Radioprotección en radioyodoterapia para cáncer tiroideo / Radioprotection in radioiodine therapy for thyroid cancer

Radioiodine therapy is a widely useful tool used in adjuvant treatment for differentiated thyroid cancer and has proven beneficial effect. Is crucial to safeguard and prevent caregivers, medical staff and the general public from the patients treated with I-131 in order to minimize radiation exposure and avoid unnecessary irradiation. There are many guidelines recomendations (ATA, EANM) that are helpful for the prevention, minimize of exposure and possible contamination from the patient. The aim of this study is to provide radiation protection measures used in radioiodine therapy order to avoid contamination of the patient and his environment...

[Normal 131iodine uptake values at 2 and 24 hours]. / Valores normales de captación de 131Yodo de 2 y 24 horas.

BACKGROUND: Radiolabeled iodine uptake is a useful tool in the study of thyroid diseases. AIM: To obtain normal values for 131 Iodine thyroid uptake in healthy volunteers. MATERIAL AND METHODS: A total of 105 subjects were included (52 males and 53 females), with a mean age of 45 years (range: 20 to 68, evenly distributed in decades). A questionnaire was applied and a clinical examination was performed to rule out endocrine diseases. Serum TSH and anti-thyroperoxidase antibodies were also measured. The oral 131I dose was 5-10 microCi, and a Thyrad equipment was used for measurements at 2 and 24 h. RESULTS: Mean global iodine uptake was 5.5%+/-1.8% (range: 2.3-12.0) at 2 h and 16.2+/-4.8% (range: 6.5-30.1) at 24 h. The values at 2 h among women and men were 6.0+/-1.8 and 4.9+/-1.6%, respectively, (p<0.02). At 24 h, the figures were 17.3+/-4.5 and 15.0+/-4.9%, respectively (p=0.01). Compared to their younger counterparts, radioactive iodine uptake was lower among volunteers older than 40 years, at 2 h (5.0+/-1.7 and 6.0+/-1.8, respectively, p<0.02) and at 24 h (14.9+/-4.4 and 17.6+/-4.9%, respectively, p<0.01). CONCLUSIONS: Normal thyroid uptake values in adults are influenced by gender and age. Normal thyroid iodine uptake values are slightly higher in females. Iodine thyroid uptake values decrease slightly in subjects aged more than 40 years.

[Fusion of SPECT with computed tomography or magnetic resonance for the interpretation of abnormal tracer uptake]. / Utilidad clínica de la fusión SPECT/CT con marcadores externos en patología oncológica.

BACKGROUND: Interpretation of abnormal foci with high tracer uptake may require morphological correlation. Fusion of functional images obtained by single photon emission computed tomography (SPECT) and anatomical images obtained by computed tomography (CT) or magnetic resonance (RM) allows an integrated comprehension of complementary information. AIM: To demonstrate that SPECT/CT fusion with external markers is useful in clinical practice to clarify the location and pathological meaning of questionable foci. MATERIAL AND METHODS: Thirty four pairs of images from separate equipments (31 SPECT/CT and 3 SPECT/RM) pertaining to 29 patients, were fused. Fifty one foci of abnormal tracer uptake of uncertain pathological meaning were analyzed. These were classified before and after the fusion as probably malignant or probably benign. RESULTS: Seventy percent of patients had a differentiated thyroid carcinoma. The fusion localized 100% of foci. Nine percent had a normal and 26% an abnormal anatomy. Before fusion 82% of foci were classified as potentially malignant. This figure changed to 59% after the fusion (p <0.01). Therefore the suspicion of malignancy was presumptively confirmed in 72% of foci and fusion results would have reached a 27% of incremental diagnostic value in 14 cases that changed of category (11 with differentiated thyroid carcinoma, one with colorectal cancer, one with a nasal Ewing sarcoma and one with a brain tumor). CONCLUSIONS: The fusion of SPECT and CT is useful in selected patients, specially those with differentiated thyroid carcinoma. The fusion of SPECT and RM is also feasible.

[Role of 18Fluorine-deoxyglucose (FDG) positron emission tomography in the management of lymphomas]. / Utilidad de la deoxiglucosa marcada con flúor-18 (FDG) en el manejo de los linfomas.

Positron emission tomography (PET) with fluorine-18 labeled deoxyglucose (FDG) is useful in the management of lymphomas. In this review, some general concepts of this metabolic test are defined. It has an excellent diagnostic yield in Hodgkin disease as well as in most non Hodgkin lymphomas. Staging, restaging residual mass evaluation and the control of therapy are the main indications for FDG-PET. Images with FDG have a high diagnostic and prognostic value, that is superior to anatomical images and conventional staging techniques. They are also helpful for the assessment of tumor activity in abnormal lymph nodes or large masses that have been treated and reduce their size slowly or show an incomplete resolution. Currently, the resolution of dedicated PET equipments is 6 mm and bigger lesions can easily be detected. The main differences and advantages of FDG versus gallium-67 in lymphoma are also discussed, as well as the initial local experience with the technique in lymphoma patients.

Valores normales de captación de 131Yodo de 2 y 24 horas / Normal 131Iodine uptake values at 2 ano 24 hours

Background: Radiolabeled iodine uptake is a useful tool in the study of thyroid diseases. Aim: To obtain normal values for 131 Iodine thyroid uptake in healthy volunteers. Material and methods: A total of 105 subjects were included (52 males and 53 females), with a mean age of 45 years (range: 20 to 68, evenly distributed in decades). A questionnaire was applied and a clinical examination was performed to rule out endocrine diseases. Serum TSH and anti-thyroperoxidase antibodies were also measured. The oral 131I dose was 5-10 fiCi, and a Thyrad equipment was used for measurements at 2 and 24 h. Results: Mean global iodine uptake was 5.5 percent±1.8 percent (range: 2.3-12.0) at 2 h and 16.2±4.8 percent (range: 6.5-30.1) at 24 h. The values at 2 h among women and men were 6.0±1.8 and 4.9±1.6 percent, respectively, (p <0.02). At 24 h, the figures were 17.3±4.5 and 15.0±4.9 percent, respectively (p =0.01). Compared to their younger counterparts, radioactive iodine uptake was lower among volunteers older than 40 years, at 2 h (5.0±1.7 and 6.0±1.8, respectively, p <0.02) and at 24 h (14.9±4.4 and 17.6±4.9 percent, respectively, p <0.01). Conclusions: Normal thyroid uptake values in adults are influenced bygender and age. Normal thyroid iodine uptake values are slightly higher in females. Iodine thyroid uptake values decrease slightly in subjects aged more than 40years.

Utilidad del PET--FDG en patología neuropediatrica / Usefulness of PET--FDG in neuropediatric pathology

Due to the recent incorporation of positron technology (PET) it appears interesting to review the present indications of fluor-deoxyglucose (FDG) in neuropediatric pathology. The main indication is in the evaluation of refractory epilepsy mainly in cases with negative magnetic resonance or discordance with electroencephalography Some uses in tumors are also discussed, such as tumor characterization and differentiation between radionecrosis and recurrence. The experience between years 2003 and 2007 at the Santiago Military Hospital, using FDG in 66 children and adolescents cases with diverse neurological indications was reviewed.

La incorporación relativamente reciente en nuestro medio de la tecnología de positrones (PET) nos motivó a revisar el uso actual de la flúor-deoxiglucosa (FDG) en neuropediatría. La principal indicación es la evaluación de epilepsia refractaria, especialmente en casos de resonancia magnética negativa o discordancia de ésta con los hallazgos electroencefalográficos. Algunas utilizaciones en tumores también son discutidas, como la caracterización tumoralyla diferenciación entre radionecrosis y recurrencia. Se revisa la casuística del Centro PET del Hospital Militar de Santiago entre los años 2003 y 2007, que comprende 66 casos de niños y adolescentes estudiados con metabolismo glucídico con diversas patologías neurológicas.

Utilidad del PET--FDG en patología gineco-oncológica / Usefulness of PET--FDG in gynecological-oncological pathology

El PET-FDG es un estudio de imágenes de cuerpo entero que evalúa el metabolismo glucídico celular. Su mayor utilidad es en oncología tanto en adultos como en niños. Permite distinguir tumores malignos de benignos, seleccionar los sitios de biopsia, etapificar las neoplasias, determinar la respuesta al tratamiento y distinguir entre cicatriz y enfermedad residual post tratamiento. Diversos estudios han concluido que el PET-FDG es un examen útil en el manejo de la patología gineco-oncológica, destacando en cáncer de endometrio, cérvico uterino y ovárico. En este trabajo, se revisan las indicaciones de la técnica en las diversas patologías ginecológicas neoplásicas y su rendimiento. Asimismo, se presenta la experiencia chilena inicial realizada en el Hospital Militar de Santiago con equipo PET dedicado, donde se han estudiado más de 1.500 pacientes en su gran mayoría oncológicos.

FDG-PET is a whole body scan that evaluates glucose cell metabolism. Its main utility is in adult and children oncology. PET scan is useful differentiating benign from malignant neoplasm, selecting the site for biopsy, staging of the malignancy, evaluating response to therapy and distinguishing scar from residual neoplasm. Different studies have concluded that FDG-PET is a useful study in the gyneco-oncological management, especially in endometrial, cervical and ovarian cancer. This work reviews the principal indications of PET in this pathology and also the initial Chilean experience at the Military Hospital of Santiago with a dedicated PET, where we have studied more than 1,500 cases, most of them in cancer patients.

Utilidad clínica de la fusión SPECT/CT con marcadores externos en patología oncológica / Fusion of SPECT with computed tomography or magnetic resonance for the interpretation of abnormal tracer uptake

Background: Interpretation of abnormal foci with high tracer uptake may require morphological correlation. Fusion of functional images obtained by single photon emission computed tomography (SPECT) and anatomical images obtained by computed tomography (CT) or magnetic resonance (RM) allows an integrated comprehension of complementary information. Aim To demonstrate that SPECT/CT fusion with external markers is useful in clinical practice to clarify the location and pathological meaning of questionable foci. Material and methods: Thirty four pairs of images from separate equipments (31 SPECT/CT and 3 SPECT/RM) pertaining to 29 patients, were fused. Fifty one foci of abnormal tracer uptake of uncertain pathological meaning were analyzed. These were classified before and after the fusion as probably malignant or probably benign. Results: Seventy percent of patients had a differentiated thyroid carcinoma. The fusion localized 100 percent of foci. Nine percent had a normal and 26 percent an abnormal anatomy. Before fusion 82 percent of foci were classified as potentially malignant. This figure changed to 59 percent after the fusion (p <0.01). Therefore the suspicion of malignancy was presumptively confirmed in 72 percent of foci and fusion results would have reached a 27 percent of incremental diagnostic value in 14 cases that changed of category (11 with differentiated thyroid carcinoma, one with colorectal cancer, one with a nasalEwingsarcoma and one with a brain tumor). Conclusions: The fusion of SPECT and CT is useful in selected patients, specially those with differentiated thyroid carcinoma. The fusion of SPECT and RM is also feasible.

Utilidad de la tomografía de emisión de positrones en oncología pediátrica / Utility of positron emission tomography in pediatric oncology

El PET-FDG es una técnica que evalúa el metabolismo glucídico celular. Su mayor utilidad es en oncología, ya que permite distinguir tumores malignos de benignos, seleccionar los sitios de biopsia, etapificar las neoplasias, determinar la respuesta a tratamiento y distinguir entre cicatriz y enfermedad residual post tratamiento. En niños, las principales indicaciones son linfomas, tumores del sistema nervioso central, sarcomas de tejidos blandos, osteosarcoma y sarcoma de Ewing, neuroblastoma y nefroblastoma. Existen otros tumores menos comunes que también pueden ser evaluados eficazmente con FDG tales como: tumores de la vaina de nervios periféricos, hepatoblastomas, tumor de Wilms y cáncer de tiroides. Hay pocas publicaciones en esta población debido al pequeño número de pacientes estudiados y la baja incidencia de cáncer. Es importante considerar las variaciones en la distribución normal del trazador respecto al adulto para optimizar la interpretación de las imágenes. El objetivo de este artículo es efectuar una revisión de las indicaciones del PET–FDG y presentar nuestra casuística inicial en población pediátrica.

Utilidad de la deoxiglucosa marcada con flúor-18 (FDG) en el manejo de los linfomas / Role of 18Fluorine-deoxyglucose (FDG) positron emission tomography in the management of lymphomas

Positron emission tomography (PET) with fluorine-18 labeled deoxyglucose (FDG) is useful in the management of lymphomas. In this review, some general concepts of this metabolic test are defined. It has an excellent diagnostic yield in Hodgkin disease as well as in most non Hodgkin lymphomas. Staging, restaging residual mass evaluation and the control of therapy are the main indications for FDG-PET. Images with FDG have a high diagnostic and prognostic value, that is superior to anatomical images and conventional staging techniques. They are also helpful for the assessment of tumor activity in abnormal lymph nodes or large masses that have been treated and reduce their size slowly or show an incomplete resolution. Currently, the resolution of dedicated PET equipments is 6 mm and bigger lesions can easily be detected. The main differences and advantages of FDG versus gallium-67 in lymphoma are also discussed, as well as the initial local experience with the technique in lymphoma patients.

Uso de la tomografía de emisión de positrones PET con F18-FDG en la evaluación de lesiones pulmonares sospechosas de neoplasia / Use of positron-emission tomography with F18-fluorodeoxyglucose for the assessment of lung lesions suspicious of malignancy

Positron-emission tomography (PET) with F18-fluorodeoxyglucose (FDG) is very helpful in the evaluation and management of lung lesions. It is specially useful for the characterization of solitary nodules, for the staging, evaluation of recurrence and therapeutic response in non-small cell lung cancer, for the evaluation of small cell lung cancer and for the assessment of pulmonary metastases. This article is a literature review on PET with FDG in lung cancer. A preliminary analysis of PET results at the Military Hospital in Santiago, Chile, is also presented.

Evaluación radiosotópica en cardiología / Radiosotopic evaluation in cardiology

The current applications of nuclear cardiology techniques are reviewed. Coronary artery disease is the most important and prevalent cardiovascular problem in most developed countries and also in Chile. Different approaches can be employed for its diagnosis and prognosis, as well as for risk stratification and preoperative evaluation. Myocardial infarction assessment and ischemia recognition with radionuclide perfusion images are also reviewed, including new protocols applying functional parameters addition. Viability detection after myocardial infarction or in patients with ischemic cardiomyopathy are discussed. Stress protocols with the use of exercise or pharmacological action for ischemia production, the diagnostic value of perfusion SPECT and the use of Thallium-201, Tc-99m-Sestamibi and metabolic images with Fluorine18-Fluordeoxyglucose are also mentioned.

Se revisan las aplicaciones comunes de las técnicas de medicina nuclear en cardiología. La más importante y prevalente patología cardiovascular en países desarrollados y también en Chile es la enfermedad coronaria. Diferentes aproximaciones pueden ser empleadas para su estudio, pronóstico, estadificación de riesgo y evaluación preoperatoria. Se revisan, además, el infarto miocárdico y el reconocimiento de isquemia con estudio de perfusión incluyendo nuevos protocolos que aplican pro- ducción de isquemia; el valor diagnóstico del SPECT de perfusión, el uso de Talio; Tc-99m Sestamibi e imágenes metabólicas con Flúor-18- Fluorodeoxiglucosa son también mencionadas.

Uso de la tomografía de emisión de positrones en el cáncer colorrectal / Use of positron emission tomography in colorectal cancer

The value of PET (Positron Emission Tomography) in colorectal cancer is presented. PET is a novel technique that uses F-18-FDG (fluorodeoxiglucose) to assess glucose metabolism by whole body imaging. It has been demonstrated that malignant cells have both increase of glucose uptake and utilization. In colorectal cancer, PET is indicated for staging, assess recurrence, liver metastasis and treatment follow-up. PET is more sensitive and specific than CT (Computed Tomography) and is cost effective. In 30% of cases PET may change patient management, avoiding unnecessary procedures.

El valor de la tomografía de emisión de positrones (PET) en el cáncer colorrectal es revisado en esta corta comunicación. El PET es una nueva técnica que emplea F-18-FDG (Fluoro-deoxiglucosa) para evaluar el metabolismo glucídico de las células mediante imágenes de todo el cuerpo en un solo examen. Se ha demostrado que las células malignas tienen captación y utilización aumentada de la glucosa. En el cáncer colorrectal el PET esta indicado para el diagnóstico de extensión inicial, sospecha de recurrencia, evaluación de metástasis hepáticas, recidiva tumoral y control de terapias. El PET es más sensible y específico que la tomografía computada y es una técnica costo efectiva. En aproximadamente un 30% de los casos ayuda a cambiar el manejo terapéutico de los pacientes evitando procedimientos innecesarios. Este año entrará en funciones un ciclotrón en la Comisión Chilena de Energía Nuclear y la primera cámara PET multicristal de alta resolución de Chile y Sudamérica será instalada en el Hospital Militar de Santiago.

PET, tomografía por emisión de positrones: presentación de un caso clínico / Positron emission tomography (PET): a clinical case report

Se presenta un caso clínico de una paciente estudiada por nódulo pulmonar solitario con Tomografía por Emisión de Positrones utilizando Flúor18-deoxiglucosa. Con el estudio metabólico quedó en evidencia la malignidad del nódulo y la aparición de dos nuevos focos sugerentes de diseminación, no demostrados por otras técnicas diagnósticas.

Eficacia de F18_fluorodeoxiglucosa SPECT para evaluar infarto reciente y viabilidad miocárdica / Efficacy of F18_fluorodeoxiglucose SPECT for recent infarction evaluation and myocardial viability

El mejor examen disponible para evaluar viabilidad miocárdica es el Fluor18-fluordeoxiglucosa (F18FDG) que mide metabolismo celular y utilización de glucosa como sustrato. Su asociación a marcadores de flujo miocárdico permiten conocer la existencia y extensión de tejido con función potencialmente recuperable. El objetivo de este trabajo fue evaluar el rendimiento del F18FDG SPECT en pacientes con infarto reciente de miocardio. Material y Método: Se estudiaron preliminarmente 23 pacientes (7M,16H), edad promedio 63 ñ 13 años (rango:40-85), con evolución promedio de 10 días postinfarto (rango:5-24). En 14 casos, el infarto fue anterior y en 9 casos inferior. Se realizó F18FDG en cámara ADAC doble cabezal con colimadores de 511 Kev, con dosis promedio de 211 MBq (rango: 52-444) , con adquisición de las imágenes a los 45 min postinyección. Contemporáneamente, se efectuó Tl201 SPECT reposo redistribución con dosis de 148 MBq y adquisición de imágenes a los 10 min y 3 hrs. Se realizó análisis visual de ambos estudios en forma independiente dividiendo el miocardio en 17 segmentos (total de segmentos: 391). Resultados: Tanto en el SPECT con Tl201 como en el con F18 FDG hubo 21/23 (91 por ciento) de casos con segmentos alterados, en que hubo concordancia de 83 por ciento. En el Tl201 reposo redistribución, se encontraron 32 por ciento de segmentos alterados y en el estudio conjunto Tl201 reposo F18 FDG, se observó un 34 por ciento de segmentos alterados del total de los analizados. En dichos segmentos, el Tl201 reposo redistribución mostró 65 por ciento de segmentos viables y el Tl201 F18 FDG 77 por ciento de segmentos con viabilidad. Conclusión: 1) Tanto el Tl201 como el estudio con F18 FDG tienen buena concordancia, tanto por pacientes como por segmentos, en el infarto reciente de miocardio. 2) El SPECT Tl201 asociado a F18 FDG detecta un mayor número de segmentos viables que el examen de Tl201 reposo- redistribución aislado

Valor de la tomografía de emisión de positrones con F18-fluordeoxiglucosa (PET-FDG) en pacientes con cáncer de mama / Use of positron emisión tomography (pet) with F18-fluorodeoxyglucose in patients with breast cancer

El PET es un técnica de imágenes que permite evaluar el hipermetabolismo glucídico tumoral con Flúor-18deoxiglucosa (FDG). Su utilidad en cáncer de mama ha sido ampliamente estudiada. El objetivo fue evaluar los resultados del PET-FDG en nuestro medio en pacientes con cáncer de mama. Método: SE analizaron 52 estudios en 44 pacientes con cáncer de mama (100 por ciento mujeres, edad: 52 ± 12 años). Se utilizó equipo PET dedicado y se realizaron imágenes de cuerpo entero. Se efectuó seguimiento clínico e histológico cuando estaba disponible. Resultados: A. Diagnóstico inicial y etapificación: En 2 pacientes, se encontraron focos hipermetabólicos en mamas, sin compromiso a distancia y fueron sometidas a cirugía con confirmación histológica. Tres pacientes fueron evaluadas sólo para etapificación. B. Reetapificación: De 23 pacientes, en 11 se demostró diseminación secundaria, por lo que fueron tratadas con quimioterapia u hormonoterapia, sin confirmación histológica de las lesiones. En 12 pacientes, el PET fue negativo y el seguimiento clínico no ha demostrado alteraciones hasta la fecha. C. Sospecha de recidiva: En 15 pacientes se realizó el PET por alteraciones en la mamografía, elevación de marcadores tumorales o alteraciones sospechosas en otros estudios. Se encontró recidiva local en 2 pacientes, metástasis en 6 y PET normal en 7. D. Evaluación de terapia: En 9 pacientes, se controló la respuesta a tratamiento, encontrando regresión parcial, progresión o respuesta mixta en 8 de ellas y un estudio negativo (respuesta completa). Conclusión: En esta serie inicial, se confirma que el PET FDG es una herramienta útil en el control del cáncer de mama, tanto en diagnóstico, etapificación, reetapificación, evaluación de recurrencia y control de terapia.

Osteopenia en cirrosis biliar primaria: estudio en 20 pacientes / Osteopenia in primary biliary cirrhosis: study in 20 patients

We studied 20 female patients, aged 51 ñ 13.6 years old, with the diagnosis of Primary Biliary Cirrhosis (PBC) to assess osteopenia, main involved sites and its relation to menopause, some parameters of mineral metabolism and the degree of histological liver involvement. The diagnosis of PBC was based in histological, clinical and laboratory features. Bone densitometry was measured with dual-photon densitometer and compared with values of a normal female population from the laboratory. When compared to controls, studied patients had a significantly lower lumbar spine bonedensity and total bone mineral content and a non significantly lower density in femoral neck and total body. Serum calcium, phosphorus, magnesium, PTH and urinary calcium/creatinine ratio were within normal limits. Lumbar spine density was no significantly lower in patients with more severe liver histological involvement and in postmenopausal women. No correlation was found between the duration of postmenopausal period and the degree of osteopenia. It is concluded that patients with PBC have a clear lumbar spine osteopenia and a lower total mineral content and that these parameters worsen in a non significant fashion in subjects along with liver histological involvement and with the length of post menopausal period