Purpose: To retrospectively determine the diffusion-weighted imaging (DWI) characteristics and apparent diffusion coefficient (ADC) values of prostate carcinoma (PCa) with urinary bladder invasion, and to compare the accuracy of T2-weighted MRI alone and T2 combined with DWI for predicting urinary bladder invasion.
Materials and methods: Sixty-eight patients with proven PCa were diagnosed with urinary bladder invasion after conventional magnetic resonance imaging (MRI) and DWI (b value = 750 sec/mm(2)) examinations. All the 68 cases underwent cystoscopy examination. DWI appearances of all urinary bladder invasion and a normal urinary bladder wall were analyzed, and their ADC values were measured. T2 images alone and then T2 images combined with DWI were scored for the likelihood of urinary bladder invasion on the basis of radiologists' written reports. The area under the receiver operating characteristic curve (AUC) was used to assess accuracy. Statistical significance was inferred at P < 0.05.
Results: After cystoscopy examination, 45 (66%) of 68 cases were pathologically proven urinary bladder invasion. The mean ADCs for urinary bladder invasion and normal urinary bladder wall were (0.963 +/- 0.155) x 10(-3)mm(2)/sec and (1.517 +/- 0.103) x 10(-3)mm(2)/sec, respectively. The ADC values of urinary bladder invasion were significantly lower than those of normal urinary bladder wall (P = 0.000). The AUC for T2-weighted imaging plus DW imaging (0.861) was significantly larger than that for T2-weighted imaging alone (0.734) or for DW imaging alone (0.703) (P < 0.001).
Conclusion: Urinary bladder invasion had lower ADC values compared with normal urinary bladder wall. T2 images plus DWI is significantly better than T2-weighted imaging alone in the detection of urinary bladder invasion in patients with PCa.
(c) 2009 Wiley-Liss, Inc.