Diagnostic Performance of DWIBS for Lung Cancer Staging and Postoperative Recurrence Detection: An Exploratory Non-Inferiority Analysis Compared with PET-CT

Background: Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) is a radiation-free whole-body MRI technique that may provide an alternative to PET-CT for lung cancer evaluation. This study compared the diagnostic performance of DWIBS with that of PET-CT plus brain MRI for lung cancer staging and with PET-CT for postoperative recurrence detection. Methods: A total of 136 patients with lung cancer were evaluated. Clinical staging was assessed in 81 patients using DWIBS and PET-CT plus brain MRI. Postoperative recurrences were assessed in 55 patients, including 37 who underwent both DWIBS and PET-CT. Sensitivity, specificity, and accuracy were calculated. Paired differences in accuracy were evaluated using Newcombe's Method 10, and exploratory non-inferiority analyses were performed using margins of −5, −10, and −15 percentage points. Results: For clinical staging, DWIBS correctly classified 61 of 81 patients (75.3%), compared with 56 of 81 (69.1%) with PET-CT plus brain MRI. The observed difference in accuracy was +6.17 percentage points (95% CI, +0.30 to +12.27), supporting non-inferiority at all three margins. For postoperative recurrence detection, DWIBS demonstrated a sensitivity of 96.9%, specificity of 100.0%, and accuracy of 98.2%. Among the 37 patients who underwent both DWIBS and PET-CT, the accuracy was 100.0% for DWIBS and 91.9% for PET-CT. The observed difference was +8.11 percentage points (95% CI, −2.69 to +21.30), supporting non-inferiority at all three margins. Conclusions: DWIBS demonstrated diagnostic performance comparable to PET-CT-based imaging for lung cancer staging and postoperative recurrence detection. DWIBS may represent a useful radiation-free alternative to PET-CT.