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

Captación miocárdica de pirofosfato en amiloidosis cardíaca: caso clínico / Myocardial pyrophosphate uptake in cardiac amyloidosis: clinical case

We report a previously healthy 73 years old woman, who was hospitalised with increasing dyspnea and signs of congestive heart failure. Echocardiography showed a normal left ventricular cavity with increased echogenicity of its walls and severe pulmonary hypertension. A lung ventilation/perfusion scintigraphy concluded that there was a low probability for pulmonary embolism. Coronary angiography was normal. A restrictive cardiomyopathy due to amyloid deposits was suspected. Myocardial pyrophosphate scintigraphy showed intense pyrophosphate uptake in the left ventricle wall. An abdominal fat tissue biopsy was positive for amyloid deposits

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)

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

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

Definiendo la necesidad de especialistas y gammacámaras en medicina nuclear / Defining the need of specialists and gammacameras in nuclear medicine

The aim of this work was to establish the relationship between the number of gammacameras, nuclear medicine specialists and the number of inhabitants in different countries, including Chile. Information was obtained from the International Atomic Energy Agency, Britannic and Canadian Nuclear Medicine Societies, Pan-American Health Organization and American College of Nuclear Physicians. Industrialized countries have approximately 1 specialist and 0.5-3.3 gammacameras per 100,000 inhabitants. The respective figures in Chile are 0.25 and 0.25. Due to the unequal distribution of resources in Chile, the specialists and gammacameras rate in the Metropolitan area is 0.6, some regions or communities do not have these resources and in other communities the rate can raise up to nine. Compared to industrialized countries, Chile lacks nuclear medicine specialists and gammacameras and these resources are unevently distributed

Hipertensión arterial renovascular: rol del cintigrama renal en su detección y en la predicción de la respuesta clínica a la revascularización / Renovascular arterial hypertension: role of renal scintigraphy on it detection and on the prediction of clinical response to revascularization

The most frequently used non invasive tests in the diagnosis of renovascular hypertension are the measurement of peripheral blood renin before and after captopril administration, intravenous pyelogram, renal Doppler examination and radionuclide renography without and with angiotensin converting enzyme inhibitor administration. Measurement of renal vein renin levels and renal angiography are invasive tests commonly used. The latter allows an anatomical disgnosis of renal veins stenosis but does not give information about pressure to revascularization. Radionuclide renography has become the most useful non invasive diagnostic test, with a sensitivity and specificity of 83-94 and 85-97 percent respectively. It also predicts clinical response to revascularization and is useful for follow up after surgery or angioplasty. It also had good results in patients with renal failure, bilateral stenosis or stenosis in a solitary kidney and in transplantated patients

Evaluación del compromiso óseo en alcohólicos intermitentes y continuos, sin daño hepático evidente / Assessment of bone compromised in intermitent and continuing alcoholics without hepatic damage

The effect of chronic alcoholism on bone mass and density has been a subject of considerable controversy. The goal of the present study was to evaluate bone mineral content and density in 2 groups of alcoholic men without evidence of liver damage and determine if the modality of alcohol consumption could cause an alcohol-mediated bone loss. We studied 70 alcoholic non cirrhotic men divided into intermittent (n=38) and continuos (n=32) drinkers. They were compared to 109 normal men. Dual photon densitometry technique using a Gd 153 source was utilized and bone mineral density (BMD) of lumbar spine, femoral neck, Ward's triangle, trochanter, total body bone density (TBBD) and mineral (TBBM) were measured. Hematologic, serum and urinary tests of mineral metabolism were also carried out. No significant differences were found in lumbar spine BMD between normals and alcoholics regardless of the type of alcohol consumption and duration of alcoholism. In the femoral neck, a significant decrease in BMD was found in alcoholics when plotted as regression curves (r=25;p=0,02). In this site duration of alcoholism was significantly correlated to decreased BMD in the total group of alcoholics (r=0,27;p=0,02) and also in the continuous drinker group (r=0,40;p=0,02) when considered duration of alcohol abuse. Total bone mineral was significantly lower in alcoholics (p<0.001) and the subgroups compared to normals and correlated with duration of alcohol abuse (p=0,01). Chemical values revealed normal calcium, phosphorus, alkaline phosphatases, PTH and Ca/Cr concentration. Only serum magnesium was found disminished in 16,6 percent of studied subjects. We conclude that pure alcoholism may affect femoral neck density and total body mineral content, being proportional to the duration of alcohol abuse. Spine density appears unaffected. The type of alcoholic abuse was less important than its duration to cause bone mass abnormalities

Evaluación de masa ósea en fractura de cadera cuantificando columna lumbar y cadera contralateral con densitometría ósea / Evaluation of bone mass in hip fracture, quantifying lumbar bone marrow and contralateral hip with bone densitometry

Hip fracture is frecuent in postmenopausal women with osteoporosis. The aim of this work was to assess bone mass in women with hip fracture and compare it with that of normal women. Bone densities of lumbar spine (considering areas with and without spondylosis), female neck, greater trochanter and unfractures hip Ward's triangle were measured with a double beam isotopic densitometer. Thirty one women aged 58-95 years old were studied and compared with normal women studied at the same laboratory. Bone densities in fractures and normal women were 0.82ñ0.16 and 0.85ñ0.05 g/cm2 in lumbar spine respectively (NS), 0.74ñ0.15 and 0.85ñ0.05 g/cm2 in lumbar spine without spondylosis respectively (p<0.001), 0.60ñ0.11 and 0.65ñ0.08 g/cm2 in femoral neck respectively (NS), 0.49ñ0.09 and 0.52ñ0.09 g/cm2 in greater trochanter respectively (p<0.001) and 0.48ñ0.12 and 0.52ñ0.09 g/cm2 in Ward's triangle respectively (NS). It is concluded that the larger differences in bone density between women with and without hip fracture are observed in the greater trochanter

Estudio comparativo de vaciamiento y tiempo de tránsito de estómago y colon intratorácico post esofagectomía total con técnica radioisotópica / Comparative study of clearence and time of stomach transit and intrathoraxic total post esophagectomy with radioisotopic technique

Después de efectuarse esofagectomía total, ya sea por cáncer o por patología benigna, las alternativas de reconstrucción del tránsito digestivo son el ascenso de un tubo gástrico o la intreposición de un segmento de colon, fectuándose una anastomosis a nivel cervical. El objetivo del presente estudio fue evaluar la motilidad y el vaciamiento del segmento ascendido o interpuesto, mediante técnica radio-isotópica, 3 meses después de la cirugía. Se estudiaron 13 pacientes a quienes se le efectuó ascenso gástrico y 13 pacientes con interposición de colon. Después de la ingesta de un bolo radiactivo de Tc99 súlfuro coloide, se determina el porcentaje de vaciamiento y las características motoras del segmento ascendido a los 15 y 50 seg, 5 y 10 min. y tiempo de tránsito total, tanto en decúbito supino como en posición de pie. Tanto en estómago ascendido como en colon interpuesto, se observan alteraciones motoras de tipo adinámico, con marcado retardo en el tiempo de tránsito y vaciamiento, observándose una mejoría parcial en posición de pie

Cintigrafía de glóbulos rojos marcados con tecnecio en el diagnóstico diferencial entre hemangiomas periféricos y otras masas blandas / Red blood cell scintigraphy tagged with technetium in the differential diagnosis among peripheral hemangiomas and other soft mass

Se evaluó la utilidad de la cintigrafía con glóbulos rojos marcados en el diagnóstico diferencial entre hemangiomatosis periféricas y otras lesiones no hemangiomatosas. Se estudiaron 36 pacientes con diagnóstico presuntivo de hemamgiomas u otras lesiones de partes blandas como malformaciones vasculares y tumores. El estudio cintigráfico se realizó empleando la modalidad planar y la evaluación de las lesiones se hizo mediante la inspección visual, clasificando la intensidad de constraste en una escala de calificaciones de cuatro grados. Además se calculó, mediante computador, un índice de actividad dividiendo las cuentas obtenidas sobre la lesión por las registradas en un área corporal sana de control. Una vez obtenidos los diagnósticos definitivos, por biopsia y evolución clínica, los casos fueron separados en hemangiomas y no hemangiomas. En el grupo de los hemangiomas la calificación promedio de la intensidad de la captación fue 2,9 ñ 1,1 y en el de los no hemangiomas 1,5 ñ 1,1. El índice de actividad promedio en los casos de hemangiomas fue 2,2 ñ 1,1 y en los no hemangiomas 1,2 ñ 0,3. Las diferencias fueron estadísticamente significativamente entre ambos grupos para los dos criterios, que pueden, en conclusión, considerarse útiles para diferenciar hemangiomas de otras lesiones

Aporte de cardiología nuclear al diagnóstico de arritmias / Contribution of nuclear cardiology in the diagnosis of arrhythmias

Se presenta una revisión actualizada del rol de los procedimientos de cardiología nuclear al diagnóstico de arritmias. El enfoque es eminentemente práctico y conceptual. Los procedimientos en general tienen aplicación en investigación; sin embargo, hay aplicaciones específicas de utilidad clínica. En particular, se ha empleado el Análisis de Fase (Fourier), obtenido de ventrículografía radioisotópica en la localización de haces accesorios en pacientes con Síndrome de Wolff-Parkinson-White, con buen rendimiento cuando el haz está lateralizado. Si la vía accesoria se encuentra en el séptum, entonces la diferenciación con la vía normal es más difícil. El Análisis de Fase también se ha empleado en la detección de origen de taquicardias ventriculares, focos de extrasistolia ventricular, bloqueos de rama y la displasia arritmogénica del ventriculo derecho. En pacientes con arritmias puede utilizar las técnicas de perfusión con Talio 201 o Tc99m MIBI, para descartar la presencia de isquemia miocárdica