Comparative Analysis of Whole-Body Diffusion-Weighted Imaging and PET/CT in Metastasis Detection: A Prospective Study

Introduction Tumor staging is essential for determining treatment strategies and predicting prognosis in cancer patients. Accurate imaging techniques are critical for staging, metastasis screening, treatment response assessment, and recurrence detection. Objective In this prospective study, we aimed to compare the sensitivity of whole-body diffusion-weighted imaging (WB-DWI) with positron emission tomography/computed tomography (PET/CT) in detecting metastases. Materials and methods Twenty-one patients with metastatic cancer disease confirmed by PET/CT examination were prospectively examined with WB-DWI. PET/CT scans were performed using 18-fluorodeoxyglucose (18F-FDG). To assess and localize metastatic lesions, each case was evaluated at 18 different sites, including the skeletal system, visceral areas, and lymph nodes. Lesions were localized and counted using both radiological modalities. Results Twenty-one patients with metastatic disease were included (12 men, 9 women; mean age 58 years). All patients underwent PET/CT followed by WB-DWI. The average interval between PET/CT and WB-DWI was 22.5 days. Of the 378 regions examined, PET/CT detected 68 metastases, while WB-DWI detected 64 metastases. Liver metastases were detected in 2 out of 3 patients by WB-DWI. WB-DWI demonstrated substantial agreement with PET/CT in detecting liver metastases (κ (Cohen's kappa) = 0.77, p < .001) and lung metastases (κ = 0.74, p < .001). All adrenal gland and soft tissue metastases were detected by WB-DWI, with perfect agreement (κ = 1, p < .001). WB-DWI detected 31 metastatic lymph nodes identified by PET/CT, also with perfect agreement (κ = 1, p < .001). Conclusion WB-DWI offers significant advantages over PET/CT, including reduced imaging time, no radiation exposure, and lower costs. WB-DWI demonstrates comparable sensitivity to PET/CT in metastasis screening, suggesting the potential to reduce PET/CT usage with further improvements in DWI parameters and MRI technology.