Quantitative MRI techniques are becoming increasingly popular in cancer imaging, as they aid in monitoring and diagnosing Prostate Cancer (PCa). Variations in imaging protocols and hardware characteristics (such as magnetic field strength, type of coils) can impact the accuracy and reproducibility of quantitative measurements across different scanners, vendors and centres. This study aims to compare the diagnostic performance of quantitative ADC values and ADC ratios for the diagnosis of prostate cancer, as well as to identify factors influencing their performance, to suggest the potential use of ADCratio as a diagnostic measure for PCa in the future.
A systematic literature search was conducted in the MEDLINE, EMBASE and Web of Science databases to identify relevant articles. Screening and selection of the articles included in the meta-analysis were based on the inclusion and exclusion criteria of the protocol. The methodological quality was evaluated using the revised tool for the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). Publication bias was assessed by using the Deeks funnel plot asymmetry test. Pooled sensitivity and specificity were calculated for both ADC and ADCratio for differentiating histological grades of PCa with the bivariate mixed effects model in STATA. Summary ROC (SROC) curve was constructed for each parameter. Q statistic of the chi-square value test and the inconsistency index (I2) were used to estimate the heterogeneity among included studies. Metaregression analysis and subgroup analysis were used to explore other factors that contributed to the heterogeneity present.
Figure 2. The overall scores for the QUADAS-2 questions are summarized. There was an overall low risk of bias.
There were 1038 patients in the meta-analysis, and a total of 1441 prostatic lesions were assessed by both ADC and ADC ratios, of which 645 (44.7%) were positive for highly aggressive lesions.
Figure 1. As shown in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram, 13 studies were included in this systematic review and meta-analysis.
Table 1. Summary of the thirteen included studies.
Table 2. The main analysis, subgroup and metaregression analysis results are shown.
This study showed that history of biopsy prior to MRI, Gleason score aggressiveness > 3+4, region of prostate analysed (PZ and TZ zone), reference standard and MRI field strength for ADC ratio and history of biopsy prior to MRI and region of prostate analysed (PZ and TZ zone) for ADC parameters were shown to contribute significantly to the heterogeneity for ADC and ADCratio. The results indicate that both ADC and ADCratio were of very good diagnostic performance and performed with the same diagnostic accuracy.
Figure 3. Forest plots of sensitivities and specificities from the fourteen subsets of data from the thirteen studies for ADC, as well as the SROC curve.
Figure 4. Forest plots of sensitivities and specificities from the fourteen subsets of data from the thirteen studies for ADCratio, as well as the SROC curve.