Song, Bin

BackgroundMultiparametric MRI may cause overdiagnosis of clinically significant prostate cancer (csPCa) with the Prostate Imaging Reporting and Data System version 2.1 (PI‐RADS v2.1).ObjectivesTo investigate the diagnostic performance of stiffness as a standalone and complementary marker to PI‐RADS v2.1 for diagnosing csPCa.Study TypeProspective.SubjectsOne hundred forty‐seven participants with pathologically confirmed prostate lesions (≥1 cm), including 71 with csPCa.Field Strength/SequenceT1‐weighted fast spin‐echo, T2‐weighted fast spin‐echo, single‐shot echo‐planar diffusion‐weighted imaging, fast 3D gradient‐echo T1‐weighted dynamic contrast‐enhanced imaging, and 3D single‐shot spin‐echo based echo‐planar MR elastography at 3.0 T.AssessmentThe PI‐RADS v2.1 score was assessed by three radiologists independently. Lesion shear stiffness (SS) values at 60 Hz and 90 Hz were measured. A modified PI‐RADS integrating stiffness with PI‐RADS v2.1 was developed. Diagnostic performance for csPCa was compared between stiffness, PI‐RADS v2.1 and the modified PI‐RADS.Statistical TestSpearman's correlation, Fleiss κ and intraclass correlation, Pearson correlation, one‐way analysis of variance, area under the receiver operating characteristic curve (AUC), and the Delong test. Significance level was P < 0.05.ResultsIn the peripheral zone, csPCa (N = 35) had significantly higher SS than non‐csPCa at 60 Hz (3.22 ± 0.66 kPa vs. 2.56 ± 0.56 kPa) and at 90 Hz (5.64 ± 1.30 kPa vs. 4.48 ± 0.84 kPa). PI‐RADS v2.1 showed 100% sensitivity, 58% specificity, and 0.79 AUC for detecting csPCa. SS achieved 97% sensitivity, 52% specificity, and 0.80 AUC at 60 Hz, while SS had 63% sensitivity, 87% specificity, and 0.78 AUC at 90 Hz. The modified PI‐RADS, combing SS at 60 Hz with PI‐RADS v2.1, resulted in a significantly increased AUC (0.86) compared to that of PI‐RADS v2.1, with a sensitivity of 97% and specificity of 75%.Data ConclusionStiffness can help identifying csPCa in the peripheral zone. Combining stiffness with the PI‐RADS v2.1 improved the diagnostic accuracy and specificity for csPCa.Evidence Level1Technical EfficacyStage 2

Background To standardize renal functional magnetic resonance imaging (MRI), it is important to understand the influence of side‐to‐side variation, regional variation within the organ, and hydration states in MRI and to search for variables that are not affected by those variations. Purpose To assess MRI‐based biomarkers for characterizing the kidney in healthy volunteers while considering variations in anatomic factors and hydration states. Study Type Prospective. Subjects Twenty‐five healthy volunteers (15 females and 10 males, median age 25 years). Field Strength/Sequence 3.0 T intravoxel incoherent motion diffusion‐weighted imaging, arterial spinning labeling imaging, blood oxygenation level dependent imaging, and three‐dimensional MR elastography. Assessment Functional variables were measured before and after water challenge. Regions of interest were manually drawn by two investigators (JC and ZZ, with 8‐ and 5‐year experiences in abdominal radiology) in the cortex, the medulla, and the entire kidney. The medulla/cortex ratio was calculated. Statistical Tests Paired t ‐test or Wilcoxon signed rank test; interobserver correlation coefficient; repeatability coefficients; Spearman's correlation; significance level: P < 0.05. Results Diffusion parameters were only subject to regional variation. R2*, RBF, and renal stiffness (RS) showed regional variation, side variation, and dependence on hydration states. For each side and hydration state, the cortex showed significantly higher standard apparent diffusion coefficient (sADC), higher true diffusion ( D ), lower R2*, and lower RS than the medulla. For each region at baseline, the left kidney showed significantly higher R2*, higher RS, and lower renal blood flow (RBF) than the right kidney. For each region and side, RS and RBF increased significantly while R2* decreased significantly after water intake. After introducing the intrinsic regional difference, significantly higher medulla/cortex ratio of RS remained after water intake except for RS@90 Hz in the right kidney. Data Conclusion Renal multiparametric MRI quantifications were affected by regional variation, side variation, and hydration states. Level of Evidence 2 Technical Efficacy Stage 1