Magnetic resonance picture of changes in the prostate gland in patients with localized prostate cancer after radical external beam radiotherapy

Abstract

Introduction. Magnetic resonance imaging (MRI) is a highly informative imaging technique, but now days is not recommended for detecting prostate cancer revealing after external beam radiation therapy (EBRT) at localized prostate cancer.Purpose of the study. To study the magnetic resonance imaging of changes in the prostate gland in patients with localized prostate cancer after radical EBRT. Materials and methods. Studied and compared the data of clinical and histological studies of a series of MRI in nine patients with prostate cancer before and after EBRT. Standard sequences (T2-weighted images, diffusion-weighted images, dynamic con trast enhancement) were used for MRI. Results. After irradiation, in a delayed period, atrophy and fibrotic changes occur in the structure of the prostate gland, which leads to a decrease in its size, uneven contours, and the impossibility of differentiating the zonal anatomy on T2-VI. After RT, the intensity of the MR signal from the tumor on DWI with a high b-factor decreases, the difference in the ADC of the peripheral, transient zones and the tumor is practically leveled. After RT, the hypervascularity of the tumor progressively decreases, there fore, in the delayed period, in most cases, type 3 of the contrast curve is observed in DCE. In general, MRI gives results consistent with the dynamics of serum PSA levels. However, one patient after EBRT showed signs of local progression on MRI without signs of biochemical progression.Conclusion. MRI can be used as a method for early diagnosis of local recurrence of prostate cancer after EBRT, however, its clinical significance requires further study.