Assessment of anatomical variations of nose and paranasal sinuses in multidetector computed tomography

Introduction: Paranasal sinuses are a group of air filled spaces developed as an expansion of the nasal cavities, eroding the adjacent bone structures. Conventional radiology does not permit a detailed study of anatomical variations of nose and paranasal sinuses. Currently, MDCT scanning is the standard imaging modality in the evaluation of the paranasal sinuses and anatomical variations. Methodology: A cross-sectional hospital based study of 128 patients referred for CT scan of PNS was conducted from October 2015 to February 2016. CT scan was done in 128 slice Siemens Somatom Definition AS+ CT scanner machine applying standard protocol set by the department of radiology and imaging, Tribhuvan University Teaching Hospital, Maharajgunj. The images were evaluated for presence of any anatomical variants in paranasal sinuses. Results: The absolute frequency of anatomical variations are Agger Nasi cell (75.8%) and DNS (68%) along with Concha Bullosa (35.9%), Paradoxical middle turbinate (26.6%), Haller’s cell (15.7%) and Onodi cell (18.8%). In this study the most frequent type of olfactory fossa was Keros type 2 (63.3%). The typical orientation of uncinate process was found in both sides 199 (77.73%) whereas medial deviation in left side (20.3%) and right side was (18.8%) along with lateral deviation in left side was (3.9%) and right side was found in (1.6%) only. Conclusion: Anatomical variations of nose and paranasal sinuses are best depicted on MDCT scan of PNS on coronal plane with thin slice (3.0 mm) section along with bone algorithm. Agger nasi cell is the commonest anatomical variation (75.8%) followed by DNS, Concha bullosa, Paradoxical middle turbinate, Onodi cells and Haller’s cells.