Comparison of Whole Body Diffusion Weighted MRI and PET CT in Detection of Malignant Tumours
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Abstract
Background: Accurate whole-body assessment of malignancies is crucial for staging, treatment planning, and monitoring. Whole-body diffusion-weighted MRI (WB-DWI-MRI) and positron emission tomography-computed tomography (PET-CT) are increasingly utilized for this purpose, yet direct comparative data remain limited.
Objectives: This study aimed to compare the diagnostic performance of WB-DWI-MRI and PET-CT in detecting malignant lesions, evaluate their correlation with quantitative biomarkers—apparent diffusion coefficient (ADC) and standardized uptake value (SUV)—and characterize metastatic patterns across cancer types.
Methods: Nineteen patients with various histologically or radiologically diagnosed malignancies underwent both WB-DWI-MRI and PET-CT imaging. Detected lesions were analyzed for number, distribution, ADC, and SUV values. Diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each modality.
Results: Both WB-DWI-MRI and PET-CT showed high diagnostic performance. DWI-MRI achieved an overall sensitivity of 83.3%, specificity of 90%, PPV of 88.2%, and NPV of 85.7%, whereas PET-CT showed slightly higher values with a sensitivity of 88.9%, specificity of 95%, PPV of 94.7%, and NPV of 90.9%. A significant inverse correlation was observed between ADC and SUV values, indicating that lesions with lower ADC generally exhibited higher metabolic activity. Breast, thyroid, and gastrointestinal cancers showed the highest lesion burden, while thyroid cancers displayed more localized metastases.
Conclusion: PET-CT and WB-DWI-MRI are both highly effective for whole-body oncologic imaging. While PET-CT offers superior diagnostic accuracy, WB-DWI-MRI provides a radiation-free alternative suitable for younger or radiation-sensitive patients.Their complementary strengths support integrated use for improved tumor detection, staging, and follow-up in oncology practice.