Pamela Humeres

Is the addition of ECG gating to technetium-99m sestamibi SPET of value in the assessment of myocardial viability ? An evaluation based on two-dimensional echocardiography following revascularization

The main goal of this study was to evaluate whether the addition of ECG gating to technetium-99m sestamibi single-photon emission tomography (SPET) perfusion imaging assists the prediction of recovery of regional wall motion abnormalities after revascularization. Thirty-six patients with coronary artery disease were included in the study. All had wall motion abnormalities, and 31 (86%) had a clinical history of myocardial infarction. Coronary artery bypass surgery was performed in 18 patients and angioplasty in the remainder. All underwent ECG-gated and non-gated SPET at rest and after intravenous dipyridamole. Two-dimensional echocardiography was performed at a mean of 27 days before revascularization and at a mean of 69 days following revascularization to assess segmental wall motion changes. Perfusion prior to revascularization was analysed qualitatively and quantitatively on gated and non-gated SPET, and the results compared with those of echocardiography. Bullseye parameters were obtained from a normal database, generated from data in 40 normal volunteers, using dipyridamole ECG-gated and non-gated sestamibi SPET. There was good concordance between gated and non-gated qualitative analysis (79% with kappa=0.65) for normal, viable or necrotic segments. Gated SPET predicted functional recovery in 27 of 35 (77%) segments showing echocardiographic improvement while non-gated SPET did so in 30 of 39 (77%) such segments. Gated SPET predicted no functional recovery in 20 of 45 (44%) segments that did not show improved wall motion after revascularization, while with non-gated SPET the figure was 18 of 51 (35%). The positive predictive values of gated and non-gated SPET with regard to the recovery of wall motion following revascularization were 52% and 48%, while the negative predictive values were 71% and 67%, respectively.99mTc-sestamibi had a low predictive value for recovery of function if visual assessment was used in the analysis of SPET data. Quantitative bullseye sestamibi parameters (defect extension and severity, reversibility and percentage change in extension), from gated or non-gated studies, appear best to distinguish which segments will display improved motility on the echocardiogram after revascularization. The addition of ECG gating does not significantly increase the predictive value of SPET imaging with regard to recovery of function.

Increased bone mineral density in dual X-ray densitometry due to gluteal implants

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.

Análisis de 1.000 casos de estudios metabólicos en Chile con PET 18Flúor-deoxiglucosa (FDG)

Ninetyseven percent of exams were done for oncological indications, mainly lung lesions, lymphoma,colorectal and gastroesophageal, cancer and breast tumors. Only 1% of patients had braintumors. Non tumor neurological indications corresponded to 1.7%. Cardiac studies were only0.3% and inflammatory process corresponded to 1%. The 5.6% corresponded to pediatricpopulation. Six percent of patients were aged less than 18 years and in 50% of them, theindication was oncological, mainly lymphomas, brain tumors, endocrine cancers andsarcomas. The remaining 50% had a neurological indications, mainly for refractory epilepsy.

The predictive value of201Tl rest-redistribution and18F-fluorodeoxyglucose SPECT for wall motion recovery after recent reperfused myocardial infarction

Abstract201Tl and18F-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.MethodsForty-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. SPECT201Tl injected at rest and redistribution (R-R) and also18F-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.ResultsSensitivity [Confidence Interval] for201Tl 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). Both201T1 R-R and18F-FDG presented high negative predictive value (p: ns).Conclusion: In recent MI, SPECT201Tl R-R is a valuable and widely available technique for viability detection, with similar sensitivity and significant better specificity than SPECT18F-FDG.

USO DE LA TOMOGRAFIA DE EMISION DE POSITRONES EN EL CANCER COLORRECTAL

Abstract: Abstract: The value of PET (Positron EmissionTomography) in colorectal cancer is presented. PETis a novel technique that uses F-18-FDG(fluorodeoxiglucose) to assess glucose metabolismby whole body imaging. It has been demonstratedthat malignant cells have both increase of glucoseuptake and utilization. In colorectal cancer, PET isindicated for staging, assess recurrence, livermetastasis and treatment follow-up. PET is moresensitive and specific than CT (ComputedTomography) and is cost effective. In 30% of casesPET may change patient management, avoidingunnecessary procedures.Key words:Key words: PET; F-18-FDG (fluorodeoxiglucose),Colorectal cancer.Resumen: Resumen: El valor de la tomografia de emision depositrones (PET) en el cancer colorrectal es revisa-do en esta corta comunicacion. El PET es una nue-va tecnica que emplea F-18-FDG (Fluoro-deoxiglucosa) para evaluar el metabolismo glucidicode las celulas mediante imagenes de todo el cuerpoen un solo examen. Se ha demostrado que las celu-las malignas tienen captacion y utilizacion aumenta-da de la glucosa. En el cancer colorrectal el PET estaindicado para el diagnostico de extension inicial, sos-pecha de recurrencia, evaluacion de metastasis he-paticas, recidiva tumoral y control de terapias. El PETes mas sensible y especifico que la tomografia com-putada y es una tecnica costo efectiva. En aproxi-madamente un 30% de los casos ayuda a cambiarel manejo terapeutico de los pacientes evitando pro-cedimientos innecesarios. Este ano entrara en fun-ciones un ciclotron en la Comision Chilena de Ener-gia Nuclear y la primera camara PET multicristal dealta resolucion de Chile y Sudamerica sera instaladaen el Hospital Militar de Santiago.Palabras claves:Palabras claves: PET; Cancer Colorrectal; F-18-FDG(fluorodeoxiglucosa).IntroduccionLa tomografia de emision de positrones (PET),es una tecnica de creciente utilizacion en la practicaclinica, en paises donde se encuentra disponible. Sebasa en el uso de radiofarmacos emisores depositrones, los cuales se unen a moleculas trazadorasde mecanismos fisiopatologicos como el flujo sangui-neo y metabolismo celular. La tabla I nos muestraalgunos de estos elementos, siendo el mas emplea-do la Fluor-18 FDG (fluorodeoxiglucosa), que nos in-forma acerca del metabolismo glucidico y se le em-plea en oncologia, cardiologia y neurologia

Simultaneous assessment of function and perfusion during dipyridamolehandgrip Tc-99m sestamibi imaging in chronic coronary artery disease

The main goal of this work was to know the value of ventricular function in addition to perfusion Tc-99m sestamibi images in the assessment of coronary artery disease (CAD) when using dipyridamole (DIP) associated to isometric exercise. We analyzed 52 patients with suspected CAD; 40 of them had coronary lesions ≥ 50% and 12 patients without CAD, conforming study and control groups, respectively. Twenty-eight patients had prior myocardial infarction. A two-day sestamibi protocol was employed with i.v. DIP-handgrip and rest injections, acquiring ECG-gated first pass and planar perfusion images.Sensitivity for perfusion images was 85% and specificity was 91.7%. There was no change between rest and DIP ejection fraction (EF) in controls. CAD patients presented a significant EF decrease with DIP (p: 0.0015). Patients with ischemia in perfusion images had larger EF decrease (p: 0.0001). For the analysis, an EF drop ≥ 5% and any wall motion abnormality (WMA) were considered as having an abnormal response to DIP. CAD sensitivity improved significantly to 92.5% when adding EF drop and to 90% when adding WMA parameters, but specificity decreased to 75% with EF drop, and to 58.3% with WMA. In conclusion, first pass parameters from DIP-isometric exercise in addition to perfusion images are not a significant help in the assessment of CAD.

Evaluación de nódulos y masas pulmonares con PET FDG de alta resolución

Resumen es: Introduccion: El diagnostico y etapificacion de pacientes portadores de lesiones pulmonares con PETFDG permite optimizar el manejo y seleccionar la terap...