This recovery process is known as relaxation . MR pulse sequences: what every radiologist wants to know but is afraid to ask.
Author information: (1)Department of Medical Imaging, University of Toronto, Fitzgerald Building, 150 College St, Room 112, Toronto, Ontario, Canada M5S 3E2. e-MRI Sequences . Forewords Richard L. Ehman xiii Paul C. Lauterbur xv Preface xvii PART I: BACKGROUND Introduction 3 CHAPTER I TOOLS 1 .1 Fourier Transforms (M .A. Abstract.

However, to understand what different type of MRI contrast means and how they are created, we will take a trip to the heart of MRI as called MR pulse sequences. These unique requirements include performing whole-body scanning, estimating the photon attenuation for accurate PET reconstructions, diffusion-weighted imaging as an important contrast in many tumor types, and lung imaging for pulmonary nodule screening. Figure 10. The ability to produce true T2 contrast is appealing. MRI is the imaging technique that has most benefited from technological innovation. By repeating radiofrequent (RF) pulses, fat will have more transversal magnetization than water. As a result, echo time ( TE ) is generally shorter for GRE sequences than for SE sequences. Arguably, one of the most important advantages of MRI is its ability to create multiple imaging contrasts such as T1, T2, and proton density. When radiofrequent pulses are repeated, fat will contribute more to the final MRI image and therefore be represented as a high signal (white).

But the longer scan times, may make this set of imaging sequences less desirable, given our patients’ conditions and clinical situations..

This relaxation time varies from one type of tissue to another. When GRE sequences are used with low-flip-angle excitations, short values of repetition time ( TR ) … The spin echo is the pulse sequence that helps us obtain higher quality images in terms of image contrast.
Handbook of MRI Pulse Sequences edited by Bernstein, Matt A., King, Kevin F., and Zhou, Xiaohong Joe. Burlington, MA, Elsevier Academic Press, ISBN:0‐12‐092861‐2, 1017 pp. Bitar R(1), Leung G, Perng R, Tadros S, Moody AR, Sarrazin J, McGregor C, Christakis M, Symons S, Nelson A, Roberts TP. Zhou) 2 1 PART II: RADIOFREQUENCY PULSES Introduction 3 1 CHAPTER 2 RADIOFREQUENCY PULSE …

The many advances have led to improvements in quality and acquisition speed of MRI sequence. First, because only one RF-pulse is applied, the echo can be recorded much more quickly in a GRE sequence. HANDBOOK OF MRI PULSE SEQUENCES MATT A. BERNSTEIN. KEVIN F. KING, XIAOHONG JOE ZHOU. Radiofrequency pulses are sent in, causing the atoms to ‘flip’ into another plane and then ‘relax’ back when the pulse is turned off. Bernstein) 5 1 .2 Rotating Reference Frame (X .J. PET/MRI systems have unique requirements for the MRI scan components, which consist of various MR pulse sequences.