Whole-body MRI versus fluorodeoxyglucose PET/CT for extra-nodal metastatic staging in lung adenocarcinoma

To evaluate the diagnostic accuracy and cost-effectiveness of whole-body magnetic resonance imaging (WB-MRI) versus 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for detecting extra-nodal metastatic lesions in lung adenocarcinoma.

This prospective single-centre study enrolled 70 patients with biopsy-proven lung adenocarcinoma who underwent FDG-PET/CT and WB-MRI (3 T) for initial staging; one patient was excluded (mucinous adenocarcinoma). The final cohort comprised 69 patients (mean age 55.8 ± 13.1 years, 46 men): 40 with metastatic disease and 29 without (true negatives). Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), and inter-modality agreement were calculated at lesion level against histopathology or six-month follow-up imaging. Paired comparisons used McNemar's test.

Sixty-nine patients (mean age 55.8 ± 13.1 years, 46 men) were evaluated. WB-MRI detected 278 lesions versus 260 for FDG-PET/CT. WB-MRI achieved sensitivity of 95.10 % (95 % CI: 91.95-97.06 %), specificity of 95.57 % (95 % confidence interval (CI): 92.42-97.45 %), and accuracy of 95.33 % (95 % CI: 93.25-96.79 %). FDG-PET/CT achieved sensitivity of 91.85 % (95 % CI: 87.97-94.56 %), specificity of 95.65 % (95 % CI: 92.56-97.50 %), and accuracy of 93.77 % (95 % CI: 91.42-95.51 %). WB-MRI sensitivity was significantly higher than FDG-PET/CT (McNemar's test, p < 0.001); specificity was equivalent (p = 0.074). Inter-modality agreement was almost perfect (κ = 0.91). WB-MRI cost 148 Euro (16,000 Indian Rupee [INR]) per patient versus 442 Euro (48,000 INR) for FDG-PET/CT.

WB-MRI demonstrates diagnostic accuracy equivalent to FDG-PET/CT for extra-nodal metastatic staging in lung adenocarcinoma, with the additional advantages of no ionising radiation and substantially lower cost.