Diagnostic yield of 18F-FDG PET/CT in suspected diagnosis of vascular graft infection: A prospective cohort study

Background. Prosthetic vascular graft infection (PVGI) is a severe complication associated with high morbidity and mortality. Clinical diagnosis is complex, requiring image testing such as CT angiography or leukocyte scintigraphy, which has considerable limitations. The aim of this study was to know the diagnostic yield of PET/CT with 18F-Fluorodeoxyglucose (18F-FDG) in patients with suspected PVGI. Methods. We performed a prospective cohort study including 49 patients with suspected PVGI, median age of 62 ± 14 years. Three uptake patterns were defined following published recommendations: (i) focal, (ii) patched (PVGI criteria), and (iii) diffuse (no PVGI criterion). Results. Sensitivity, specificity, and positive and negative predictive values for 18F-FDG-PET/ CT were 88%, 79%, 67%, and 93%, respectively. 18F-FDG-PET/CT identified 14/16 cases of PVGI showing a focal (n = 10) or patched pattern (n = 4), being true negative in 26/33 cases with either a diffuse pattern (n = 16) or without uptake (n = 10). Five of the seven false-positive cases (71%) showed a patched pattern and all coincided with the application of adhesives for PVG placement. Conclusions. 18F-FDG-PET/CT is a useful technique for the diagnosis of PVGI. A patched pattern on PET/CT in patients in whom adhesives were applied for prosthetic vascular graft placement does not indicate infection. (J Nucl Cardiol 2018) Key Words: Fluorodeoxyglucose (FDG) Æ diagnostic and prognostic application Æ PET/CT imagin

Outcome of Enterococcus faecalis infective endocardits according to the length of antibiotic therapy: Prelininary data from a cohort of 78 patients.

Background International guidelines recommend 4 weeks of treatment with ampicillin plus gentamicin (A+G) for uncomplicated native valve Enterococcus faecalis infective endocarditis (EFIE) and 6 weeks in the remaining cases. Ampicillin plus ceftriaxone (A+C) is always recommended for at least 6w, with no available studies assessing its suitability for 4w. We aimed to investigate differences in the outcome of EFIE according to the duration (4 versus 6 weeks) of antibiotic treatment (A+G or A+C). Methods Retrospective analysis from a prospectively collected cohort of 78 EFIE patients treated with either A+G or A+C. Results 32 cases (41%) were treated with A+G (9 for 4w, 28%) and 46 (59%) with A+C (14 for 4w, 30%). No significant differences were found in 1-year mortality according to the type of treatment (31% and 24% in A+G and A+C, respectively; P = 0.646) or duration (26% and 27% at 4 and 6w, respectively; P = 0.863). Relapses were more frequent among survivors treated for 4w than in those treated for 6w (3/18 [17%] at 4w and 1/41 [2%] at 6w; P = 0.045). Three out of 4 (75%) relapses occurred in cirrhotic patients. Conclusions A 4-week course of antibiotic treatment might not be suitable neither for A+G nor A+C for treating uncomplicated native valve EFIE

Reappraisal of [18F]FDG-PET/CT for diagnosis and management of cardiac implantable electronic device infections

Introduction and objectives: The role of [18F]FDG-PET/CT in cardiac implantable electronic device (CIED) infections requires better evaluation, especially in the diagnosis of systemic infections. We aimed to determine the following: a) the diagnostic accuracy of [18F]FDG-PET/CT in each CIED topographical region, b) the added value of [18F]FDG-PET/CT over transesophageal echocardiography (TEE) in diagnosing systemic infections, c) spleen and bone marrow uptake in differentiating isolated local infections from systemic infections, and d) the potential application of [18F]FDG-PET/CT in follow-up. Methods: Retrospective single-center study including 54 cases and 54 controls from 2014 to 2021. The Primary endpoint was the diagnostic yield of [18F]FDG-PET/CT in each topographical CIED region. Secondary analyses described the performance of [18F]FDG-PET/CT compared with that of TEE in systemic infections, bone marrow and spleen uptake in systemic and isolated local infections, and the potential application of [18F]FDG-PET/CT in guiding cessation of chronic antibiotic suppression when completed device removal is not performed. Results: We analyzed 13 (24%) isolated local infections and 41 (76%) systemic infections. Overall, the specificity of [18F]FDG-PET/CT was 100% and sensitivity 85% (79% pocket, 57% subcutaneous lead, 22% endovascular lead, 10% intracardiac lead). When combined with TEE, [18F]FDG-PET/CT increased definite diagnosis o fsystemic infections from 34% to 56% (P=.04). Systemic infections with bacteremia showed higher spleen (P=.05) and bone marrow metabolism (P=.04) than local infections. Thirteen patients without complete device removal underwent a follow-up [18F]FDG-PET/CT, with no relapses after discontinuation of chronic antibiotic suppression in 6 cases with negative follow-up [18F]FDG-PET/CT. Conclusions: The sensitivity of [18F]FDG-PET/CT for evaluating CIED infections was high in local infections but much lower in systemic infections. However, accuracy increased when [18F]FDG-PET/CT was combined with TEE in endovascular lead bacteremic infection. Spleen and bone marrow hypermetabolism could differentiate bacteremic systemic infection from local infection. Although further prospective studies are needed, follow-up [18F]FDG-PET/CT could play a potential role in the management of chronic antibiotic suppression therapy when complete device removal is unachievable

The Combination of Daptomycin plus Fosfomycin has Synergistic, Potent and Rapid Bactericidal Activity against Methicillin-ResistantStaphylococcus aureus(MRSA) in a Rabbit Model of Experimental Endocarditis (EE).

This study aims to investigate whether the addition of fosfomycin or cloxacillin to daptomycin provides better outcomes in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) experimental aortic endocarditis in rabbits. Five MRSA strains were used to perform in vitro time-kill studies at standard (105) and high (108) inocula. Combined therapy was compared with daptomycin monotherapy treatment in the MRSA experimental endocarditis model. A human-like pharmacokinetics model was applied and the equivalents of cloxacillin 2g/4hiv, fosfomycin 2g/6h iv and daptomycin 6-10mg/kg/d iv were administered. The combination of daptomycin and fosfomycin or cloxacillin was synergistic in the five strains tested at both inocula. A bactericidal effect was detected in four out of five strains tested with both combinations. The MRSA-277 strain (vancomycin MIC, 2 mcg/mL) was used for the experimental endocarditis model. Daptomycin plus fosfomycin significantly improved the efficacy of daptomycin monotherapy at 6 mg/kg/d in terms of both the proportion of sterile vegetations (100% vs. 72%, P=.046) and the decrease in the density of bacteria within the vegetations (P=.025). Daptomycin plus fosfomycin was as effective as daptomycin monotherapy at 10 mg/kg/d (100% vs. 93%, P=1.00) and had similar activity to daptomycin plus cloxacillin when daptomycin was administered at 6 mg/kg/d (100% vs. 88%, P=0.48). Daptomycin non-susceptibility was not detected in any of the isolates recovered from vegetations. In conclusion, for the treatment of MRSA experimental endocarditis, the combination of daptomycin plus fosfomycin showed synergistic and bactericidal activity.Copyright © 2018 American Society for Microbiology

Diagnostic accuracy of 18F-FDG PET/CT in infective endocarditis and implantable cardiac electronic device infection: A cross-sectional study.

Early diagnosis of infective endocarditis (IE) is based on the yielding of blood cultures and echocardiographic findings. However, they have limitations and sometimes the diagnosis is inconclusive, particularly in patients with prosthetic valves (PV) and implantable cardiac electronic devices (ICED). The primary aim of this study was to evaluate the diagnostic accuracy of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in patients with suspected IE an ICED infection. METHODS: A prospective study with 80 consecutive patients with suspected IE and ICED infection (65 men and 15 women with a mean age of 68±13 years old) between June 2013 and May 2015 was performed in our hospital. The inclusion criteria was clinically suspected IE and ICED infection at the following locations: native valve (NV) (n = 21), PV (n = 29) or ICED (n = 30) [(automatic implantable defibrillator (n = 11) or pacemaker (n = 19)]. Whole-body 18F-FDG PET/CT with a myocardial uptake suppression protocol with unfractionated heparin was performed in all patients. The final diagnosis of infection was established by the IE study Group according to the clinical, echocardiographic and microbiological findings. RESULTS: A final diagnosis of infection was confirmed in 31 patients: NV (n = 6), PV (n = 12) and ICED (n = 13). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for 18F-FDG PET/CT was 82%, 96%, 94% and 87%, respectively. 18F-FDG PET/CT was false negative in all cases with infected NV. 18F-FDG PET/CT was able to reclassify 63/70 (90%) patients initially classified as possible IE by modified Duke criteria. In 18/70 cases 18F-FDG PET/CT changed possible to definite IE (26%) and in 45/70 cases changed possible to rejected IE (64%). Additionally, 18F-FDG PET/CT identified 8 cases of septic embolism and 3 colorectal cancer in patients with final diagnosis of IE. CONCLUSION: 18F-FDG PET/CT proved to be a useful diagnostic tool in suspected IE and ICED infection and should be included in the diagnostic algorithm for early diagnosis. 18F-FDG PET/CT is not useful in the diagnosis of IE in NV, but should be also considered in the initial assessment of this complex scenario to rule out extracardiac complications and possible neoplasms

Cuantificación de la captación gammagráfica de 99mTc-tetrofosmina en pacientes con neoplasia pulmonar de célula no pequeña: relación con los niveles tumorales de glicoproteína-P y la respuesta a la quimioterapia

[spa] DE LA TESIS: La multiresistencia a drogas de algunos tumores sigue siendo un grave problema para el manejo del paciente oncológico candidato a tratamiento sistémico con quimioterapia. Actualmente no existen técnicas diagnósticas no invasivas que puedan determinar de forma precisa la respuesta a la quimioterapia en la mayoría de tumores. Este trabajo evalúa si existe asociación entre la captación tumoral de 99mTc-tetrofosmina y los niveles de glicoproteína-P y si la gammagrafía con 99mTc-tetrofosmina puede ser útil para predecir la respuesta a la quimioterapia en el cáncer de pulmón de célula no pequeña. Se administraron 20 mCi de 99mTc-tetrofosmina a todos los pacientes obteniendo imágenes planares del tórax en proyección anterior y posterior de 300 segundos a los 15 minutos (fase precoz) y a las 2 horas (fase tardía) post-inyección del radiotrazador. Se realizaron imágenes del tórax en modo SPECT a las 2 horas tras finalizar la adquisición planar tardía. Se cuantificó el lavado de radiotrazador de la lesión tumoral comparando la captación en la imagen planar en fase precoz y tardía y se obtuvo un índice de captación del tumor en las imágenes en modo SPECT. Los pacientes se clasificaron como "si respuesta" cuando hubo una respuesta parcial o completa a la quimioterapia y como "no respuesta" cuando la enfermedad mostró una estabilidad o progresión tras el tratamiento con quimioterapia. Los resultados mostraron una correlación estadísticamente significativa (P<0.005) entre la respuesta a la quimioterapia y el lavado del radiotrazador, observándose más casos de "sí respuesta" en los pacientes con un lavado más lento. Además, el índice de captación en la SPECT para los pacientes con "sí respuesta" fue de 1.69 o superior, mientras que en el grupo de "no respuesta" el índice de captación fue siempre inferior a 1.80 con índices globalmente más bajos. En el análisis de la glicoproteína-P, se observó que teniendo en cuenta la expresión de esta glicoproteína en el tejido pulmonar sano en cada paciente, existían diferencias estadísticas en ambos grupos, tanto en el lavado de la lesión como en su índice de captación (P<0.05). La conclusión principal del estudio es que la gammagrafía con 99mTc-tetrofosmina puede ser una técnica útil para predecir y monitorizar la respuesta a la quimioterapia en pacientes con cáncer de pulmón de célula no pequeña. Esta técnica permite valorar la expresión de glicoproteína-P en estos pacientes

Validation of an automatic dose injection system for Ictal SPECT in epilepsy

The purpose of our study was to evaluate the performance and clinical usefulness of an automated injector system (AIS) that administers an automated injection for ictal SPECT after calculating the volume of tracer to be injected over time. Methods: To test the AIS, repeated injections were performed at different times after tracer preparation. The clinical study consisted of 56 patients with drug-resistant, complex partial seizures. Tracer for ictal SPECT was injected using automated injection in 27 patients and manual injection (MI) in the remaining 29. Injection time (TI) was measured in seconds from seizure onset to the end of volume injection. The SISCOM (Subtraction Ictal Spect Co-registered to MRI) procedure was used to locate the epileptogenic seizure focus with SPECT. The definition of seizure focus was made by consensus of the epilepsy unit using conventional diagnostic methods. Results: During the experimental phase, there were no system failures, and the error in injected doses when using automated injection was lower than with MI. During the clinical phase, TI using manual injection was 41 s with a range of 14-103 s, compared with an AIS average of 33 s with a range of 19-63 s (P , 0.05). Ictal SPECT and SISCOM successfully localized the seizure focus in 21 of the 27 patients (78%) by AIS and in 19 of the 29 patients (65%) by MI (P 5 0.14). Furthermore, nursing staff found the AIS method more convenient than the MI method. Conclusion: An AIS can improve the quality of work of the nursing staff in the neurology ward and allow a finer adjustment of the injection dose. Early results using an AIS would indicate a reduction in injection time and improved SPECT accuracy

Relationship between Vancomycin MIC and Virulence Gene Expression in Clonal Complexes of Methicillin-Susceptible Staphylococcus aureus Strains Isolated from Left-sided Endocarditis

Higher vancomycin MICs have been associated with more complicated courses and higher mortality rates in patients with Staphylococcus aureus bacteremia and infective endocarditis (IE). The aim of this study was to investigate whether the strains belonging to the cohort of 93 patients from a previously published study in which patients with strains with vancomycin MICs of ≥1.5 μg/ml presented higher mortality rates and systemic emboli than patients with strains with vancomycin MICs of <1.5 μg/ml had specific patterns of virulence factors, clonal complex (CC) types, or the ability to form biofilms. Vancomycin MICs were determined by Etest, and the isolates underwent spa typing to infer the CC, biofilm studies, a thrombin-induced platelet microbicidal assay, and multiplex PCR for the presence of virulence genes. We found no differences in genes encoding adhesins, toxins, or other putative virulence genes according to the vancomycin MIC group. CC30, CC34, and CC45 represented nearly half of the isolates, and there was no association with the vancomycin MIC. agr subgroups I and III predominated, with no association with the vancomycin MIC. Isolates with higher vancomycin MICs exhibited a poorer ability to form biofilms with and without the presence of vancomycin (2.03 versus 2.48 [P < 0.001], respectively, for isolates with higher vancomycin MICs and 2.60 versus 2.87 [P = 0.022], respectively, for isolates with lower vancomycin MICs). In the multivariable analysis, efb and V8 were risk factors for major emboli (adjusted odds ratio [aOR] = 7.5 and 95% confidence interval [CI] = 1.2 to 46.6 for efb, and aOR = 3.9 and 95% CI = 1.1 to 14.1 for V8), whereas no genotypic predictors of in-hospital mortality were found. No clear associations between genes encoding virulence factors, agr type, clonal complexes, mortality, and major embolic events according to vancomycin MIC group were found

Diagnostic accuracy of 18F-FDG PET/CT in infective endocarditis and implantable cardiac electronic device infection: A cross-sectional study.

Early diagnosis of infective endocarditis (IE) is based on the yielding of blood cultures and echocardiographic findings. However, they have limitations and sometimes the diagnosis is inconclusive, particularly in patients with prosthetic valves (PV) and implantable cardiac electronic devices (ICED). The primary aim of this study was to evaluate the diagnostic accuracy of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in patients with suspected IE an ICED infection. METHODS: A prospective study with 80 consecutive patients with suspected IE and ICED infection (65 men and 15 women with a mean age of 68±13 years old) between June 2013 and May 2015 was performed in our hospital. The inclusion criteria was clinically suspected IE and ICED infection at the following locations: native valve (NV) (n = 21), PV (n = 29) or ICED (n = 30) [(automatic implantable defibrillator (n = 11) or pacemaker (n = 19)]. Whole-body 18F-FDG PET/CT with a myocardial uptake suppression protocol with unfractionated heparin was performed in all patients. The final diagnosis of infection was established by the IE study Group according to the clinical, echocardiographic and microbiological findings. RESULTS: A final diagnosis of infection was confirmed in 31 patients: NV (n = 6), PV (n = 12) and ICED (n = 13). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for 18F-FDG PET/CT was 82%, 96%, 94% and 87%, respectively. 18F-FDG PET/CT was false negative in all cases with infected NV. 18F-FDG PET/CT was able to reclassify 63/70 (90%) patients initially classified as possible IE by modified Duke criteria. In 18/70 cases 18F-FDG PET/CT changed possible to definite IE (26%) and in 45/70 cases changed possible to rejected IE (64%). Additionally, 18F-FDG PET/CT identified 8 cases of septic embolism and 3 colorectal cancer in patients with final diagnosis of IE. CONCLUSION: 18F-FDG PET/CT proved to be a useful diagnostic tool in suspected IE and ICED infection and should be included in the diagnostic algorithm for early diagnosis. 18F-FDG PET/CT is not useful in the diagnosis of IE in NV, but should be also considered in the initial assessment of this complex scenario to rule out extracardiac complications and possible neoplasms