# Acquisition, image quality, and PI-RADS agreement of ultrahigh-gradient DWI in prostate 3-T MRI

## TL;DR

Ultrahigh b-value diffusion-weighted MRI for prostate cancer shows worse image quality and no better diagnostic performance than standard methods.

## Contribution

Demonstrates that ultrahigh b-values do not improve prostate cancer detection and may reduce image quality.

## Key findings

- Ultrahigh b-values (2500–4500 s/mm²) showed worse lesion conspicuity and signal-to-noise ratios than standard b-values.
- PI-RADS agreement was good between b1500 and b2500 but only moderate for higher b-values.
- Diagnostic performance for prostate cancer did not improve with ultrahigh b-values.

## Abstract

New magnetic resonance imaging (MRI) gradient technology enables the acquisition of ultrahigh b-value diffusion-weighted imaging (DWI). We assessed its impact on image quality and Prostate Imaging Reporting and Data System (PI-RADS) scores in prostate MRI.

Participants with cancer suspicion prospectively underwent 3-T prostate MRI (maximum gradient strength 200 mT/m). Sequences with b-values of 0/800, 1,500, 2,500, 3,500, and 4,500 s/mm² were acquired. Lesion conspicuity was rated from 1 (non-diagnostic) to 5 (excellent). Apparent signal-to-noise ratios (aSNR) and acquisition times were determined. Cumulative link mixed-effects models, repeated measures ANOVA, and Cohen/Fleiss κ statistics were used.

A total of 107 participants, aged 67 ± 8 years (mean ± standard deviation), were included. Compared to DWI(b1500), the DWI(b2500), DWI(b3500), and DWI(b4500) acquisitions were worse regarding both lesion conspicuity (median score, 5 [interquartile interval 4–5] versus 4 [3–4] versus 2 [2–3] versus 2 [1–2], respectively; all p < 0.001) and aSNR (19.0 ± 7.5 versus 12.7 ± 4.8 versus 11.8 ± 4.1 versus 11.4 ± 2.6, respectively; all p < 0.001). Acquisition times increased from DWI(b1500) (107 ± 9 s) to DWI(b4500) (329 ± 26 s). Cohen κ for PI-RADS score agreement was good to moderate (DWI(b2500): 0.87 [confidence interval 0.81, 0.94]; DWI(b3500): 0.75 [0.65, 0.84]; DWI(4500): 0.61 [0.49, 0.72]).

Acquired ultrahigh gradient DWI sequences with ultrahigh b-values in prostate MRI had worse image quality than standard b-values, while PI-RADS agreement between DWI(b1500) and DWI(b2500) was good. However, diagnostic estimates for clinically significant prostate carcinoma remained limited due to a small biopsy sample size (50/107 patients).

Ultrahigh b-value DWI showed no improved diagnostic performance in comparison to standard b-value DWI regarding the identification of potential prostate cancer. Ultrahigh b-value should not replace standard high b-values (1,500 s/mm²) for imaging workup of patients with suspicion for prostate cancer.

Acquired ultrahigh b-values (b2500–4500) using ultrahigh gradients of up to 140 T/m were utilized for prostate DWI.Both, overall image quality and diagnostic confidence decreased from good for DWI(b1500) to non-diagnostic for DWI(b4500).PI-RADS agreement between DWI(b1500) and DWI(b2500) was good, while it was only moderate between DWI(b1500) and DWI(b4500).

Acquired ultrahigh b-values (b2500–4500) using ultrahigh gradients of up to 140 T/m were utilized for prostate DWI.

Both, overall image quality and diagnostic confidence decreased from good for DWI(b1500) to non-diagnostic for DWI(b4500).

PI-RADS agreement between DWI(b1500) and DWI(b2500) was good, while it was only moderate between DWI(b1500) and DWI(b4500).