Accelerated multi ‐snapshot free‐breathing mapping based on the dual refocusing echo acquisition mode technique (DREAM): An alternative to measure RF nonuniformity for cardiac MRI

BackgroundField inhomogeneities in MRI caused by interactions between the radiofrequency field and the patient anatomy can lead to artifacts and contrast variations, consequently degrading the overall image quality and thereby compromising diagnostic value of the images.PurposeTo develop an efficient free ‐breathing and motion‐robust mapping method that allows for the investigation of spatial homogeneity of the transmitted radiofrequency field in the myocardium at 3.0T. Three joint approaches are used to adapt the dual refocusing echo acquisition mode (DREAM) sequence for cardiac applications: ( 1) electrocardiograph triggering; (2) a multi‐snapshot undersampling scheme, which relies on the Golden Ratio, to accelerate the acquisition; and (3) motion‐compensation based on low‐resolution images acquired in each snapshot.Study typeProspective.Phantom/subjectsEurospin II T05 system, torso phantom, and five healthy volunteers.Field strength/sequence3.0T/DREAM.AssessmentThe proposed method was compared with the Bloch ‐Siegert shift (BSS) method and validated against the standard DREAM sequence. Cardiac maps were obtained in free‐breathing and breath‐hold as a proof of concept of the in vivo performance of the proposed method.Statistical testsMean and standard deviation (SD) values were analyzed for six standard regions of interest within the myocardium. Repeatability was assessed in terms of SD and coefficient of variation.ResultsPhantom results indicated low deviat...
Source: Journal of Magnetic Resonance Imaging - Category: Radiology Authors: Tags: Original Research Source Type: research