Diffusion-weighted imaging b value and apparent diffusion coefficient for predicting invasiveness of bladder cancer / 中国医学影像技术

ABSTRACT

Objective: To explore the value of diffusion-weighted imaging b value and apparent diffusion coefficient (ADC) in assessment of invasiveness of bladder cancer. Methods: Totally 58 bladder cancer patients with 64 lesions confirmed by pathology were retrospectively analyzed. All patients underwent conventional MRI and DWI. The b values were set as 0, 600, 1 000 and 1 500 s/mm2, respectively. The invasiveness of bladder cancer was classified as low-, intermediate-or high-invasiveness according to its pathological phenotype. ADC of bladder cancers with different b value were measured, and the correlation between ADC and invasiveness of bladder cancer was analyzed. The diagnostic efficacy of ADC values for invasive bladder cancer was analyzed by using ROC curve. Results: The mean diameter of bladder cancer in high-invasive group ([3.37±1.58]cm) was significantly higher than that in low-invasive group ([2.18±0.51]cm) and intermediate-invasive group ([2.32±0.53]cm, both P<0.01). The invasiveness of bladder cancer was negatively correlated with ADC value (r=-0.673, P<0.05). When b value was set as 1 500 s/mm2, DWI could clearly show the lesion, and image contrast was relative higher. The diagnostic specificity and accuracy of tumor ADC value was better in <2.5 cm tumors. ROC curve showed that ADC value 0.93×10-3 mm2/s was optimal cut-off for diagnosis of invasiveness of bladder cancer. Conclusion: DWI and ADC can be used to predict the invasiveness of bladder cancer, especially of small-diameter bladder cancer, therefore providing guidance for follow-up treatment.