Asymmetric-echo, short TE, retrospectively gated MR imaging of the heart and pulmonary vessels. Academic Article uri icon

Overview

abstract

  • Although retrospectively cardiac-gated (cine) magnetic resonance imaging has shown promise for large-vessel pulmonary vascular imaging, it has not been able to depict the peripheral pulmonary vasculature, where signal is dephased because of susceptibility and/or motion artifacts. The authors developed a cine pulse sequence that uses asymmetric echoes and radio-frequency envelopes to achieve reduced gradient moments and a short TE, thereby reducing signal losses due to disordered flow and susceptibility effects. The effects of TE (2.8-12 msec) and the degree of echo symmetry as measured by the echo symmetry fraction (ESF) (0.6-1.0) are considered in the pulmonary vasculature and the heart. In pulmonary vessels, the signal-to-noise ratio nearly doubled as TE was decreased from 12 to 2.8 msec, but there was only about a 15% difference as the ESF decreased from 1.0 to 0.6, consistent with T2* losses dominating gradient moment dephasing. At a TE of 2.8 msec, the sequence improves visualization of pulmonary vessels and may be helpful for diagnosing pulmonary emboli. In the heart, however, the contrast-to-noise ratio between blood and cardiac tissue decreased by 30% as TE decreased from 12 to 2.8 msec and was not affected by changes in ESF. Flow artifacts in the cardiac blood pool, including those that can aid in diagnosis (eg, signal loss due to "jet" flow), are much less pronounced when a small ESF and short TE are used, making this sequence less attractive for investigation of cardiac flow irregularities. The reduced flow artifacts in this case, however, permit excellent depiction of gross cardiac anatomy.

publication date

  • January 1, 1994

Research

keywords

  • Coronary Vessels
  • Image Enhancement
  • Magnetic Resonance Imaging
  • Pulmonary Artery
  • Pulmonary Veins

Identity

Scopus Document Identifier

  • 0028390777

Digital Object Identifier (DOI)

  • 10.1002/jmri.1880040205

PubMed ID

  • 8180450

Additional Document Info

volume

  • 4

issue

  • 2