RESUMEN
BACKGROUND: The decreasing image quality in heavier patients can be compensated by administration of a patient-specific dose in myocardial perfusion imaging (MPI) using a cadmium zinc telluride-based SPECT camera. Our aim was to determine if the same can be achieved when using a conventional SPECT camera. METHODS: 148 patients underwent SPECT stress MPI using a fixed Tc-99m tetrofosmin tracer dose. Measured photon counts were normalized to administered tracer dose and scan time and were correlated with body weight, body mass index, and mass per length to find the best predicting parameter. From these data, a protocol to provide constant image quality was derived, and subsequently validated in 125 new patients. RESULTS: Body weight was found to be the best predicting parameter for image quality and was used to derive a new dose formula; A admin (MBq) = 223·body weight (kg)(0.65)/T scan (min). The measured photon counts decreased in heavier patients when using a fixed dose (P < .01) but this was no longer observed after applying a body-weight-dependent protocol (P = .20). CONCLUSIONS: Application of a patient-specific protocol resulted in an image quality less depending on patient's weight. The results are most likely independent of the type of SPECT camera used, and, hence, adoption of patient-specific dose and scan time protocols is recommended.
Asunto(s)
Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Imagen de Perfusión Miocárdica/instrumentación , Compuestos Organofosforados/administración & dosificación , Compuestos de Organotecnecio/administración & dosificación , Tomografía Computarizada de Emisión de Fotón Único/instrumentación , Anciano , Peso Corporal , Medios de Contraste/administración & dosificación , Enfermedad de la Arteria Coronaria/fisiopatología , Esquema de Medicación , Diseño de Equipo , Análisis de Falla de Equipo , Femenino , Cámaras gamma , Humanos , Aumento de la Imagen/instrumentación , Interpretación de Imagen Asistida por Computador/instrumentación , Masculino , Imagen de Perfusión Miocárdica/métodos , Atención Dirigida al Paciente/métodos , Modelación Específica para el Paciente , Radiofármacos/administración & dosificación , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Tomografía Computarizada de Emisión de Fotón Único/métodosRESUMEN
BACKGROUND: Guidelines for SPECT myocardial perfusion imaging (MPI) traditionally recommend a fixed tracer dose. Yet, clinical practice shows degraded image quality in heavier patients. The aim was to optimize and validate the tracer dose and scan time to obtain a constant image quality less dependent on patients' physical characteristics. METHODS: 125 patients underwent Cadmium Zinc Telluride (CZT)-SPECT stress MPI using a fixed Tc-99m-tetrofosmin tracer dose. Image quality was scored by three physicians on a 4-point grading scale and related to the number of photon counts normalized to tracer dose and scan time. Counts were correlated with various patient-specific parameters dealing with patient size and weight to find the best predicting parameter. From these data, a formula to provide constant image quality was derived, and subsequently tested in 92 new patients. RESULTS: Degradation in image quality and photon counts was observed for heavier patients for all patients' specific parameters (P < .01). We found body weight to be the best-predicting parameter for image quality and derived a new dose formula. After applying this new body weight-depended tracer dose and scan time in a new group, image quality was found to be constant (P > .19) in all patients. CONCLUSIONS: Also in CZT SPECT image quality decreases with weight. The use of a tracer dose and scan time that depends linearly on patient's body weight corrected for the varying image quality in CZT-SPECT MPI. This leads to better radiation exposure justification.
Asunto(s)
Tamaño Corporal , Dosis Máxima Tolerada , Imagen de Perfusión Miocárdica/métodos , Compuestos Organofosforados/administración & dosificación , Compuestos de Organotecnecio/administración & dosificación , Tomografía Computarizada de Emisión de Fotón Único/métodos , Cadmio/efectos de la radiación , Femenino , Humanos , Interpretación de Imagen Asistida por Computador/métodos , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Seguridad del Paciente , Dosis de Radiación , Protección Radiológica/métodos , Radiofármacos/administración & dosificación , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Telurio/efectos de la radiación , Recuento Corporal Total/métodos , Zinc/efectos de la radiaciónRESUMEN
BACKGROUND: The coronary calcium score (CCS) provides independent diagnostic and prognostic information on top of myocardial perfusion imaging (MPI) in patients suspected for coronary artery disease, but requires an additional computed tomography (CT) scan. OBJECTIVE: We investigated the accuracy and inter-reader reproducibility of visual estimation of the CCS on the CT used for attenuation correction. METHODS: 250 patients undergoing single photon emission computed tomography MPI and Agatston CCS were included. The CCS was also visually estimated on the CT for attenuation correction by two separate readers blinded to the Agatston CCS, and was categorized into a six-point scale (0, 1-10, 11-100, 101-400, 401-1000 and > 1000). RESULTS: The median Agatston CCS was 82 [25th-75th percentile: 0-562], with a range from 0 to 7287. Of the visually estimated CCS, 60% (reader 1) and 65% (reader 2) were classified correctly into the 6 categories. 93% (reader 1) and 88% (reader 2) of the visually estimated CCS did not vary by more than one category from the Agatston CCS. The intraclass correlation coefficient for agreement between the Agatston CCS and the visually estimated CCS was 0.95 for reader 1 and 0.94 for reader 2. The intraclass correlation coefficient for inter-reader reproducibility of the visually estimated CCS was 0.96. CONCLUSION: The CCS can be accurately estimated on the CT for attenuation correction, as high agreement is demonstrated with the Agatston CCS and inter-reader reproducibility is excellent. If no traditional Agatston CCS is performed, the degree of atherosclerosis should be assessed by means of estimating CCS on the CT for attenuation correction.
Asunto(s)
Angiografía por Tomografía Computarizada , Angiografía Coronaria/métodos , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Vasos Coronarios/diagnóstico por imagen , Tomografía Computarizada Multidetector , Imagen de Perfusión Miocárdica/métodos , Tomografía Computarizada por Tomografía Computarizada de Emisión de Fotón Único , Calcificación Vascular/diagnóstico por imagen , Anciano , Enfermedad de la Arteria Coronaria/fisiopatología , Circulación Coronaria , Vasos Coronarios/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador , Valor Predictivo de las Pruebas , Pronóstico , Reproducibilidad de los Resultados , Índice de Severidad de la Enfermedad , Calcificación Vascular/fisiopatologíaRESUMEN
OBJECTIVE: Regadenoson is a recently approved selective adenosine-2A receptor agonist to induce pharmacological stress in myocardial perfusion imaging (MPI) procedures using a single bolus injection. MATERIAL AND METHODS: We included 123 patients referred for MPI because of suspected coronary arterial disease (CAD). Of these, 66 patients underwent a regadenoson stress test and 57 patients underwent an adenosine stress test preceding standard myocardial SPECT imaging. Technicians, physicians and patients were asked to report their experience using questionnaires. RESULTS: As compared to adenosine, regadenoson did not produce any atrio-ventricular block (0 vs. 10% with adenosine), but did produce minor tachycardia and minimal blood pressure changes while all other side effects were milder and shorter. There were fewer patients with severe complaints after taking regadenoson than adenosine (17% vs. 32%, respectively, p<0.01). The most frequent complaint reported was dyspnea, followed by flushing and chest pain. However, when they did occur, they usually disappeared rapidly. The overall symptom score, including severity and duration of side effects, was significantly lower after regadenoson than after adenosine (6.7±6.3 vs. 10.0±7.9, respectively; p<0.01.) SPECT imaging results were similar. The regadenoson procedure was faster and more practical. CONCLUSION: Regadenoson, the new selective adenosine-2A receptor agonist, is a stress agent for MPI with a patient- and department friendly profile.
Asunto(s)
Agonistas del Receptor de Adenosina A2/farmacología , Enfermedad Coronaria/diagnóstico por imagen , Prueba de Esfuerzo/métodos , Imagen de Perfusión Miocárdica/métodos , Purinas/farmacología , Pirazoles/farmacología , Tomografía Computarizada de Emisión de Fotón Único/métodos , Adenosina/efectos adversos , Adenosina/farmacología , Agonistas del Receptor de Adenosina A2/administración & dosificación , Agonistas del Receptor de Adenosina A2/efectos adversos , Adulto , Anciano , Anciano de 80 o más Años , Bloqueo Atrioventricular/inducido químicamente , Disnea/inducido químicamente , Femenino , Rubor/inducido químicamente , Corazón/efectos de los fármacos , Humanos , Inyecciones Intravenosas , Masculino , Persona de Mediana Edad , Países Bajos , Purinas/administración & dosificación , Purinas/efectos adversos , Pirazoles/administración & dosificación , Pirazoles/efectos adversos , Encuestas y Cuestionarios , Taquicardia/inducido químicamenteRESUMEN
IMPLICATIONS: We describe a patient with frontal hygroma after spinal anesthesia--a rare complication. This condition should be considered in patients after spinal anesthesia with persisting orthostatic headache. Risk factors include ventriculo-peritoneal shunt or brain atrophy caused by old age.