Avaliação cintilográfica de diferentes dosagens de Tecnécio-99m na padronização da perfusão pulmonar em cães da raça Rottweiller

A avaliação da função pulmonar em cães pode ser obtida mediante exames cintilográficos, os quais incluem a injeção de radiofármacos, seguida de radiografias. Neste estudo, foram utilizados 10 cães machos hígidos da raça Rottweiler e radiograficamente normais e soronegativos para dirofilariose, com administração de doses variadas de macroagregado de albumina sérica humana marcados com tecnécio-99m ([99mTc](MAA)). Os resultados foram avaliados qualitativa e quantitativamente, considerando o índice de perfusão pulmonar e sua homogeneidade, sendo dessa maneira visualizado um aumento na homogeneidade da imagem diretamente relacionado ao número de partículas de MAA injetado. Este estudo define os critérios de normalidade e de dosagem na perfusão pulmonar em cães hígidos da raça Rottweiller estabelecidos com a técnica de cintilografia.

Cardiac resynchronization therapy evaluated by myocardial scintigraphy with (99m)Tc-MIBI: changes in left ventricular uptake, dyssynchrony, and function

(99m)Tc-MIBI gated myocardial scintigraphy (GMS) evaluates myocyte integrity and perfusion, left ventricular (LV) dyssynchrony and function. Cardiac resynchronization therapy (CRT) may improve the clinical symptoms of heart failure (HF), but its benefits for LV function are less pronounced. We assessed whether changes in myocardial (99m)Tc-MIBI uptake after CRT are related to improvement in clinical symptoms, LV synchrony and performance, and whether GMS adds information for patient selection for CRT. A group of 30 patients with severe HF were prospectively studied before and 3 months after CRT. Variables analysed were HF functional class, QRS duration, LV ejection fraction (LVEF) by echocardiography, myocardial (99m)Tc-MIBI uptake, LV end-diastolic volume (EDV) and end-systolic volume (ESV), phase analysis LV dyssynchrony indices, and regional motion by GMS. After CRT, patients were divided into two groups according to improvement in LVEF: group 1 (12 patients) with increase in LVEF of 5 or more points, and group 2 (18 patients) without a significant increase. After CRT, both groups showed a significant improvement in HF functional class, reduced QRS width and increased septal wall (99m)Tc-MIBI uptake. Only group 1 showed favourable changes in EDV, ESV, LV dyssynchrony indices, and regional motion. Before CRT, EDV, and ESV were lower in group 1 than in group 2. Anterior and inferior wall (99m)Tc-MIBI uptakes were higher in group 1 than in group 2 (p < 0.05). EDV was the only independent predictor of an increase in LVEF (p=0.01). The optimal EDV cut-off point was 315 ml (sensitivity 89%, specificity 94%). The evaluation of EDV by GMS added information on patient selection for CRT. After CRT, LVEF increase occurred in hearts less dilated and with more normal (99m)Tc-MIBI uptake.

TECNETIUM-99m AS ALTERNATIVE TO PRODUCE SOMATOSTATIN-LABELED DERIVATIVES: COMPARATIVE BIODISTRIBUTION EVALUATION WITH (111)In-DTPA-OCTREOTIDE

Synthetic somatostatin (SST) analogues have been used in the preparation of receptor-specific radiopharmaceuticals for diagnostic and therapy of neuroendocrine tumors. This work studied the labeling conditions with (99m)Tc and biological distribution in Swiss mice of two SST analogs (HYNIC-Tyr(3)-Octreotide and HYNIC-Tyr(3)-Octreotate) and compared the biodistribution pattern with (111)In-DTPA-Octreotide. Biological distribution studies were performed after injection of radiopharmaceuticals on Swiss mice. Labeling procedures resulted on high radiochemical yield for all three preparations and the labeled products presented high in vitro stability. Biological distribution studies evidenced similar general biodistribution of (99m)Tc-labeled peptides when compared with indium-labeled peptide with fast blood clearance and elimination by urinary tract. Kidneys uptake of (99m)Tc-HYNIC-TATE are similar to (111)In-DTPA-Octreotide, and both are significantly higher than (99m)Tc-HYNIC-OCT. All labeled peptides presented similar uptake on liver, but the retention in time at intestines, particularly at large intestine, was more expressive for (111)In-labeled peptide. The %ID of (99m)Tc-HYNIC-OCT and (99m)Tc-HYNIC-TATE in organs with high density of SST receptors like pancreas and adrenals were significant and similar to obtained for (111)In-DTPA-Octreotide, confirming the affinity of these radiopharmaceuticals for the receptors.

Tc-99m-labeled dextran for mammary lymphoscintigraphy in dogs

Lymphoscintigraphy is the technique of choice for sentinel lymph node detection in women with early breast cancer, but there is limited information evaluating the value of this technique in animals. We investigated mammary lymphatic drainage in 25 young female mongrel dogs by intramammary injection of 18.5 MBq of Tc-99m-dextran (70,000 Da). Lymph node anatomical referencing was obtained using an external marker, bone scintigraphy, or scintiscanning the body contour. Cranial and caudal thoracic mammary glands drained into the cranial sternal lymph node and axillary lymph center. The cranial thoracic mammary gland also drained into the superficial cervical lymph node in two of five animals. The cranial abdominal gland was drained by the axillary lymph center. The caudal abdominal mammary gland was drained by the superficial inguinal lymph node in all animals and simultaneously by medial iliac lymph nodes in four of five animals. In one dog, this mammary gland was also drained by the mediastinal and the superficial cervical lymph nodes. The inguinal mammary gland was drained by superficial inguinal lymph nodes and simultaneously via the medial iliac lymph node in one animal. Lymphatic communications between lymph nodes were identified in 11 of 25 (44%) animals. Tc-99m-dextran mammary lymphoscintigraphy was easy and rapid to perform and may provide valuable information for further studies.

Prognostic value of technetium-99m-labeled single-photon emission computerized tomography in the follow-up of patients after their first myocardial revascularization surgery

OBJECTIVE: To assess the prognostic value of Technetium-99m-labeled single-photon emission computerized tomography (SPECT) in the follow-up of patients who had undergone their first myocardial revascularization. METHODS: We carried out a retrospective study of 280 revascularized patients undergoing myocardial scintigraphy under stress (exercise or pharmacological stress with dipyridamole) and at rest according to a 2-day protocol. A set of clinical, stress electrocardiographic and scintigraphic variables was assessed. Cardiac events were classified as "major" (death, infarction, unstable angina) and "any" (major event or coronary angioplasty or new myocardial revascularization surgery). RESULTS: Thirty-six major events occurred as follows: 3 deaths, 11 infarctions, and 22 unstable anginas. In regard to any event, 22 angioplasties and 7 new surgeries occurred in addition to major events, resulting a total of 65 events. The sensitivity of scintigraphy in prognosticating a major event or any event was, respectively, 55% and 58%, showing a negative predictive value of 90% and 83%, respectively. Diabetes mellitus, inconclusive stress electrocardiography, and a scintigraphic visualization of left ventricular enlargement were significant variables for the occurrence of a major event. On multivariate analysis, abnormal myocardial scintigraphy was a predictor of any event. CONCLUSION: Myocardial perfusion tomography with Technetium-99m may be used to identify high-risk patients after their first myocardial revascularization surgery.

Clinical significance of transient left ventricular dilation assessed during myocardial Tc-99m sestamibi scintigraphy

OBJECTIVE: To assess the clinical significance of transient ischemic dilation of the left ventricle during myocardial perfusion scintigraphy with stress/rest sestamibi. METHODS: The study retrospectively analyzed 378 patients who underwent myocardial perfusion scintigraphy with stress/rest sestamibi, 340 of whom had a low probability of having ischemia and 38 had significant transient defects. Transient ischemic dilation was automatically calculated using Autoquant software. Sensitivity, specificity, and the positive and negative predictive values were established for each value of transient ischemic dilation. RESULTS: The values of transient ischemic dilation for the groups of low probability and significant transient defects were, respectively, 1.01 ± 0.13 and 1.18 ± 0.17. The values of transient ischemic dilation for the group with significant transient defects were significantly greater than those obtained for the group with a low probability (P<0.001). The greatest positive predictive values, around 50%, were obtained for the values of transient ischemic dilation above 1.25. CONCLUSION: The results suggest that transient ischemic dilation assessed using the stress/rest sestamibi protocol may be useful to separate patients with extensive myocardial ischemia from those without ischemia.

Cintilografia do miocárdio com tecnécio 99m-MIBI e administração de adenosina em portadores de doença arterial coronária: correlação dos resultados com a angiografia coronária e o ultra-som intracoronário

OBJETIVO: Estabelecer a correlação da cintilografia de perfusão do miocárdio (CPM) com Tecnécio 99m-MIBI (MIBI) e injeção de adenosina, empregando a angiografia coronária quantitativa (ACQ) e o ultra-som intracoronário (UIC) como comparação. MÉTODOS: Estudo de 70 pacientes com doença arterial coronária (DAC), encaminhados à CPM com MIBI e adenosina. As manifestações clínicas, do eletrocardiograma (ECG) e os resultados das imagens foram correlacionadas às variáveis da análise visual e quantitativa da angiografia, bem como ao UIC. RESULTADOS: A média de idades foi de 60,6 anos, com 39 pacientes do sexo masculino. A angiografia coronária evidenciou estenose do diâmetro da luz (E%) de 49,94% em 105 artérias, com reavaliação à ACQ em 83 artérias (79%) e média de 44,20%, p<0,05. Infradesnível de ST durante adenosina associou-se a maiores graus de E% (55,0% vs 47,8%), p<0,05). A isquemia cintilográfica correlacionou-se a maior área porcentual de obstrução da luz pelo UIC (AO%). Os achados clínicos, do ECG e das imagens foram considerados em conjunto e expressos como respostas globais isquêmicas versus não-isquêmicas . A isquemia associou-se a menores valores do diâmetro mínimo da luz (DML) e da área mínima da luz (AML), obtidos à ACQ e ao UIC. CONCLUSÃO: A cintilografia do miocárdio com 99mTc-MIBI e adenosina correlaciona-se à AO% ao UIC, considerando-se as imagens de perfusão. Na avaliação dos resultados globais da prova observa-se associação com os diâmetros e as áreas da luz nos locais de obstrução, obtidos à ACQ e ao UIC.

Valor prognóstico da cintilografia miocárdica de perfusão com tetrofosmin marcado com Tecnécio-99m sincronizada com o ciclo cardíaco (" Gated SPECT" ) na avaliação de pacientes com diabete melito e suspeita clínica de doença arterial coronariana

FUNDAMENTO: A doença cardiovascular é a principal causa de morte em diabéticos, tornando-se primordial a identificação dos indivíduos sob maior risco de eventos cardiovasculares. OBJETIVO: Avaliar o valor prognóstico da cintilografia miocárdica de perfusão com " gated SPECT" em pacientes com diabete melito (DM) e suspeita clínica de doença arterial coronariana. MÉTODOS: Estudo retrospectivo envolvendo 232 pacientes diabéticos submetidos à cintilografia miocárdica com " gated SPECT" . Foram avaliados os parâmetros da cintilografia de perfusão (escores e número de segmentos alterados) e da função ventricular (fração de ejeção, volumes e contratilidade do ventrículo esquerdo). Foram considerados eventos cardiovasculares futuros ocorrência de óbito cardíaco, síndrome coronariana isquêmica aguda, procedimentos de revascularização ou acidente vascular encefálico. Foi realizada a análise uni e multivariada pelo modelo de regressão logística múltipla (p < 0,05). RESULTADOS: Estiveram associados com desfechos futuros na análise univariada: idade (p=0,02); angina de peito (p=0,01); tratamento com insulina (p=0,02); anormalidades na perfusão miocárdica (p<0,0001); número de segmentos envolvidos (p=0,0001); escores de perfusão (p=0,0001); fração de ejeção (p=0,004); volume sistólico final (p=0,03) e achado de alteração segmentar na contratilidade do VE (p<0,0001). Na análise multivariada, o sexo masculino (p=0,007), a idade (p=0,03), a angina (p=0,001), o uso de insulina (p=0,007) e o SDS > 3 (p=0,0001) e o número de segmentos alterados > 3 (p=0,0001) foram preditores de eventos. CONCLUSÃO: A cintilografia miocárdica com " gated SPECT" adiciona informações independentes para a estratificação do risco de eventos cardiovasculares futuros em pacientes com diabete melito e suspeita de doença arterial coronariana.

Ressonância magnética vs cintilografia com pirofosfato marcado com tecnécio-99m para a detecção de necrose miocárdica perioperatória

FUNDAMENTO: O infarto do miocárdio perioperatório (IMPO) é uma complicação da cirurgia de revascularização miocárdica (CRM) com potencial impacto prognóstico. A cintilografia miocárdica (CM) com pirofosfato marcado com tecnécio-99m é utilizada no diagnóstico de IMPO, mas demonstra limitada sensibilidade para lesões subendocárdicas. A ressonância magnética cardiovascular (RMC), por sua vez, detém alta acurácia para a detecção de necrose miocárdica. OBJETIVO: Comparar a RMC e a CM para a detecção de IMPO após CRM. MÉTODOS: Foram estudados 24 pacientes portadores de doença arterial coronária crônica, com a técnica de realce tardio pela RMC e com a CM, antes e depois da CRM, analisando-se o surgimento de áreas de necrose miocárdica perioperatória (IMPO). Mensuraram-se também marcadores bioquímicos de lesão miocárdica (CKMB e troponina I), antes e depois da cirurgia. RESULTADOS: Dezenove pacientes completaram o estudo. Desses, 6 (32%) apresentaram IMPO à RMC, e 4 (21%) à CM (p = NS). Dos 323 segmentos do ventrículo esquerdo avaliados, 17 (5,3%) exibiram necrose perioperatória à RMC, e 7 (2,2%) à CM (p = 0,013). Observou-se moderada concordância entre os métodos (kappa = 0,46), havendo divergência, quanto ao diagnóstico de IMPO, em 4 (21%) casos, a maioria com pequenas áreas de necrose perioperatória à RMC, não visualizadas à CM. Em todos os casos com IMPO à RMC, houve elevação significativa de CKMB e troponina I. CONCLUSÃO: Houve moderada concordância diagnóstica entre os métodos para a detecção de IMPO, mas a RMC permitiu a visualização de pequenas áreas de necrose miocárdica perioperatória, não identificadas pela CM e associadas à elevação de marcadores bioquímicos de lesão miocárdica.

Miocárdio viável pela tomografia computadorizada com Tc-99m (MIBI) sensibilizada por nitroglicerina endovenosa

FUNDAMENTO: A seleção de pacientes com doença coronariana crônica para recanalização baseia-se na detecção do miocárdio comprometido, potencialmente viável. OBJETIVO: Avaliar o miocárdio isquêmico, potencialmente viável pelo SPECT com MIBI sensibilizado por nitroglicerina em dose máxima tolerada. MÉTODOS: Investigamos de forma prospectiva, de abril de 2004 a novembro de 2005, pela tomografia computadorizada por emissão de fóton único SPECT com Tc-99m (MIBI), 40 pacientes (média etária 62 ± 8,9 anos, 30 homens) com obstrtução coronariana demonstrada angiograficamente, e a cintilografia miocárdica foi realizada em repouso e com nitroglicerina endovenosa (EV), iniciando com a dose (1 µg/kg/min) e incremento a cada minuto, até a queda da pressão arterial sistólica em 20 mmHg. A redução da perfusão dos segmentos foi classificada em moderada e severa, e comparada depois da nitroglicerina. Analisamos as variáveis angiográficas, hemodinâmicas e de perfusão miocárdica. RESULTADOS: Analisamos 680 segmentos miocárdicos em repouso: 538 com distribuição homogênea e 142 com hipoperfusão (54 com redução moderada e 88 severa). Depois da nitroglicerina, ocorreu aumento da perfusão em 19 (47,5%) de 40 pacientes. Tornaram-se viáveis 55 de 142 segmentos: 33 (61,1%) com redução moderada e 22 (25%) com redução severa, ambos apresentaram aumento significativo da distribuição do radiofármaco (p < 0,001, qui-quadrado). CONCULSÃO: Dos componentes com Tc-99m, está incluído o Tc-99m-2-methoxy-isobutil-isonitrila (MIBI) que, utilizado com dose otimizada de nitroglicerina EV, pode aumentar a captação do radiofármaco em áreas com hipoperfusão moderada e severa. Os resultados deste estudo sugerem aumento da sensibilidade do Tc-99m (MIBI) pela nitroglicerina para detecção de miocárdio viável.

Tc-99m-Besilesomab Antigranulozytenszintigraphie: Diagnostische Wertigkeit und Einfluss auf die Therapieentscheidung bei Patienten mit Verdacht auf entzündliche Veränderungen des muskuloskelettalen Apparates - Ergebnisse einer Blinded-Read-Studie

Magdeburg, Univ., Med. Fak., Diss., 2012

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

Well-differentiated papillary mesothelioma of the tunica vaginalis testis: imaging on Tc-99m heat-denatured red blood cell scintigraphy.

An 18-year-old man presented with a growing painless left scrotal mass. Sonography showed a hydrocele and a homogeneous, well-encapsulated left extratesticular mass with similar echogenicity as the normal testis, suggestive of a splenogonadal fusion. To substantiate the diagnosis, the patient underwent Tc-99m heat-denatured red blood cell scintigraphy showing normal physiological hyperactivity in the spleen but activity similar to the blood pool projecting on the upper part of the left testis. This made testicular splenic tissue less likely. The patient underwent resection and histopathology revealed a well-differentiated papillary mesothelioma. Inguinal orchidectomy was subsequently performed and the patient was free of recurrence at 18 months.

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.