Diffusion-weighted Imaging is Superior to Positron Emission Tomography in the Detection and Nodal Assessment of Lung Cancers

Background: Diffusion-weighted magnetic resonance imaging (DWI) makes it possible to detect malignant tumors based on the difference in the diffusion of water molecules among tissues. The aims of this study are to examine the usefulness of DWI compared with positron emission tomography-computed tomography (PET-CT) in the assessment of lung cancer, and the relationships between the apparent diffusion coefficient (ADC) value and several pathologic factors.

Methods: Sixty-three patients with primary non-small cell lung cancer were enrolled in this study. The DWI and PET-CT were performed before surgery. There were 42 adenocarcinomas, 19 squamous cell carcinomas, and 2 other cell types.

Results: Sixty-one lung cancers (97%) were detected visually with DWI. This was significantly higher than 54 lung cancers (86%) with PET-CT. The accuracy for N staging by DWI was 0.81 (51 of 63), which was not significantly higher than 0.71 (45 of 63) by PET-CT. The sensitivity (0.75) for individual metastatic lymph node stations by DWI was significantly higher than that (0.48) by PET-CT. The specificity for individual nonmetastatic lymph node stations was 0.99 by DWI and 0.97 by PET-CT, respectively. The accuracy (0.95) for the diagnosis of lymph node stations by DWI was significantly higher than that (0.90) by PET-CT. There was a weak reverse relationship (correlation coefficient: 0.286) between the ADC value and the maximum standardized uptake value, but no relationship between ADC value and tumor size. The ADC values increased while the cell differentiation increased.

Conclusions: Diffusion-weighted magnetic resonance imaging is superior to PET-CT in the detection of primary lesions and nodal assessment of non-small cell lung cancers.