Aplicaciones clínicas del PET / Positron emission tomography imaging, PET, in clinical practice

Functional imaging using PET (positron emission tomography) has a great impact on current medical practice. It allows to explore, in a very precise way, different processes such as tissue flow and metabolism. Fluor-deoxyglucose labeled with F18 fluorine represents glucose metabolism. Among its main applications are detection, staging, follow up and recurrence assessment of malignant tumors; myocardial viability detection in patients with myocardial infarction or ischemic cardiomyopathy, and evaluation of hyperactive epileptogenic foci in brain. The basis and clinical applications of PET tomography are reviewed especially oriented to its cost benefit relationship, change in patient management and diagnostic value of the most accepted oncological indications. Important economic resources may be saved with PET in this field, considering appropriate staging and recurrence detection, avoiding expensive therapeutic approaches in advanced disease

Rendimiento del SPECT talio 201: reposo redistribución para predecir viabilidad post infarto reciente del miocardio / Performance of thallium 201 rest redistribution SPECT to predict viability in recent myocardial infarction

Background: The detection of viability after acute myocardial infarction is primordial to select the most appropriate therapy, to decrease cardiac events and abnormal remodeling. Thallium201 SPECT is one of the radionuclide techniques used to detect viability. Aim: To evaluate the use of Thallium201 rest-redistribution SPECT to detect myocardial viability in reperfused patients after a recent myocardial infarction. Patients and methods: Forty one patients with up to of 24 days of evolution of a myocardial infarction were studied. All had angiographically demonstrated coronary artery disease and were subjected to a successful thrombolysis, angioplasty or bypass grafting. SPECT Thallium201 images were acquired at rest and after 4 h of redistribution. These results were compared with variations in wall motion score, studied at baseline and after 3 or 4 months with echocardiography. Results: The sensitivity of rest-redistribution Thallium201 SPECT, to predict recovery of wall motion was 91 percent when patient analysis was performed and 79 percent when segmental analysis was done in the culprit region. The figures for specificity were 56 and 73 percent respectively. Conclusions: Rest-distribution Thallium201 SPECT has an excellent sensitivity to predict myocardial viability in recent myocardial infarction. The data obtained in this study is similar to that reported for chronic coronary artery disease

F 18-FDG heart uptake in oncologic pet studies

Background: PET scanning with F-18 FDG is a useful technique to detect malignant lesions. The goal of this work to analyze the frequency of increased heart uptake in routine PET oncologic studies and to correlate F-18 FDG Standardized Uptake Values (SUV) to blood glucose level (BGL)

Utilidad de la medición de permeabilidad alveolocapilar con TC99m-DTPA en el compromiso pulmonar de pacientes portadores del virus de inmunodeficiencia adquirida / Value of Tc99m-DTPA alveolar permeability in lung involvement detection of patients with HIV infection

Se evaluó la utilidad de la medición de permeabilidad alveolocapilar con Tc99m -DTPA en pacientes VIH positivo con posible compromiso pulmonar e infección por pneumocystis carinii (PC) . Se incluyeron 20 pacientes con síntomas respiratorios y 4 con síntomas sistémicos usando como control a un grupo de 11 asintomáticos con similar valor de linfocitos CD, todos con suspensión de tabaco previa. Se realizaron radiografía de tórax, hemograma, esputo inducido y/o fibrobroncoscopía, obteniéndose confirmación de presencia o ausencia de PC en 16 pacientes sintomáticos y 3 asintomáticos. Para detección de PC la sensibilidad fue 78 por ciento, la especificidad 40 por ciento y la seguridad diagnóstica 58 por ciento. Para procesos inflamatorios pulmonares los valores fueron 85 por ciento, 60 por ciento y 79 por ciento, respectivamente. Cuatro de seis pacientes falsos positivos para PC tenían cuadros que explicaban la alteración del DTPA. Concluyendo, el DTPA es sensible pero poco específico para detectar infección pulmonar por PC, siendo superior para procesos inflamatorios

Tomografía SPECT con F18 fluorodeoxiglucosa en infarto reciente del miocardio: caso clínico / Fluorodexyglucose SPECT in recent myocardial infarction: clinical case

We report a 50-year-old woman with a recent myocardial infarction in whom a myocardial perfusion single photon emission computed tomography (SPECT) with Thallium201 was done simultaneously with a F18-fluordeoxyglucose (FDG) SPECT to study glucose metabolism. Myocardial infarction was located in the anteroseptal and apical regions and an echocardiography, done at the second day of evolution, showed a septo-apical hypokinesia. On the tenth day, a coronary angiography showed a critical lesion of the anterior descending coronary artery and an angioplasty with stent placement was performed on the next day. On the twelfth day, a resting, redistribution 201Tl SPECT to study viability and a FDG-SPECT with a dual head high-energy collimator camera were done. Images, acquired 45 min after injection, were analyzed visually. In anterior and medial apical sectors, discordance between flux and metabolism, considered a classical mismatch, was observed. Echocardiographic hypokinesia disappeared three month after revascularization

Tratamiento del hipertiroidismo con radioyodo: efecto de la dosis administrada sobre la función tiroidea y complicaciones asociadas / Treatment of hyperthyroidism with radioiodine: effects of administered dose on complications and thyroid function

Background: Radio-iodine is a definite therapy for Graves disease hyperthyroidism. However, the optimal dosage is still debatable. Aim: To assess the effects of different radioiodine doses on thyroid function and complications in patients with hyperthyroidism. Material and methods: A retrospective analysis of 139 patients with hyperthyroidism, treated with ratioiodine between 1988 and 1998. Radio iodine dose used was classified as low (<10 mCi), intermediate (10-14.9 mCi) or high (ü 15 mCi). Results: Thirty five patients were treated with low doses, 33 with intermediate doses and 71 with high doses. There were no differences between these patients in age, disease severity, frequency of post treatment euthyroidism or complications. Patients treated with low doses had a higher frequency of persistent hyperthyroidism than patients treated with high doses (25.7 and 4.2 percent respectively, p<0,001). Likewise, the frequency of subsequent hypothyroidism was 60 percent in patients treated with low doses and 84.5 percent of those with high doses, in whom it also appeared earlier. Associated complications were clinically irrelevant. In seven patients, Graves ophtalmopathy progressed after treatment, but this progression was not associated with the dose used. Conclusions: Radio iodine in high doses is useful, safe and effective for the treatment of Graves hyperthyroidism

Caso de interés: resultado preliminar de proyecto Fondecyt F 18 flúordeoxiglucosa SPECT para evaluación de miocardio atontado y viabilidad en el infarto reciente / Preliminary results of FONDECYT project F18 fludeoxyglucose SPECT for stunnig myocardial evaluation and infarction viability

Es sabido que la primera causa de muerte en nuestro país es de origen cardiovascular, siendo el infarto agudo una de sus manifestaciones. Se ha demostrado que la presencia de viabilidad miocárdica en la zona infartada, se asocia a un mayor número de eventos coronarios, que disminuyen si se revasculariza, por otro lado la revascularización disminuye la remodelación y la dilatación ventricular izquierda. Entre las técnicas que más han evaluado la viabilidad miocárdica están: el PET F18 FDG. SPECT TI 201 reposo-redistribución y ecocardiografía con dobutamina. Son escasos los estudio que han evaluado viabilidad en el infarto reciente y en consideración a que en Chile no se ha desarrollado el estudio con positrones (PET o SPECT), se presentó un proyecto Fondecyt multiinstitucional, con el fin de implementar esta técnica. Se estudiaron un grupo de 60 pacientes con infarto agudo (con o sin revascularización precoz), con anatomía conocida (coronariografía), correlacionándola con el estudio clásico de Talio reposo-redistribución, evaluando cual de las dos técnicas puede predecir mejor la viabilidad, se considero como gold standar de tejido viable, la recuperación de la motilidad por ecocardiografía al 3er mes post infarto. En la siguiente presentación se muestran los resultados preliminares y un ejemplo de viabilidad en un infarto de un paciente de 23 años

Respuesta analgésica y efectos secundarios en pacientes con metástasis osteoblásticas tratados con samario-153 etilendiaminotetrametilenfosfato / Samarium 153 EDTMP in the treatment of metastatic bone pain: evaluation of analgesic response and secondary effects

Background: Samarium153 EDTMP, a beta and gamma emitter, is used in the palliative therapy of painful bone metastases. Aim: To evaluate the analgesic effects and myelotoxicity of Samarium153 EDTMP in patients with prostate, breast and renal carcinoma. Patients and methods: Twenty patients with bone metastases (11 males), aged 65 years old as a mean, received a 1 to 2 mCi/kg intravenous dose of Samarium153 EDTMP, produced in Chile. Patients were followed thereafter during 4 to 40 weeks. Pain was assessed using a visual analogue scale. Results: Pain decreased from a score of 6.4 prior to treatment, to 2.7 at the fourth week of therapy and the effect lasted a mean of 12.5 weeks. Myelotoxicity was observed in 68percent of cases (WHO stage I in 21 percent, stage II in 37 percent, stage III in 11percent and no patients in stage IV). Platelets were the most affected series and neutrophils the least affected. Cell counts returned to normal between the sixth and eighth week. Seventy nine percent of patients decreased their basal analgesic therapy at the sixth week and 88percent did so at the eighth week. Forty one percent of these patients discontinued all analgesics. Conclusions: Samarium153 EDTMP is effective in the treatment of pain in patients with bone metastases and its myelotoxicity is low to moderate. It should be considered as a therapy for this type of pain, with the precaution of performing periodical bood counts

Antraciclinas y cardiotoxicidad: papel de los estudios isotópicos / Antracyclines and cardiotoxicity: isotopic studies

La pesquisa y seguimiento de cardiotoxicidad secundaria a antraciclinas debe ser considerada, debido a su acción acumulativa y al grave pronóstico en casos con factores de riesgo. La ventriculografía radioisotópica permite: a) evaluar la función ventricular en forma seriada simple y reproducible; b) modificar la terapia, en caso de demostrarse alteración de fracción de eyección ventricular y/o indicar biopsia selectivamente