MRI of Bladder Cancer: Local and Nodal Staging

Abstract

Accurate staging of bladder cancer (BC) is critical, with local tumor staging directly influencing management decisions and affecting prognosis. However, clinical staging based on clinical examination, including cystoscopy and transurethral resection of bladder tumor (TURBT), often understages patients compared to final pathology at radical cystectomy and lymph node (LN) dissection, mainly due to underestimation of the depth of local invasion and the presence of LN metastasis. MRI has now become established as the modality of choice for the local staging of BC and can be additionally utilized for the assessment of regional LN involvement and tumor spread to the pelvic bones and upper urinary tract (UUT). The recent development of the Vesical Imaging‐Reporting and Data System (VI‐RADS) recommendations has led to further improvements in bladder MRI, enabling standardization of image acquisition and reporting. Multiparametric magnetic resonance imaging (mpMRI) incorporating morphological and functional imaging has been proven to further improve the accuracy of primary and recurrent tumor detection and local staging, and has shown promise in predicting tumor aggressiveness and monitoring response to therapy. These sequences can also be utilized to perform radiomics, which has shown encouraging initial results in predicting BC grade and local stage. In this article, the current state of evidence supporting MRI in local, regional, and distant staging in patients with BC is reviewed.Level of Evidence3Technical Efficacy Stage2 J. Magn. Reson. Imaging 2020;52:649–667.

Systematic Review and Meta-Analysis of Vesical Imaging-Reporting and Data System (VI-RADS) Inter-Observer Reliability: An Added Value for Muscle Invasive Bladder Cancer Detection

“…Similarly, preoperative diagnostic tools such as computer tomography (CT) and MRI are available for clinical stage determination of BCa, but still lack a high degree of reliability. The accuracy of MRI for primary BCa staging varies indeed from 73% to 96%, according to various studies [ 1 , 4 , 31 ]. With the aim of standardizing staging, diagnosis, and eventually, therapeutic response to neoadjuvant systemic regimens, the VI-RADS scoring system has been recently introduced and validated through a consensus-driven approach to reproducible imaging and reporting [ 7 ].…”

“…The indications for multiparametric magnetic resonance imaging (mpMRI) for bladder cancer (BCa) are recently expanding and have demonstrated reliable accuracy in staging applications [ 1 , 2 , 3 , 4 , 5 , 6 ]. The Vesical Imaging-Reporting and Data System (VI-RADS) has been introduced to provide preoperative BCa staging and has been prospectively shown to be reliable in assessing the presence of muscle invasion in the pre-TURBT (trans-urethral resection of bladder tumor) setting [ 7 , 8 ].…”

The Role of Imaging in Bladder Cancer Diagnosis and Staging

“…The highly vascular inner layer (urothelium and lamina propria) is not well visualized on T2W imaging and DWI, but can be seen during DCE imaging when it enhances avidly early (approximately 20 s after GBCA administration). In distinction, the muscularis propria enhances later, slowly and progressively (approximately 60 s after GBCA administration) [40]. On T2W imaging and DWI the inner layer is not seen, and the muscularis propria is seen as a low-signal intensity line on T2W imaging and intermediate linear signal on DWI [31,35].…”

“…MRI is the cross-sectional imaging modality of choice for assigning T-stage in patients with known BC [30,34,40,42,43]. MRI is being increasingly used for the preoperative local staging of BC because of its high soft-tissue contrast resolution with resultant anatomic detail that allows for the accurate assessment of bladder wall invasion depth [30,40]. Beyond the structural visualization afforded by T2W imaging, the functional sequences of mpMRI (e.g., DWI and DCE imaging) have further improved tumor staging performance [44].…”

“…In addition to staging tumors, MRI is able to depict perivesical fat tissue extension, regional lymph node involvement, and the presence of pelvic sidewall or osseous metastases. Second only to T-stage, nodal status is the most important prognostic variable and correlates with decreased 5-year disease-free survival [40]. Nodal metastasis correlates with tumor stage with nodal disease present in approximately 30% of T2 cancers and 60% in T3 or T4 tumors.…”