Detection of Myocardial Metabolic Abnormalities by 18F-FDG PET/CT and Corresponding Pathological Changes in Beagles with Local Heart Irradiation

OBJECTIVE: To determine the efficacy of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the detection of radiation-induced myocardial damage in beagles by comparing two pre-scan preparation protocols as well as to determine the correlation between abnormal myocardial FDG uptake and pathological findings. MATERIALS AND METHODS: The anterior myocardium of 12 beagles received radiotherapy locally with a single X-ray dose of 20 Gy. 18F-FDG cardiac PET/CT was performed at baseline and 3 months after radiation. Twelve beagles underwent two protocols before PET/CT: 12 hours of fasting (12H-F), 12H-F followed by a high-fat diet (F-HFD). Regions of interest were drawn on the irradiation and the non-irradiation fields to obtain their maximal standardized uptake values (SUVmax). Then the ratio of the SUV of the irradiation to the non-irradiation fields (INR) was computed. Histopathological changes were identified by light and electron microscopy. RESULTS: Using the 12H-F protocol, the average INRs were 1.18 +/- 0.10 and 1.41 +/- 0.18 before and after irradiation, respectively (p = 0.021). Using the F-HFD protocol, the average INRs were 0.99 +/- 0.15 and 2.54 +/- 0.43, respectively (p < 0.001). High FDG uptake in irradiation field was detected in 33.3% (4/12) of 12H-F protocol and 83.3% (10/12) of F-HFD protocol in visual analysis, respectively (p = 0.031). The pathology of the irradiated myocardium showed obvious perivascular fibrosis and changes in mitochondrial vacuoles. CONCLUSION: High FDG uptake in an irradiated field may be related with radiation-induced myocardial damage resulting from microvascular damage and mitochondrial injury. An F-HFD preparation protocol used before obtaining PET/CT can improve the sensitivity of the detection of cardiotoxicity associated with radiotherapy.

Estudo dos efeitos da radioterapia no tecido cardíaco e sua associação com o metabolismo energético / Study of the effects of radiation therapy in cardiac tissue and its association with energy metabolism

Durante o tratamento radioterápico para tumores localizados na região torácica, parte do coração frequentemente é incluída no campo de tratamento e pode receber doses de radiação ionizante, significativas em relação à terapêutica. A irradiação do coração é capaz de causar importantes complicações cardíacas ao paciente, caracterizadas por alterações funcionais progressivas cerca de 10 a 20 anos após a exposição do órgão. Devido ao seu alto grau de contração e grande consumo energético, o tecido cardíaco é altamente dependente do metabolismo oxidativo que ocorre nas mitocôndrias. Danos as estas organelas podem levar ao decréscimo da produção de energia, tendo um impacto direto sobre a performance cardíaca. Ainda, ao interagir com as células, a radiação ionizante pode gerar uma série de eventos bioquímicos que conduzem a uma resposta celular complexa, em que muitas proteínas parecem estar envolvidas. Tendo em vista tais conhecimentos, o objetivo do estudo foi avaliar o aspecto ultraestrutural do tecido cardíaco, a bioenergética mitocondrial e a expressão diferencial de proteínas após irradiação. Os ensaios foram realizados em amostras de tecido cardíaco de ratos Wistar irradiados com dose única de 20 Gy direcionada ao coração. As análise tiveram início 4 e 32 semanas após irradiação. A análise ultraestrutural foi realizada através de microscopia eletrônica de transmissão. A respiração mitocondrial foi mensurada em oxígrafo, a partir das taxas de consumo de oxigênio pelas fibras cardíacas. A identificação de proteínas diferencialmente expressas foi investigada através de duas técnicas proteômicas: 2D-DIGE (2-D Fluorescence Difference Gel Electrophoresis) e uma abordagem label-free seguida de espectrometria de massas. Os resultados mostraram que os efeitos tardios da radiação incluem a degeneração das mitocôndrias e das unidades contráteis do tecido cardíaco, disfunções na cadeia respiratória mitocondrial e expressão diferencial de proteínas...

During radiotherapy for tumors located at toracic region, part of the heart is often included in the treatment field and may receive a significant ionizing radiation dose comparing to the therapeutics. Heart irradiation is able to cause substantial cardiac complications to patient, characterized by functional progressive changes from 10 to 20 years after the exposure of the organ. Because of its high level of contraction and large energetic consumption, cardiac tissue is highly depending on oxidative metabolism which happens at mitochondrias. Damage to these organelles can lead to decreased energy production, having a direct impact on cardiac performance. Even when interacting with cells, ionizing radiation can generate a series of biochemical events that lead to a complex cellular response, in many proteins seem to be involved. Given this knowledge, the aim of the study was to evaluate the ultrastructural appearance of cardiac tissue, mitochondrial bioenergetics and differential expression of proteins after irradiation. The tests were performed on samples of cardiac tissue of rats irradiated with single dose of 20 Gy directed to the heart. The analysis started 4 to 32 weeks after irradiation. The ultrastructural analysis was performed by transmission electron microscopy. Mitochondrial respiration was measured in oxigraph from rates of oxygen consumption by cardiac fibers. The identification of differentially expressed proteins was investigated using two proteomic techniques: 2D-DIGE (2-D Fluorescence Difference Gel Electrophoresis) and a label-free approach followed by mass spectrometry. The results showed that the late effects of radiation include degeneration of mitochondria and contractile units of cardiac tissue, dysfunction in the mitochondrial respiratory chain and differential expression of proteins involved in energy metabolism of carbohydrates, lipids and phosphocreatine. In general, the study showed that the cardiac irradiation damages...

Neuroblastoma torácico en la adolescencia: caso clínico / Thoracic neuroblastoma in adolescence: clinical case

Neuroblastoma is predominantly a tumor of early childhood, most cases occur in children under 5 years old. It originates in the adrenal gland and paravertebral ganglion cells (neural crest-derived), being the most common an extracranial solid tumor in children. It is characteristic a spontaneous regression, However in some cases it shows progression and dissemination to other organs. Objetive: To show a neuroblastoma in adolescence, with poor response to chemotherapy and radiotherapy, requiring surgery treatment. Clinical case: A 16 y.o. Female patient, previously asymptomatic, who after a body temperature rise up to 39 ° C, was found to have a tumor in the right hemithorax. Biopsy was compatible with neuroblastoma. Surgical removal of a large 20 x 19 cm tumor was achieved, the only complication presented 10 days postop was recurrent pneumothorax. Conclusion: Despite little or no response to standard treatment, surgical resection of this large tumor achieved complete remission for this patient.

El neuroblastoma es predominantemente un tumor de la infancia temprana que en la mayoría de los casos se presenta en menores de 5 años. Se origina en la glándula suprarrenal y células ganglionares paravertebrales (derivadas de la cresta neural), siendo el tumor sólido extracraneal más común en pediatría, presenta regresión espontánea en algunos casos y en otros progresión y diseminación a otros órganos. Objetivo: Analizar el caso de una adolescente portadora de un neuroblastoma resistente a quimioterapia y radioterapia, que requiere tratamiento quirúrgico. Caso clínico: Paciente asintomática, edad 16 años, que a raíz de alza febril se le detecta un tumor en hemitórax derecho. La biopsia fue compatible con un neuroblastoma. Se realizo la extirpación quirúrgica de un gran tumor con diámetro de 20 cm x 19 cm. A los 10 días se complica con neumotórax recidivante. Conclusión: A pesar de la poca o nula respuesta a las armas terapéuticas habituales: quimioterapia y radioterapia, la cirugía logró la resección del tumor torácico con remisión completa.

Resección quirúrgica de plasmocitoma solitario del esternón asociado a cirugía de revascularización miocárdica: seguimiento a largo plazo / Surgical resection of solitary plasmacytoma of the sternum associated with coronary artery bypass grafting surgery: long-term follow up

The plasmacytomas tumors are caused by a malignant proliferation of plasma cells. Primary tumors of the sternum are uncommon, being this kind of tumors exceptional. We present the case of a 72 years old man with a sternal plasmacytoma, that after 2 years of receiving radiotherapy treatment, had tumor growth, associated with coronary artery disease. In this case, surgical resection of solitary sternal plasmacytoma was performed associated with coronary artery bypass grafting surgery. The chest wall reconstruction was done with a polypropylene mesh. More than 5 years long-term follow up was completed and the patient is asymptomatic and free of malignant proliferation of plasma cells.

Los plasmocitomas son tumores originados por una proliferación neoplásica de células plasmáticas. Los tumores primarios de esternón son infrecuentes, siendo los plasmocitomas solitarios de esternón excepcionales. Presentamos el caso de un hombre de 72 años con un plasmocitoma esternal que después de 2 años post tratamiento con radioterapia presentó aumento de tamaño tumoral asociado a enfermedad coronaria. Se realizó resección quirúrgica del plasmocitoma solitario del esternón asociada a cirugía de revascularización miocárdica con 4 bypass coronarios. La pared torácica fue reconstituida con una malla de polipropileno. A más de 5 años de seguimiento el paciente se encuentra asintomático cardiovascular y libre proliferación maligna de células plasmáticas.