[Bone metastases of a gallbladder carcinoma detected by positron emission tomography/computed tomography: Case report]. / Carcinoma vesicular de células en anillo de sello: diseminación poco frecuente: Reporte de un caso con tomografía computada por emisión de positrones con fluor 18-deoxiglucosa.

Signet ring gallbladder carcinoma is a rare aggressive variant of mucinous adenocarcinoma with poor prognosis. Positron emission tomography/computed tomography (PET/CT) with Fluor18 deoxyglucose (F18-FDG) is a useful tool in the staging of gallbladder cancer. We report a 68 years old man with a surgically resected acute cholecystitis, whose biopsy was positive for signet ring cell gallbladder carcinoma. During surgery, locoregional lymph nodes, liver or peritoneal involvement were not detected. A PET/CT was performed for staging, finding multiple hypermetabolic lytic bone lesions. Percutaneous biopsy of a pelvis bone lesion, confirmed a metastasis of the tumor. In this case, the staging with PET/CT allowed the diagnosis of unsuspected bone metastases and was a useful tool for deciding the best site of biopsy for histologic confirmation.

Carcinoma vesicular de células en anillo de sello: diseminación poco frecuente: reporte de un caso con tomografía computada por emisión de positrones con fluor 18-deoxiglucosa / Bone metastases of a gallbladder carcinoma detected by positron emission tomography/computed tomography: case report

Signet ring gallbladder carcinoma is a rare aggressive variant of mucinous adenocarcinoma with poor prognosis. Positron emission tomography/computed tomography (PET/CT) with Fluor18 deoxyglucose (F18-FDG) is a useful tool in the staging of gallbladder cancer. We report a 68 years old man with a surgically resected acute cholecystitis, whose biopsy was positive for signet ring cell gallbladder carcinoma. During surgery, locoregional lymph nodes, liver or peritoneal involvement were not detected. A PET/CT was performed for staging, finding multiple hypermetabolic lytic bone lesions. Percutaneous biopsy of a pelvis bone lesion, confirmed a metastasis of the tumor. In this case, the staging with PET/CT allowed the diagnosis of unsuspected bone metastases and was a useful tool for deciding the best site of biopsy for histologic confirmation.

Diferencias en la estimación de isquemia en SPECT de perfusión miocárdica con 99mTc-sestamibi usando bases de datos cuantitativos de ejercicio y dipiridamol / Different ischemia size estimation on exercise and dipyridamole quantitative databases with 99mTc-sestamibi myocardial SPECT

Introducción. Frecuentemente los estudios de perfusión miocárdica con dipiridamol (DIP) son analizados cuantitativamente usando bases de datos de ejercicio (EXE). Objetivo. Comparar un grupo de pacientes con enfermedad coronaria conocida, procesados con bases de datos de DIP y EXE. Métodos. Se analizó los SPECT de perfusión miocárdica con Tc99m-Sestamibi y DIP de 20 hombres y 19 mujeres. Luego de su procesamiento, las imágenes de DIP SPECT fueron comparadas con bases de datos de mapas polares de EXE y DIP. Se analizó la extensión (en pixeles) y la severidad (DS) de los defectos y de las zonas reversibles. Resultados. Hubo concordancia de 92 por ciento en las interpretaciones de los estudios que tenían necrosis, isquemia o ambos (kappa: 0,859). El tamaño de los defectos de estrés fue el mismo con ambas bases de datos tanto en hombres como en mujeres. Sin embargo, en hombres la reversibilidad fue mayor (156,4 +/- 107,7 versus 128,6 +/-113,6 píxeles; p=0,0251) y más severa (699,6 +/- 665,8 versus 486,6 +/- 551,9 SD; p=0,0003) con EXE. En mujeres la reversibilidad fue menor (92,8 +/- 110,3 versus 113 +/- 121,9 pixeles; p=0,0024) y menos severa (278,5 +/- 356,7 versus 363,8 +/-432,7 SD; p=0,0009) con EXE. Conclusiones. Los pacientes que se sometieron a DIP fueron clasificados correctamente como isquemia, necrosis o ambos usando bases de datos de mapas polares de EXE. No obstante, la base de datos EXE subestimó la extensión de los defectos en mujeres y la sobreestimó en hombres.

Background. Frequently, dipyridamole (DIP) myocardial perfusion SPECT is analyzed quantitatively using an exercise (EXE) database. Objective. To compare a group of patients with known coronary artery disease, processed with DIP and EXE polar maps. Method. We studied 20 males and 19 females with DIP Tc99m-Sestamibi myocardial SPECT. After similar processing, the DIP SPECT images were read using both EXE and DIP polar map databases. We analyzed defect and reversibility extension (in pixels) and severity in standard deviations. Results. Agreement to classify patients as having necrosis, ischemia or both was 92 percent (kappa: 0.859). Stress defect size was similar with both databases in males and females. However, in males reversibility resulted larger (156.4 +/- 107.7 versus 128.6 +/- 113.6 pixels; p=0.0251) and more severe (699.6 +/- 665.8 versus 486.6 +/- 551.9 SD; p=0.0003) with EXE. In females, reversibility resulted smaller (92.8 +/- 110.3 versus 113.0 +/- 121.9 pixels; p=0.0024) and less severe (278.5 +/- 356.7 versus 363.8 +/- 432.7 SD; p=0,0009) with EXE. Conclusion. Patients undergoing DIP stress were correctly classified as presenting ischemia, necrosis or both by EXE polar map database. However, EXE database underestimated ischemia extension in females and overestimated it in males.

[Chilean experience with the use of 18F-deoxyglucose positron emission tomography]. / Análisis de 1.000 casos de estudios metabólocos en Chile con PET 18Flúor-deoxiglucosa (FDG).

BACKGROUND: Clinical oncology is the main application of 18F-deoxyglucose (FDG) positron emission tomography (PET). AIM: To evaluate the first 1,000 patients studied with FDG PET in Chile. MATERIAL AND METHODS: Retrospective analysis of 1,000 patients (aged between 1 and 94 years, 550 females) studied with FDG PET, since 2003. All studies were performed in a high resolution Siemens Ecat-Exact HR (+). All reports were based on the visual analysis of three plane and three-dimensional images. RESULTS: Ninety seven percent of exams were done for oncological indications, mainly lung lesions, lymphoma, colorectal and gastroesophageal, cancer and breast tumors. Only 1% of patients had brain tumors. Non tumor neurological indications corresponded to 1.7%. Cardiac studies were only 0.3% and inflammatory process corresponded to 1%. The 5.6% corresponded to pediatric population. Six percent of patients were aged less than 18 years and in 50% of them, the indication was oncological, mainly lymphomas, brain tumors, endocrine cancers and sarcomas. The remaining 50% had a neurological indications, mainly for refractory epilepsy. CONCLUSIONS: PET FDG imaging was effective in the management of diverse diseases of children and adults.

Análisis de 1.000 casos de estudios metabólicos en Chile con PET 18Flúor-deoxiglucosa (FDG) / Chilean experience with the use of 18F-deoxyglucose positron emission tomography

Background: Clinical oncology is the main application of 18F-deoxyglucose (FDG) positron emission tomography (PET). Aim: To evaluate the first 1,000 patients studied with FDG PET in Chile. Material and methods: Retrospective analysis of 1,000 patients (aged between 1 and 94 years, 550 females) studied with FDG PET, since 2003. All studies were performed in a high resolution Siemens Ecat-Exact HR (+). All reports were based on the visual analysis of three plane and three-dimensional images. Results: Ninety seven percent of exams were done for oncological indications, mainly lung lesions, lymphoma, colorectal and gastroesophageal, cancer and breast tumors. Only 1 percent of patients had brain tumors. Non tumor neurological indications corresponded to 1.7 percent. Cardiac studies were only 0.3 percent and inflammatory process corresponded to 1 percent. The 5.6 percent corresponded to pediatric population. Six percent of patients were aged less than 18 years and in 50 percent of them, the indication was oncological, mainly lymphomas, brain tumors, endocrine cancers and sarcomas. The remaining 50 percent had a neurological indications, mainly for refractory epilepsy. Conclusions: PET FDG imaging was effective in the management of diverse diseases of children and adults.

Analysis of the initial experience with first PET scanner and 18F -FDG in Chile

La principal aplicación del PET FDG es en el manejo de pacientes oncológicos debido a la alta correlación entre metabolismo glucídico y actividad tumoral. Objetivo: analizar el grupo inicial de pacientes realizados con el primer equipo PET dedicado existente en Chile. Método: Presentamos los primeros 500 casos estudiados con la cámara Siemens HR+ usando FDG producida en las instalaciones de la Comisión Chilena de Energía Nuclear. Resultados: La mayoría de los diagnósticos de referencia fueron de causa oncológica (96 por ciento). Cuatro por ciento fueron estudiados por patología neurológica o desórdenes psiquiátricos y 1 por ciento por viabilidad miocárdica. Lesiones pulmonares, gastrointestinales, linfomas, cánceres de mama, y melanoma fueron las patologías más comunes. Los pacientes con linfoma y lesiones pulmonares, entre otros, están con seguimiento clínico. Hubo buena concordancia con imágenes anatómicas y la histología en los casos en que estuvo disponible. La fusión de FDG con tomografía computada o resonancia magnética ha sido útil. En un significativo número de casos hubo detección de nuevos sitios anormales tumorales. Conclusión: Confirmamos que las imágenes metabólicas con F18-FDG son útiles para la evaluación y manejo del cáncer, en la práctica clínica.

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

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.

[Fluorodeoxiglucose F18 positron emission tomography imaging (F18FDG) for the assessment of rising levels of serum CA 19-9 in pancreatic mucinous cystadenocarcinoma. Report of one case]. / Estudio de imágenes PET con Flúor18-Desoxiglucosa (F18FDG) en evaluación de elevación de marcador tumoral CA 19-9 en paciente con cistoadenocarcinoma mucinoso de páncreas.

We report a 38 year old female patient with a pancreatic mucinous cystadenocarcinoma. She presented at the onset with a peritoneal rupture that required emergency surgery. Five months later, the patient was subjected to a segmental pancreatectomy and splenectomy. One year later, the patient had a serious gastric bleeding secondary to a gastric ulcer. Due to a persistent increase in her CA 19-9 levels, a Positron Emission Tomography (PET) functional imaging with fluorine 18-deoxyglucose (F18FDG) was done. It showed an intense focal hypermetabolism in the gastric wall reported as a secondary tumour location. The patient was subjected to a total gastrectomy and Roux en Y anastomosis, with a good outcome. The pathological study confirmed the presence of a metastasis of an adenocarcinoma in the gastric wall. The relative value of CA 19-9 markers and FDG PET in pancreatic and gastric carcinomas is discussed.

The predictive value of 201Tl rest-redistribution and 18F-fluorodeoxyglucose SPECT for wall motion recovery after recent reperfused myocardial infarction.

UNLABELLED: 201Tl and 18F-FDG are useful for acute myocardial infarction (MI) assessment. The goal of this study was to compare their predictive value for wall motion recovery in the culprit area after a recent reperfused MI using SPECT technique. METHODS: Forty-one patients (mean age: 56 +/- 12 years) were included, 81% of them male; all were studied within 1-24 days post MI. They underwent angioplasty in 27 cases (12 primary); bypass grafting in 10 cases and successful thrombolysis in 4. SPECT 201Tl injected at rest and redistribution (R-R) and also 18F-FDG, were performed on different days. Processed tomograms were interpreted blinded to clinical or angiographic data. Segmental wall motion assessed with echocardiography at baseline was compared with the 3 month follow up. RESULTS: Sensitivity [Confidence Interval] for 201Tl R-R was 74.6% [60.5-84.5], for FDG it was 82.1% [70.8-90.4]; specificities were 73% [64.3-80.5] and 54.8% [45.6-63.7], respectively. 18F-FDG tended to be more sensitive than 201Tl R-R, but the latter was more specific (p < 0.0004). Both 201Tl RR and 18F-FDG presented high negative predictive value (p: ns). CONCLUSION: In recent MI, SPECT 201Tl R-R is a valuable and widely available technique for viability detection, with similar sensitivity and significant better specificity than SPECT 18F-FDG.

FDG F18 / Rest Tl 201 SPECT patterns in recent myocardial infarction: predictive value for regional function recovery

Background. Detecting viability is important after recent myocardial infarction (MI). SPECT FDG/Tl flow-metabolism patterns for predicting functional recovery were analyzed in this setting. Method. Forty-one patients were studied (56ñ12 years; 80 percent males) with Tl 201 at rest and FDG F18 SPECT at a mean of 8.9 days post MI (range:1-24). All had baseline and 3 month follow-up echocardiography (ECHO) and initial coronary angiography. They were submitted to primary PTCA in 12 cases, late PTCA in 15 and bypass surgery in 10 and thrombolysis was performed in 4 patients as only procedure. A total of 345 culprit artery territory segments were interpreted by 3 nuclear independent observers. Analysis included segments with or without abnormal motion. Results. FDG/Tl 201 on patient basis, had: sensitivity 91percent; specificity 56 percent; positive predictive value 88 percent; negative predictive value (NPV) 63 percent and accuracy 83 percent. The analysis of segments with abnormal contractility showed values of 67 percent, 69 percent, 44 percent, 85 percent and 68 percent, respectively. Reverse mismatch with FDG/Tl appears to predict viability similarly to classical mismatch; severe or moderate match was highly associated with no functional recovery (NPV = 85 percent). Conclusion. Flow-perfusion patterns are variable in recent MI. FDG/Tl 201 SPECT has acceptable accuracy for predicting functional recovery and excellent NPV to further exclude viability

[Clinical application of positron emission tomography (PET)]. / Aplicaciones clínicas del PET.

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.

[Performance of Thallium 201 rest-redistribution spect to predict viability in recent myocardial infarction]. / Rendimiento del SPECT talio201 reposo-redistribución para predecir viabilidad post infarto reciente del miocardio.

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% when patient analysis was performed and 79% when segmental analysis was done in the culprit region. The figures for specificity were 56 and 73% 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.

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.

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