Diagnostic accuracy of magnetic resonance imaging for tumour staging of bladder cancer: systematic review and meta-analysis

Abstract

The purpose of this study is to evaluate accuracy of magnetic resonance imaging (MRI) for local staging of bladder cancer for four clinical scenarios (T-stage thresholds) considered against current standards for clinical staging and secondarily to identify sources for variability in accuracy. Systematic review of patients with bladder cancer undergoing T-staging MRI to evaluate the diagnostic accuracy using bivariate random-effects meta-analysis. Sub-group analysis was done to explore variability; risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 tool. The search identified 30 studies (5156 patients). Pooled accuracy at multiple T-stage thresholds: ≤T1 vs ≥T2 = sensitivity 87% (95% confidence interval [CI] 82-91), specificity 79% (95% CI 72-85); T-any vs T0 = sensitivity 65% (95% CI 23-92), specificity 90% (95% CI 83-94); ≤T2 vs ≥T3 = sensitivity 83% (95% CI 75-88), specificity 87% (95% CI 78-93); and <T4b vs pT4b = sensitivity 85% (95% CI 63-95), specificity 98% (95% CI 95-99). For ≤T1 vs ≥T2, accuracy was higher in studies at low risk of bias. No variability in accuracy was identified for: field strength, transurethral resection of bladder tumour status, publication date, index test parameters. For ≤T1 vs ≥T2, accuracy was higher than reported for clinical staging. For T-any vs T0 accuracy was lower than clinical staging. For ≤T2 vs ≥T3, sensitivity was slightly lower than clinical staging but specificity was considerably higher. For <T4b vs pT4b sensitivity exceeded the estimated accuracy for clinical staging. Limitations: two scenarios had few studies (T-any vs T0; <T4b vs pT4b) and several studies were at high risk of bias. MRI staging for ≤T1 vs ≥T2, ≤T2 vs ≥T3, and <T4b vs pT4b should be considered as potentially superior to the current standard for clinical staging. MRI accuracy for T-any vs T0 may not be superior to clinical staging. However, cautious interpretation is warranted related to risk of bias and sample size; validation in trials comparing clinical staging strategies vs MRI is warranted.

Keywords: bladder cancer; diagnostic accuracy; magnetic resonance imaging; staging; systematic review.