Aim: To investigate the computed tomography (CT) findings in patients with stage IE/IIE extranodal natural killer/T-cell lymphoma (ENKTL) arising in the nasal cavity and to evaluate whether imaging findings revealed by CT have prognostic value. Materials and methods: The CT findings of 62 patients diagnosed with IE/IIE ENKTL arising in the nasal cavity were retrospectively reviewed. Imaging findings were investigated, and evaluated imaging findings were analysed for the prognostic value of overall survival (OS) and disease-free survival (DFS). Results: Of the 62 patients, 21 (34%) presented with a superficial infiltrative, 38 (61%) with a mass forming, and three (5%) with a combined pattern. Of all imaging findings, local invasiveness (n = 26, 42%), including bony destruction, erosion, or soft-tissue involvement, was the only independent prognostic factor for OS [p = 0.008; hazard ratio (HR): 3.85; 95% confidence intervals (CI): 1.42-10.44] and DFS (p = 0.001; HR: 4.25; 95% CI: 1.72-10.47). In a subgroup analysis of 36 cases with no local invasiveness, a superficial infiltrative pattern in one nasal cavity was a positive prognostic factor for OS (p = 0.028) and DFS (p = 0.008). Conclusion: Imaging findings at CT provided clinically useful predictions for treatment outcomes. Local invasiveness revealed by CT findings was a strong prognostic factor for poor OS and DFS. In addition, in patients with no local invasiveness, a superficial infiltrative pattern in one nasal cavity predicted favourable OS and DFS.