Evaluation of chemotherapy in advanced urinary bladder cancer with fast dynamic contrast-enhanced MR imaging

Abstract

Purpose: To evaluate if the failure of chemotherapy in patients with advanced urinary bladder cancer can be predicted early in the course of chemotherapy with fast dynamic contrast material-enhanced magnetic resonance (MR) imaging.

Materials and methods: In this prospective study, 22 consecutive patients with histologically proved advanced urinary bladder cancer underwent MR imaging before and after two, four, and six cycles of chemotherapy with methotrexate, vinblastine, adriamycin, and cisplatin (MVAC). The response after two chemotherapy cycles was evaluated by using conventional tumor size parameters at unenhanced MR imaging and with changes in the time to the start of tumor or lymph node enhancement at fast dynamic contrast-enhanced MR imaging. The results obtained with these techniques were compared with the findings at histopathology in cystectomy (n = 9) or multiple transurethral resection (n = 13) specimens obtained after completion of chemotherapy.

Results: After two MVAC cycles, the accuracy, sensitivity, and specificity in distinguishing responders from nonresponders with conventional MR imaging were 73%, 79%, and 63%, respectively. With the dynamic technique, these were 95%, 93%, and 100%, respectively. Although the differences between these values are not significant (P = .48 for sensitivity, .25 for specificity, and .07 for accuracy), the data indicate that dynamic enhanced MR imaging performed better than unenhanced MR imaging. Dynamic imaging yielded correct results after two MVAC cycles in 21 cases, and in all cases after four cycles. After four MVAC cycles, the accuracy of dynamic MR imaging was significantly better (P < .05). Persisting early enhancement after four MVAC cycles correctly corresponded with lack of response in all nine cases, and after two cycles in eight of these cases. The unenhanced MR technique showed initial tumor size reduction in three of these cases.

Conclusion: Conventional and dynamic enhanced MR imaging were used to evaluate chemotherapy after two, four, and six cycles of MVAC in 22 patients with bladder cancer. After two cycles, dynamic MR imaging helped detect 13 of 14 responders and eight of eight nonresponders. It helped detect five of seven lymph node responders and two of two nonresponders. Thus, it may be possible to predict after two MVAC cycles whether a patient will respond to chemotherapy.