High-b-value diffusion-weighted MRI for the detection of prostate cancer at 3 T

• Using of a b 1,500 s/mm2 resulted in best SNR and tumor-to-PZ/TZ contrast on the DW images.
• ADCs using b 1,500 s/mm2 had better diagnostic performance.
• 1,500 s/mm2 should be considered more optimal b value for detecting prostate cancer.

AimTo compare tumour visibility on diffusion-weighted (DW) images and the diagnostic performance of the apparent diffusion coefficient (ADC) maps obtained using b-values of 1000, 1500, and 2000 s/mm2.Materials and methodsForty patients with biopsy-proven prostate cancer were retrospectively included in the study. DWI was examined under different pairs of b-values (b = 0, 1000 s/mm2; 0, 1500 s/mm2; and 0, 2000 s/mm2) and apparent diffusion coefficient (ADC) maps were generated with a mono-exponential fitting. The tumour-to-normal tissue [in the peripheral gland and transitional gland, peripheral zone (PZ) and central gland] contrast ratio (CR) and prostate tumour signal-to-noise ratio (SNR) were compared between different b-value DWI images. ADC was measured and areas under the receiver operating characteristic curve (Az) were calculated.ResultsThe CR of the tumour-to-PZ/central gland was significantly higher in the b = 1500 s/mm2 images than in images created using other b-values (both p < 0.01). The tumour SNR was statistically significantly higher in b = 1500 s/mm2 images than in the other b-value images (p < 0.01), and was significantly higher in b = 1000 s/mm2 images than in images created at b = 2000 s/mm2 (p = 0.035). The Az for b = 1500 s/mm2 was significantly higher than the Az for b = 2000 s/mm2 in the PZ (p = 0.016) and central gland (p = 0.037), and higher than the Az for b = 1000 s/mm2, but not reach statistical significance in the PZ (p = 0.16) and in the central gland (p = 0.23).ConclusionAt 3 T MRI, DWI images and ADC maps using b = 1500 s/mm2 should be considered more effective than those at b = 2000 s/mm2 or b = 1000 s/mm2 for detecting prostate cancer.