Role of diffusion-weighted magnetic resonance imaging in predicting sensitivity to chemoradiotherapy in muscle-invasive bladder cancer.
ABSTRACT In chemoradiation (CRT)-based bladder-sparing approaches for muscle invasive bladder cancer (MIBC), patients who respond favorably to induction CRT enjoy the benefits of bladder preservation, whereas nonresponders do not. Thus, accurate prediction of CRT sensitivity would optimize patient selection for bladder-sparing protocols. Diffusion-weighted MRI (DW-MRI) is a functional imaging technique that quantifies the diffusion of water molecules in a noninvasive manner. We investigated whether DW-MRI predicts CRT sensitivity of MIBC.
The study cohort consisted of 23 MIBC patients (cT2/T3 = 7/16) who underwent induction CRT consisting of radiotherapy to the small pelvis (40 Gy) with two cycles of cisplatin (20 mg/day for 5 days), followed by partial or radical cystectomy. All patients underwent DW-MRI before the initiation of treatment. Associations of apparent diffusion coefficient (ADC) values with CRT sensitivity were analyzed. The proliferative potential of MIBC was also assessed by analyzing the Ki-67 labeling index (LI) in pretherapeutic biopsy specimens.
Thirteen patients (57%) achieved pathologic complete response (pCR) to CRT. These CRT-sensitive MIBCs showed significantly lower ADC values (median, 0.63 × 10(-3) mm(2)/s; range, 0.43-0.77) than CRT-resistant (no pCR) MIBCs (median, 0.84 × 10(-3) mm(2)/s; range, 0.69-1.09; p = 0.0003). Multivariate analysis identified ADC value as the only significant and independent predictor of CRT sensitivity (p < 0.0001; odds ratio per 0.001 ×10(-3) mm(2)/s increase, 1.03; 95% confidence interval, 1.01-1.08). With a cutoff ADC value at 0.74 × 10(-3) mm(2)/s, sensitivity/specificity/accuracy in predicting CRT sensitivity was 92/90/91%. Ki-67 LI was significantly higher in CRT-sensitive MIBCs (p = 0.0005) and significantly and inversely correlated with ADC values (ρ = -0.67, p = 0.0007).
DW-MRI is a potential biomarker for predicting CRT sensitivity in MIBC. DW-MRI may be useful to optimize patient selection for CRT-based bladder-sparing approaches.
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Article: Advances in bladder cancer imaging.[show abstract] [hide abstract]
ABSTRACT: The purpose of this article is to review the imaging techniques that have changed and are anticipated to change bladder cancer evaluation. The use of multidetector 64-slice computed tomography (CT) and magnetic resonance imaging (MRI) remain standard staging modalities. The development of functional imaging such as dynamic contrast-enhanced MRI, diffusion-weighted MRI and positron emission tomography (PET)-CT allows characterization of tumor physiology and potential genotypic activity, to help stratify and inform future patient management. They open up the possibility of tumor mapping and individualized treatment solutions, permitting early identification of response and allowing timely change in treatment. Further validation of these methods is required however, and at present they are used in conjunction with, rather than as an alternative to, conventional imaging techniques.BMC Medicine 04/2013; 11(1):104. · 6.68 Impact Factor