Can MRI Improve Triage of Bladder Cancer Patients John Chang, M.D., Ph.D. Banner MD Anderson Cancer Center
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MRI for Bladder Cancer Background Bladder cancer staging and treatment Literature results for MRI staging of bladder cancer Conclusions
Bladder Cancer Incidence https://seer.cancer.gov/statfacts/html/urinb.html
Bladder Cancer Incidence Stable incidence and death over past 20 years https://seer.cancer.gov/statfacts/html/urinb.html
Bladder Cancer Staging Ta Papillary Tumors Tis Confined to mucosa T1 Involves lamina propria T2 Involves the muscularis T3 Involves perivesicular fat T4 Invades adjacent organs or pelvic sidewall Verma et al., RadioGraphics 2012
Bladder Cancer Treatment Non-muscle invasive bladder cancer: TURBT Residual tumor: treated with intravesicle BCG Up to T1 stage Muscle invasive bladder cancer: TURBT followed by induction therapy Cystectomy if residual disease Consolidation if no residual disease after induction therapy T2 T3 stage Prado et al., Bladder 2014, vol 1.
Imaging Options CT: 85% sensitivity, 94% specificity for detecting bladder cancer Limited detection for flat lesions, Tis, or lesions < 1 cm in size Limited tissue contrast US and PET/CT: No role in detecting primary bladder cancer Hafeez and Huddart, BMC Medicine, 2013
Imaging Options MRI: Using T2, T1, and post-gadolinium sequences 85% accuracy in differentiating NMIBC from MIBC 82% accuracy in differentiating organ-confined from non-organ confined BC Using diffusion sequence to detect water diffusion 67% accuracy (diffusion) vs 15% (T2) for organconfined disease 64% (T1), 76% (T2), 94% (T3), and 88% (T4) accuracy with DWI+T2 ADC < 0.001x10-3mm2/s suggests G3 disease Hafeez and Huddart, BMC Medicine, 2013 El-Assmy et al., Eur Radiol, 2009 Takeuchi et al., Radiol, 2009
Case Examples Tumors isodense to contrast on CT Tumors seen on T2 sequence Tumors enhance earlier than muscle NMIBC Verma et al., RadioGraphics 2012
Case Examples Difficult to detect muscle invasion on CT Tumor disrupts T2 dark and enhancing muscle layer T2 tumor. Difficult to identify T3a disease. Verma et al., RadioGraphics 2012
Case Examples Extensive extravesicular invasion Similar between CT and MR T3b disease Verma et al., RadioGraphics 2012
Case Examples CT shows possible invasion into adjacent small bowel Diffusion showed preservation of serosa T2b disease on pathology MR can generate different forms of contrast Verma et al., RadioGraphics 2012
Case Examples MR detects subtle mucosal lesion without perivesicular involvement T2b disease on biopsy Lee et al., AJR 2017
MRI Sequences T2 and post-gadolinium sequences: Defines anatomy and muscle invasion Diffusion sequence: Can problem solve muscle and perivesicular fat invasion if T2 and post-gadolinium sequences are insufficient MRI will not work well on patients who cannot remain still Lee et al., AJR 2017
MR Staging In staging, MR predominantly overstages disease Differentiating small differences is difficult on MR Tekes et al., AJR 2005
Summary MRI has greater than 80% accuracy in differentiating NMIBC from MIBC and organ-confined disease Higher soft tissue contrast and multiple sequences can better differentiate muscle invasion MRI tends to overstage disease Differentiating small differences is difficult even on MR Tekes et al., AJR 2005
Q1. Which stages of bladder cancer can be better differentiated using MRI than CT? 1. Ta vs Tis, Tis vs T1 2. T1 vs T2, T3 vs T4 3. T1 vs T2, T2 vs T3 4. Tis vs T1, T1 vs T2
Q2. What is the accuracy of detecting MIBC from NMIBC? 1. 35% 2. 65% 3. 85% 4. 100%
Case Examples Extensive extravesicular invasion Similar between CT and MR T3b disease Verma et al., RadioGraphics 2012