Three-dimensional endoanal ultrasound should be considered as first-line diagnostic tool in the preoperative work-up for perianal fistulas : The authors reply to the letter: Mathew RP, Patel V, Low G. Caution in using 3D-EAUS as the first-line diagnostic tool in the preoperative work up for perianal fistulas. Radiol Med 2020;125:155-156. - Brillantino A; Iacobellis F; Reginelli A; Renzi A; Grassi R (La Radiologia medica, 2020)