Diffusion in prostate cancer detection on a 3T scanner: How many b-values are needed?

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Diffusion-weighted imaging (DWI) is crucial for prostate cancer detection.
• Apparent diffusion coefficient (ADC) maps are key metrics in DWI analysis.
• Understanding the impact of perfusion and b-values on ADC accuracy is essential for improving diagnostic performance.

Purpose of the Study:

• To evaluate how perfusion influences ADC maps in prostate cancer detection.
• To determine the optimal number and contribution of b-value images for DWI in prostate cancer diagnosis.
• To assess the efficacy of different ADC calculation methods and b-values.

Main Methods:

• 3T MRI with DWI using b-values of 0, 500, 1000, and 1500 s/mm² was performed on patients scheduled for prostatectomy.
• Monoexponential models were used to calculate ADC, with and without the b0 (perfusion-sensitive) component, and using two b-values.
• Histology-based segmentation defined tumoral and normal prostatic voxels, and areas under the receiver operating characteristic curves (AUC) were calculated.

Main Results:

• Perfusion-sensitive ADC maps (including b0) and ADC maps using b1500 showed improved performance in detecting prostate cancer compared to perfusion-insensitive maps.
• Models combining ADC with the b1500 image parameter significantly enhanced diagnostic performance (AUCs of 0.884 and 0.883).
• Using more than two b-values did not yield further improvements in AUC.

Conclusions:

• Incorporating the b0 value in ADC calculations generates superior ADC maps for prostate cancer detection.
• The b1500 image parameter, when combined with ADC, also enhances diagnostic performance.
• The study suggests that using more than two b-values offers no additional benefit for prostate cancer detection via DWI.