Trochlear apparatus calcification (TAC) can be an incidental finding in multidetector computed tomography (MDCT) scans. TAC may be misdiagnosed as a foreign body especially in trauma patients. In this study we aim to determine the incidence and types of TAC with cranial and paranasal MDCT scans.
Materials and Methods: Consecutive 452 MDCT scans were evaluated retrospectively. Repeated exams and patients with orbital wall fracture history were excluded. CT scans were obtained by a 64-slice scanner with 0.5 mm slice thickness. Reformatted and three-dimension volume rendered images in bone window were used to assess the calcification presence and type.
Results: Four hundred forty-one MDCT exams included to study. TACs detected in 31 (7.5%) subjects. TAC was unilateral in 24 (77.4%) and bilateral in seven (22.6%) subjects. There was no significant correlation with aging (p=0.681) and between genders (p=0.808). Dot-like TAC was the most common type (n=12, 31.6%). The other types were inverted-U (n=11, 28.9%), linear (n=8, 21%), comma (n=6, 15.6%), respectively. Eight (21%) of TACs were attaching the orbital wall, mostly in comma type.
Conclusion: The TAC incidence in our study was compatible with literature. Four different types of TAC, including, dot-like, inverted U, linear and comma types detected. TACs were usually discrete from the orbital wall however they were occasionally attached. Linear type TAC and attachment to orbital wall described for the first time in this study. Knowledge of the TAC appearance may be helpful to differentiate TACs from foreign bodies.