CEUS compared with CECT, MRI, and FDG-PET/CT for diagnosing CRC liver metastases: a diagnostic test accuracy systematic review and meta-analysis

To determine the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) compared with contrast-enhanced computed tomography (CECT), magnetic resonance imaging (MRI), and Fluorine-18-deoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for diagnosing suspected liver metastases in patients with newly diagnosed colorectal cancer (CRC). The meta-analysis using the bivariate model included studies on patients with newly diagnosed CRC only and excluded patients with non-CRC liver metastases, known liver metastases, patients treated with chemotherapy and local treatments, e.g. hepatic resection or radiofrequency ablation. We used QUADAS-2 to assess the methodological quality of the studies. We included 32 studies, 6 studies evaluated the accuracy of CEUS (<i>n</i> = 937 participants), 26 studies evaluated CECT (<i>n</i> = 2,582), 8 studies evaluated MRI (<i>n</i> = 564) and 6 studies evaluated FDG-PET/CT (<i>n</i> = 813). Sensitivity: FDG-PET/CT 94.4% [95% CI: 90.7–98.1%], MRI 92.9% [95% CI: 88.8–97.0%], CEUS 86.1% [95% CI: 78.0–94.3%] and CECT 84.6% [95% CI: 79.3–89.9%]. Specificity FDG-PET/CT 97.9% [95% CI: 95.9–99.9%], CEUS 96.1% [95% CI: 93.6–98.6%], MRI 94.4% [95% CI: 90.5–98.3%], and CECT 94.3% [95% CI: 91.8–96.8%]. FDG-PET/CT had significantly higher sensitivity and specificity than CECT, and significantly higher sensitivity than CEUS. MRI had a significantly higher sensitivity than CEUS, but a lower non-significant specificity. CECT had the lowest sensitivity and specificity. CRD42017055015 and CRD42017082996.