[Pharmacokinetic MRI of the prostate: parameters for differentiating low-grade and high-grade prostate cancer].

PURPOSE

To investigate whether pharmacokinetic MRI parameters "perfusion, blood volume, mean transit time (MTT), interstitial volume, permeability, extraction coefficient, delay, and dispersion" allow the differentiation of low-grade (Gleason score < or = 6) and high-grade (Gleason score > or = 7) prostate cancer.

MATERIALS AND METHOD

Forty-two patients with prostate cancer verified by biopsy (PSA 2.7 to 31.4 ng/ml) and scheduled for prostatectomy underwent MRI at 1.5 Tesla using the dynamic contrast-enhanced inversion-prepared dual-contrast gradient echo sequence (temporal resolution, 1.65 s) and a combined endorectal body phased array coil. Parametric maps were computed using a sequential 3-compartment model and the corresponding post-processing algorithms. A total of 41 areas of prostate cancer (15 low-grade, 26 high-grade cancers) in 32 patients were able to be correlated with the prostatectomy specimens and were included in the analysis.

RESULTS

Low-grade prostate cancers had a higher mean blood volume (1.76 % vs. 1.64 %, p = 0.039), longer MTT (6.39 s vs. 3.25 s, p < 0.001), and lower mean permeability (2.57 min (-1) vs. 3.86 min (-1), p = 0.011) than high-grade cancers. No statistically significant difference was found for perfusion (p = 0.069), interstitial volume (p = 0.849), extraction coefficient (p = 0.615), delay (p = 0.489), and dispersion (p = 0.306).

CONCLUSIONS

Blood volume, MTT, and permeability allow the differentiation of low-grade and high-grade prostate cancer. They may be used to detect cancer progression by MRI in patients managed by active surveillance.