Desfechos clínicos após investigação para Embolia Pulmonar utilizando TC de tórax/membros inferiores

FUNDAMENTO: O diagnóstico de Embolia Pulmonar (EP) ainda requer longos períodos de trabalho e inúmeros testes. OBJETIVO: Nosso objetivo é avaliar os desfechos clínicos após uma investigação negativa usando um protocolo combinado de angio TC de tórax e venografia por TC (CTA/CTV) como único teste de diagnóstico em pacientes não selecionados com suspeita de EP. MÉTODOS: Estudo de coorte retrospectivo que incluiu pacientes consecutivos com suspeita de EP que foram investigados com um protocolo combinado de CTA/CTV. Os pacientes que apresentaram inicialmente uma investigação negativa e não receberam anticoagulantes foram acompanhados por seis meses para ocorrência de eventos tromboembólicos venosos recorrentes. RESULTADOS: De 425 pacientes com suspeita de EP, 62 (14,6%) tiveram diagnóstico de tromboembolismo venoso no CTA/CTV inicial. A média de idades foi de 56 ± 19 anos, e 61% da população se enquadravam na categoria de baixa probabilidade clínica. A trombose venosa profunda isolada representou 21% de todos os eventos tromboembólicos venosos, e quando se considerou toda a população, a CTV foi associada a um incremento no rendimento diagnóstico de 3,1%. Nosso grupo era composto de 320 pacientes com CTA/CTV inicialmente negativo e que não receberam anticoagulantes. Após seis meses de acompanhamento, apenas três pacientes apresentaram recorrência de eventos tromboembólicos (0,9%, IC 95% -0,1% - 2,0%) e nenhum foi fatal. Não houve mortes relacionadas com a EP. CONCLUSÕES: Nosso estudo sugere que uma estratégia de diagnóstico que utiliza CTA/CTV como único teste de diagnóstico pode descartar EP com segurança, em população com risco baixo a moderado, e está associada a resultados favoráveis, com um valor preditivo negativo de 99,1%. (Arq Bras Cardiol. 2012; [online].ahead print, PP.0-0)

Espessura do tecido subcutaneo como preditor independente de ruido em imagem de TC cardiaca

Fundamento: Há poucos dados sobre a definição de parâmetros simples e robustos para predizer artefato de imagem em tomografia computadorizada (TC) cardíaca. Objetivos: Avaliar o valor da simples medida da espessura do tecido subcutâneo (espessura pele-esterno) como preditor de artefato de imagem em TC cardíaca. Métodos: O estudo avaliou 86 pacientes submetidos a angiotomografia computadorizada cardíaca (ATCC) com sincronização prospectiva com ECG e avaliação de escore de cálcio coronário com 120 kV e 150 mA. A qualidade da imagem foi medida objetivamente pelo artefato de imagem na aorta em ATCC, sendo 'artefato baixo' definido como aquele < 30 UH. Os diâmetros torácicos anteroposterior e laterolateral, o artefato de imagem na aorta e a espessura pele-esterno foram medidos como preditores de artefato em ATCC. A associação de preditores e artefato de imagem foi avaliada usando-se correlação de Pearson. Resultados: A dose média de radiação foi 3,5 ± 1,5 mSv. O artefato de imagem médio na ATCC foi de 36,3 ± 8,5 UH, sendo o artefato de imagem médiona fase sem contraste do exame de 17,7 ± 4,4 UH. Todos os preditores foram independentemente associados com artefato em ATCC. Os melhores preditores foram espessura pele-esterno, com correlação de 0,70 (p < 0,001), e artefato de imagem na fases em contraste,com correlação de 0,73 (p < 0,001). Ao avaliar a habilidade de predizer artefato de imagem baixo, as áreas sob a curva ROC para o artefato de imagem na fases em contraste e para a espessura pele-esterno foram 0,837e 0,864, respectivamente. Conclusão: Tanto espessura pele-esterno quanto artefato de escore de cálcio são preditores simples e precisos de artefato de imagem em ATCC. Tais parâmetros podem ser incorporados aos protocolos de TC padrão para ajustar adequadamente a exposição à radiação.

Biodistribution Study of the Anaesthetic Sodium Phenobarbital Labelled with Technetium-99m in Swiss Mice Infected with Schistosoma mansoni Sambon, 1907

Technetium-99m (99mTc) is a radionuclide that has negligible enviromnental impact, is easily available, inexpensive and can be used as a radioactive tracer in biological experiences. In order to know the mode of action of sodium phenobarbital in moving adult Schistosoma mansoni worms from mesenteric veins to the liver, we labelled sodium phenobarbital (PBBT) with 99mTc and a biodistribution study in infected and non-infected Swiss mice was performed. The PBBT was incubated with stannous chloride used as reducing agent and with 99mTc, as sodium pertechnetate. The radioactivity labelling (%) was determined by paper ascending chromatography perfomed with acetone (solvent). The 99mTc-PBBT was administered by intraperitoneal route to Swiss mice infected eight weeks before. The animals were perfused after diferent periods of time (0,1,2,3,4 hr) when blood, spleen, liver, portal vein, mesenteric veins, stomach, kidneys and adult worms were isolated. The radioactivity present in these samples was counted in a well counter and the percentage was determined. The radioactivity was mainly taken up by the blood, kidney, liver and spleen. No radioactivity was found on the adult worms. We concluded that the worm shift was due to an action on the host of the sodium phenobarbital

Estudio del TEP sintomático en pacientes oncológicos mediante TC Multidetector

L´objectiu d´aquest treball és determinar de manera retrospectiva la prevalença i característiques radiològiques del tromboembolisme pulmonar mitjançant TC multidetectors en pacients oncològics amb sospita clínica de TEP, así mateix identificar altres troballes radiològiques pleuroparenquimatoses presents a aquells pacients que no mostren signes de TEP. Per a això es van revisar 223 Angio- Tc toràcics realitzats per sospita de TEP recollint les dades clíniques dels pacients oncològics (82), les característiques dels èmbols pulmonars en aquests malalts (16) i valorant l´existència d’altres causes radiològiques que justifiquessin la clínica de dispnea.

Impacto del estudio pet-tc en la planificación de radioterapia en pacientes con cáncer de pulmón

Aquest estudi té com a objectiu avaluar l’impacte de la PET-TC amb 18F-FDG en la planificació radioteràpica (PRT) en pacients amb carcinoma pulmonar, per la possible modificació en l’estadificació tumoral. Es van estudiar 33 pacients amb carcinoma de pulmó als que es va practicar una TC diagnòstica i una PET-TC d’estadificació i PRT. Es va comparar l’estadificació mitjançant ambdues tècniques i es van comptabilitzar els pacients exclosos per RT curativa. Finalment, la 18F-FDG PET-TC va permetre una millor estadificació dels pacients candidats a RT, excloent aquells no candidats per metàstasis no sospitades o per disminució de l’estadiatge.

α-N-acetylglucosamine-linked O-glycans of sialoglycoproteins (Tc-mucins) from Trypanosoma cruzi Colombiana strain

Trypanosoma cruzi sialoglycoproteins (Tc-mucins) are mucin-like molecules linked to a parasite membrane via a glycosylphosphatidylinositol anchor. We previously determined the structures of Tc-mucin O-glycan domains from several T. cruzi strains and observed significant differences among them. We now report the amino acid content and structure of Tc-mucin O-glycan chains from T. cruzi Colombiana, a strain resistant to common trypanocidal drugs. Amino acid analysis demonstrated the predominance of threonine residues (42%) and helped to identify the O-glycans as belonging to a Tc-mucin family that contain a ²-galactofuranose (²-Galf) residue attached to an α-N-acetylglucosamine (α-GlcNAc) O-4, with the most complex glycan, a pentasaccharide-GlcNAc-ol with a branched trigalactopyranose chain, on the GlcNAc O-6. The presence of ²-Galf on O-glycans from T. cruzi Colombiana mucins supports the use of glycosylation as a phylogenetic marker for the classification of Colombiana in the T. cruzi I group.

Individual monitoring of internal exposure for nuclear medicine workers in Switzerland.

Monitoring of internal exposure for nuclear medicine workers requires frequent measurements due to the short physical half-lives of most radionuclides used in this field. The aim of this study was to develop screening measurements performed at the workplace by local staff using standard laboratory instrumentation, to detect whether potential intake has occurred. Such measurements do not enable to determine the committed effective dose, but are adequate to verify that a given threshold is not exceeded. For radioiodine, i.e. (123)I, (124)I, (125)I and (131)I, a calibrated surface contamination monitor is placed in front of the thyroid to detect whether the activity threshold has been exceeded. For radionuclides with very short physical half-lives (≤6 h), such as (99m)Tc and those used in positron emission tomography  imaging, i.e. (11)C, (15)O, (18)F and (68)Ga, screening procedures consist in performing daily measurements of the ambient dose rate in front of the abdomen. Other gamma emitters used for imaging, i.e. (67)Ga, (111)In and (201)Tl, are measured with a scintillation detector located in front of the thorax. For pure beta emitters, i.e. (90)Y and (169)Er, as well as beta emitters with low-intensity gamma rays, i.e. (153)Sm, (177)Lu, (186)Re and (188)Re, the procedure consists in measuring hand contamination immediately after use. In Switzerland, screening procedures have been adopted by most nuclear medicine services since such measurements enable an acceptable monitoring while taking into account practical and economic considerations.

Impacto en el análisis con wbr™ en la valoración planar y tomográfica (SPECT-TC) de paratiroides

El estudio del hiperparatirodismo es una indicación cada vez más frecuente en Medicina nuclear debido a la incorporación de técnica híbrida SPECT-TC, que añade a la gammagrafía planar convencional de doble trazador (MIBI y Pertecnetato) y doble fase (10 minutos y 2 horas) información sobre localización, fundamentalmente. El sistema de procesado convencional (reconstrucción iterativa OSEM) presenta buenos resultados, no obstante, existen limitaciones como son la resolución espacial y ruido. El sistema de reconstrucción Wide Beam Reconstruction WBR™ mejora fundamentalmente estos aspectos. Con este objetivo, se ha realizado una comparación entre ambos métodos, en pacientes con sospecha de hiperparatiroidismo.

Transplante cardíaco (TC): a experiência do portador da doença de Chagas

O sucesso do transplante cardíaco com portadores da doença de Chagas está condicionado a cuidados especiais durante todas as fases do transplante, com necessidade de acompanhamento específico e rigoroso pela equipe de saúde. Os receptores devem estar conscientes da permanência do Trypanossoma no organismo, e das possibilidades de reativação da infecção após o transplante. Portanto, seu conhecimento dessa condição, e a sua participação ativa no próprio tratamento, têm importância fundamental. O objetivo do estudo foi investigar a experiência do transplante cardíaco vivenciada por pacientes portadores da doença de Chagas, para buscar compreender os significados que eles atribuem a esta experiência. Os procedimentos metodológicos abrangeram: a seleção dos pacientes; as entrevistas; a análise dos dados, indicando as unidades de significado e a análise individual; a busca de convergências dos discursos; e análise hermenêutica das convergências. Da análise dos dados emergiram os seguintes temas: o tempo vivido pelo receptor, portador da Doença de Chagas; a concepção do TC apresentado pelo portador de Chagas; o cuidado na trajetória do TC.

Rendimiento diagnóstico de la spect-tc post terapéutica en la estadificación inicial del cáncer diferenciado de tiroides

El rastreo corporal total (RCT) luego de la primera radioablación con 131I en pacientes diagnosticados de carcinoma diferenciado de tiroides (CDT) permite una re-estadificación de la enfermedad. Sin embargo, su información anatómica es escasa y la elevada actividad de los restos tiroideos puede interferir con la detección de adenopatías cervicales. En este estudio se determinó el valor diagnóstico de la SPECT-TC respecto al RCT, concluyendo que la misma aporta información relevante para determinar el compromiso ganglionar, resolviendo los patrones indeterminados observados en los estudios planares y permitiendo una mejor estadificación de los pacientes al final de su periodo de tratamiento.

Charge dependent substrate activity of C3' and N3 functionalized, organometallic technetium and rhenium-labeled thymidine derivatives toward human thymidine kinase 1.

Human cytosolic thymidine kinase (hTK1) has proven to be a suitable target for the noninvasive imaging of cancer cell proliferation using radiolabeled thymidine analogues such as [(18)F]3'-fluoro-3'-deoxythymidine ([(18)F]FLT). A thymidine analogue for single photon emission computed tomography (SPECT), which incorporates the readily available and inexpensive nuclide technetium-99m, would be of considerable practical interest. hTK1 is known to accommodate modification of the structure of the natural substrate thymidine at the positions N3 and C3' and, to a lesser extent, C5. In this work, we used the copper-catalyzed azide-alkyne cycloaddition to synthesize two series of derivatives in which thymidine is functionalized at either the C3' or N3 position with chelating systems suitable for the M(CO)(3) core (M = (99m)Tc, Re). The click chemistry approach enabled complexes with different structures and overall charges to be synthesized from a common precursor. Using this strategy, the first organometallic hTK1 substrates in which thymidine is modified at the C3' position were identified. Phosphorylation of the organometallic derivatives was measured relative to thymidine. We have shown that the influence of the overall charge of the derivatives is dependent on the position of functionalization. In the case of the C3'-functionalized derivatives, neutral and anionic substrates were most readily phosphorylated (20-28% of the value for the parent ligand thymidine), whereas for the N3-functionalized derivatives, cationic and neutral complexes were apparently better substrates for the enzyme (14-18%) than anionic derivatives (9%).

Extremity exposure in nuclear medicine: preliminary results of a European study.

The Work Package 4 of the ORAMED project, a collaborative project (2008-11) supported by the European Commission within its seventh Framework Programme, is concerned with the optimisation of the extremity dosimetry of medical staff in nuclear medicine. To evaluate the extremity doses and dose distributions across the hands of medical staff working in nuclear medicine departments, an extensive measurement programme has been started in 32 nuclear medicine departments in Europe. This was done using a standard protocol recording all relevant information for radiation exposure, i.e. radiation protection devices and tools. This study shows the preliminary results obtained for this measurement campaign. For diagnostic purposes, the two most-used radionuclides were considered: (99m)Tc and (18)F. For therapeutic treatments, Zevalin(®) and DOTATOC (both labelled with (90)Y) were chosen. Large variations of doses were observed across the hands depending on different parameters. Furthermore, this study highlights the importance of the positioning of the extremity dosemeter for a correct estimate of the maximum skin doses.

Bloqueo facetario guiado por TC; eficacia diagnóstica, eficacia terapéutica e indicaciones radiológicas.

El origen del dolor lumbar puede ser diverso pero una de las principales causa es el síndrome facetario. Este estudio tiene como objetivo determinar la eficacia diagnóstica y eficacia terapéutica de los bloqueos facetarios mediante infiltraciones guiadas por tomografía computarizada (TC). Asimismo establecer posibles indicaciones o criterios diagnósticos radiológicos del síndrome facetario El bloqueo facetario guiado por TC es un procedimiento simple, seguro y mínimamente invasivo que puede ser una terapia adyuvante en el tratamiento no quirúrgico del dolor lumbar crónico. Es esencial realizar una correcta selección de pacientes que puedan beneficiarse de dicho tratamiento.

Three-dimensional ordered-subset expectation maximization iterative protocol for evaluation of left ventricular volumes and function by quantitative gated SPECT: a dynamic phantom study.

The purposes of this study were to characterize the performance of a 3-dimensional (3D) ordered-subset expectation maximization (OSEM) algorithm in the quantification of left ventricular (LV) function with (99m)Tc-labeled agent gated SPECT (G-SPECT), the QGS program, and a beating-heart phantom and to optimize the reconstruction parameters for clinical applications. METHODS: A G-SPECT image of a dynamic heart phantom simulating the beating left ventricle was acquired. The exact volumes of the phantom were known and were as follows: end-diastolic volume (EDV) of 112 mL, end-systolic volume (ESV) of 37 mL, and stroke volume (SV) of 75 mL; these volumes produced an LV ejection fraction (LVEF) of 67%. Tomographic reconstructions were obtained after 10-20 iterations (I) with 4, 8, and 16 subsets (S) at full width at half maximum (FWHM) gaussian postprocessing filter cutoff values of 8-15 mm. The QGS program was used for quantitative measurements. RESULTS: Measured values ranged from 72 to 92 mL for EDV, from 18 to 32 mL for ESV, and from 54 to 63 mL for SV, and the calculated LVEF ranged from 65% to 76%. Overall, the combination of 10 I, 8 S, and a cutoff filter value of 10 mm produced the most accurate results. The plot of the measures with respect to the expectation maximization-equivalent iterations (I x S product) revealed a bell-shaped curve for the LV volumes and a reverse distribution for the LVEF, with the best results in the intermediate range. In particular, FWHM cutoff values exceeding 10 mm affected the estimation of the LV volumes. CONCLUSION: The QGS program is able to correctly calculate the LVEF when used in association with an optimized 3D OSEM algorithm (8 S, 10 I, and FWHM of 10 mm) but underestimates the LV volumes. However, various combinations of technical parameters, including a limited range of I and S (80-160 expectation maximization-equivalent iterations) and low cutoff values (< or =10 mm) for the gaussian postprocessing filter, produced results with similar accuracies and without clinically relevant differences in the LV volumes and the estimated LVEF.

Role of technetium-99m diphosphonate and gallium-67 citrate bone scanning in the early diagnosis of infectious spondylodiscitis: a comparative study

A comparative study of the parts played by technetium-99m diphosphonate and gallium-67 citrate bone scanning in the early diagnosis of infectious spondylodiscitis is presented. Nineteen patients were included in the study. All patients (11 men aged 19-70 years and eight women aged 18-72 years) had a history of back pain varying in duration from one to 15 weeks. A 99mTc diphosphonate bone scan was positive in 17 patients. The two patients with negative results had less than two weeks of back pain. The 67Ga citrate bone scan showed uptake in all patients.