Prostate Cancer Diffusion‐Weighted Magnetic Resonance Imaging: Does the Choice of Diffusion‐Weighting Level Matter?. Issue 3 (18th September 2021)

• Record Type: Journal Article
• Authors: Maier, Stephan E.; Wallström, Jonas; Langkilde, Fredrik; Johansson, Jens; Kuczera, Stefan; Hugosson, Jonas; Hellström, Mikael
• Is Part Of: Journal of magnetic resonance imaging. Volume 55:Issue 3(2022)
• Page Start: 842
• Page End: 853
• Publication Date: 2021-09-18
• Subjects: diffusion -- b‐value -- apparent diffusion coefficient -- apparent diffusion coefficient ratio -- kurtosis -- prostate peripheral zone; Magnetic resonance imaging -- Periodicals; 616
• DOI: 10.1002/jmri.27895
• Languages: English
• ISSNs: 1053-1807

Abstract

Abstract : Background: Diffusion‐weighted magnetic resonance imaging plays an important role in multiparametric assessment of prostate lesions. The derived apparent diffusion coefficient (ADC) could be a useful quantitative biomarker for malignant growth, but lacks acceptance because of low reproducibility. Purpose: To investigate the impact of the choice of diffusion‐weighting levels ( b ‐values) on contrast‐to‐noise ratio and quantitative measures in prostate diffusion‐weighted MRI. Study Type: Retrospective and simulation based on published data. Subjects: Patient cohort (21 men with Prostate Imaging‐Reporting and Data System (PI‐RADS) version 2 score ≥3) from a single‐center study. Field Strength/Sequence: 3 T/diffusion‐weighted imaging with single‐shot echo‐planar imaging. Assessment: Both clinical data and simulations based on previously acquired data were used to quantify the influence of b ‐value choice in normal peripheral zone (PZ) and PZ tumor lesions. For clinical data, ADC was determined for different combinations of b ‐values. Contrast‐to‐noise ratio and quantitative diffusion measures were simulated for a wide range of b ‐values. Statistical Tests: Tissue ADC and the lesion‐to‐normal tissue ADC ratios of different b ‐value combinations were compared with paired two‐tailed Student's t ‐tests. A P ‐value <0.05 was considered statistically significant. Results: Findings about b ‐value dependence derived from clinical data and from simulations agreed with each other. Provided measurement was limited to two b ‐values, simulation‐derived optimal b ‐value choices coincided with PI‐RADSv2 recommendations. For two‐point measurements, ADC decreased by 15% when the maximum b ‐value increased from 1000 to 1500 seconds/mm 2, but corresponding lesion‐to‐normal tissue ADC ratio showed no significant change ( P = 0.86 for acquired data). Simulations with three or more measurement points produced ADCs that declined by only 8% over this range of maximum b ‐value. Corresponding ADC ratios declined between 2.6% (three points) and 3.8% (21 points). Simulations also revealed an ADC reduction of about 19% with the shorter echo and diffusion time evaluated. Data Conclusion: The comprehensive assessment of b ‐value dependence permits better formulation of protocol and analysis recommendations for obtaining reproducible results in prostate cancer diffusion‐weighted MRI. Level of Evidence: 4 Technical Efficacy: Stage 2