Magnetic resonance imaging of short T.sub.2 species with improved contrast

US5150053A · kind A · utility

Assignee

• The Board of Trustees of the Leland Stanford Junior University · US

Inventors

• John M. Pauly · Stanford, US
• Steven M. Conolly · Walnut Creek, US
• Dwight G. Nishimura · Palo Alto, US

Key dates

• Filing date: Jan 25, 1991
• Grant date: Sep 22, 1992
• Expiry date: Jan 25, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R33/56
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Magnetic resonance signals for imaging species having short spin-spin relaxation times (T.sub.2) are obtained without the need for a refocusing lobe. A series of RF excitation pulses are applied to the species with magnetic resonance signals being detected after each RF excitation pulse is applied. The magnetic resonance signals are then combined to provide the imaging signals. In one embodiment, each RF excitation pulse is half of a conventional slice-selective pulse with each pulse being slewed to zero. Contrast between the imaged short T.sub.2 species and longer T.sub.2 species can be enhanced by first applying an RF signal having sufficient amplitude to excite the longer T.sub.2 species but insufficient amplitude to excite the short T.sub.2 species whereby the longer T.sub.2 species are tipped by the RF signal. A magnetic gradient can then be applied to dephase the tipped nuclei of the longer T.sub.2 species. The imaging signals are then obtained from magnetic resonance signals from the short T.sub.2 species.