The Diagnostic Performance of MRI for Detection of Lymph Node Metastasis in Bladder and Prostate Cancer: An Updated Systematic Review and Diagnostic Meta-Analysis

The purpose of this article is to review the diagnostic performance of MRI for the detection of pelvic lymph node (LN) metastasis in patients with bladder and prostate cancer. MEDLINE and EMBASE were searched up to January 13, 2017. We included diagnostic accuracy studies that used MRI for pelvic LN detection in patients with bladder or prostate cancer, using histopathologic analyses published since 2000 as the reference standard. Two independent reviewers assessed the methodologic quality using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Sensitivity and specificity of all studies were calculated. Per-patient and per-LN results were pooled and plotted in a hierarchic summary ROC plot. Metaregression, sensitivity, and subgroup analyses were performed. Twenty-four studies (2928 patients) were included. Pooled per-patient sensitivity (n = 21) was 0.56 (95% CI, 0.42-0.69) with a specificity of 0.94 (95% CI, 0.90-0.96). Per-LN pooled estimates (n = 9) showed consistent results: sensitivity of 0.57 (95% CI, 0.29-0.82) and specificity of 0.97 (95% CI, 0.94-0.98). At metaregression analysis, type of cancer, magnet field strength, and use of ultrasmall superparamagnetic particles of iron oxide (USPIO) were significant factors affecting heterogeneity (p ≤ 0.01). Sensitivity analyses showed that specificity estimates were comparable (range, 0.87-0.95), but sensitivity estimates showed significant differences. Studies that used USPIO (n = 4) had higher sensitivity (0.86; 95% CI, 0.62-0.96) than did those not using USPIO (n = 17; 0.46; 95% CI, 0.35-0.58). MRI shows high specificity but poor and heterogeneous sensitivity for detecting pelvic LN metastasis in patients with bladder and prostate cancer. Using USPIO can improve sensitivity.