CT mucosal window settings: a novel approach to evaluating early T-stage head and neck carcinoma

The purpose of this study is to evaluate the CT densities of small head and neck mucosal cancers as a means of deriving a CT mucosal window display of narrower window width and higher window level to better detect and delineate head and neck carcinomas.

We retrospectively studied 19 subjects with T1-2 head and neck carcinomas. The density of tumor and adjacent normal mucosa on CT were measured. CT scans for the 19 patients with tumors and 35 subjects without mucosal tumors were anonymized and interpreted by two readers using standard soft-tissue windows and were reviewed again 1 week later with the addition of mucosal windows.

The mean (± SD) attenuation of 17 visible tumors was 85.5 ± 18.3 Hounsfield units (HU) and that of the surrounding normal mucosa was 55.3 ± 15.2 HU (p < 0.0001). From our data, we derived guideline mucosal window settings-a window width of 120 HU and a window level of 60 HU. On blinded review, reader A detected 12 tumors with the addition of mucosal windows (sensitivity, 63%; specificity, 82%) and nine tumors on soft-tissue windows alone (sensitivity, 47%; specificity, 94%). Reader B detected nine tumors with use of mucosal windows (sensitivity, 47%; specificity, 71%) and eight tumors on soft-tissue windows alone (sensitivity, 42%; specificity, 74%).

Early T-stage tumors have higher CT density than normal mucosa. Their conspicuity can be amplified using display windows with narrower window width and higher window level. The potential clinical applications are for the improved detection of unknown primary tumors and delineation of a known mucosal tumor.