2-[Fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography versus whole-body diffusion-weighted MRI for detection of malignant lesions: initial experience

Objectives The new magnetic resonance whole body diffusion-weighted imaging with background body signal suppression (DWIBS) uses short tau inversion recovery-echo planar imaging sequence under normal respiration. DWIBS is different from 2-[fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography (¹⁸F-FDG PET) imaging in technology, but their images are similar. We compared the two modalities regarding the detection and characterization of malignant tumors. Methods DWIBS and ¹⁸F-FDG PET/computed tomography (CT) were performed on 16 cancer patients on the same day. The diagnoses were the following: lung cancer (n = 12), colon cancer (n = 2), breast cancer (n = 1), and pulmonary metastasis (n = 1). A total of 27 malignant tumors (15 lung cancer, 5 pulmonary metastases of parathyroid cancer, 3 pulmonary metastases of lung cancer, 3 colon cancer, 1 breast cancer) and seven reference organs around malignant lesions (two liver regions, four normal lymph nodes, one muscle region) were evaluated visually and quantitatively using the apparent diffusion coefficient (ADC) (×10⁻³ mm²/s) and standardized uptake value (SUV). Results Twenty-five (92.6%) of the 27 malignant lesions were detected visually with DWIBS imaging in contrast to 22 malignant tumors (81.5%) with ¹⁸F-FDG PET/CT imaging. The quantitative evaluation showed that there was a significant difference between the mean SUVs of the reference organs (n = 7, 1.48 ± 0.62) and the malignant (n = 22, 5.36 ± 2.80) lesions (P < 0.01). However, there was no significant difference between the mean ADCs of the reference organs (n = 7, 1.54 ± 0.24) and the malignant (n = 25, 1.18 ± 0.70) lesions. Conclusions DWIBS can be used for the detection of malignant tumors or benign tumors; however, it may be difficult to differentiate between benign and malignant lesions by ADC.