Purpose or Case Report: The diagnosis of Wilms tumor and adrenal gland neuroblastoma can be challenging, even with imaging methods such as computed tomography and magnetic resonance imaging (MRI). This study aimed to show the utility of diffusion weighted MRI (DW-MRI) in the differentiation of neuroblastoma and Wilms tumor.
Methods & Materials: Eleven histopathologically diagnosed tumors (7 neuroblastoma and 4 Wilms tumor) were evaluated in 11 patients retrospectively. The patients were scanned on a 1.5 Tesla magnetic resonance scanner (Siemens Avanto 1.5T Magnetom, Siemens AG Medical Solutions, Erlangen, Germany) and DW-MRI was performed with b-values of 50, 400, and 800 s/mm² for all patients. The apparent diffusion coefficient (ADC) values (mm²/s) of the tumors were evaluated by means of region-of-interest (ROI) measurements on a workstation (Syngo Via Console, software version 2.0, Siemens AG Medical Solutions, Erlangen, Germany). T2-weighted axial images were used as a reference to avoid measurements from cystic, necrotic and hemorrhagic areas of the tumors. The mean age (months), size (cm), and ADC values were compared with each other. Receiver operating characteristic analysis was performed to obtain the optimal cut-off value. Statistical significance was set as p < 0.05.
Results: The mean size was 14.37 ± 4.6 cm for Wilms tumor and 8.17 ± 3.45 cm for neuroblastoma. The mean age was 62.5 ±16.29 months for Wilms tumor, and 28.5 ± 17.43 months for neuroblastoma (p = 0.017). The mean ADC was 0.607×10^-3 ± 0.148×10^-3 mm²/s for neuroblastoma and 0.829×10^-3 ± 0.89×10^-3 mm²/s for Wilms tumor (p = 0.013). A cut-off ADC value of ≥ 0.733 for differentiating Wilms tumor from neuroblastoma had a sensitivity of 100%, specificity of 85.7%, positive predictive value of 87.4%, and negative predictive value of 100%.
Conclusions: Although the numbers of tumors were relatively small in this study, the mean ADC value of Wilms tumor was significantly higher than the mean ADC value of neuroblastoma. This finding could be helpful when the detection of the mass origin is challenging, and DW-MRI should be added to abdominal MRI protocols in patients with suspected Wilms tumor or neuroblastoma.