IMAGING

Retained Seminal Vesicles after Radical Prostatectomy: Frequency, MRI Characteristics, and Clinical Relevance
Sella T, Schwartz LH, Hricak H
Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
AJR Am J Roentgenol. 2006; 186: 539-46

• Objective: Changes after radical prostatectomy (RP) may present potential pitfalls in the interpretation of pelvic MRI studies in post-RP patients. One such change is retained seminal vesicles (SVs). The purpose of this study was to characterize the MRI features and evaluate the frequency of retained SV remnants in patients after RP.
• Conclusion: Retained SV remnants are a common finding after RP. Most are fibrotic distal tips. Recognition of SV remnants may prevent their misinterpretation as local recurrences.
  
  
• Editorial Comment
  During retropubic prostatectomy, among others surgical modifications, seminal vesicle sparing have been performed in order to prevent injury to vital vascular and neural structures and to obtain a better chance of continence and potency, with minimal risk of residual tumor. Despite improvements in detection of early prostate cancer and in surgical procedures, approximately 25% of patients develop biochemical recurrence after radical prostatectomy (1). The clinicians usually use PSA kinetics in order to differentiate local recurrence from mestastatic disease. Since MR imaging, particularly with endorectal coil, may be used in the evaluation of the postprostatectomy bed, for the detection of recurrent disease, it is of crucial importance to adequately differentiate retained SV remnants from recurrent disease. In this interesting study, the authors’ detected SV remnants in 52 (20%) of 263 of the patients examined, with an additional 99 patients (38%) having findings suggestive of retained fibrotic SV tips. In 22 (8%) of the patients examined, the seminal vesicles were retained at more than half their presurgical size. The appearance of SV remnants may persist for years after surgery. SV remnants showing low signal intensity on T2-weighted images ranged from intermediate to low signal intensity, compared with the signal intensity of water. The decreased signal intensity is assumed to be related to differing degrees of fibrosis. Fibrotic, SV remnants and retained fibrotic SV tips were found most commonly in the superolateral aspects of the prostatectomy fossa. The authors also pointed out that, although, retained SVs do not secrete PSA, they tend to pull down along the lateral aspects of the rectum and then may be palpated on digital rectal examination as small firm nodules and may be mistaken for a local recurrence. Another point to be considered is that local recurrence may occur within retained SVs.

Reference
1. Carroll P: Rising PSA after a radical treatment. Eur Urol. 2001; 40 (Suppl 2): 9-16.

Dr. Adilson Prando
Chief, Department of Radiology
Vera Cruz Hospital
Campinas, São Paulo, Brazil