Pitfalls in urinary stone identification using CT attenuation values: are we getting the same information on different scanner models?

Introduction: Evaluate the capability of different Computed Tomography scanners to determine urinary stone compositions based on CT attenuation values and to evaluate potential differences between each model.

Methods: 241 human urinary stones were obtained and their biochemical composition determined. Four different CT scanners (Siemens, Philips, GEMS and Toshiba) were evaluated.

Characterization of human renal stones with MDCT: advantage of dual energy and limitations due to respiratory motion.

Objective: Our aim was to determine, using CT attenuation values, the chemical composition of 241 human renal stones placed in a jelly phantom and to analyze the influence of respiratory motion on the classification.

Materials And Methods: The stones were placed in a jelly simulating the X-ray attenuation of the kidneys. A dynamic platform was used to apply to the phantom free-breathing motion (sinusoidal motion in z-axis) and motion due to lack of maintenance of a breath-hold (5 mm x s(-1) in z-axis).

Degradation of the z- resolution due to a longitudinal motion with a 64-channel CT scanner.

Isotropic acquisitions are routinely achievable with 64- channel CT scanners,. As it predecessors, it includes MultiPlanar Reformation (MPR) projection for the reconstruction of two-dimensional images and volume rendering for the creation of three dimensional images. The accuracy of images obtained with these postprocessing methods depends on the spatial resolution of image data acquired along the long axis of the patient (ie longitudinal, or z-inis spatial resolution).

Influence of a longitudinal motion on image quality with a 64-channel CT scanner.

Physiologic motions can appear during a Computed Tomography (CT) exam. Even if some motions can be prevented, others are unavoidable. To tempt to correct the resulting artifacts, it is necessary to understand their apparition and their influence on the image quality.