Evaluation of extensions of sinonasal mass lesions by computerized tomography scan

Introduction : Cross-sectional imaging has had a significant impact on the management of the sinonasal malignancy. Staging of these lesions has been closely monitored by dependence on computerized tomography (CT) scan and now in small proportion with MRI. The objective of the study was to evaluate the reliability of CT scan in assessing the extensions of the sinonasal mass lesions and their impact on tumor staging.
Materials and Methods : All cases of sinonasal lesions were reviewed retrospectively from June 2001 to May 2006 (five years) at KMIO, Bangalore. Only those cases that had CT scan reports and Histopatholgy Examination (HPE) reports were included in the study. All the cases, which were subjected to radiotherapy prior to surgery, were excluded from the study. There were a total of 38 cases with slight male preponderance. Tumor staging was done according to the sixth edition of TNM classification of malignant tumors. Two observers evaluated all the cases (Blinded Study) and sensitivity, specificity, positive predictive value, negative predictive value and predictive accuracy were estimated.
Results : The relation between the CT scan findings and HPE reports was high. Though false positivity was noted more in the ethmoid sinuses, significant impact on tumor staging was noted with false positivity of the nasopharynx. Also, false positivity was noted with orbital wall/content extensions, resulting in unnecessary exenterations of the orbit. However, CT scan reliably predicted infratemporal fossa extension in the absence of trismus. False negativity was noted more often in soft palate, indicating the need of using MRI for delineation of tumor extension. Thus, we conclude that judicious use of CT scan in all cases and MRI in selected cases will translate into better tumor-free resections and improves survival.

Keywords
Computerized tomography scan, sinonasal lesions, extensions, tumor staging