title: Comparison of echo-planar sequences for perfusion-weighted MRI: which is best?
abstract: We compared gradient-echo (GRE), spin-echo (SE) and stimulated-echo (STE) echo-planar imaging sequences for perfusion-weighted imaging at different field strengths. Focal cerebral ischaemia was induced by endovascular occlusion of the middle cerebral artery in eight rats. MR was performed at 4.7 T or 2.35 T. With each sequence, we acquired data sets before, during and after bolus injection of Gd-DTPA with a time resolution of 1.2 s per image. The perfusion-weighted images were assessed with regard to image quality, artefacts, signal-to-noise ratio (SNR), and signal-at-tenuation-to-noise ratio (delta SNR) of the non-ischaemic tissue. Visual assessment showed GRE-EPI images acquired at 4.7 T to suffer from distortion due to susceptibility artefacts. Artefacts were less marked with the SE and STE series. The GRE-EPI sequence gave the highest SNR and delta SNR. At 2.35 T, the SNR of the STE sequences was less than 3 and therefore did not allow construction of reliable signal-time curves. SE-EPI was best suited for perfusion-weighted imaging at high field strength thanks to its minimal distortion artefacts and high SNR. Using lower field strengths (2.35 T and less), susceptibility artefacts are reduced; GRE-EPI sequences are then best suited, because they have the highest SNR and T2* sensitivity.
authors.affiliation: Department of Neuroradiology, University of Heidelberg Medical School, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Heiland
authors.forename: W
authors.initials: W
authors.lastname: Kreibich
authors.forename: W
authors.initials: W
authors.lastname: Reith
authors.forename: T
authors.initials: T
authors.lastname: Benner
authors.forename: A
authors.initials: A
authors.lastname: Dörfler
authors.forename: M
authors.initials: M
authors.lastname: Forsting
authors.forename: K
authors.initials: K
authors.lastname: Sartor
mesh_terms: D000818:Animals; D001921:Brain / Q000098:blood supply; D002545:Brain Ischemia / Q000175:diagnosis*; D003287:Contrast Media; D017352:Echo-Planar Imaging / Q000295:instrumentation*; D019786:Gadolinium DTPA; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000502:physiology; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA