Catálogo de publicaciones - libros

imaging. This trend is influenced technically by the advent of more efficient detectors, improved image processing methods, faster computers, brighter and sharper displays and larger systems for image storage and archiving. The evolution of digital imaging reflects the fast development of information processing technology. In this context measures to describe the quality of medical images are very important. Intuitively we use the terms sharpness, contrast and the amount of noise in an image dependent on the applied radiation dose and the biophysical properties of the examined objects. Quantitative methods for specifying and evaluating the imaging capacity of digital radiographic systems have become an important tool for users, researchers, engineers and service specialists. Of most applications conventional film based methods may be replaced by digital

An overview of five lectures introducing the basic principles of nuclear magnetic resonance, factors affecting relaxation properties and signal, pulse sequences, equipment for magnetic resonance imaging, image acquisition and reconstruction, together with examples of applications, is provided. References to more detailed sources are included.

In this introductory chapter to MRI the main concepts useful to obtain a diagnostic image are summarized. This short overview does not pretend to be rigorous nor exhaustive. It is primarily intended to be a guideline to understand the physics that is developed in the subsequent chapters (see M.O Leach chapter^1). Only the essential is presented. For instance, the concept of echo is not a prerequisite to understand the MRI, though essential to make MRI practical. It will be briefly outlined at the end.

This paper will address two issues in quality assurance: i) Biological effects and safety in MR imaging; ii) MRI artifacts and quality control.

Despite that Magnetic Resonance Imaging (MRI) was introduced as aclinical imaging tool more than 25 years ago, it continues to be characterized by fast-paced technological evolution that has a profound influence on its clinical applicability. This chapter presents a few selected recent technological MRI innovations and new clinical applications.

This chapter summarizes the background for and the applications of several MRI methodologies that image physiological and functional parameters in the brain. These include diffusion MRI, perfusion MRI and Blood Oxygen Level Dependent functional MRI.

Magnetic resonance spectroscopy (MRS) detects electromagnetic signals produced by the atomic nuclei within molecules that are present in living tissues. It can be used to obtain in situ concentration measures for certain chemicals in living systems. This chapter will introduce the physics and technology of MRS signal detection. It will also introduce a few basic biochemical concepts that are relevant to MRS.

The aim of this report is to show the use of MRI in clinical routine, to explain what we can see and what we cannot see with MRI.

Ultrasound has been used in medicine for at least 50 years. Its current importance can be judged by the fact that, of all the various kinds of diagnostic images produced in the world, 1 in 4 is an ultrasound scan. Ultrasound energy is exactly like sound energy, it is a variation in the pressure within a medium. The only difference is that the rate of variation of pressure, the frequency of the wave, is too rapid for humans to hear. Medical ultrasound lies within a frequency range of 30 kHz to 500 MHz. Generally, the lower frequencies (30 kHz to 3 MHz) are for therapeutic purposes, the higher ones (2 to 40 MHz) are for diagnosis (imaging and Doppler), the very highest (50 to 500 MHz) are for microscopic images. For diagnostic purposes two main techniques are employed; the pulse-echo method is used to create images of tissue distribution; the Doppler effect is used to assess tissue movement and blood flow.

Ultrasound imaging modality has the major advantage, as compared to other medical imaging modes, to provide real-time acquisitions. It is a cheap modality compared to MRI and others, and it is non-invasive. One interest in using ultrasound imaging is to study the dynamic behaviour of various organs such as arteries, liver, heart. Today’s scanners allow the visualization of the structures in gray scale images and the visualization of the flow information in color Doppler mode images. Both information can be acquired simultaneously. In this chapter we will present the basic principles leading to the design of probes.