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A two-way comparison of whole-body 18FDG PET-CT and whole-body contrast-enhanced MRI for distant metastasis staging in patients with malignant tumors: a meta-analysis of 13 prospective studies.

BACKGROUND
The correct staging of distant metastasis is crucial in deciding an adequate course of therapy for cancer patients. This meta-analysis was carried out to produce an evaluation and comparison of the performances of 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18FDG PET-CT) and contrastenhanced magnetic resonance imaging (MRI) in detecting distant metastasis in patients suffering malignant tumors. Systematic literature searches of the MEDLINE and Embase databases were conducted to identify relevant studies in the period from December 31, 1950 to August 1, 2019. We used the following search terms: MRI, magnetic resonance imaging, PET, positron emission tomography, staging, distant metastasis, and distant recurrence. The searches were carried out by two independent reviewers. We only included relevant studies that evaluated both 18FDG PET-CT and contrast-enhanced MRI in relation to distant metastasis detection in the same patients with malignant tumors. The two reviewers independently extracted relevant data from the eligible studies, and the quality of each study was determined with "Quality Assessment of Diagnostic Accuracy Studies-2". Using the bivariate model, we obtained pooled estimates for sensitivity and specificity. The area under the curve (AUC) of summary receiver operating characteristic (SROC) curves for 18FDG PET-CT and contrast-enhanced MRI was used to extra and synthesize, respectively.


METHODS
Pooled sensitivities and specificities, and the AUC of SROC curves for 18FDG PET-CT and contrast-enhanced MRI were used to measure the main outcomes, respectively.


RESULTS
Across all 13 studies (1,465 patients), 18FDG PET-CT had similar sensitivity (0.84 vs. 0.85) and specificity (0.96 vs. 0.98) to contrast-enhanced MRI. In the 5 studies related to head and neck cancer (511 patients), 18FDG PET-CT had similar sensitivity (0.82 vs. 0.81) and specificity (0.97 vs. 0.98) to contrastenhanced MRI. In the 6 lung cancer-related studies (779 patients), sensitivity (0.72 vs. 0.85) and specificity (0.95 vs. 1.00) tended to be lower in 18FDG PET-CT than in contrast-enhanced MRI.


CONCLUSIONS
:18FDG PET-CT and contrast-enhanced MRI both performed well as detectors of distant metastasis in the diagnosis of cancer patients. The subgroup analysis suggests that 18FDG PET-CT and contrast-enhanced MRI may possess different advantageous qualities for distant metastasis staging of patients with various types of tumor.