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Logallo N, Fromm A, Waje-Andreassen U, Thomassen L, Matre K.Logallo N, et al.J Ultrasound. 2014 Jan 29;17(1):21-6. doi: 10.1007/s40477-014-0065-x. eCollection 2014 Mar.J Ultrasound. 2014.PMID: 24616748Free PMC article.