RESUMEN
OBJECTIVES: To assess evaluability and diagnostic accuracy of a low dose CT angiography (CTA) protocol for carotid arteries using latest Iterative Reconstruction (IR) algorithm in comparison with standard 100â¯kVp protocol using previous generation CT and IR. MATERIALS AND METHODS: 105 patients, referred for CTA of the carotid arteries were prospectively enrolled in our study and underwent CTA with 80â¯kVp and latest IR algorithm (group 1). Data were retrospectively compared with 100 consecutive patients with similar examination indications that had previously undergone CTA of carotid arteries with a standard 100â¯kVp protocol and a first generation IR algorithm (group 2). Image quality was evaluated with a 4-point Likert-scale. For each exam CT number, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) at level of common carotid artery (CCA), internal carotid artery (ICA) and at level of Circle of Willis and Effective Dose (ED) were evaluated. 62 Group 1 patients underwent a clinically indicated DSA and results were compared with CTA. RESULTS: No exams reported as not diagnostic. The overall mean CT number value of all arterial segments was above 450 HU in both groups. Significant lower noise, and higher SNR and CNR values were found in group 1 in comparison with group 2 despite the use of 80â¯kVp. In 62-group 1 patients studied by DSA, CTA showed in a segment-based analysis a sensitivity, negative predictive value and accuracy of 100%, 100% and 99% respectively. Mean ED in group 1 was 0.54⯱â¯0.1â¯mSv with a dose reduction up to 86%. CONCLUSIONS: CTA for carotid arteries using latest IR algorithm allows to perform exams with submillisievert radiation exposure maintaining good image quality, overall evaluability and diagnostic accuracy.
Asunto(s)
Algoritmos , Arterias Carótidas/diagnóstico por imagen , Estenosis Carotídea/diagnóstico por imagen , Angiografía por Tomografía Computarizada/instrumentación , Tomografía Computarizada Multidetector/instrumentación , Interpretación de Imagen Radiográfica Asistida por Computador , Tomógrafos Computarizados por Rayos X , Anciano , Anciano de 80 o más Años , Angiografía de Substracción Digital , Bases de Datos Factuales , Diseño de Equipo , Estudios de Factibilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Dosis de Radiación , Exposición a la Radiación/efectos adversos , Exposición a la Radiación/prevención & control , Reproducibilidad de los Resultados , Estudios Retrospectivos , Índice de Severidad de la EnfermedadRESUMEN
INTRODUCTION: Multidetector Computed Tomography Angiography (MDCTA) is presently the imaging modality of choice for aortic disease. However, the effective radiation dose and the risk related to the use of contrast agents associated with MDCTA is an issue of concern. Aim of this study was to assess image quality of a low dose ECG-gated MDCTA of thoracic aorta using different concentration contrast media without tailored injection protocol. METHODS: Two-hundred patients were randomised into four different scan protocols: Group A (Iodixanol 320 and 80 Kvp tube voltage), Group B (Iodixanol 320 and 100 Kvp tube voltage), Group C (Iomeprol 400 and 80 Kvp tube voltage) and Group D (Iomeprol 400 and 100 Kvp tube voltage). Image quality, noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and effective dose (ED) were compared among groups. RESULTS: No significant differences in image noise, SNR and CNR between groups with the same tube voltage. Significant differences in SNR and CNR were found among groups with 80 kV versus groups using 100 kV but without differences in terms of image quality. ED was significantly lower in groups with 80 kV. CONCLUSIONS: Multidetector Computed Tomography Angiography protocols using 80 kV and low concentration contrast media are feasible without need of tailored injection protocols.