TY - JOUR T1 - MRI appearance does not change in the first 7 days after acute hamstring injury—a prospective study JF - British Journal of Sports Medicine JO - Br J Sports Med SP - 1087 LP - 1092 DO - 10.1136/bjsports-2016-096881 VL - 51 IS - 14 AU - Arnlaug Wangensteen AU - Roald Bahr AU - Robbart Van Linschoten AU - Emad Almusa AU - Rodney Whiteley AU - Erik Witvrouw AU - Johannes L Tol Y1 - 2017/07/01 UR - http://bjsm.bmj.com/content/51/14/1087.abstract N2 - Background The optimal timing of MRI following acute hamstring injury is not known and is mainly based on expert opinions.Aims To describe the day-to-day changes in the extent of oedema and investigate the optimal timing for detection of fibre disruption on MRI following acute hamstring injuries.Study design Prospective, descriptive study.Methods We performed standardised MRI (1.5T) ≤1 day after injury in male athletes with acute hamstring injury. If initial MRI revealed positive signs of injury (increased signal intensity on fluid sensitive sequences), consecutive MRIs were obtained daily throughout the subsequent week (ie, 7 times). The MRI parameters (day 1–7) were scored by a single radiologist using a standardised scoring form. The day-to-day changes in the extent of oedema (distance from tuber, craniocaudal length, mediolateral width and anteroposterior depth) and the presence and extent of fibre disruption (tear) were assessed with descriptive statistics and repeated measures using analysis of variance of log-transformed data. The overall main effect for time was reported with a significance level set at p<0.05.Results 13 out of 132 male athletes assessed for eligibility between January 2014 and December 2015 were included. 1 dropped out, while 12 (31 years, range 20–49) completed the study; 11 had 7 MRI scans each and one had 5 MRI scans performed. There were no significant day-to-day changes for any of the extent of oedema measures (p values ranging from 0.12 to 0.81). Fibre disruption (tear), present in 5 of the athletes, was detectable from day 1, with small and insignificant day-to-day changes (p values ranging from 0.45 to 0.95).Conclusions We observed insignificant day-to-day changes in the extent of oedema throughout the first week following acute hamstring injury. Fibre disruption (tear) was detectable from the first day after injury. These findings indicate that MRI can be performed on any day during the first week following an acute (hamstring) muscle injury. ER -