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Está establecida en la literatura la utilidad de la tomografía por emisión de positrones (PET) con 18F-flúordeoxiglucosa (FDG) en la etapificación, reetapificación y seguimiento del melanoma maligno. Objetivo: Evaluar los resultados del PET FDG en melanoma maligno en nuestro centro. Material y Método: Entre febrero 2003 y julio 2004, se estudiaron 33 pacientes (edad 49±14 años, 52% sexo masculino) referidos para etapificación y reetapificación de melanoma maligno. El examen fue realizado en equipo de alta resolución Siemens Ecat Exact HR+ con dosis de 13±3 mCi de FDG y glicemias en ayunas preinyección de 96±16 mg/dL. Se adquirieron imágenes de cuerpo entero, incluyendo cabeza y extremidades inferiores. El informe se basó en el análisis visual e índice cuantitativo de captación (SUV). Se comparó con otros estudios de imágenes e histología cuando estaban disponibles y se realizó seguimiento clínico. Resultados: Nueve pacientes fueron derivados para etapificación y 24 para reetapificación. En 29 casos, la localización inicial del primario era conocida y en 4 la enfermedad se diagnosticó por la presencia de metástasis ganglionares. Respecto de la localización tumoral, 6 fueron en cabeza y cuello (2 metástasis ganglionares), 5 en coroides, 5 en tronco, 5 en extremidades superiores, 11 en extremidades inferiores y 1 en mucosa (rectal). En 13 pacientes, el PET fue positivo para presencia de actividad tumoral hipermetabólica, 7 en ubicación próxima al primario y 6 alejados de éste, correspondiendo uno de estos últimos a un segundo primario (carcinoma rectal confirmado con histología). De este grupo, en 11 pacientes se confirmó tumor: en 7 hubo confirmación histológica postcirugía y en los restantes, hubo concordancia con imágenes anatómicas y clínica (1 paciente falleció); además, el PET demostró lesiones no sospechadas por otros estudios, las que no han sido confirmadas con histología. Dos fueron falsos positivos, uno por hematoma y otro por ...

Background: The usefulness of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) for the staging and follow up of malignant melanoma, is well established. Aim: To assess the results of PET FDG in patients with malignant melanoma. Patients and Methods: Thirty three patients with malignant melanoma (aged 49 ± 14 years, 17 males), referred for staging and restaging, were studied. The tomography was performed using a Siemens Ecat Exat high resolution equipment. The dose of FDG was 13 ± 3 mCi and the blood glucose levels prior to injection were 96 ± 16 mg/dl. Whole body images, including the head and legs were acquired. The report was based on the visual analysis and standardized uptake value (SUV). Results: Nine patients were referred for staging and 24 for restaging. The location of the primary tumor was known in 29 cases and in four, the disease was diagnosed due to the presence of lymph node metastases. The tumor was located in the head and neck in six patients (including two lymph node metastases), in the choroid in five, in the trunk in five, in the superior limbs in five, in the inferior limbs in 11 and in the rectal mucosa in one. In 13 patients, PET was positive for the presence of hypermetabolic tumor activity. In seven, the location was near the primary tumor and in six, it was distant. In seven patients the presence of tumor was confirmed by surgery and in four, there was concordance between the anatomical imaging and clinical outcome. Two false positive images were detected, one hematoma and one due to the presence of lymph node inflammation. In 16 cases, PET was negative and in four it was not conclusive, all these patients do not have evidence of tumor in the clinical follow up. The primary location of the tumor was not identified in patients referred for lymph node metastases. Conclusions: FDG PET is useful for the staging and re staging of patients with malignant melanoma.

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Introducción: El diagnóstico y etapificación de pacientes portadores de lesiones pulmonares con PET-FDG permite optimizar el manejo y seleccionar la terapia más adecuada para cada uno. Objetivo: Analizar nuestra experiencia preliminar con PET-FDG en la caracterización metabólica de nódulos o masas pulmonares, correlacionándolo con histología cuando estaba disponible y evaluando el impacto en la conducta terapéutica. Material y Método: Se analizaron 58 pacientes referidos para evaluación de nódulo o masa pulmonar (62±7 años de edad; 48% sexo masculino; 40% fumadores). Los PET se realizaron en ayunas, utilizando 13 mCi de FDG-F18, con glicemia preinyección de 101± 5 mg/dl. Se adquirieron imágenes de cuerpo entero con análisis visual de cortes coronales, sagitales y transaxiales e imágenes 3D, así como análisis cuantitativo del índice de captación estandarizada SUV. Los estudios se compararon con histología y seguimiento clínico. Resultados: En 22 pacientes (38%), las lesiones pulmonares fueron hipermetabólicas y en 64%, no hubo evidencias de actividad tumoral. En 24% de los pacientes, se encontraron además lesiones extrapulmonares no sospechadas por otras técnicas de imágenes. El rango de tamaño de los nódulos/masas pulmonares era de 0,5 a 7 cm; en el grupo de PET positivo, el tamaño era mayor a 0,8 cm. Se obtuvo histología en 16/58: en 12 de ellos, se confirmó la presencia de neoplasia (75%), correspondiendo la mayoría a adenocarcinoma. Dos pacientes fueron falsos positivos, demostrándose en uno, un schwanoma abscedado y en el otro, un hamartoma. En 2 pacientes con nódulos sin actividad hipermetabólica al PET (estudio normal), sometidos a cirugía por las características del nódulo al TC, se corroboraron lesiones benignas. En los restantes pacientes con lesiones negativas, el seguimiento clínico no ha demostrado eventos hasta la fecha. Un paciente referido por nódulo pulmonar no fue incluido en el análisis debido a que en el PET presentaba ...

Background: The diagnosis and staging of pulmonary lesions with positron emission tomography (PET) with 18fluorodeoxyglucose (FDG) helps in the selection of the optimal therapy. Aim: To analyze the usefulness of FDG PET in the characterization of pulmonary nodules. Patients and Methods: Fifty eight patients referred for the assessment of a pulmonary nodule or mass (aged 62 ± 7 years, 28 males, 40% smokers), were studied. The imaging study was perfomed in the fasting state injecting 13 mCi of 18FDG. Pre injection blood glucose was 101 ± 5 mg/dl. Whole body images were acquired with visual analysis of coronal, sagittal and trans axial slices and three dimensional images. The standardized uptake value (SUV) was also calculated. Results: Pulmonary lesions were hypermetabolic in 22 patients (38%) and in the rest, there was no evidence of tumor activity. Extrapulmonary lesions were detected in 24% of patients. The size of the nodules ranged from 0.5 to 7 cm. in diameter. Those with positive PET had lesions over 0.8 cm diameter. In 12 of 16 patients with pathological study, the presence of cancer was confirmed. Two patients had false positive images. One had an abscessed Schwanoma and the other, a hamartoma. Two patients with PET images not suspicious of tumor, were operated and the pathology confirmed the absence of cancer. In the rest of patients with a negative study, the clinical follow up has been uneventful. In one patient with multiple hypermetabolic lesions with a pattern suggestive of sarcoidosis, the diagnosis was pathologically confirmed. Conclusions: FDG PET is useful for the characterization of pulmonary lesions and nodules.

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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-fluorodeoxyglucose (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.

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The results of dual x-ray bone densitometry in a patient with bilateral gluteal implants are presented. The patient underwent three measurements of the spine and hips, and one of them was before surgery. A baseline study showed mild osteopenia. After surgery, bone mineral density increased in both femoral necks, because of the superimposition of the implants. A spine phantom with and without a similar implant reproduced the findings in the patient. It is important to consider this type of surgery as a cause of potential bone mineral density artifact.

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We studied left ventricular perfusion and motility in 37 patients with coronary artery disease and disturbances of parietal motility, aged 57 +/- 9 years old, before and after revascularization. Perfusion was assessed with dipyridamole-tc99m MIBI SPECT and motility was assessed with two dimensional echocardiography with amrinone. Myocardial segments were defined as normal, viable or necrotic in both studies. Eighteen subjects were subjected to angioplasty and 19 to coronary bypass surgery. Submitted SPECT and echocardiography were repeated 64 +/- 15 and 69 +/- 23 days after revascularization respectively. The concordance between SPECT and echocardiographic pre-revascularization diagnosis was 60.1% Eighty one percent of segments considered viable with SPECT and 71% thus considered with echocardiography improved after revascularization. Likewise, 50% of segments considered necrotic with SPECT and 68% of segment thus considered with echocardiography did not improve. It is concluded that although there is a good concordance between both methods, they have limitations on the study of myocardial viability and should be considered as second choice.

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We evaluated 148 patients (mean age 45 years) with clinically evident gastroesophageal reflux. A radioisotopic test with 99mTc sulphur-colloid was performed in all; endoscopy in 146, biopsy in 24, acid reflux test and manometric evaluation in 141 and radiologic studies in 85. Sensitivity of the different techniques was: radioisotopes 92%, radiology 87%, acid reflux test 84%; endoscopy 63% and manometric studies 61%. Severity of reflux and esophagitis was adequately predicted from radioisotopic evaluation. We conclude that this radioisotopic test is highly reliable for the diagnosis of gastroesophageal reflux.

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