Prostate and seminal vesicles after irradiation: MR appearance

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Interpreting follow-up magnetic resonance (MR) studies requires understanding post-pelvic irradiation morphologic changes in the prostate and seminal vesicles (SV).
• Radiation therapy can induce significant alterations in pelvic organs, potentially mimicking other pathologies.

Purpose of the Study:

• To characterize the spectrum of morphologic and signal intensity (SI) changes in the prostate and SV following pelvic irradiation.
• To establish the significance of these changes for differential diagnosis in irradiated patients.

Main Methods:

• Retrospective analysis of MR studies from 38 patients treated with pelvic radiation for prostatic or other pelvic tumors.
• Comparison of SI and morphologic features with 10 control patients.
• Evaluation of the impact of additional treatment modalities.

Main Results:

• Abnormal prostatic zonal patterns and signal intensities were observed in a significant proportion of irradiated patients.
• Seminal vesicles showed varied changes, including reduced tubules and diffuse signal loss.
• Irradiated patients exhibited statistically significant lower mean SI in the prostate and SV compared to controls.
• Prostate and SV size reduction occurred in 33% of patients with baseline studies.
• Additional treatments correlated with increased likelihood of abnormal changes.

Conclusions:

• The prostate and SV can exhibit diverse signal intensity abnormalities after irradiation.
• Diffuse low signal intensity in the prostate and SV post-radiation is a key indicator for considering radiation fibrosis in differential diagnoses.