Abstract
BackgroundRoutine screening of prostate specific antigen (PSA) is no longer recommended because of a high rate of over-diagnosis of prostate cancer (PCa).ObjectiveTo evaluate the efficacy of diffusion-weighted magnetic resonance imaging (DW-MRI) for PCa detection, and to explore the clinical utility of ultrahigh b-value DW-MRI in predicting prostate biopsy outcomes.Methodology73 male patients were selected for the study. They underwent 3T MRI using T2WI conventional DW-MRI with b-value 1000 s/mm2, and ultrahigh b-value DW-MRI with b-values of 2000 s/mm2 and 3000 s/mm2. Two radiologists evaluated individual prostate gland images on a 5-point rating scale using PI-RADS, for the purpose of region-specific comparisons among modalities. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV) and likelihood ratios (LR) were investigated for each MRI modality. The area under the receiver operating characteristic (ROC) curve (AUC) was also calculated.ResultsResults showed the improved diagnostic value of ultrahigh b-value DWI-MRI for detection of PCa when compared to other b values and conventional MRI protocols. Sensitivity values for 3000 s/mm2 in both peripheral zone (PZ) and transition zone (TZ) were significantly higher than those observed with conventional DW-MRI—Specificity values for 3000 s/mm2 in the TZ were significantly higher than other b-value images, whereas specificity values using 3000 s/mm2 in the PZ were not significantly higher than 2000 s/mm2 images. PPV and NPV between 3000 s/mm2 and the other three modalities were significantly higher for both PZ and TZ images. The PLRs and NLRs of b-value 3000 s/mm2 DW-MRI in the PZ and TZ were also recorded. ROC analysis showed greater AUCs for the b value 3000 s/mm2 DWI than for the other three modalities.ConclusionsDW-MRI with a b-value of 3000 s/mm2 was found to be the most accurate and reliable MRI modality for PCa tumor detection and localization, particularly for TZ lesion discrimination. It may be stated that the b-value of 3000 s/mm2 is a novel, improved diagnostic biomarker with greater predictive accuracy for PCa prior to biopsy.
Highlights
Prostate cancer (PCa) is the second most commonly diagnosed cancer worldwide, accounting for about one-quarter of newly diagnosed cases in males [1,2]
Ultrahigh B-Value DWI as an Innovative Biomarker in Prostate Screening for 3000 s/mm2 in both peripheral zone (PZ) and transition zone (TZ) were significantly higher than those observed with conventional Diffusion-weighted magnetic resonance imaging (DW-MRI)—Specificity values for 3000 s/mm2 in the TZ were significantly higher than other b-value images, whereas specificity values using 3000 s/mm2 in the PZ were not significantly higher than 2000 s/mm2 images
positive predictive value (PPV) and negative predictive value (NPV) between 3000 s/mm2 and the other three modalities were significantly higher for both PZ and TZ images
Summary
Prostate cancer (PCa) is the second most commonly diagnosed cancer worldwide, accounting for about one-quarter of newly diagnosed cases in males [1,2]. Despite its low specificity for diagnosing PCa, PSA screening still remains the most frequently used tool for this purpose [6].The PSA test yields a positive predictive value of 25.1%, with a range of 17.0% to 57.0% [7]. The b-value is the essential parameter that affects PCa detection capability, but the normal prostate signal intensity is often not suppressed in DWI, despite using b-values of approximately 1000 s/mm2 [12]. A higher b-value DWI would be more advantageous for highlighting the contrast between cancer signal intensity and normal tissue, because of greater diffusivity and less T2 shine-through effect. Routine screening of prostate specific antigen (PSA) is no longer recommended because of a high rate of over-diagnosis of prostate cancer (PCa)
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