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Pediatr Radiol (2006) 36: 10821085 DOI 10.1007/s00247-006-0255-6
TECHNICAL INNOVATION
Janaka Wansapura . Robert Fleck . Eric Crotty . William Gottliebson
Frequency scouting for cardiac imaging with SSFP at 3 Tesla
Received: 24 March 2006 / Revised: 3 May 2006 / Accepted: 23 May 2006 / Published online: 8 July 2006 # Springer-Verlag 2006
Abstract Steady-state free precision techniques are often used in cine cardiac MRI, but are highly susceptible to off-resonance artifacts. In this article, we review the types and prevalence of off-resonance artifacts in the left ventricle on a 3 T MR scanner and describe the implementation of a technique to mitigate these artifacts. A group of 16 healthy children underwent SSFP cine imaging in the short axis. The synthesizer frequency was adjusted after scouting for the optimal frequency in a series of SSFP images with different frequency shifts. A total of 136 short-axis slices were examined for artifacts after the frequency adjustment. A significant number of slices in the apex region contained dark bands, flow artifacts and/or bright out-of-plane coherent artifacts. However, only five slices (3.6%) had artifacts that were detrimental to the accurate detection of myocardial boundaries. This technique offers a fast and easy way to suppress off-resonance artifacts in SSFP imaging at 3 T.
Keywords SSFP . True FISP . 3 Tesla . Cardiac MRI .
Off-resonance . Artifacts
Introduction With the wide availability of clinical 3 T whole-body MR scanners, interest in cardiac imaging applications at 3 T has been steadily growing. Improvement of gradient capabilities has also contributed to implementation of fast imaging techniques such as steady-state free precision (SSFP) also known as TrueFISP, bFFE and FIESTA at higher field strengths, according to the vendors. These techniques have become the workhorse of cardiac imaging for assessing wall motion and ventricular function because of the superior contrast of blood to the myocardial wall. Recent studies have shown that SSFP images have increased signal-to-noise ratio (SNR) and increased tissueblood contrast at 3 T compared to 1.5 T [13]. At 3 T, the SSFP technique has been used for coronary artery imaging [4, 5] and first-pass perfusion [6, 7] in addition to routine cine imaging and has benefited tremendously from the higher SNR.
However, SSFP imaging at 3 T is not without...