512 slice multidetector row ct scanner

Images were obtained using a 512-slice multi-detector row CT scanner (General Electric Healthcare, Milwaukee, WI, USA). The following scanning parameters were used: axial plane, 0.625 mm slice thickness, 230 mAs, 140 kV, and rotation time 1 s with 0.3 mm reconstruction in axial and coronal views. The patient's imaging scans were uploaded to General Electric Universal Viewer software 6.0 SP10.2 (GE Co, Barrington, IL, USA). Two trained neuro-otologists blindly performed the measurements using the OTOPLAN software as follows (Figure 1): (i) the cochlear diameter (A-value) was determined by measuring the length of a straight line starting from the midpoint of the round window passing through the mid-modiolus axis and reaching the furthest point on the basal turn; (ii) the width of the cochlear base (B-value) was measured as a straight line perpendicular to the A-value line at the mid-modiolus; and (iii) the cochlear height (H-value) was measured as a straight line starting from the lowest point at the base and ending at the apex. Next, the software automatically calculated the CDL at the organ of Corti level based on the following formulas: