reports were compared for all patients (group I; N = 159), for a subgroup that neither had fasting plasma glucose levels > or =130 mg/dL or known elevated levels of C-reactive protein ([CRP], group II; n = 123), and for the remaining patients (group III; n = 36). For group I, accuracy values (areas under receiver operating characteristic [ROC] curves) for differentiation of benign/malignant masses were 0.86 (PET), 0.93 (ERCP), 0.82 (CT), and 0.95 for ERCP + PET (N = 159). For group II, ROC areas increased to 0.92 (PET), 0.94 (p < 0.05; n = 123) (ERCP), 0.82 (CT), 0.97 (p < 0.05; n = 123) (ERCP + PET). The results for group III were 0.71 (PET), 0.81 (CT), and 0.93 (ERCP); (n = 36). With 54 patients of group II that either had contradictory or indeterminate/technically unsuccessful CT/ERCP, PET was correct in 43 patients (84%). Sensitivity/specificity for lymph node staging was 49%/63%, respectively. For patients with hepatic metastasis, PET was 70% sensitive and 95% specific, missing some metastasis that were <1 cm. PET detected peritoneal metastasis in 25% of patients, missing poorly localized microscopic spread. For selected patients who have indeterminate pancreatic masses but no hyperglycemia or serologic evidence of active inflammation, FDG-PET is an independent functional assay that significantly adds to the diagnostic accuracy of ERCP and CT in the differentiation of benign and malignant pancreatic disease. PET can reliably detect hepatic, peritoneal, and other distant metastases that are > or =1 cm.


Asunto(s)
Fluorodesoxiglucosa F18 , Enfermedades Pancreáticas/diagnóstico por imagen , Radiofármacos , Tomografía Computarizada de Emisión , Área Bajo la Curva , Glucemia/análisis , Colangiopancreatografia Retrógrada Endoscópica , Humanos , Neoplasias Hepáticas/diagnóstico por imagen , Neoplasias Hepáticas/secundario , Metástasis Linfática/diagnóstico , Metástasis Linfática/diagnóstico por imagen , Persona de Mediana Edad , Enfermedades Pancreáticas/diagnóstico , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/diagnóstico por imagen , Cuidados Preoperatorios , Curva ROC , Sensibilidad y Especificidad , Tomografía Computarizada por Rayos X
17.
J Clin Oncol ; 17(8): 2381-9, 1999 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-10561300

RESUMEN

PURPOSE: Previous studies have shown that bone metastases are revealed by magnetic resonance imaging (MRI) or bone marrow scintigraphy several months before they are visible by conventional bone scintigraphy (BS). We present a new approach for detecting bone metastases in patients with breast cancer. We compared findings obtained with fluoride ion (F-18) and positron emission tomography (PET) with those obtained with conventional BS. PATIENTS AND METHODS: Thirty-four breast cancer patients were prospectively examined using F-18-PET and conventional BS. F-18-PET and BS were performed within 3 weeks of each other. Metastatic bone disease was previously known to be present in six patients and was suspected (bone pain or increasing levels of tumor markers, Ca(2+), alkaline phosphatase) in 28 patients. Both imaging modalities were compared by patient-by-patient analysis and lesion-by-lesion analysis, using a five-point scale for receiver operating characteristic (ROC) curve analysis. A panel of reference methods was used, including MRI (28 patients), planar x-ray (17 patients), and spiral computed tomography (four patients). RESULTS: With F-18-PET, 64 bone metastases were detected in 17 patients. Only 29 metastases were detected in 11 patients with BS. As a result of F-18-PET imaging, clinical management was changed in four patients (11.7%). For F-18-PET, the area under the ROC curve was 0.99 on a lesion basis (for BS, it was 0.74; P <.05) and 1.00 on a patient basis (for BS, it was 0.82; P <.05). CONCLUSION: F-18-PET demonstrates a very early bone reaction when small bone marrow metastases are present, allowing accurate detection of breast cancer bone metastases. This accurate detection has a significant effect on clinical management, compared with the effect on management brought about by detection with conventional BS.


Asunto(s)
Neoplasias Óseas/diagnóstico , Neoplasias Óseas/secundario , Neoplasias de la Mama/patología , Fluorodesoxiglucosa F18 , Tomografía Computarizada de Emisión , Adulto , Anciano , Neoplasias Óseas/diagnóstico por imagen , Femenino , Humanos , Imagen por Resonancia Magnética , Persona de Mediana Edad , Estudios Prospectivos , Curva ROC
18.
Eur J Nucl Med ; 26(6): 599-605, 1999 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10369945

RESUMEN

Since musculoskeletal tumours comprise a large heterogeneous group of entities with different biological behaviour, clinical diagnosis of such lesions can be very difficult. The aim of this prospective study was to assess the usefulness of 2-[F-18]-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) in the non-invasive evaluation of soft tissue tumours. One hundred and two patients with suspected soft tissue neoplasms were investigated by FDG-PET. The uptake of FDG was evaluated semiquantitatively by determining the tumour to background ratio (TBR). All patients underwent biopsy, resulting in the histological detection of 39 high-grade sarcomas, 16 intermediate-grade sarcomas, 11 low-grade sarcomas, 25 benign tumours, 10 tumour-like lesions such as spontaneous myositis ossificans (n = 6) and one non-Hodgkin lymphoma. All lesions except for two lipomas disclosed an increased FDG uptake. Sarcomas showed significantly higher TBR values than latent or active benign lesions (P<0.001) and aggressive benign lesions (P<0.05). Using a TBR cut-off level of 3.0 for malignancy, sensitivity of FDG-PET was 97.0%, specificity 65.7% and accuracy 86. 3%. From our data there are three main conclusions: (1) Except for patients with pseudotumoral myositis ossificans, lesions with a TBR >3 were sarcomas (91.7%) or aggressive benign tumours (8.3%). (2) Tumours with a TBR <1.5 were latent or active benign lesions, exclusively. (3) The group with intermediate TBR values (<3 and >1. 5) comprised primarily latent or active benign lesions, but also four aggressive benign tumours and two low-grade sarcomas. Our data suggest that FDG-PET represents a useful tool for the evaluation of the biological activity of soft tissue neoplasms.


Asunto(s)
Fluorodesoxiglucosa F18 , Radiofármacos , Neoplasias de los Tejidos Blandos/diagnóstico por imagen , Tomografía Computarizada de Emisión , Femenino , Radioisótopos de Flúor , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos
19.
J Nucl Med ; 40(2): 250-5, 1999 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-10025831

RESUMEN

UNLABELLED: We evaluated the potential of the glucose analog [18F]fluorodeoxyglucose (FDG) as a PET tracer for the hepatic staging in 168 patients designated for resective pancreatic surgery. METHODS: Metastatic liver disease was confirmed or excluded during surgery or with CT follow-up for at least 6 mo. Proven metastases were then retrospectively identified on preoperative CT (gold standard). Hepatic PET scans of all patients were interpreted blindly. Any focal FDG uptake was considered malignant. Both proven hepatic metastases and suspicious hepatic PET lesions were then compared, lesion by lesion, with CT. Standardized uptake values (SUV) and tumor-to-liver ratios (T/L) were determined for the most intense lesion of each patient. RESULTS: Sensitivity of FDG PET was 68% (15 of 22 patients). The lesion detection rate was 97% (28 of 29 metastases) for lesions >1 cm and 43% (16 of 37 metastases) for lesions < or = 1 cm. Specificity was 95% (138 of 146 patients). Six of eight patients with false-positive results had marked intrahepatic cholestasis (versus 3 of 15 patients with true-positive lesions), one had an infrahepatic abscess and one had a right basal pulmonary metastasis. The SUV and T/L were 4.6+/-1.4 and 2.3+/-1.1, respectively, for malignant lesions and 4.1+/-1.5 and 1.9+/-0.3, respectively, for false-positive lesions and therefore are of limited value. CONCLUSION: FDG PET provides reliable hepatic staging for lesions >1 cm. False-positive results are associated with the presence of marked intrahepatic cholestasis. For lesions < or = 1 cm, FDG PET can define malignancy in 43% of suspicious CT lesions in the absence of dilated bile ducts.


Asunto(s)
Fluorodesoxiglucosa F18 , Neoplasias Hepáticas/diagnóstico por imagen , Neoplasias Hepáticas/secundario , Neoplasias Pancreáticas/patología , Radiofármacos , Tomografía Computarizada de Emisión , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Pancreáticas/cirugía , Sensibilidad y Especificidad , Tomografía Computarizada por Rayos X
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