Diffusion-Weighted Magnetic Resonance Imaging for the Evaluation of Prostate Cancer: Optimal B Value at 3T

Abstract

ObjectiveTo retrospectively determine the optimal b value of diffusion-weighted imaging (DWI) for predicting the presence of localized prostate cancer, and to evaluate the utility of DWI under different b values in differentiating between cancers and benign prostatic tissues.Materials and MethodsEighty patients with suspected prostate cancer underwent MRI including DWI at 3T, followed by radical prostatectomy. DWI was examined under different b values. Apparent diffusion coefficient (ADC) maps were generated by using b = 0, and other b values of 300, 700, 1000 or 2000 s/mm2. For predicting the presence of cancers, four different ADC maps were analyzed independently by two blinded readers. ADCs were measured in benign and malignant tissues.ResultsFor predicting the presence of 110 prostate cancers, the sensitivity and area under the curve (AUC) for an experienced reader was significantly greater at b = 1000 (85% and 0.91) than b = 300, 700 or 2000 s/mm2 (p < 0.01). For a less-experienced reader, the AUC was significantly greater at b = 700, 1000 or 2000 than b = 300 s/mm2 (p < 0.01). Mean ADCs of the cancers in sequence from b = 300 to 2000 s/mm2 were 1.33, 1.03, 0.88 and 0.68 × 10-3 mm2/s, which were significantly lower than those of benign tissues (p < 0.001).ConclusionThe optimal b value for 3T DWI for predicting the presence of prostate cancer may be 1000 s/mm2.

Assessment of early renal allograft dysfunction with blood oxygenation level-dependent MRI and diffusion-weighted imaging

“…Contrarily, the renal medulla may have relatively less susceptibility artifact due to its inner location. On DWI, both cortical and medullary ADC values at ADC 800 were significantly lower than those at ADC 500 : it might be explained by a previous study demonstrated that ADC value decreases as the last b-value increases in other body parts [29]. Nevertheless, in ROC curve analysis of our study, no difference of AUCs between two different MR protocols was found for predicting early renal allograft dysfunction using BOLD MRI and DWI.…”

Implementation of Multi-parametric Prostate MRI in Clinical Practice

“…Rather, diffusion-weighted images must be acquired using at least two different b values, from which a diffusion coefficient can be calculated. The most widely applied coefficient in clinical practice is the apparent diffusion coefficient (ADC) [21]. The ADC map better reflects the diffusivity of water molecules than the directly acquired b value images themselves, which in fact reflect a combination of both diffusion weighting and T2 weighting.…”

Threshold-based parametric analysis of diffusion-weighted magnetic resonance imaging at 3.0 Tesla to identify men with prostate cancer

“…Further evaluation of the constraints associated with this approach is necessary. In the future, automatic color-look-up-tables corresponding to specific ADC values could be developed providing acquisition parameters (field strength, b-values use of specific coils) are standardized [32] . This would aid rapid, objective image review and facilitate rapid identification of malignant lesions by virtue of their ADC values alone or alongside qualitative analysis.…”