Initial Experience of Diffusion-weighted Magnetic Resonance Imaging to Assess Therapeutic Response to Induction Chemoradiotherapy Against Muscle-invasive Bladder Cancer

Yoshida, Soichiro; Koga, Fumitaka; Kawakami, Satoru; Ishii, Chikako; Tanaka, Hiroshi; Numao, Noboru; Sakai, Yasuyuki; Saito, Kazutaka; Masuda, Hitoshi; Fujii, Yasuhisa; Kihara, Kazunori

doi:10.1016/j.urology.2009.06.111

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Volume 75, Issue 2 , Pages 387-391, February 2010

Initial Experience of Diffusion-weighted Magnetic Resonance Imaging to Assess Therapeutic Response to Induction Chemoradiotherapy Against Muscle-invasive Bladder Cancer

Soichiro Yoshida
- Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
Fumitaka Koga
- Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
- Reprint requests: Fumitaka Koga, M.D., Department of Urology, Tokyo Medical and Dental University Graduate School, 1-5-45 Yushima, Bunkyo-Ku, Tokyo 113-8519, Japan
Satoru Kawakami
- Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
Chikako Ishii
- Department of Radiology, Ochanomizu Surugadai Clinic, Tokyo, Japan
Hiroshi Tanaka
- Department of Radiology, Ochanomizu Surugadai Clinic, Tokyo, Japan
Noboru Numao
- Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
Yasuyuki Sakai
- Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
Kazutaka Saito
- Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
Hitoshi Masuda
- Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
Yasuhisa Fujii
- Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan
Kazunori Kihara
- Department of Urology, Tokyo Medical and Dental University Graduate School, Tokyo, Japan

Received 7 April 2009; accepted 28 June 2009. published online 16 November 2009.

Objectives

To investigate the feasibility of diffusion-weighted magnetic resonance imaging (DWI) in predicting therapeutic response to low-dose chemoradiotherapy (LCRT) against muscle-invasive bladder cancer (MIBC). Accurate assessment of response to induction therapy is an essential part of bladder-sparing therapeutic protocols against MIBC. However, conventional imaging studies are not useful in evaluating therapeutic response because of their inability to distinguish residual cancer from changes secondary to the treatment.

Methods

Twenty patients with clinical T2-4aN0M0 bladder urothelial carcinoma (T2/T3/T4a: n = 10/8/2) who underwent induction LCRT comprising external beam radiotherapy to the bladder (40 Gy) concomitant with 2 cycles of cisplatin administration (20 mg/d for 5 days) followed by partial (n = 13) or radical cystectomy (n = 7) were prospectively enrolled. The patients underwent magnetic resonance imaging examinations with T2-weighted imaging (T2W), dynamic contrast-enhanced T1-weighted imaging (DCE), and DWI after LCRT. A finding of each protocol was compared with a pathologic finding of cystectomy specimen.

Results

Pathologic examination of cystectomy specimens revealed pathologic complete response in 13 (65%) of the 20 patients. The sensitivity/specificity/accuracy of T2W, DCE, and DWI in predicting pathologic response was 43/45/44%, 57/18/33%, and 57/92/80%, respectively. Despite comparable sensitivity, DWI was significantly superior in specificity and accuracy to T2W (P = .03 and .02, respectively) and DCE (P = .002 for both).

Conclusions

This is the first study to show the feasibility of DWI over T2W and DCE for assessing therapeutic response to induction chemoradiotherapy against MIBC. The high specificity of DWI indicates that DWI is useful to accurately predict pathologic complete response, allowing more optimal patient selection in bladder-sparing protocols.