High Resolution Diffusion Weighted Imaging in Prostate

Magnetic Resonance Imaging (MRI) with the Prostate Imaging Reporting and Data System (PI-RADS) is a state-of-the-art strategy, not only for standardizing prostate MRI scanning, but also for PCa detection, diagnosis and staging. In PI-RADS score evaluation, diffusion weighted imaging (DWI) is an important component of the prostate MRI examination, which is considered to be the dominant sequence for the assessment of lesions in the peripheral zone (PZ) and is also regarded as the auxiliary sequence for the upgrade of lesions in the transitional zone (TZ). DWI reflects the random motion of water molecules, that should include high b-value images (at least b≥1400s/mm²) and an calculated ADC map. As the b-value increases, DWI enables detection of small changes because of better contrast between malignant and background tissue. Meanwhile, the problems arise. DWI is often plagued by poor spatial resolution, distortion, and artifacts, as well as decreased signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). This is a major obstacle to the application, interpretation, and ultimate impact of prostate MRI. Improving the quality of DWI images would be helpful in lesion orientation and detection of small cancers.Recently, a novel denoising technique, that operating on repetitively acquired MRI data and only removing components that cannot be distinguished from zero-mean Gaussian distributed noise, has been proposed for acquisition of ultra-high resolution images. Recent studies have shown that ultra-high resolution images significantly improvements in temporal-SNR, the detection and reproducibility of stimulus-induced signal changes, and the accuracy of images. Based on reconstruction algorithms with trainable components, high resolution DWI (hrDWI) can increase the SNR and CNR, yielding high-fidelity images with less noise in general, and thus to improve the diagnostic accuracy of PCa in particular than conventional DWI (cDWI).Therefore, we made the hypothesis that hrDWI might be an alternative to cDWI for the prostate imaging. The purpose of this study includes two aspects: 1) compare objective and subjective image quality and lesion conspicuity of hrDWI with cDWI in prostate MRI; 2) test the non-inferiority of hrDWI in terms of PCa diagnosis against cDWI in a cohort of suspcious patients.

Inclusion criteria

• Patients who underwent standard MR scanning including T2WI, cDWI , hrDWI and respective calculated apparent diffusion coefficient (ADC) maps;
• Complete clinical information.

Exclusion criteria

Men were excluded if they were using 5-alpha-reductase inhibitors at time of examination or has used such during the previous six months; or if they had a previous history of prostatic biopsy, prostatic surgery, or treatment for PCa