RESUMEN
OBJECTIVES: The purpose of this study was to assess the efficacy of attenuation-corrected (AC) technetium-99m (99mTc)-tetrofosmin single-photon emission computed tomography (SPECT) in detecting viable myocardium compared to 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). BACKGROUND: The role of 99mTc-labeled perfusion tracers in the assessment of myocardial viability remains controversial. Attenuation artifacts affect the diagnostic accuracy of SPECT images. METHODS: Twenty-four patients with coronary artery disease (mean left ventricular ejection fraction 30%) underwent resting 99mTc-tetrofosmin SPECT and FDG PET imaging. Both AC and non-attenuation-corrected (NC) SPECT images were generated. RESULTS: Using a 50% threshold for viability by FDG PET, the percentage of concordant segments of viability between 99mTc-tetrofosmin and FDG on the patient basis increased from 79.8%+/-14.0% (mean+/-SD) on the NC images to 90.8%+/-10.6% on the AC images (p=0.002). The percentage of 99mTc-tetrofosmin defect segments within PET-viable segments, an estimate for the degree of underestimation of viability, decreased from 19.8%+/-15.2% on the NC images to 9.7%+/-12.6% on the AC images (p=0.01). Similar results were obtained when a 60% threshold was used to define viability by FDG PET. When the anterior-lateral and inferior-septal regions were separately analyzed, the effect of attenuation correction was significant only in the inferior-septal region. CONCLUSIONS: The results indicate that AC 99mTc-tetrofosmin SPECT improves the detection of viable myocardium mainly by decreasing the underestimation of viability particularly in the inferior-septal region, although some underestimation/overestimation of viability may still occur even with attenuation correction.
Asunto(s)
Enfermedad Coronaria/diagnóstico por imagen , Fluorodesoxiglucosa F18 , Corazón/diagnóstico por imagen , Compuestos Organofosforados , Compuestos de Organotecnecio , Radiofármacos , Tomografía Computarizada de Emisión de Fotón Único , Tomografía Computarizada de Emisión , Anciano , Anciano de 80 o más Años , Enfermedad Coronaria/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Contracción MiocárdicaRESUMEN
OBJECTIVES: Myocardial blood flow (MBF) in children late after arterial switch operation (ASO) was investigated quantitatively by positron emission tomography (PET). BACKGROUND: In children with transposition of the great arteries (TGA), ASO is widely accepted as the management of choice. The long-term patency of coronary arteries after surgical transfer to the neo-aorta, however, remains a concern. METHODS: Twenty-two normally developed, symptom-free children were investigated by PET with nitrogen-13 ammonia at rest and during adenosine vasodilation 10+/-1 years after ASO. A subgroup of 15 children (9+/-1 years; group A) had simple TGA and underwent ASO within 20 days after birth while 7 (13+/-3 years; group B) had complex TGA and underwent ASO and correction of associated anomalies later after birth. Ten young, healthy adults (26+/-6 years) served as the control group. RESULTS: Resting MBF was not different between groups. After correction for the rate-pressure product as an index of cardiac work, younger children of group A had significantly higher MBF at rest compared to healthy adults (102+/-29 vs. 77+/-6 ml/100 g/min; p = 0.012) while flow in group B was not different from the other groups (85+/-22 ml/100 g/min; p = NS). Hyperemic blood flows were significantly lower in both groups after ASO compared to normals (290+/-42 ml/100 g/min for group A, 240+/-28 for group B, 340+/-57 for normals; p < 0.01); thus, coronary flow reserve was significantly lower in both groups after ASO compared to healthy adults (3.0+/-0.6 for group A, 2.9+/-0.6 for group B, 4.6+/-0.9 for normals; p < 0.01). CONCLUSIONS: Blood flow measurements suggest decreased coronary reserve in the absence of ischemic symptoms in children late after arterial switch repair of TGA. The global impairment of stress flow dynamics may indicate altered vasoreactivity; however, the prognostic significance of these findings needs to be determined.
Asunto(s)
Circulación Coronaria , Transposición de los Grandes Vasos/cirugía , Adolescente , Niño , Vasos Coronarios/fisiología , Femenino , Corazón/diagnóstico por imagen , Humanos , Interpretación de Imagen Asistida por Computador , Masculino , Periodo Posoperatorio , Estudios Prospectivos , Flujo Sanguíneo Regional , Tomografía Computarizada de Emisión de Fotón Único , Transposición de los Grandes Vasos/diagnóstico por imagen , Transposición de los Grandes Vasos/fisiopatologíaRESUMEN
UNLABELLED: This study was designed to evaluate gated 99mTc-tetrofosmin SPECT for prediction of functional recovery proven by sequential MRI. 99mTc-labeled tetrofosmin is a recently introduced tracer for myocardial perfusion. However, its role for viability assessment is still under investigation. METHODS: 99mTc-tetrofosmin uptake in 19 patients with coronary artery disease and severe left ventricular dysfunction was correlated to regional wall thickening before and 4.5 +/- 0.8 mo after successful coronary artery bypass grafting, as derived from corresponding gated short-axis MRI. Preoperative wall thickening determined by gated SPECT was used as an additional parameter for prediction of functional outcome. Optimal threshold cutoffs to separate reversible from irreversible dysfunction were determined by receiver operator characteristic (ROC) analysis. RESULTS: The sensitivity and specificity of regional 99mTc-tetrofosmin for prediction of functional recovery was 87% and 42%, respectively (cutoff: 50% of maximum tracer retention). The area under ROC curves for prediction of functional recovery measured 0.66 +/- 0.01. Segments with > or =50% uptake and impaired but detectable wall thickening determined by gated SPECT had a significantly higher likelihood for functional improvement compared with segments with absent wall thickening (P < 0.05). There was no difference in segments with <50% tracer retention. There was good agreement for ejection fraction measurements by MRI and gated SPECT (mean ejection fraction 32 +/- 12 versus 34 +/- 11; r = 0.71, P < 0.001). CONCLUSION: Regional 99mTc-tetrofosmin uptake provided high sensitivity but limited specificity for prediction of functional recovery after revascularization, leading to fair overall accuracy. Wall thickening assessment derived from gated SPECT may improve the specificity of 99mTc-tetrofosmin uptake for prediction of functional recovery but not the sensitivity in low-flow areas. In addition to the assessment of global function, gated data acquisition can be helpful to improve the overall accuracy of 99mTc-tetrofosmin SPECT for prediction of functional recovery after bypass surgery.
Asunto(s)
Compuestos Organofosforados , Compuestos de Organotecnecio , Tomografía Computarizada de Emisión de Fotón Único , Disfunción Ventricular Izquierda/diagnóstico por imagen , Puente de Arteria Coronaria , Enfermedad Coronaria/diagnóstico , Enfermedad Coronaria/cirugía , Electrocardiografía , Femenino , Corazón/diagnóstico por imagen , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Curva ROC , Radiofármacos , Sensibilidad y Especificidad , Tomografía Computarizada de Emisión de Fotón Único/métodos , Disfunción Ventricular Izquierda/diagnósticoRESUMEN
Standard nuclear medical procedures, such as functional, blood-pool and colloid scintigraphy, play a minor role in the routine workup of liver tumors. However, these techniques are capable of assessing specific organ functions and frequently allow the diagnosis of unclear liver lesions. The sensitivity of scintigraphic procedures can be increased using tomographic imaging (SPECT), the specificity with the introduction of hybrid scanners such as SPECT/CT. Whole body positron emission tomography with 18F-fluoro-deoxy-glucose (FDG) in combination with CT scanning (PET/CT) represents one of the most sensitive imaging modalities for the detection of hepatic metastases and extrahepatic tumor manifestations. For the staging and follow-up of colorectal cancer, FDG-PET/CT represents a standard imaging modality. Metastases from neuroendocrine tumors can be detected using PET and specific tracers such as [68Ga]DOTATOC and [18F]DOPA. Molecular imaging with PET allows the quantification of metabolic processes which can be used for the assessment of an early response to treatment.
Asunto(s)
Carcinoma Hepatocelular/diagnóstico por imagen , Procesamiento de Imagen Asistido por Computador , Neoplasias Hepáticas/diagnóstico por imagen , Tomografía de Emisión de Positrones , Cintigrafía , Tomografía Computarizada de Emisión de Fotón Único , Tomografía Computarizada por Rayos X , Neoplasias Colorrectales/diagnóstico por imagen , Neoplasias Colorrectales/patología , Diagnóstico Diferencial , Hemangioma Cavernoso/diagnóstico por imagen , Hemangioma Cavernoso/patología , Humanos , Neoplasias Hepáticas/patología , Neoplasias Hepáticas/secundario , Estadificación de Neoplasias , Tumores Neuroendocrinos/diagnóstico por imagen , Tumores Neuroendocrinos/patología , Sensibilidad y EspecificidadRESUMEN
Positron emission tomography provides unique qualitative and quantitative information on myocardial perfusion, metabolism and membrane function which potentially has an important impact on diagnostic workup and treatment in patients with known or suspected coronary artery disease (CAD). CAD contributes up to one third of all deaths among persons between the ages of 35 to 60 in western countries. Risk factors and symptoms turned out to have low specificity to identify persons with the disease and thus, will not help to establish objective diagnostic workup. Assessing severity of CAD by coronary angiography and means of binary classification (disease yes/no) of morphological abnormalities, i.e. stenosis > 50%, has shown to poorly correlate with coronary blood flow and, thus, might not serve as an optimal reference standard for the disease. Cardiac PET using N-13 ammonia and Rb-82 represents a well validated and clinically usable technique for both quantitative and qualitative (semiquantitative) assessment of myocardial blood flow. However, the clinical benefit of absolute flow values for diagnosis and localisation of CAD remains controversial. Most centers rely on qualitative image interpretation due to the technical requirements for image processing needed for determination of absolute flow values. However, quantitative assessment of myocardial blood flow might offer advantages when measurement of coronary flow reserve in response to medical or interventional therapy is necessary and in addition may provide early detection of CAD in asymptomatic patients who have risk factors.
Asunto(s)
Circulación Coronaria , Enfermedad Coronaria/diagnóstico por imagen , Enfermedad Coronaria/fisiopatología , Corazón/diagnóstico por imagen , Humanos , Tomografía Computarizada de Emisión , Tomografía Computarizada de Emisión de Fotón ÚnicoRESUMEN
PURPOSE: To evaluate use of positron emission tomography (PET) versus computed tomography (CT) in detection of pancreatic cancer and determine the value of quantitative and visual image interpretation of these techniques. MATERIALS AND METHODS: Within 8 weeks before surgery, 73 patients with suspected pancreatic cancer or chronic pancreatitis underwent imaging with CT and with static PET after injection of 250-350 MBq of 2-(fluorine-18)-fluoro-2-deoxy-D-glucose (FDG). Focal FDG uptake, considered a sign of malignancy, was calculated with standardized uptake values (SUVs) 60 minutes after injection. RESULTS: With FDG PET, pancreatic carcinoma was correctly diagnosed in 41 (95%) of 43 patients, and chronic pancreatitis in 27 (90%) of 30 patients. With an SUV cutoff value of 1.53, both sensitivity and specificity for detection of malignancy were 93%. With CT, pancreatic cancer was correctly diagnosed in 33 (80%) of 41 patients, whereas results in seven (26%) of 27 patients with chronic pancreatitis were false-positive (specificity, 74%). CONCLUSION: FDG PET enabled reliable differentiation of pancreatic adenocarcinoma from chronic pancreatitis. The sensitivity and specificity of visual image interpretation with FDG PET was statistically significantly higher (P < .05) than with CT.
Asunto(s)
Adenocarcinoma/diagnóstico por imagen , Desoxiglucosa/análogos & derivados , Radioisótopos de Flúor , Neoplasias Pancreáticas/diagnóstico por imagen , Tomografía Computarizada de Emisión/métodos , Adulto , Enfermedad Crónica , Diagnóstico Diferencial , Femenino , Fluorodesoxiglucosa F18 , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Persona de Mediana Edad , Pancreatitis/diagnóstico por imagen , Valor Predictivo de las Pruebas , Curva ROC , Sensibilidad y Especificidad , Tomografía Computarizada por Rayos XRESUMEN
We investigated the use of visual and quantitative technetium 99m tetrofosmin ECG-gated single-photon emission tomography (SPET) for the assessment of regional myocardial wall thickening (WT) and left ventricular (LV) ejection fraction (EF) in comparison with gated magnetic resonance imaging (MRI) in patients with a low angiographic LVEF. Gated SPET using 99mTc-labelled flow tracers offers potential for simultaneous assessment of myocardial perfusion and LV function. Few data are available on the use of visual and quantitative gated SPET in patients with low LVEF. In this study 21 patients with low angiographic LVEF (mean 37%+/-5%) were studied. Resting gated 99mTc-tetrofosmin SPET and gated MRI were performed within 48 h. WT was assessed by visual interpretation (five point score) and quantitative analysis based on count increase. There was good agreement for EF measurements by MRI and gated SPET (mean EF: 33%+/-12% vs 35%+/-11%, r = 0.86, P<0.001). Areas under receiver operator characteristic curves (AUC) for differentiation between MRI WT score points ranged from 0.60 to 0.66 for visual SPET WT analysis, from 0.59 to 0.71 for delta count increase values and from 0.46 to 0.60 for % WT, indicating substantial overlap between WT categories. Absolute agreement for visual WT between MRI and gated SPET ranged from 25% to 57% (kappa 0.03-0.25) depending on tracer uptake, and was limited in areas with moderate to severe perfusion defects (kappa 0.03-0.13). It is concluded that gated SPET provided reliable estimates of regional WT and global function in patients with low angiographic LVEF.