The ability and utility of diffusion-weighted magnetic resonance imaging with different ‘b’ values in the differentiation of benign from malignant lung lesions

Introduction
To evaluate the ability and the utility of diffusion-weighted magnetic resonance imaging (MRI) with different ‘b’ values to visualise benign and malignant lung lesions, and to determine which ‘b’ value (b = 300, 500, or 1000 s/mm²) was most useful in differentiating benign from malignant lung lesions.

Material and methods
A total of 100 patients (28 women, 72 men; mean age = 57.19 ± 13.44 years; age range = 20-83 years). Diffusion-weighted imaging (DWI) was obtained with ‘b’ values of 300, 500, and 1000 s/mm². The signal intensity of lesions on DWI images was analysed, and the apparent diffusion coefficient (ADC) values of the lesions were calculated. MRI was performed in all patients after having presented at our department for thoracic computed tomography for various reasons.

Results
A statistically significant difference in DWI signal scores was detected between benign and malignant lesions for all ‘b’ factors (p < 0.0001 for each). The sensitivity and specificity were 95% and 64%, respectively, when a score of 3 for β = 300 s/mm²; 90% and 69%, respectively, when a score of 3 for β = 500 s/mm²; and 84% and 74%, respectively, when a score of 3 for β = 1000 s/mm². ADC values showed significant differences between benign and malignant lesions for all ‘b’ factors (p < 0.0001 for each).

Conclusions
Using ‘b’ values of 300, 500, and 1000 s/mm², DWI signal intensity scores and ADC values are effective methods for the differential diagnosis of malignant and benign pulmonary lesions.