ABSTRACT
Objective:To investigate the reproducibility of inflow-based vascular-space-occupancy (iVASO)-MRI in quantifying skeletal muscle perfusion and its potential clinical value in patients with dermatomyositis (DM).Methods:Totally 15 consecutive patients with DM and 15 healthy volunteers were enrolled in this prospective study from December 2018 to April 2019 at Nanfang Hospital, Southern Medical University. All subjects underwent T 1WI, short-tau inversion recovery (STIR) T 2WI, and iVASO-MRI of thigh on a 3.0 T MR scanner. According to findings on T 1WI and STIR T 2WI, the muscles were divided into normal, unaffected, edematous and atrophic or fat-infiltrated groups. Maximum arteriolar muscular blood volume (MBVa_max) and mean MBVa (MBVa_mean) of these 4 groups of muscles were obtained by 2 radiologists independently. In order to evaluate the reproducibility of iVASO, the repeated scan was performed 3 days later in 17 subjects (12 healthy volunteers and 5 DM patients), and the MBVa values were measured to calculate the intraclass correlation coefficients (ICC). The MBVa_max and MBVa_mean among the 4 groups were compared by using Kruskal-Wallis H test and the differences of each 2 groups was compare by using Mann-Whitney U test. Results:The ICC between the 2 observers was 0.95 and 0.96 for MBVa_max and MBVa_mean, respectively. The ICC between repeated tests was 0.87 and 0.89 for MBVa_max and MBVa_mean, respectively.There was significant difference among normal muscles, unaffected muscles, edematous muscles and atrophic or fat-infiltrated muscles ( P<0.001). Post hoc comparisons of MBVa_max and MBVa_mean showed that compared to normal muscles, unaffected muscles, edematous muscles and atrophic or fat-infiltrated muscles had a significant decrease of MBVa ( P<0.05). Unaffected muscles and edematous muscles showed no significant difference in terms of MBVa_max and MBVa_mean (both P=0.99), which were significantly higher than those of atrophic or fat-infiltrated muscles ( P<0.05). Conclusions:iVASO-MRIcan reliably quantify the MBVa of thigh muscular arteriolar, and it is potentially valuable in the diagnosis of DM.