Introduction to magnetic resonance imaging

✍ Scribed by Talagala, S. Lalith ;Lowe, Irving J.

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 1009 KB
• Volume: 3
• Category: Article
• ISSN: 1043-7347
• DOI: 10.1002/cmr.1820030303

✦ Synopsis

Cross-sectional magnetic resonance imaging using the spin-warp technique is described in detail. NMR signals originating from different positions in a three-dimensional object are discriminated viu slice-selection, phaseencoding, and frequency-encoding procedures. During slice selection, magnetization corresponding to a narrow slice of the object is excited by a frequency selective rf pulse applied in the presence of a magnetic field gradient perpendicular to the slice. The spatial information along one of the dimensions in the imaged plane is encoded into the phase of the ensuing signal by incrementing, in successive experiments, the magnitude of a field gradient applied before signal detection (phase-encoding). The spatial information along the other dimension defining the imaged plane is incorporated into the frequency of the signal by imposing a gradient during signal detection. Cross-sectional images are obtained by two-dimensional Fourier transformation of a series of appropriately phase-and frequencyencoded echoes. Extension of the method to multi-slice imaging is also discussed.